CA2087809C - Fluid line condition detection - Google Patents
Fluid line condition detectionInfo
- Publication number
- CA2087809C CA2087809C CA002087809A CA2087809A CA2087809C CA 2087809 C CA2087809 C CA 2087809C CA 002087809 A CA002087809 A CA 002087809A CA 2087809 A CA2087809 A CA 2087809A CA 2087809 C CA2087809 C CA 2087809C
- Authority
- CA
- Canada
- Prior art keywords
- fluid
- signal
- head pressure
- pressure
- segment
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests
- A61M5/14—Infusion devices, e.g. infusing by gravity; Blood infusion; Accessories therefor
- A61M5/168—Means for controlling media flow to the body or for metering media to the body, e.g. drip meters, counters ; Monitoring media flow to the body
- A61M5/16831—Monitoring, detecting, signalling or eliminating infusion flow anomalies
- A61M5/16854—Monitoring, detecting, signalling or eliminating infusion flow anomalies by monitoring line pressure
- A61M5/16859—Evaluation of pressure response, e.g. to an applied pulse
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests
- A61M5/14—Infusion devices, e.g. infusing by gravity; Blood infusion; Accessories therefor
- A61M5/168—Means for controlling media flow to the body or for metering media to the body, e.g. drip meters, counters ; Monitoring media flow to the body
- A61M5/16831—Monitoring, detecting, signalling or eliminating infusion flow anomalies
- A61M5/1684—Monitoring, detecting, signalling or eliminating infusion flow anomalies by detecting the amount of infusate remaining, e.g. signalling end of infusion
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S128/00—Surgery
- Y10S128/13—Infusion monitoring
Abstract
A compliant chamber is formed in a fluid line which connects a fluid supply to a fluid receiver. The compliant chamber is alternately in fluid communication with the upstream and downstream segments of the fluid line. When the chamber communicates with the upstream segment it receives and stores fluid at the head pressure. When the segment communicates with the downstream segment, a pressure equalization pulse occurs. A pressure sensor in the downstream segment measures the pressure equalization pulse which is proportional to the head pressure.
Processing the equalization pulse with the downstream fluid system resistance, the compliance of the compliant chamber and the equilibrium pressure results in a determination of the head pressure. Comparing the head pressure to thresholds permits determination of an occlusion or empty fluid supply. Where a peristaltic pump is used, the chamber is formed between the end fingers of the pump.
Processing the equalization pulse with the downstream fluid system resistance, the compliance of the compliant chamber and the equilibrium pressure results in a determination of the head pressure. Comparing the head pressure to thresholds permits determination of an occlusion or empty fluid supply. Where a peristaltic pump is used, the chamber is formed between the end fingers of the pump.
Description
FLUID LINE CONDITION DETECTION
BACKGROUND
The invention relates generally to mnn;lol~ng fluid flow, and more particularly, to det~ting fluid line comlition~ U~ill'ealn of the mo~ o, ;ng positlon.
Fluid delivery systems having ~sili~,e press~e pumps for infusing 5 parenteral fluid to a patient have ~'C4~e fairly ~,---~-on In many cases the pump is a pe~ict~ltie type in which a plur~lity of fingers, rollers, or other devices, se~uenti~11y corl~1T;ct i flexible tube through which the pale.ll~al fluid is supplied. Such fluid delivery systems also in~ de~ in ~ditioll to the pump, an in~elt~ bottle or bag or other means of supply 10 of ~ll~l fluid, an inl,a~u.ls (IV) a~ ralion set which is sec~r~
to the supply of parellte~l fluid and i-~cludes the flexible tube, and a csnn~ which is .~nlcd to the distal end of the tube and which is ~pted to be'inserted into the patient's blood vessel to thereby infuse the ~renl~l fluid.
One commQn problem facing infusion systems is the evalu~tion of the co~itioll of the fluid supply system u~" of the pump. Where an occ.lusion of the tube exists u~lr~,. of the pump, the pump will not suGceed in infusing the pare~llel~l fluid to the patient even though the ", pump may cQntinlle to operate. Where the parenteral fluid supply be~mes depleted, once again the pump may co"~nue to operate but no parenteral fluid will be delivered to the patient.
A prior metho~ for det~ling depletion of the fluid supply or an 5 upstream occlusi~n was visual ol,sel~ation. A drip chamber may be inserted in the fluid line at a position do~llsL,~--I from the fluid supply for mon,toling the rate and 4u&nlily of fluid adminictered. However, visually verifying the eYi~tenoe of drops requires the time of an ~ttçnd~nt which can be an u~-dP-s~.dble burden on the hospi~l staff. Opto-electric 10 drop de,tc~l~-s may be utili7e~ in conjunction with the drip chamber.
These detectors are capable of ~lo~ ;c~llydetecting upstream occlusions due t~ a clamp or Ic~k in the u~tr~l~ ~bing and an empty IV fluid supply c~n~ er by det~ an Pbse~-e of drops. An uyslrcalll occlusion can also be detected by the addition o~ a pres~ e sensor to the fluid line lS u~slr~ of the pump. Ho..~ r, the use of these devices can add a col-ciderable ~1clition~ ~nse. Additionally, movement of the r~lmini~ration set, if severe enou~h, c,an cause extra drops to fall from the drop former or can il~lollu~)l the drops c~ ;n~ false counts and false alarms. ~mkient light can also int~re~e with an optical drop sensor and 20 render it inaecllrate.
In some c,ases it would be usefi~l to ?.,(o~ ;cally provide infol"~alion lelaling to ~e l.~s~ule of the supply fluid or the "head"
l)ressllre. From the head pressure, an up~ un occlusion can be detected as well as an empty fluid supply.
.. _ Pump systems have been disclosed which include a dow~ am l~ressurc sensor used for detecting i",~ro~r fluid co-".~ n;c~tion with the patient. Such systems include U.S. Patent 4,743,228 to Bu~te~eld; U.S.
Patent 4,460,355 to ~yman; U.S. Patent 4,534,756 to Nelson; and U.S.
S Patent 4,846,792 to Bobo, Jr. et al. Where such systems use a pump or other fluid pressule control means which co.~ ;c~tes the head l)rcssu,e to the outlet side of the pump, it would be of value to utilize the existing do~"stleal-, prcs~ure sensor to determine uyslream fluid conditions. This would result in less expense both in the pump and in the ~dministration 10 sets.
Hence, those skilled in the art have r~ogn~ed the need for a fluid line rn. ~-;lo- ;n~ system-which can ~J(Q ~ lly detect u~ll~" fluid line oc~lusion~ as well as measure the hcad pressule. Additionally, those sl~lled in the art have reco~i7ed a need to reduce the cost of detern~ining 15 such upstream fluid line conditions. The ~resenl invention fulfills these needs.
.~,, SUMMARY OF THE INVENTION
According to the invention, there is provided a fluid line condition detection apparatus for use with a fluid delivery system which includes a fluid line having an upstream segment coupled to a fluid supply and a downstream segment coupled to a fluid receiver, the apparatus comprising: a fluid chamber disposed in fluid communication with the upstream segment and with the downstream segment of the fluid line; control means for alternately opening the fluid chamber to fluid communication with the upstream segment of the fluid line and with the down-stream segment of the fluid line, wherein when opened to the upstream segment, the chamber receives and stores fluid at head pressure and wherein when opened to the downstream segment, the chamber communicates the fluid stored at head pressure to fluid residing in the downstream segment thereby causing a pressure equalization pulse in the downstream segment; pressure sensor means for sensing the pressure equalization pulse and for providing an equalization signal representative of the pressure equalization pulse; and processor means responsive to said equalization signal for determining the head pressure.
The invention also provides a fluid line condition detection apparatus for use with a fluid delivery system which includes a fluid line having an upstream segment coupled to a fluid supply and a downstream segment coupled to the vascular system of a patient, and a flexible segment coupled to both the upstream and downstream segments, the apparatus comprising:
a fluid chamber disposed in fluid communication with the C
~n~ os upstream segment and with the downstream segment of the fluid line; control means for operating on a flexible segment of the fluid line to control the pressure of the fluid in the fluid line and for alternately opening the fluid chamber to fluid communication with the upstream segment of the fluid line and with the downstream segment of the fluid line, wherein when opened to the upstream segment, the chamber receives and stores fluid at head pressure and wherein when opened to the down-stream segment, the chamber communicates the fluid stored at head pressure to fluid residing in the downstream segment thereby causing a pressure equalization pulse in the downstream segment; pressure sensor means for sensing the pressure equalization pulse and for providing an equalization signal representative of the pressure equalization pulse and for sensing equilibrium pressure in the downstream segment and for providing an equilibrium signal representative thereof;
resistance means for providing a resistance signal representa-tive of the resistance to fluid flow downstream of the fluid chamber; processor means for taking the difference between the equilibrium signal and the equalization signal, integrating said difference and scaling the integrated difference by the resistance signal in determining the head pressure, said processor means also for providing a head pressure signal representative of the determined head pressure; and an alarm generator which receives the head pressure signal, compares the received signal to a first threshold and if the head pressure signal is less than the first threshold, provides an 8 ~ 9 occlusion alarm signal.
The invention further provides a fluid line condition detection apparatus coupled between a fluid supply and a fluid receiver, the apparatus comprising: a fluid line having an upstream segment coupled to the fluid supply for receiving fluid from the fluid supply at head pressure and a downstream segment coupled to the fluid receiver; a fluid chamber disposed in fluid communication with the upstream segment and with the downstream segment of the fluid line; control means for alternately opening the fluid chamber to fluid communication with the upstream segment of the fluid line and with the downstream segment of the fluid line, wherein when opened to the upstream segment, the chamber receives and stores fluid at head pressure and wherein when opened to the downstream segment, the chamber communicates the fluid stored at head pressure to fluid residing in the downstream segment thereby causing a pressure equalization pulse in the downstream segment; pressure sensor means for sensing equilibrium pressure in the downstream segment and for providing an equilibrium signal representative thereof and for also sensing the pressure equalization pulse and for providing an equalization signal representative of the pressure equalization pulse; and processor means responsive to said equilibrium signal and to said equalization signal for taking the difference between the equilibrium signal and the equalization signal and for integrating the difference in determining the head pressure.
The invention additionally provides a fluid line -5a-C
~78 ~
,.
condition detection apparatus coupled between a fluid supply and the vascular system of a patient, the apparatus comprising:
a fluid line having an upstream segment coupled to the fluid supply for receiving fluid from the fluid supply at head pressure and a downstream segment coupled to the vascular system of the patient; a fluid chamber comprising a flexible segment of the fluid line disposed between and in fluid communication with the upstream segment and with the downstream segment of the fluid line; control means for operating on the flexible segment of the fluid chamber to control the pressure of the fluid in the fluid line and for alternately opening the fluid chamber to fluid communication with the upstream segment of the fluid line and with the downstream segment of the fluid line, wherein when opéned to the upstream segment, the chamber receives and stores fluid at head pressure and wherein when opened to the downstream segment, the chamber communicates the fluid stored at head pressure to fluid residing in the down-stream segment thereby causing a pressure equalization pulse in the downstream segment; pressure sensor means for sensing the pressure equalization pulse and for providing an equaliza-tion signal representative of the pressure equalization pulse and for sensing equilibrium pressure in the downstream segment and for providing an equilibrium signal representative thereof;
resistance means for providing a resistance signal representa-tive of the resistance to fluid flow downstream of the fluid chamber; processor means for taking the difference between the equilibrium signal and the equalization signal, integrating -5b-~a~7~
said difference and scaling the integrated difference by the resistance signal in determining the head pressure, said processor means also for providing a head pressure signal representative of the determined head pressure; and an alarm generator which receives the head pressure signal, compares the received signal to a first threshold and if the head pressure signal is less than the first threshold, provides an occlusion alarm signal.
The invention still further describes a fluid line condition detection apparatus coupled between a fluid supply and the vascular system of a patient, the apparatus comprising a fluid line having an upstream segment coupled to the fluid supply receiving fluid from the fluid supply at head pressure and a downstream segment coupled to the vascular system of the patient; a fluid chamber in the form of a flexible segment coupled to fluid communication with the upstream and downstream segments; fluid pressure control means operating on the flexible segment of the fluid line to control the pressure of the fluid in the fluid line and alternately opening the fluid chamber to fluid communication with the upstream segment of the fluid line and with the downstream segment of the fluid line, wherein when opened to the upstream segment, the chamber receives and stores fluid at head pressure and wherein when opened to the down-stream segment, the chamber communicates the fluid stored at head pressure to fluid residing in the downstream segment thereby causing a pressure equalization pulse in the downstream segment; pressure sensor means sensing the pressure -5c-2~8~8 ~9 equalization pulse and providing an equalization signal representative of the pressure equalization pulse and sensing equilibrium pressure in the downstream segment and providing an equilibrium signal representative thereof; resistance means providing a resistance signal representative of the resistance to fluid flow downstream of the fluid chamber; processor means, and an alarm generator, the apparatus being characterized by:
said flexible segment having a predetermined effective compliance; said processor means taking the difference between the equilibrium signal and the equalization signal, integrating said difference with respect to time and multiplying the integrated difference by the reciprocal of the product of the resistance signal and the compliance, whereby the head pressure is achieved by adding the equilibrium pressure to the above-mentioned product, said processor means also providing a head pressure signal representative of the determined head pressure; and said alarm generator receiving the head pressure signal, comparing the received signal to a first threshold, and if the head pressure signal is less than the first threshold, providing an occlusion alarm signal.
From another aspect, the invention provides a method for detecting the condition of a fluid delivery system which includes a fluid line having an upstream segment coupled to a fluid supply and a downstream segment coupled to a fluid receiver, the delivery system having a fluid pressure control means for operating on a flexible segment of the fluid line to control the pressure of the fluid in the fluid line, the fluid -5d-2Q8~8 ~9 .
upstream of the fluid pressure control means being at head pressure, the method comprising the steps of: storing fluid at the head pressure in a fluid chamber disposed in fluid communication with the upstream segment and with the downstream segment of the fluid line; alternately opening the fluid chamber to fluid communication with the upstream segment of the fluid line and with the downstream segment of the fluid line, wherein when opened to the upstream segment, the chamber receives and stores fluid at head pressure and wherein when opened to the downstream segment, the chamber communicates the fluid stored at head pressure to fluid residing in the down-stream segment thereby causing a pressure equalization pulse in the downstream segment; sensing the pressure equalization pulse and providing an equalization signal representative of the pressure equalization pulse; and processing the equaliza-tion signal to determine the head pressure.
The invention also provides a method for detecting the condition of a fluid delivery system which includes a fluid line having an upstream segment coupled to a fluid supply and a downstream segment coupled to a fluid receiver, the delivery system having a fluid pressure control means for operating on a flexible segment of the fluid line to control the pressure of the fluid in the fluid line, the fluid upstream of the fluid pressure control means being at head pressure, the method comprising the steps of: storing fluid at the head pressure in a fluid chamber disposed in fluid communication with the upstream segment and with the downstream -5e-2~78 Q9 segment of the fluid line; alternately opening the fluid chamber to fluid communication with the upstream segment of the fluid line and with the downstream segment of the fluid line, wherein when opened to the upstream segment, the chamber receives and stores fluid at head pressure and wherein when opened to the downstream segment, the chamber communicates the fluid stored at head pressure to fluid residing in the downstream segment thereby causing a pressure equalization pulse in the downstream segment; sensing the equilibrium pressure in the downstream segment and providing an equilibrium signal representative thereof and also sensing the pressure equalization pulse and providing an equalization signal representative of the pressure equalization pulse; and processing the equalization signal to determine the head pressure including the steps of taking the difference between the equilibrium signal and the equalization signal and integrating the difference in determining the head pressure.
The invention further provides a method for detecting the condition of a fluid delivery system, utilizing the apparatus defined above, the fluid upstream of the fluid pressure control means being at head pressure, the method being characterized by the steps of: storing fluid at the head pressure in a fluid chamber disposed in fluid communication with the upstream segment and with the downstream segment of the fluid line; alternately opening the fluid chamber to fluid communication with the upstream segment of the fluid line and with the downstream segment of the fluid line, wherein when r~
2~8~8 ~
opened to the upstream segment, the chamber receives and stores fluid at head pressure and wherein when opened to the downstream segment, the chamber communicates the fluid stored at head pressure to fluid residing in the downstream segment thereby causing a pressure equalization pulse in the downstream segment;
sensing the pressure equalization pulse and providing an equalization signal representative of the pressure equalization pulse; and processing the equalization signal to determine the head pressure, including the steps of taking the difference between the equilibrium pressure and the equalization signal, integrating the difference with respect to time, and adding the equilibrium pressure in determining the head pressure.
Other aspects and advantages of the invention will become apparent from the following detailed description and accompanying drawings, illustrating by way of example, the features of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 iS a block diagram of an apparatus for detect-ing conditions in an upstream fluid line incorporating the principles of the invention as applied to an intravascular fluid infusion system;
FIGS. 2A, 2B and 2C are diagrams of the operation of a linear peristaltic pump on a segment of compliant tubing showing in particular the establishment of a compliant fluid chamber; and FIG. 3 is a block diagram of a signal processing embodiment for determining head pressure in accordance with the invention.
-5g-"~
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to the drawings with more particularity, wherein like reference numerals designate like or corresponding elements among the several views, there is shown in FIG. 1 a system 10 for detecting conditions in a fluid line upstream of a monitoring position. A fluid line, which may be an administration set formed of flexible tubing, is positioned between a fluid supply 12 and a patient 14 and comprises an upstream segment 16, a downstream segment 18 and a pumping segment 44 (shown in FIGS. 2A, 2B and 2C). In this case, the fluid supply -5h-~ 20878~9 comprises an ill~e,l~d bottle. The ~ ri~ segment 44 is operated on by a ~ressu~control means which colnprices in this eull,odinlent, an infusion pump 20 to form a co.~.pli~n~ cl~llber as will be descri~aed in more detail below. A p~es~ule t~n-~ucsr n is coupled to the do~n~(l~ll fluid line S se.~Pnt 18 to sense the pi~s~ule in that se~nPnt 18 and provide a signal re~lesenl~ e of that sensed ~)lCS~ule. An analog-to4igital co-l~eller 24 is coupled to the plessule tr~ns~ucer 22 to provide a digital signal to a signal l,~ocessor 26 shown in this case as a micro~loc~sor which is part of the pump ~sembly apparatus.
In FIG. 1, the ~I~Jsll~ fluid line se~Tnent 16 is co~ e~ to the supply bottle 12 through a drip cl~ll~cr 28 in ~is e~ enl The u~llcalu se,,~ent 16 su~li~s fluid to the infusion pump 20 which in the e "1~.".P~.1 of FIGS. 1 and 2 is a linear peri~t~ltie pump. The p~es~,ln of the fluid at the pump inlet 54 will be the "head" lJleS~ u'e. A motor 30 15 and control el~nics 32 are used to drive the peristaltic fingers of the linear perist~ltiG pump 20. The pump system in this e~ .nt further comp~i.ccs the ulicr~foeess~r 26, a memory 34, an alan~i 36, an ope~tor control panel 38 and a &splay 40. The display unit 40 may co~.~pl.-ce a nlonil~r or s~ chart recorder for displaying ~e head lns~--n as 20 det~ll~il~ed by the lli~cr~r~cessor 26. Mounted at the distal end of the do~.ns~ll fluid line s~-~e~l 18 is a c~nn~ 42 used to CQ~ e~l the dvwl~ll fluid line se.~nert 18 to the ~r~ccul~r system of the padent 14.
The pump 20 supplies the y~e,lt~l fluid to the patient 14 at a sele~
rate and pl~es~fe which may be different from ~e head pns~-ln.
20g7gos In some prior systems, the output signal from the ~lessule tr~n~ducer 22 is processe~ to detect the e~isten~ce of a do~ r~n occlusion, infiltration or other condition. Some of these systems are mentioned in the ~r~cAi-~g Bac~lou~d section. Thus, a l,res~.lre S tr~n~ducer 22 which will supply a press.lre signal is already installed in some pump systems.
A typical linear peristaltic pump operates by se~uenti~lly pressing on a segment of flexible tubing by means of cam-following fingers. The pressuie is applied in se~ eY~ locations of the tubing, I,c,~ ing at the 10 inlet end of the pump and ~ ing toward the outlet end. At least one finger is always l)ressing hard enough to occlude the tubing. As a practical matter, one finger does not retract from occluding the tubing until the next one has already oc~luded the tubing; thus, at no time is there a direct fluid path from the inlet to the outlet of the pump.
R~f~lulg now to FIGS. 2A and 2B, the operadon of a linear peristaltic pump 20 in fo~ a head ~es~ e co~ )liA.n chal.l~cr is shown. The per~ tic pump fingers intlic~t~ c~ ly by n.ln~e~
create a IllO~U~g zone of oc~lus;o~ l the length of a ~ p:ng seglllcnl 44. In FIG. 2A, the most do~ stlea,l- part of the ~ p;ng 20 seg~ n~ or pump outlet 56 is oc~l~,de~ by ~.ri~Pltic finger 48 while the most u~r~n peristaltic finger 50 has not yet ocr1~,d~ the ~ p;~g segment 44 at the pump inlet 54. Thus, fluid at head ~ess.l~ is flowing into the ~n~p;~-e segment 44 from the u~lr~n s~-~-cul 16 but is evelllcd from co~ ;cating with the fluid in the do~llsll~ll segment '- 2~(~7~9 18 by the occlusion caused by the most do~sllea"l peristaltic finger 48.
Therefore, the ~J~pi~g segl-,enl 44iS now at head ~essurc.
In FIG. 2B, form~tiQrl of the c~ pliAI~l chdnll cr 44iS shown. As ~iscucse~ above, a second finger occlndes before an occluding first finger S retracts ~ereby preve.~ g a direct fluid flow lJcl~. een the supply and the patient. In this case, the u~l.e~ finger SO occludes before the downslre~lfmger48 retracts and there exists a point in time when both fingers 48 and SO occlude as is shown in FIG. 2b thereby forrning the co,.,pli~nt chamber 44 which t*aps fluid at he~d ~res~ e.
In FIG. 2C, the most UySl~ peristaltic finger SO continues to occlude the yu-..p;.~ se.~ne-nt 44 prior to the most downstre~m finger48 retracting from an o.~ ;n~ I-os;tion- The fluid at head ples~.lre which was trapped in the c~ iA.~ cl~ l e r 44iS now free to co.. ~.Jn;~ e with the fluid in the downstre~m fluid line-scE;",enl 18. ThUS, the c)n.~ nt lS cha---~r 44 iS allc~ ely in fluid co-----~ -;c~tio~ with the upsll'eam segment 16 and the do...lsl~~ca-,- se~nent 18 of the fluid line.
When the most d~....s~n, peristaltic finger 48 retracts thereby allowing fluid c~ c~tion with the co..~ challll,cr 44, the most peristaltic finger S0 has already ocrl~ ed the fluid line, thus a 20 bolus of fluid at head p.;essur~, the bolus being the ,lu~~ stored in the co..-p!i~n( ch~ ~r 44, is released into the du~ segment 18 of the fluid line. Upon its release, the pr~ss.lle in the co...pli~ cl~,ll~r 44 and the pres~ule in the d~."sl,~l- fluid line se~nent 18 will e(lu~li7e. A
measurable press.lre e~li7~tio~ pulse is prod~lced which will be sensed 25 by the pressure lr~.sJ~,cer 22. This pulse is ~rû~ lional to the difference ~ 20~78~9 g between the head and the do~n~ )res~ es, and may be processed to dctell,.in~ the head ~ress~e in accoLdance with the invention.
The flexible material foll,~g the comrli~nt cha-llber 44 has some co.~ ce (Cp"~p) which is taken into n~nt in one embo~im~ when S det~l,-ining head ~ressurc. It has been found that the com~ nre is for all practical ~ll)oses a l)rop~lly of the tubing bec~use IV fluids are virtually incolnl)ressible. When the pres~.-re is changed &om P, to P2, a quantity of fluid ~Q~ will flow but the quandty is dependent on the tubing comrli~nce as follows:
Q=C~ p(Pz~Pl) eq. 1 If P2 is greater than Pl, flow will occur in a rol~ard direcdon and if Pl is greater than P2, flow will occur in a bacLw~r~ direcdon. As used 15 herein, ~col.~ e~ refers to a measure of el~stietty of the l,.atel;al Çol.. ing the co~ liA.n cha--ll~r. It is given here as a co~ n~
The ~luan~ of fluid Q which will flow is also affected by the re-si~t~nee R of the fluid system in acco-~ance with the following:
Q= Rro(P(t)~P~
eq. 2 20~7809 -1~
where: R is the total resistance to fluid flow;
P(t) is dynamic lnes~ure; and Poq is equilibrium pressulc Sub~ ing P~ for P2 and PO9 for P, in equation 1 and colllS~ g S equations 1 and 2 yields:
~ 'g RC~ro ~*
eq. 3 where: P~ d is *e head ylcs~ule; and Cp""p is the errcclive colnrli~nce of the co,.pli~ ch~mbçr As shown in e~ti~n 3 above, e~uilihrillm presslre PO9 and reSic~nee R are also collc;dered when ~et~ n;n~ the head ~lcs~urc.
lS ~lthou~h ~ete ~ utiQIl of e~ libri~ ressure may be based upon a mea~we."elll of press.~re in the system before ~,lu-b&tion of the fluid flow by the bolus of fluid at head ~r~,s~iie, e~ilihrium plcssure is preferably averaged over a ~lullllxr of ~ress.,re re~ ngs both before and after the ~Cl~rement of the ples~wre response to the bolus. It is not 20 ~e~cssAry that the e~l-ilibrillm state be a state of zero flow. The equilibnum pressure is rather a dynamic one, which is mo~ or~ and dete, ~ 41 periodic~lly. It is only n~ess~ry for the fluid system to be in ~878 ~
~quilibrium prior to release of the head pressure bolus, and the pressure response can be integrated until it again returns to equilibrium. The baseline or equilibrium pressure Pe~ is thus average pressure (including that due to flow) in the equilibrium state.
The total fluid flow resistance R is preferably determined by the means disclosed in U. S. Patent 5,087,245 to Doan, or by the technique disclosed in U. S. Patent 4,743,228 to Butterfield.
The accuracy of this method of determining head pressure depends on the stability of the compliance of the pump-ing segment 44 from set to set and over time. For use as an occlusion detector, however, great accuracy is not important.
If the line is occluded, the pump will produce a large negative pressure; i. e., less than atmospheric very quickly. This results in a large negative equalization pulse at the pressure transducer 22 which is readily identifiable. However, for use as an empty supply detector, a greater degree of accuracy is needed. The supply would be assumed to be empty if the fluid head pressure fell below a specified minimum pressure threshold, or if the head pressure began to change rapidly as it would if the level of the supply fluid were down in the narrow part of the drip chamber, or in the tubing itself.
Further associated with the microprocessor 26 and operator control 28 is an alarm generator 36 responsive to cGmparisons of the head pressure with one or more reference values or thresholds which are stored in the system memory 34.
Reference values may also be input into the memory 34 at the cperatGr control 38 or may be preprogrammed.
n ?
~ 66239-1772 2~87809 .. ..
Referring now to FIG. 3, a processin~ system 57 in accordance with the principles of the invention for dete ...;~ head pressure is shown. It is preferable to use as the e~ilihnllm pres~ure Pq the average of dete~ ;n~lions of ples~ule before and after the release of the head S pres~ule bolus by the comrli~nt chamber 44. This provides con~iderable immuni1y from artifacts such as l,ressurc changes due to patient motion.
It should be noted that re.pe~t~d s~mrlin~ of downstream l)ressure is inten~e~ to be timed so that samples can be equally spaced in time, at intervals of 0.005 seconds for eY~mrle.
The eqnilibriunl pleS;~Ure 58 is dete~ .~ as desr,ribed above. A
series of dynamic prcs~ule ~mrlin~s are taken, to be co.~ rcd with the e~Jilibrium pres;,ulc 58 as P(t) - POq in the cQ~ t~r 60. An int~ ~r 62 for c~ lJl~tin~ the &fference over time is ~ l~rted to ge.le,~te a signal re~ese~ the integTal. This integral signal is recei~cd and scaled in the 15 scaler section 64 accoldillg to the fluid flow resi~t~nce 66 in the infusion system and the cQlnrli~nce 68 of the n~te~ial fonnin~ the co..~pliA.~
chamber 44. Resi~t~nce 66 in the infusion system may change over time and the reCict~nce det~ ;n~tion may be ~lp~Ated, The comrli~nce 68 is preferably stored in Ille.llGly at 34 to be ~~,cess:~ to the scaler 64.
Sc~li~ 64 by the fluid flow res;ct~nce 66 and the c~ pli~nce 68 of the con~pli~nt c~ ~r 44 results in a value which may be l~fe,l~d to as the differential l)res~ e (Ptj~. to which the e~uilibrium ~es~-re is added in the adder 70 to det~---ine head pres~ure. The value of the he~d pressure is com~red in com~-ator 72 to a first threshold reference value 74 to det~ .ine whether the fluid source ~res~ule has fallen below a 2~087~09 , ...
specified ~--ini-~ and thereby indicating an empty fluid supply. The head ylessule value is com~red in com~rator 72 to a second l}lr~l.old reference value 76 to determine if the head ~iessure is so low as to in-lic~te that an u~lr~-- occlusion exists.
S The co~ ~ ator 72 may also be yr~glA.... ne~1 to monitor the change . een measurements of head yress~lre and if the head pressure were to begin to change rapidly, such change may be taken to indicate that the fluid level is down in the neck of the supply bottle or the nalro~v yart of the drip chamber or in the t~ubing itself in the case where the supply has 10 a greater cross-sectional area than the tubing. Therefore, the dif~r~ce . ccess;~e P~ d pres~.~.es is coll,~r~ to a third threshold 78 to ~etçrmine if such a ~fh~;~;OI- exists. M~n;lQ.;~ the flow rate 79 to consider its effecton head pres~ure change can be used in dete.nlil~ing the e~istence of an empty fluid supply co~-t~iner. For e-~...ple, if the flow 15 rate re~ sin~ steady while the change in head ~,ess.lre increased, an empty fluid supply cont~iner could be indicated.
In an allell~Lve em~odilllenl, the do~lslr~lll pressure meas.~remc"ls may be provided to the comparator 72 along line 82 and directly coln~r~ in the comp~rator Z2 with a fourth threshold 80 for 20 dete----;--;ne a gross ~,~iance u~ith a predeten,ined n~in;-..u~ to also detect an u~lream occlusion of the fluid line.
r-o~ tor 72 is ~ rtGd to generate an alarm signal 82 when the press.lle values fall below the ll~eshold values or the change in press.lre exceeds a thresllold.
'- 20878~9 -1~
The alarm signal 82 is received by an alarm generator 86 for generating an audio and/or visual or other type of alarm signal. Different alarm signals from the con,~tor 72 may result in different alarms. Por ~ example, an occlusion alarm may be a conli"~ous eone while a low head S pressure alarm may be a repcAtil~g tone. The display 40 displays ehe head yressuie and the alarms as desired and may display oeher system il~fol",ation. Additionally, the microprocessor 26 may stop pump operation automatically upon i~su~nce of an alarm signal by the alarm generator.
10Oeher implement~tion~ of ehe integrator may include the use of electronic analog integration, hydraulic i.~legl~.tion, or "l~lunic~l inl~lalion. Other ~ ~s which can evaluate the integral of a pressule wave can be used to imple~"enl this tçchnique. Addidonally, other types of pumps may also be used if the pump acco",."odates a compli~nt 15 chanl~r capable of storing fluid at one of the pres~,u~es and ~l,s~ue-ntly co~necting the chA...ber to the pordon of the fluid line at the other ~rcssure.
Re~l"llg again to FIG. 1, an ~.-,bodi,-,ent is shown in which a float valve 88 is included with the drip chamber so that when the level of 20 fluid in the drip chamber drops below a ~ ;---v-~l level, the float valve 88 will occlude the ups~", line 16. Colltinue~l operation of the pump 20 will produce the large negati~le ~iessure in the co...pli~nt challll~r 44 as mçntiorled above and the large llegali~e e~u~li7~ion pulse. Thus, the empty supply condition will be signalled through the occlusion alarm.
25 Other similar mech~ni~ms which will not pass air, such as hydrophilic filter, may also be utilized in forcing an occlusion situation when the fluid source becomes empty.
In view of the for~oil~g, it can be ap~rcciated that the apparatus and method for detecting Up~ l co~ition~ in the i~ àvenous fluid line S in an intravascular fluid adminictration system provide such detection without the necessity of modifying an existing peristaltic pump merh~nisrn. In the case where a downstream pressure transducer has already been installed, the signal processing can be modified in accordance with the invention to provide such upstream condition detection. The 10 apparatus and method for ~ete~ting conditions in an intravenous fluid line in an intravascular fluid ~dmini~tration system provide a simple, low cost way of monilo~ing u~ occluc~on will~oul the t~&ce,s~ y of mctlifi~tion of existing peristaltic pump me~h~nicmc. Placed in a do~r,s~ " configuration, the system of the invention can be readily 15 adapted to monitor upsll~" occlusio~ in eyicting peristaltic pump IV
infusion systems.
Additior~lly, where the height 90 of the fluid supply above the c4,..pli~nt chamber is known as well as the inner diameter 90 of the u~~ tubing and the cross-sectional area 90 of the fluid supply 20 col-t~iner~ the ~m~lnt of fluid rem~inin~ in the fluid supply could be determine~ from head pressure. Where the flow rate 79 through the pump of the fluid in the tubing is known, the amount of time rem~inin~ before the fluid supply is depleted can also be determined.
Although plefe~led and alternative embodiments of the invention 25 have been described and illustrated, it is clear that the invention is -1~
succeptihle to numerous modifications and adaptations within the ability of those skilled in the art and without the exercise of inventive faculty.
Thus, it should be understood that various changes in form, detail and usage of the l)rese"l invention may be made without departing from the S spirit and scope of the invention.
BACKGROUND
The invention relates generally to mnn;lol~ng fluid flow, and more particularly, to det~ting fluid line comlition~ U~ill'ealn of the mo~ o, ;ng positlon.
Fluid delivery systems having ~sili~,e press~e pumps for infusing 5 parenteral fluid to a patient have ~'C4~e fairly ~,---~-on In many cases the pump is a pe~ict~ltie type in which a plur~lity of fingers, rollers, or other devices, se~uenti~11y corl~1T;ct i flexible tube through which the pale.ll~al fluid is supplied. Such fluid delivery systems also in~ de~ in ~ditioll to the pump, an in~elt~ bottle or bag or other means of supply 10 of ~ll~l fluid, an inl,a~u.ls (IV) a~ ralion set which is sec~r~
to the supply of parellte~l fluid and i-~cludes the flexible tube, and a csnn~ which is .~nlcd to the distal end of the tube and which is ~pted to be'inserted into the patient's blood vessel to thereby infuse the ~renl~l fluid.
One commQn problem facing infusion systems is the evalu~tion of the co~itioll of the fluid supply system u~" of the pump. Where an occ.lusion of the tube exists u~lr~,. of the pump, the pump will not suGceed in infusing the pare~llel~l fluid to the patient even though the ", pump may cQntinlle to operate. Where the parenteral fluid supply be~mes depleted, once again the pump may co"~nue to operate but no parenteral fluid will be delivered to the patient.
A prior metho~ for det~ling depletion of the fluid supply or an 5 upstream occlusi~n was visual ol,sel~ation. A drip chamber may be inserted in the fluid line at a position do~llsL,~--I from the fluid supply for mon,toling the rate and 4u&nlily of fluid adminictered. However, visually verifying the eYi~tenoe of drops requires the time of an ~ttçnd~nt which can be an u~-dP-s~.dble burden on the hospi~l staff. Opto-electric 10 drop de,tc~l~-s may be utili7e~ in conjunction with the drip chamber.
These detectors are capable of ~lo~ ;c~llydetecting upstream occlusions due t~ a clamp or Ic~k in the u~tr~l~ ~bing and an empty IV fluid supply c~n~ er by det~ an Pbse~-e of drops. An uyslrcalll occlusion can also be detected by the addition o~ a pres~ e sensor to the fluid line lS u~slr~ of the pump. Ho..~ r, the use of these devices can add a col-ciderable ~1clition~ ~nse. Additionally, movement of the r~lmini~ration set, if severe enou~h, c,an cause extra drops to fall from the drop former or can il~lollu~)l the drops c~ ;n~ false counts and false alarms. ~mkient light can also int~re~e with an optical drop sensor and 20 render it inaecllrate.
In some c,ases it would be usefi~l to ?.,(o~ ;cally provide infol"~alion lelaling to ~e l.~s~ule of the supply fluid or the "head"
l)ressllre. From the head pressure, an up~ un occlusion can be detected as well as an empty fluid supply.
.. _ Pump systems have been disclosed which include a dow~ am l~ressurc sensor used for detecting i",~ro~r fluid co-".~ n;c~tion with the patient. Such systems include U.S. Patent 4,743,228 to Bu~te~eld; U.S.
Patent 4,460,355 to ~yman; U.S. Patent 4,534,756 to Nelson; and U.S.
S Patent 4,846,792 to Bobo, Jr. et al. Where such systems use a pump or other fluid pressule control means which co.~ ;c~tes the head l)rcssu,e to the outlet side of the pump, it would be of value to utilize the existing do~"stleal-, prcs~ure sensor to determine uyslream fluid conditions. This would result in less expense both in the pump and in the ~dministration 10 sets.
Hence, those skilled in the art have r~ogn~ed the need for a fluid line rn. ~-;lo- ;n~ system-which can ~J(Q ~ lly detect u~ll~" fluid line oc~lusion~ as well as measure the hcad pressule. Additionally, those sl~lled in the art have reco~i7ed a need to reduce the cost of detern~ining 15 such upstream fluid line conditions. The ~resenl invention fulfills these needs.
.~,, SUMMARY OF THE INVENTION
According to the invention, there is provided a fluid line condition detection apparatus for use with a fluid delivery system which includes a fluid line having an upstream segment coupled to a fluid supply and a downstream segment coupled to a fluid receiver, the apparatus comprising: a fluid chamber disposed in fluid communication with the upstream segment and with the downstream segment of the fluid line; control means for alternately opening the fluid chamber to fluid communication with the upstream segment of the fluid line and with the down-stream segment of the fluid line, wherein when opened to the upstream segment, the chamber receives and stores fluid at head pressure and wherein when opened to the downstream segment, the chamber communicates the fluid stored at head pressure to fluid residing in the downstream segment thereby causing a pressure equalization pulse in the downstream segment; pressure sensor means for sensing the pressure equalization pulse and for providing an equalization signal representative of the pressure equalization pulse; and processor means responsive to said equalization signal for determining the head pressure.
The invention also provides a fluid line condition detection apparatus for use with a fluid delivery system which includes a fluid line having an upstream segment coupled to a fluid supply and a downstream segment coupled to the vascular system of a patient, and a flexible segment coupled to both the upstream and downstream segments, the apparatus comprising:
a fluid chamber disposed in fluid communication with the C
~n~ os upstream segment and with the downstream segment of the fluid line; control means for operating on a flexible segment of the fluid line to control the pressure of the fluid in the fluid line and for alternately opening the fluid chamber to fluid communication with the upstream segment of the fluid line and with the downstream segment of the fluid line, wherein when opened to the upstream segment, the chamber receives and stores fluid at head pressure and wherein when opened to the down-stream segment, the chamber communicates the fluid stored at head pressure to fluid residing in the downstream segment thereby causing a pressure equalization pulse in the downstream segment; pressure sensor means for sensing the pressure equalization pulse and for providing an equalization signal representative of the pressure equalization pulse and for sensing equilibrium pressure in the downstream segment and for providing an equilibrium signal representative thereof;
resistance means for providing a resistance signal representa-tive of the resistance to fluid flow downstream of the fluid chamber; processor means for taking the difference between the equilibrium signal and the equalization signal, integrating said difference and scaling the integrated difference by the resistance signal in determining the head pressure, said processor means also for providing a head pressure signal representative of the determined head pressure; and an alarm generator which receives the head pressure signal, compares the received signal to a first threshold and if the head pressure signal is less than the first threshold, provides an 8 ~ 9 occlusion alarm signal.
The invention further provides a fluid line condition detection apparatus coupled between a fluid supply and a fluid receiver, the apparatus comprising: a fluid line having an upstream segment coupled to the fluid supply for receiving fluid from the fluid supply at head pressure and a downstream segment coupled to the fluid receiver; a fluid chamber disposed in fluid communication with the upstream segment and with the downstream segment of the fluid line; control means for alternately opening the fluid chamber to fluid communication with the upstream segment of the fluid line and with the downstream segment of the fluid line, wherein when opened to the upstream segment, the chamber receives and stores fluid at head pressure and wherein when opened to the downstream segment, the chamber communicates the fluid stored at head pressure to fluid residing in the downstream segment thereby causing a pressure equalization pulse in the downstream segment; pressure sensor means for sensing equilibrium pressure in the downstream segment and for providing an equilibrium signal representative thereof and for also sensing the pressure equalization pulse and for providing an equalization signal representative of the pressure equalization pulse; and processor means responsive to said equilibrium signal and to said equalization signal for taking the difference between the equilibrium signal and the equalization signal and for integrating the difference in determining the head pressure.
The invention additionally provides a fluid line -5a-C
~78 ~
,.
condition detection apparatus coupled between a fluid supply and the vascular system of a patient, the apparatus comprising:
a fluid line having an upstream segment coupled to the fluid supply for receiving fluid from the fluid supply at head pressure and a downstream segment coupled to the vascular system of the patient; a fluid chamber comprising a flexible segment of the fluid line disposed between and in fluid communication with the upstream segment and with the downstream segment of the fluid line; control means for operating on the flexible segment of the fluid chamber to control the pressure of the fluid in the fluid line and for alternately opening the fluid chamber to fluid communication with the upstream segment of the fluid line and with the downstream segment of the fluid line, wherein when opéned to the upstream segment, the chamber receives and stores fluid at head pressure and wherein when opened to the downstream segment, the chamber communicates the fluid stored at head pressure to fluid residing in the down-stream segment thereby causing a pressure equalization pulse in the downstream segment; pressure sensor means for sensing the pressure equalization pulse and for providing an equaliza-tion signal representative of the pressure equalization pulse and for sensing equilibrium pressure in the downstream segment and for providing an equilibrium signal representative thereof;
resistance means for providing a resistance signal representa-tive of the resistance to fluid flow downstream of the fluid chamber; processor means for taking the difference between the equilibrium signal and the equalization signal, integrating -5b-~a~7~
said difference and scaling the integrated difference by the resistance signal in determining the head pressure, said processor means also for providing a head pressure signal representative of the determined head pressure; and an alarm generator which receives the head pressure signal, compares the received signal to a first threshold and if the head pressure signal is less than the first threshold, provides an occlusion alarm signal.
The invention still further describes a fluid line condition detection apparatus coupled between a fluid supply and the vascular system of a patient, the apparatus comprising a fluid line having an upstream segment coupled to the fluid supply receiving fluid from the fluid supply at head pressure and a downstream segment coupled to the vascular system of the patient; a fluid chamber in the form of a flexible segment coupled to fluid communication with the upstream and downstream segments; fluid pressure control means operating on the flexible segment of the fluid line to control the pressure of the fluid in the fluid line and alternately opening the fluid chamber to fluid communication with the upstream segment of the fluid line and with the downstream segment of the fluid line, wherein when opened to the upstream segment, the chamber receives and stores fluid at head pressure and wherein when opened to the down-stream segment, the chamber communicates the fluid stored at head pressure to fluid residing in the downstream segment thereby causing a pressure equalization pulse in the downstream segment; pressure sensor means sensing the pressure -5c-2~8~8 ~9 equalization pulse and providing an equalization signal representative of the pressure equalization pulse and sensing equilibrium pressure in the downstream segment and providing an equilibrium signal representative thereof; resistance means providing a resistance signal representative of the resistance to fluid flow downstream of the fluid chamber; processor means, and an alarm generator, the apparatus being characterized by:
said flexible segment having a predetermined effective compliance; said processor means taking the difference between the equilibrium signal and the equalization signal, integrating said difference with respect to time and multiplying the integrated difference by the reciprocal of the product of the resistance signal and the compliance, whereby the head pressure is achieved by adding the equilibrium pressure to the above-mentioned product, said processor means also providing a head pressure signal representative of the determined head pressure; and said alarm generator receiving the head pressure signal, comparing the received signal to a first threshold, and if the head pressure signal is less than the first threshold, providing an occlusion alarm signal.
From another aspect, the invention provides a method for detecting the condition of a fluid delivery system which includes a fluid line having an upstream segment coupled to a fluid supply and a downstream segment coupled to a fluid receiver, the delivery system having a fluid pressure control means for operating on a flexible segment of the fluid line to control the pressure of the fluid in the fluid line, the fluid -5d-2Q8~8 ~9 .
upstream of the fluid pressure control means being at head pressure, the method comprising the steps of: storing fluid at the head pressure in a fluid chamber disposed in fluid communication with the upstream segment and with the downstream segment of the fluid line; alternately opening the fluid chamber to fluid communication with the upstream segment of the fluid line and with the downstream segment of the fluid line, wherein when opened to the upstream segment, the chamber receives and stores fluid at head pressure and wherein when opened to the downstream segment, the chamber communicates the fluid stored at head pressure to fluid residing in the down-stream segment thereby causing a pressure equalization pulse in the downstream segment; sensing the pressure equalization pulse and providing an equalization signal representative of the pressure equalization pulse; and processing the equaliza-tion signal to determine the head pressure.
The invention also provides a method for detecting the condition of a fluid delivery system which includes a fluid line having an upstream segment coupled to a fluid supply and a downstream segment coupled to a fluid receiver, the delivery system having a fluid pressure control means for operating on a flexible segment of the fluid line to control the pressure of the fluid in the fluid line, the fluid upstream of the fluid pressure control means being at head pressure, the method comprising the steps of: storing fluid at the head pressure in a fluid chamber disposed in fluid communication with the upstream segment and with the downstream -5e-2~78 Q9 segment of the fluid line; alternately opening the fluid chamber to fluid communication with the upstream segment of the fluid line and with the downstream segment of the fluid line, wherein when opened to the upstream segment, the chamber receives and stores fluid at head pressure and wherein when opened to the downstream segment, the chamber communicates the fluid stored at head pressure to fluid residing in the downstream segment thereby causing a pressure equalization pulse in the downstream segment; sensing the equilibrium pressure in the downstream segment and providing an equilibrium signal representative thereof and also sensing the pressure equalization pulse and providing an equalization signal representative of the pressure equalization pulse; and processing the equalization signal to determine the head pressure including the steps of taking the difference between the equilibrium signal and the equalization signal and integrating the difference in determining the head pressure.
The invention further provides a method for detecting the condition of a fluid delivery system, utilizing the apparatus defined above, the fluid upstream of the fluid pressure control means being at head pressure, the method being characterized by the steps of: storing fluid at the head pressure in a fluid chamber disposed in fluid communication with the upstream segment and with the downstream segment of the fluid line; alternately opening the fluid chamber to fluid communication with the upstream segment of the fluid line and with the downstream segment of the fluid line, wherein when r~
2~8~8 ~
opened to the upstream segment, the chamber receives and stores fluid at head pressure and wherein when opened to the downstream segment, the chamber communicates the fluid stored at head pressure to fluid residing in the downstream segment thereby causing a pressure equalization pulse in the downstream segment;
sensing the pressure equalization pulse and providing an equalization signal representative of the pressure equalization pulse; and processing the equalization signal to determine the head pressure, including the steps of taking the difference between the equilibrium pressure and the equalization signal, integrating the difference with respect to time, and adding the equilibrium pressure in determining the head pressure.
Other aspects and advantages of the invention will become apparent from the following detailed description and accompanying drawings, illustrating by way of example, the features of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 iS a block diagram of an apparatus for detect-ing conditions in an upstream fluid line incorporating the principles of the invention as applied to an intravascular fluid infusion system;
FIGS. 2A, 2B and 2C are diagrams of the operation of a linear peristaltic pump on a segment of compliant tubing showing in particular the establishment of a compliant fluid chamber; and FIG. 3 is a block diagram of a signal processing embodiment for determining head pressure in accordance with the invention.
-5g-"~
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to the drawings with more particularity, wherein like reference numerals designate like or corresponding elements among the several views, there is shown in FIG. 1 a system 10 for detecting conditions in a fluid line upstream of a monitoring position. A fluid line, which may be an administration set formed of flexible tubing, is positioned between a fluid supply 12 and a patient 14 and comprises an upstream segment 16, a downstream segment 18 and a pumping segment 44 (shown in FIGS. 2A, 2B and 2C). In this case, the fluid supply -5h-~ 20878~9 comprises an ill~e,l~d bottle. The ~ ri~ segment 44 is operated on by a ~ressu~control means which colnprices in this eull,odinlent, an infusion pump 20 to form a co.~.pli~n~ cl~llber as will be descri~aed in more detail below. A p~es~ule t~n-~ucsr n is coupled to the do~n~(l~ll fluid line S se.~Pnt 18 to sense the pi~s~ule in that se~nPnt 18 and provide a signal re~lesenl~ e of that sensed ~)lCS~ule. An analog-to4igital co-l~eller 24 is coupled to the plessule tr~ns~ucer 22 to provide a digital signal to a signal l,~ocessor 26 shown in this case as a micro~loc~sor which is part of the pump ~sembly apparatus.
In FIG. 1, the ~I~Jsll~ fluid line se~Tnent 16 is co~ e~ to the supply bottle 12 through a drip cl~ll~cr 28 in ~is e~ enl The u~llcalu se,,~ent 16 su~li~s fluid to the infusion pump 20 which in the e "1~.".P~.1 of FIGS. 1 and 2 is a linear peri~t~ltie pump. The p~es~,ln of the fluid at the pump inlet 54 will be the "head" lJleS~ u'e. A motor 30 15 and control el~nics 32 are used to drive the peristaltic fingers of the linear perist~ltiG pump 20. The pump system in this e~ .nt further comp~i.ccs the ulicr~foeess~r 26, a memory 34, an alan~i 36, an ope~tor control panel 38 and a &splay 40. The display unit 40 may co~.~pl.-ce a nlonil~r or s~ chart recorder for displaying ~e head lns~--n as 20 det~ll~il~ed by the lli~cr~r~cessor 26. Mounted at the distal end of the do~.ns~ll fluid line s~-~e~l 18 is a c~nn~ 42 used to CQ~ e~l the dvwl~ll fluid line se.~nert 18 to the ~r~ccul~r system of the padent 14.
The pump 20 supplies the y~e,lt~l fluid to the patient 14 at a sele~
rate and pl~es~fe which may be different from ~e head pns~-ln.
20g7gos In some prior systems, the output signal from the ~lessule tr~n~ducer 22 is processe~ to detect the e~isten~ce of a do~ r~n occlusion, infiltration or other condition. Some of these systems are mentioned in the ~r~cAi-~g Bac~lou~d section. Thus, a l,res~.lre S tr~n~ducer 22 which will supply a press.lre signal is already installed in some pump systems.
A typical linear peristaltic pump operates by se~uenti~lly pressing on a segment of flexible tubing by means of cam-following fingers. The pressuie is applied in se~ eY~ locations of the tubing, I,c,~ ing at the 10 inlet end of the pump and ~ ing toward the outlet end. At least one finger is always l)ressing hard enough to occlude the tubing. As a practical matter, one finger does not retract from occluding the tubing until the next one has already oc~luded the tubing; thus, at no time is there a direct fluid path from the inlet to the outlet of the pump.
R~f~lulg now to FIGS. 2A and 2B, the operadon of a linear peristaltic pump 20 in fo~ a head ~es~ e co~ )liA.n chal.l~cr is shown. The per~ tic pump fingers intlic~t~ c~ ly by n.ln~e~
create a IllO~U~g zone of oc~lus;o~ l the length of a ~ p:ng seglllcnl 44. In FIG. 2A, the most do~ stlea,l- part of the ~ p;ng 20 seg~ n~ or pump outlet 56 is oc~l~,de~ by ~.ri~Pltic finger 48 while the most u~r~n peristaltic finger 50 has not yet ocr1~,d~ the ~ p;~g segment 44 at the pump inlet 54. Thus, fluid at head ~ess.l~ is flowing into the ~n~p;~-e segment 44 from the u~lr~n s~-~-cul 16 but is evelllcd from co~ ;cating with the fluid in the do~llsll~ll segment '- 2~(~7~9 18 by the occlusion caused by the most do~sllea"l peristaltic finger 48.
Therefore, the ~J~pi~g segl-,enl 44iS now at head ~essurc.
In FIG. 2B, form~tiQrl of the c~ pliAI~l chdnll cr 44iS shown. As ~iscucse~ above, a second finger occlndes before an occluding first finger S retracts ~ereby preve.~ g a direct fluid flow lJcl~. een the supply and the patient. In this case, the u~l.e~ finger SO occludes before the downslre~lfmger48 retracts and there exists a point in time when both fingers 48 and SO occlude as is shown in FIG. 2b thereby forrning the co,.,pli~nt chamber 44 which t*aps fluid at he~d ~res~ e.
In FIG. 2C, the most UySl~ peristaltic finger SO continues to occlude the yu-..p;.~ se.~ne-nt 44 prior to the most downstre~m finger48 retracting from an o.~ ;n~ I-os;tion- The fluid at head ples~.lre which was trapped in the c~ iA.~ cl~ l e r 44iS now free to co.. ~.Jn;~ e with the fluid in the downstre~m fluid line-scE;",enl 18. ThUS, the c)n.~ nt lS cha---~r 44 iS allc~ ely in fluid co-----~ -;c~tio~ with the upsll'eam segment 16 and the do...lsl~~ca-,- se~nent 18 of the fluid line.
When the most d~....s~n, peristaltic finger 48 retracts thereby allowing fluid c~ c~tion with the co..~ challll,cr 44, the most peristaltic finger S0 has already ocrl~ ed the fluid line, thus a 20 bolus of fluid at head p.;essur~, the bolus being the ,lu~~ stored in the co..-p!i~n( ch~ ~r 44, is released into the du~ segment 18 of the fluid line. Upon its release, the pr~ss.lle in the co...pli~ cl~,ll~r 44 and the pres~ule in the d~."sl,~l- fluid line se~nent 18 will e(lu~li7e. A
measurable press.lre e~li7~tio~ pulse is prod~lced which will be sensed 25 by the pressure lr~.sJ~,cer 22. This pulse is ~rû~ lional to the difference ~ 20~78~9 g between the head and the do~n~ )res~ es, and may be processed to dctell,.in~ the head ~ress~e in accoLdance with the invention.
The flexible material foll,~g the comrli~nt cha-llber 44 has some co.~ ce (Cp"~p) which is taken into n~nt in one embo~im~ when S det~l,-ining head ~ressurc. It has been found that the com~ nre is for all practical ~ll)oses a l)rop~lly of the tubing bec~use IV fluids are virtually incolnl)ressible. When the pres~.-re is changed &om P, to P2, a quantity of fluid ~Q~ will flow but the quandty is dependent on the tubing comrli~nce as follows:
Q=C~ p(Pz~Pl) eq. 1 If P2 is greater than Pl, flow will occur in a rol~ard direcdon and if Pl is greater than P2, flow will occur in a bacLw~r~ direcdon. As used 15 herein, ~col.~ e~ refers to a measure of el~stietty of the l,.atel;al Çol.. ing the co~ liA.n cha--ll~r. It is given here as a co~ n~
The ~luan~ of fluid Q which will flow is also affected by the re-si~t~nee R of the fluid system in acco-~ance with the following:
Q= Rro(P(t)~P~
eq. 2 20~7809 -1~
where: R is the total resistance to fluid flow;
P(t) is dynamic lnes~ure; and Poq is equilibrium pressulc Sub~ ing P~ for P2 and PO9 for P, in equation 1 and colllS~ g S equations 1 and 2 yields:
~ 'g RC~ro ~*
eq. 3 where: P~ d is *e head ylcs~ule; and Cp""p is the errcclive colnrli~nce of the co,.pli~ ch~mbçr As shown in e~ti~n 3 above, e~uilihrillm presslre PO9 and reSic~nee R are also collc;dered when ~et~ n;n~ the head ~lcs~urc.
lS ~lthou~h ~ete ~ utiQIl of e~ libri~ ressure may be based upon a mea~we."elll of press.~re in the system before ~,lu-b&tion of the fluid flow by the bolus of fluid at head ~r~,s~iie, e~ilihrium plcssure is preferably averaged over a ~lullllxr of ~ress.,re re~ ngs both before and after the ~Cl~rement of the ples~wre response to the bolus. It is not 20 ~e~cssAry that the e~l-ilibrillm state be a state of zero flow. The equilibnum pressure is rather a dynamic one, which is mo~ or~ and dete, ~ 41 periodic~lly. It is only n~ess~ry for the fluid system to be in ~878 ~
~quilibrium prior to release of the head pressure bolus, and the pressure response can be integrated until it again returns to equilibrium. The baseline or equilibrium pressure Pe~ is thus average pressure (including that due to flow) in the equilibrium state.
The total fluid flow resistance R is preferably determined by the means disclosed in U. S. Patent 5,087,245 to Doan, or by the technique disclosed in U. S. Patent 4,743,228 to Butterfield.
The accuracy of this method of determining head pressure depends on the stability of the compliance of the pump-ing segment 44 from set to set and over time. For use as an occlusion detector, however, great accuracy is not important.
If the line is occluded, the pump will produce a large negative pressure; i. e., less than atmospheric very quickly. This results in a large negative equalization pulse at the pressure transducer 22 which is readily identifiable. However, for use as an empty supply detector, a greater degree of accuracy is needed. The supply would be assumed to be empty if the fluid head pressure fell below a specified minimum pressure threshold, or if the head pressure began to change rapidly as it would if the level of the supply fluid were down in the narrow part of the drip chamber, or in the tubing itself.
Further associated with the microprocessor 26 and operator control 28 is an alarm generator 36 responsive to cGmparisons of the head pressure with one or more reference values or thresholds which are stored in the system memory 34.
Reference values may also be input into the memory 34 at the cperatGr control 38 or may be preprogrammed.
n ?
~ 66239-1772 2~87809 .. ..
Referring now to FIG. 3, a processin~ system 57 in accordance with the principles of the invention for dete ...;~ head pressure is shown. It is preferable to use as the e~ilihnllm pres~ure Pq the average of dete~ ;n~lions of ples~ule before and after the release of the head S pres~ule bolus by the comrli~nt chamber 44. This provides con~iderable immuni1y from artifacts such as l,ressurc changes due to patient motion.
It should be noted that re.pe~t~d s~mrlin~ of downstream l)ressure is inten~e~ to be timed so that samples can be equally spaced in time, at intervals of 0.005 seconds for eY~mrle.
The eqnilibriunl pleS;~Ure 58 is dete~ .~ as desr,ribed above. A
series of dynamic prcs~ule ~mrlin~s are taken, to be co.~ rcd with the e~Jilibrium pres;,ulc 58 as P(t) - POq in the cQ~ t~r 60. An int~ ~r 62 for c~ lJl~tin~ the &fference over time is ~ l~rted to ge.le,~te a signal re~ese~ the integTal. This integral signal is recei~cd and scaled in the 15 scaler section 64 accoldillg to the fluid flow resi~t~nce 66 in the infusion system and the cQlnrli~nce 68 of the n~te~ial fonnin~ the co..~pliA.~
chamber 44. Resi~t~nce 66 in the infusion system may change over time and the reCict~nce det~ ;n~tion may be ~lp~Ated, The comrli~nce 68 is preferably stored in Ille.llGly at 34 to be ~~,cess:~ to the scaler 64.
Sc~li~ 64 by the fluid flow res;ct~nce 66 and the c~ pli~nce 68 of the con~pli~nt c~ ~r 44 results in a value which may be l~fe,l~d to as the differential l)res~ e (Ptj~. to which the e~uilibrium ~es~-re is added in the adder 70 to det~---ine head pres~ure. The value of the he~d pressure is com~red in com~-ator 72 to a first threshold reference value 74 to det~ .ine whether the fluid source ~res~ule has fallen below a 2~087~09 , ...
specified ~--ini-~ and thereby indicating an empty fluid supply. The head ylessule value is com~red in com~rator 72 to a second l}lr~l.old reference value 76 to determine if the head ~iessure is so low as to in-lic~te that an u~lr~-- occlusion exists.
S The co~ ~ ator 72 may also be yr~glA.... ne~1 to monitor the change . een measurements of head yress~lre and if the head pressure were to begin to change rapidly, such change may be taken to indicate that the fluid level is down in the neck of the supply bottle or the nalro~v yart of the drip chamber or in the t~ubing itself in the case where the supply has 10 a greater cross-sectional area than the tubing. Therefore, the dif~r~ce . ccess;~e P~ d pres~.~.es is coll,~r~ to a third threshold 78 to ~etçrmine if such a ~fh~;~;OI- exists. M~n;lQ.;~ the flow rate 79 to consider its effecton head pres~ure change can be used in dete.nlil~ing the e~istence of an empty fluid supply co~-t~iner. For e-~...ple, if the flow 15 rate re~ sin~ steady while the change in head ~,ess.lre increased, an empty fluid supply cont~iner could be indicated.
In an allell~Lve em~odilllenl, the do~lslr~lll pressure meas.~remc"ls may be provided to the comparator 72 along line 82 and directly coln~r~ in the comp~rator Z2 with a fourth threshold 80 for 20 dete----;--;ne a gross ~,~iance u~ith a predeten,ined n~in;-..u~ to also detect an u~lream occlusion of the fluid line.
r-o~ tor 72 is ~ rtGd to generate an alarm signal 82 when the press.lle values fall below the ll~eshold values or the change in press.lre exceeds a thresllold.
'- 20878~9 -1~
The alarm signal 82 is received by an alarm generator 86 for generating an audio and/or visual or other type of alarm signal. Different alarm signals from the con,~tor 72 may result in different alarms. Por ~ example, an occlusion alarm may be a conli"~ous eone while a low head S pressure alarm may be a repcAtil~g tone. The display 40 displays ehe head yressuie and the alarms as desired and may display oeher system il~fol",ation. Additionally, the microprocessor 26 may stop pump operation automatically upon i~su~nce of an alarm signal by the alarm generator.
10Oeher implement~tion~ of ehe integrator may include the use of electronic analog integration, hydraulic i.~legl~.tion, or "l~lunic~l inl~lalion. Other ~ ~s which can evaluate the integral of a pressule wave can be used to imple~"enl this tçchnique. Addidonally, other types of pumps may also be used if the pump acco",."odates a compli~nt 15 chanl~r capable of storing fluid at one of the pres~,u~es and ~l,s~ue-ntly co~necting the chA...ber to the pordon of the fluid line at the other ~rcssure.
Re~l"llg again to FIG. 1, an ~.-,bodi,-,ent is shown in which a float valve 88 is included with the drip chamber so that when the level of 20 fluid in the drip chamber drops below a ~ ;---v-~l level, the float valve 88 will occlude the ups~", line 16. Colltinue~l operation of the pump 20 will produce the large negati~le ~iessure in the co...pli~nt challll~r 44 as mçntiorled above and the large llegali~e e~u~li7~ion pulse. Thus, the empty supply condition will be signalled through the occlusion alarm.
25 Other similar mech~ni~ms which will not pass air, such as hydrophilic filter, may also be utilized in forcing an occlusion situation when the fluid source becomes empty.
In view of the for~oil~g, it can be ap~rcciated that the apparatus and method for detecting Up~ l co~ition~ in the i~ àvenous fluid line S in an intravascular fluid adminictration system provide such detection without the necessity of modifying an existing peristaltic pump merh~nisrn. In the case where a downstream pressure transducer has already been installed, the signal processing can be modified in accordance with the invention to provide such upstream condition detection. The 10 apparatus and method for ~ete~ting conditions in an intravenous fluid line in an intravascular fluid ~dmini~tration system provide a simple, low cost way of monilo~ing u~ occluc~on will~oul the t~&ce,s~ y of mctlifi~tion of existing peristaltic pump me~h~nicmc. Placed in a do~r,s~ " configuration, the system of the invention can be readily 15 adapted to monitor upsll~" occlusio~ in eyicting peristaltic pump IV
infusion systems.
Additior~lly, where the height 90 of the fluid supply above the c4,..pli~nt chamber is known as well as the inner diameter 90 of the u~~ tubing and the cross-sectional area 90 of the fluid supply 20 col-t~iner~ the ~m~lnt of fluid rem~inin~ in the fluid supply could be determine~ from head pressure. Where the flow rate 79 through the pump of the fluid in the tubing is known, the amount of time rem~inin~ before the fluid supply is depleted can also be determined.
Although plefe~led and alternative embodiments of the invention 25 have been described and illustrated, it is clear that the invention is -1~
succeptihle to numerous modifications and adaptations within the ability of those skilled in the art and without the exercise of inventive faculty.
Thus, it should be understood that various changes in form, detail and usage of the l)rese"l invention may be made without departing from the S spirit and scope of the invention.
Claims (86)
1. A fluid line condition detection apparatus for use with a fluid delivery system which includes a fluid line having an upstream segment coupled to a fluid supply and a downstream segment coupled to a fluid receiver, the apparatus comprising:
a fluid chamber disposed in fluid communication with the upstream segment and with the downstream segment of the fluid line;
control means for alternately opening the fluid chamber to fluid communication with the upstream segment of the fluid line and with the downstream segment of the fluid line, wherein when opened to the upstream segment, the chamber receives and stores fluid at head pressure and wherein when opened to the downstream segment, the chamber communicates the fluid stored at heat pressure to fluid residing in the downstream segment thereby causing a pressure equalization pulse in the downstream segment;
pressure sensor means for sensing the pressure equalization pulse and for providing an equalization signal representative of the pressure equalization pulse; and processor means responsive to said equalization signal for determining the head pressure.
a fluid chamber disposed in fluid communication with the upstream segment and with the downstream segment of the fluid line;
control means for alternately opening the fluid chamber to fluid communication with the upstream segment of the fluid line and with the downstream segment of the fluid line, wherein when opened to the upstream segment, the chamber receives and stores fluid at head pressure and wherein when opened to the downstream segment, the chamber communicates the fluid stored at heat pressure to fluid residing in the downstream segment thereby causing a pressure equalization pulse in the downstream segment;
pressure sensor means for sensing the pressure equalization pulse and for providing an equalization signal representative of the pressure equalization pulse; and processor means responsive to said equalization signal for determining the head pressure.
2. The apparatus of claim 1 wherein:
the pressure sensor means is also for sensing equilibrium pressure in the downstream segment and for providing an equilibrium signal representative thereof; and the processor means is also for taking the difference between the equilibrium signal and the equalization signal and for integrating the difference in determining the head pressure.
the pressure sensor means is also for sensing equilibrium pressure in the downstream segment and for providing an equilibrium signal representative thereof; and the processor means is also for taking the difference between the equilibrium signal and the equalization signal and for integrating the difference in determining the head pressure.
3. The apparatus of claim 2 further comprising:
resistance means for providing a resistance signal representative of the resistance to fluid flow downstream of the fluid chamber;
wherein the processor means is also for scaling the integrated difference by the resistance signal in determining head pressure.
resistance means for providing a resistance signal representative of the resistance to fluid flow downstream of the fluid chamber;
wherein the processor means is also for scaling the integrated difference by the resistance signal in determining head pressure.
4. The apparatus of claim 2 wherein the processor is also for scaling the integrated difference by a compliance signal in determining head pressure, the compliance signal being representative of the compliance of the material forming the fluid chamber.
5. The apparatus of claim 2 wherein the processor is also for adding the integrated difference to the equilibrium signal in determining head pressure.
6. The apparatus of claim 1 wherein:
the processor means is also for providing a head pressure signal representative of the determined head pressure; and the apparatus further comprising an alarm generator which receives the head pressure signal, compares the received signal to a first threshold and if the head pressure signal is less than the first threshold, provides an occlusion alarm signal.
the processor means is also for providing a head pressure signal representative of the determined head pressure; and the apparatus further comprising an alarm generator which receives the head pressure signal, compares the received signal to a first threshold and if the head pressure signal is less than the first threshold, provides an occlusion alarm signal.
7. The apparatus of claim 1 wherein:
the processor means is also for providing a head pressure signal representative of the determined head pressure; and the apparatus further comprising an alarm generator which receives the head pressure signal, compares the received signal to a second threshold and if the head pressure signal is less than the second threshold, provides an alarm signal indicating that the fluid supply is empty.
the processor means is also for providing a head pressure signal representative of the determined head pressure; and the apparatus further comprising an alarm generator which receives the head pressure signal, compares the received signal to a second threshold and if the head pressure signal is less than the second threshold, provides an alarm signal indicating that the fluid supply is empty.
8. The apparatus of claim 1 wherein:
the processor means is also for comparing head pressures determined at different times to each other and for providing a head pressure difference signal representative of the difference between compared head pressures; and the apparatus further comprising an alarm generator which receives the head pressure difference signal, compares said difference signal to a third threshold and if said difference signal exceeds the third threshold, provides an alarm signal indicating that the fluid supply is empty.
the processor means is also for comparing head pressures determined at different times to each other and for providing a head pressure difference signal representative of the difference between compared head pressures; and the apparatus further comprising an alarm generator which receives the head pressure difference signal, compares said difference signal to a third threshold and if said difference signal exceeds the third threshold, provides an alarm signal indicating that the fluid supply is empty.
9. The apparatus of claim 8 wherein the processor means is also for receiving the flow rate and for comparing the change in the flow rate to the change in head pressure to determine the head pressure difference signal.
10. The apparatus of claim 1 wherein the processor means is also for receiving the size of the fluid line, the size of the fluid supply and the height of the fluid supply and based on head pressure, said sizes and height, determining the quantity of fluid remaining in the fluid supply.
11. The apparatus of claim 10 wherein the processor means is also for receiving the flow rate and based on the received flow rate and the quantity remaining in the fluid supply, providing a time remaining signal indicative of the amount of time remaining berfore the fluid supply is empty.
12. The apparatus of claim 1 wherein:
the fluid line is formed of flexible tubing; and the control means comprises a peristaltic pump having a plurality of peristaltic occluding means for operating on a pumping segment of the flexible tubing for sequentially occluding the segment wherein said fluid line pumping segment comprises the fluid chamber.
the fluid line is formed of flexible tubing; and the control means comprises a peristaltic pump having a plurality of peristaltic occluding means for operating on a pumping segment of the flexible tubing for sequentially occluding the segment wherein said fluid line pumping segment comprises the fluid chamber.
13. The apparatus of claim 1 further comprising valve means for preventing the flow of air into the upstream segment of the fluid line when the fluid supply becomes empty.
14. The apparatus of claim 13 wherein said valve means comprises a float valve.
15. A fluid line condition detection apparatus for use with a fluid delivery system which includes a fluid line having an upstream segment coupled to a fluid supply and a downstream segment coupled to the vascular system of a patient, and a flexible segment coupled to both the upstream and downstream segments, the apparatus comprising:
a fluid chamber disposed in fluid communication with the upstream segment and with the downstream segment of the fluid line;
control means for operating on a flexible segment of the fluid line to control the pressure of the fluid in the fluid line and for alternately opening the fluid chamber to fluid communication with the upstream segment of the fluid line and with the downstream segment of the fluid line, wherein when opened to the upstream segment, the chamber receives and stores fluid at head pressure and wherein when opened to the downstream segment, the chamber communicates the fluid stored at head pressure to fluid residing in the downstream segment thereby causing a pressure equalization pulse in the downstream segment;
pressure sensor means for sensing the pressure equalization pulse and for providing an equalization signal representative of the pressure equalization pulse and for sensing equilibrium pressure in the downstream segment and for providing an equilibrium signal representative thereof;
resistance means for providing a resistance signal representative of the resistance to fluid flow downstream of the fluid chamber;
processor means for taking the difference between the equilibrium signal and the equalization signal, integrating said difference and scaling the integrated difference by the resistance signal in determining the head pressure, said processor means also for providing a head pressure signal representative of the determining head pressure; and an alarm generator which receives the head pressure signal, compares the received signal to a first threshold and if the head pressure signal is less than the first threshold, provides an occlusion alarm signal.
a fluid chamber disposed in fluid communication with the upstream segment and with the downstream segment of the fluid line;
control means for operating on a flexible segment of the fluid line to control the pressure of the fluid in the fluid line and for alternately opening the fluid chamber to fluid communication with the upstream segment of the fluid line and with the downstream segment of the fluid line, wherein when opened to the upstream segment, the chamber receives and stores fluid at head pressure and wherein when opened to the downstream segment, the chamber communicates the fluid stored at head pressure to fluid residing in the downstream segment thereby causing a pressure equalization pulse in the downstream segment;
pressure sensor means for sensing the pressure equalization pulse and for providing an equalization signal representative of the pressure equalization pulse and for sensing equilibrium pressure in the downstream segment and for providing an equilibrium signal representative thereof;
resistance means for providing a resistance signal representative of the resistance to fluid flow downstream of the fluid chamber;
processor means for taking the difference between the equilibrium signal and the equalization signal, integrating said difference and scaling the integrated difference by the resistance signal in determining the head pressure, said processor means also for providing a head pressure signal representative of the determining head pressure; and an alarm generator which receives the head pressure signal, compares the received signal to a first threshold and if the head pressure signal is less than the first threshold, provides an occlusion alarm signal.
16. The apparatus of claim 15 wherein the processor means further comprises adder means for adding the integrated difference to said equilibrium signal in determining the head pressure.
17. The apparatus of claim 15 wherein the processor is also for scaling the integrated difference by a compliance signal in determining head pressure, the compliance signal being representative of the compliance of the material forming the fluid chamber.
18. The apparatus of claim 15 wherein the processor is also for adding the integrated difference to the equilibrium signal in determining head pressure.
19. The apparatus of claim 15 wherein the alarm generator compares the received signal to a second threshold and if the head pressure signal is less than the second threshold, provides an alarm signal indicating that the fluid supply is empty.
20. The apparatus of claim 15 wherein the processor means is also for comparing determined head pressures to each other and for providing a head pressure difference signal representative of the difference between compared head pressures; and the alarm generator receives the pressure difference signal, compares said difference signal to a third threshold and if said difference signal exceeds the third threshold, provides an alarm signal indicating that the fluid supply is empty.
21. The apparatus of claim 20 wherein the processor means is also for receiving the flow rate and for comparing the change in the flow rate to the change in head pressure to determine the head pressure difference signal.
22. The apparatus of claim 15 wherein the processor means is also for receiving the size of the fluid line, the size of the fluid supply and the height of the fluid supply and based on head pressure, said sizes and height, determining the quantity of fluid remaining in the fluid supply.
23. The apparatus of claim 22 wherein the processor means is also for receiving the flow rate and based on the received flow rate and the quantity remaining in the fluid supply, providing a time remaining signal indicative of the amount of time remaining berfore the fluid supply is empty.
24. The apparatus of claim 15 wherein the fluid pressure control means comprises a peristaltic pump having a plurality of peristaltic means for operating on the flexible segment of the tubing for sequentially occluding the flexible segment wherein said fluid line pumping segment comprises the fluid chamber.
25. The apparatus of claim 15 further comprising valve means for preventing the flow of air into the upstream segment of the fluid line when the fluid supply becomes empty.
26. A method for detecting the condition of a fluid delivery system which includes a fluid line having an upstream segment coupled to a fluid supply and a downstream segment coupled to a fluid receiver, the delivery system having a fluid pressure control means for operating on a flexible segment of the fluid line to control the pressure of the fluid in the fluid line, the fluid upstream of the fluid pressure control means being at head pressure, the method comprising the steps of:
storing fluid at the head pressure in a fluid chamber disposed in fluid communication with the upstream segment and with the downstream segment of the fluid line;
alternately opening the fluid chamber to fluid communication with the upstream segment of the fluid line and with the downstream segment of the fluid line, wherein when opened to the upstream segment, the chamber receives and stores fluid at head pressure and wherein when opened to the downstream segment, the chamber communicates the fluid stored at head pressure to fluid residing in the downstream segment thereby causing a pressure equalization pulse in the downstream segment;
sensing the pressure equalization pulse and providing an equalization signal representative of the pressure equalization pulse; and processing the equalization signal to determine the head pressure.
storing fluid at the head pressure in a fluid chamber disposed in fluid communication with the upstream segment and with the downstream segment of the fluid line;
alternately opening the fluid chamber to fluid communication with the upstream segment of the fluid line and with the downstream segment of the fluid line, wherein when opened to the upstream segment, the chamber receives and stores fluid at head pressure and wherein when opened to the downstream segment, the chamber communicates the fluid stored at head pressure to fluid residing in the downstream segment thereby causing a pressure equalization pulse in the downstream segment;
sensing the pressure equalization pulse and providing an equalization signal representative of the pressure equalization pulse; and processing the equalization signal to determine the head pressure.
27. The method of claim 26 wherein:
the step of sensing further comprises the steps of sensing equilibrium pressure in the downstream segment and providing an equilibrium signal representative thereof; and the step of processing further comprises the steps of taking the difference between the equilibrium signal and the equalization signal and integrating the difference in determining the head pressure.
the step of sensing further comprises the steps of sensing equilibrium pressure in the downstream segment and providing an equilibrium signal representative thereof; and the step of processing further comprises the steps of taking the difference between the equilibrium signal and the equalization signal and integrating the difference in determining the head pressure.
28. The method of claim 27:
further comprising the steps of determining the resistance to fluid flow downstream of the fluid chamber and providing a resistance signal representative of said resistance;
wherein the step of processing further comprises the step of scaling the integrated difference by the resistance signal in determining head pressure.
further comprising the steps of determining the resistance to fluid flow downstream of the fluid chamber and providing a resistance signal representative of said resistance;
wherein the step of processing further comprises the step of scaling the integrated difference by the resistance signal in determining head pressure.
29. The method of claim 27:
further comprising the step of determining the compliance of the material forming the fluid chamber; and wherein the step of processing further comprises the step of scaling the integrated difference by the compliance in determining head pressure.
further comprising the step of determining the compliance of the material forming the fluid chamber; and wherein the step of processing further comprises the step of scaling the integrated difference by the compliance in determining head pressure.
30. The method of claim 27 wherein the step of processing comprises the step of adding the integrated difference to the equilibrium signal in determining head pressure.
31. The method claim 26:
wherein the step of processing further comprises providing a head pressure signal representative of the determined head pressure; and further comprising the step of comparing the head pressure signal to a first threshold and providing an occlusion alarm signal if the head pressure is less than the first threshold.
wherein the step of processing further comprises providing a head pressure signal representative of the determined head pressure; and further comprising the step of comparing the head pressure signal to a first threshold and providing an occlusion alarm signal if the head pressure is less than the first threshold.
32. The method of claim 26:
wherein the step of processing further comprises providing a head pressure signal representative of the determined head pressure; and further comprising the step of comparing the head pressure signal to a second threshold and providing an empty supply alarm signal if the head pressure is less than the second threshold.
wherein the step of processing further comprises providing a head pressure signal representative of the determined head pressure; and further comprising the step of comparing the head pressure signal to a second threshold and providing an empty supply alarm signal if the head pressure is less than the second threshold.
33. The method of claim 26:
wherein the processing step further comprises the steps of comparing determined head pressures to each other and providing a head pressure difference signal representative of the difference between compared head pressures; and further comprising the step of comparing said difference signal to a third threshold and providing an alarm signal indicating that the fluid supply is empty if said difference signal exceeds the third threshold.
wherein the processing step further comprises the steps of comparing determined head pressures to each other and providing a head pressure difference signal representative of the difference between compared head pressures; and further comprising the step of comparing said difference signal to a third threshold and providing an alarm signal indicating that the fluid supply is empty if said difference signal exceeds the third threshold.
34. The method of claim 33 wherein the processor means is also for receiving the flow rate and for comparing the change in the flow rate to the change in head pressure to determine the head pressure difference signal.
35. The method of claim 26 wherein the processor means is also for receiving the size of the fluid line, the size of the fluid supply and the height of the fluid supply and based on head pressure, said sizes and height, determining the quantity of fluid remaining in the fluid supply.
36. The method of claim 35 wherein the processor means is also for receiving the flow rate and based on the received flow rate and the quantity remaining in the fluid supply, providing a time remaining signal indicative of the amount of time remaining before the fluid supply is empty.
37. The method of claim 26 further comprising the step of preventing the flow of air into the upstream segment of the fluid line when the fluid supply becomes empty.
38. A fluid line condition detection apparatus coupled between a fluid supply and a fluid receiver, the apparatus comprising:
a fluid line having an upstream segment coupled to the fluid supply for receiving fluid from the fluid supply at head pressure and a downstream segment coupled to the fluid receiver;
a fluid chamber disposed in fluid communication with the upstream segment and with the downstream segment of the fluid line;
control means for alternately opening the fluid chamber to fluid communication with the upstream segment of the fluid line and with the downstream segment of the fluid line, wherein when opened to the upstream segment, the chamber receives and stores fluid at head pressure and wherein when opened to the downstream segment, the chamber communicates the fluid stored at head pressure to fluid residing in the downstream segment thereby causing a pressure equalization pulse in the downstream segment;
pressure sensor means for sensing equilibrium pressure in the downstream segment and for providing an equilibrium signal representative thereof and for also sensing the pressure equalization pulse and for providing an equalization signal representative of the pressure equalization pulse; and processor means responsive to said equilibrium signal and to said equalization signal for taking the difference between the equilibrium signal and the equalization signal and for integrating the difference in determining the head pressure.
a fluid line having an upstream segment coupled to the fluid supply for receiving fluid from the fluid supply at head pressure and a downstream segment coupled to the fluid receiver;
a fluid chamber disposed in fluid communication with the upstream segment and with the downstream segment of the fluid line;
control means for alternately opening the fluid chamber to fluid communication with the upstream segment of the fluid line and with the downstream segment of the fluid line, wherein when opened to the upstream segment, the chamber receives and stores fluid at head pressure and wherein when opened to the downstream segment, the chamber communicates the fluid stored at head pressure to fluid residing in the downstream segment thereby causing a pressure equalization pulse in the downstream segment;
pressure sensor means for sensing equilibrium pressure in the downstream segment and for providing an equilibrium signal representative thereof and for also sensing the pressure equalization pulse and for providing an equalization signal representative of the pressure equalization pulse; and processor means responsive to said equilibrium signal and to said equalization signal for taking the difference between the equilibrium signal and the equalization signal and for integrating the difference in determining the head pressure.
39. The apparatus of claim 38 further comprising:
resistance means for providing a resistance signal representative of the resistance to fluid flow downstream of the fluid chamber;
wherein the processor means is also for scaling the integrated difference by the resistance signal in determining head pressure.
resistance means for providing a resistance signal representative of the resistance to fluid flow downstream of the fluid chamber;
wherein the processor means is also for scaling the integrated difference by the resistance signal in determining head pressure.
40. The apparatus of claim 38 wherein:
the fluid chamber has compliance;
the apparatus further comprising compliance means for providing a compliance signal representative of the compliance of the fluid chamber; and wherein the processor is also for scaling the integrated difference by the compliance signal in determining head pressure.
the fluid chamber has compliance;
the apparatus further comprising compliance means for providing a compliance signal representative of the compliance of the fluid chamber; and wherein the processor is also for scaling the integrated difference by the compliance signal in determining head pressure.
41. The apparatus of claim 38 wherein the processor is also for scaling the integrated difference and adding the scaled, integrated difference to the equilibrium signal in determining head pressure.
42. The apparatus of claim 38 wherein:
the processor means is also for providing a head pressure signal representative of the determined head pressure;
and the apparatus further comprising an alarm generator which receives the head pressure signal, compares the received signal to a first threshold and if the head pressure signal is less than the first threshold, provides an occlusion alarm signal.
the processor means is also for providing a head pressure signal representative of the determined head pressure;
and the apparatus further comprising an alarm generator which receives the head pressure signal, compares the received signal to a first threshold and if the head pressure signal is less than the first threshold, provides an occlusion alarm signal.
43. The apparatus of claim 38 wherein:
the processor means is also for providing a head pressure signal representative of the determined head pressure;
and the apparatus further comprising an alarm generator which receives the head pressure signal, compares the received signal to a second threshold and if the head pressure signal is less than the second threshold, provides an alarm signal indicating that the fluid supply is empty.
the processor means is also for providing a head pressure signal representative of the determined head pressure;
and the apparatus further comprising an alarm generator which receives the head pressure signal, compares the received signal to a second threshold and if the head pressure signal is less than the second threshold, provides an alarm signal indicating that the fluid supply is empty.
44. The apparatus of claim 38 wherein:
the process means is also for comparing head pressures determined at different times to each other and for providing a head pressure difference signal representative of the difference between compared head pressures; and the apparatus further comprising an alarm generator which receives the head pressure difference signal, compares said difference signal to a third threshold and if said difference signal exceeds the third threshold, provides an alarm signal indicating that the fluid supply is empty.
the process means is also for comparing head pressures determined at different times to each other and for providing a head pressure difference signal representative of the difference between compared head pressures; and the apparatus further comprising an alarm generator which receives the head pressure difference signal, compares said difference signal to a third threshold and if said difference signal exceeds the third threshold, provides an alarm signal indicating that the fluid supply is empty.
45. The apparatus of claim 44 further comprising:
flow rate means fox sensing the flow rate of the fluid and providing a flow rate signal representative of the sensed flow rate;
wherein the processor means is also for receiving the flow rate signal and for comparing the change in the flow rate from the flow rate signal to the change in head pressure to determine the head pressure difference signal.
flow rate means fox sensing the flow rate of the fluid and providing a flow rate signal representative of the sensed flow rate;
wherein the processor means is also for receiving the flow rate signal and for comparing the change in the flow rate from the flow rate signal to the change in head pressure to determine the head pressure difference signal.
46. The apparatus of claim 38 wherein the processor means is also for receiving the size of the fluid line, the size of the fluid supply and the height of the fluid supply and based on head pressure, said sizes and height, determining the quantity of fluid remaining in the fluid supply.
47. The apparatus of claim 46 further comprising:
flow rate means for sensing the flow rate of the fluid and providing a flow rate signal representative of the sensed flow rate;
wherein the processor means is also for receiving the flow rate signal and based on the received flow rate signal and the quantity remaining in the fluid supply, providing a time remaining signal indicative of the amount of time remaining before the fluid supply is empty.
flow rate means for sensing the flow rate of the fluid and providing a flow rate signal representative of the sensed flow rate;
wherein the processor means is also for receiving the flow rate signal and based on the received flow rate signal and the quantity remaining in the fluid supply, providing a time remaining signal indicative of the amount of time remaining before the fluid supply is empty.
48. The apparatus of claim 38 wherein:
the fluid chamber is formed of flexible tubing which is connected at one end with the upstream segment of the fluid line and at the other end with the downstream segment of the fluid line; and the control means comprises a peristaltic pump having a plurality of peristaltic occluding means for sequentially occluding the fluid chamber.
the fluid chamber is formed of flexible tubing which is connected at one end with the upstream segment of the fluid line and at the other end with the downstream segment of the fluid line; and the control means comprises a peristaltic pump having a plurality of peristaltic occluding means for sequentially occluding the fluid chamber.
49. The apparatus of claim 38 further comprising valve means for preventing the flow of air into the upstream segment of the fluid line when the fluid supply becomes empty.
50. The apparatus of claim 49 wherein said valve means comprises a float valve disposed in fluid communication with the upstream segment of the fluid line between the fluid supply and the fluid chamber.
51. A fluid line condition detection apparatus coupled between a fluid supply and the vascular system of a patient, the apparatus comprising:
a fluid line having an upstream segment coupled to the fluid supply for receiving fluid from the fluid supply at head pressure and a downstream segment coupled to the vascular system of the patient;
a fluid chamber comprising a flexible segment of the fluid line disposed between and in fluid communication with the upstream segment and with the downstream segment of the fluid line;
control means for operating on the flexible segment of the fluid chamber to control the pressure of the fluid in the fluid line and for alternately opening the fluid chamber to fluid communication with the upstream segment of the fluid line and with the downstream segment of the fluid line, wherein when opened to the upstream segment, the chamber receives and stores fluid at head pressure and wherein. when opened to the downstream segment, the chamber communicates the fluid stored at head pressure to fluid residing in the downstream segment thereby causing a pressure equalization pulse in the downstream segment;
pressure sensor means for sensing the pressure equalization pulse and for providing an equalization signal representative of the pressure equalization pulse and for sensing equilibrium pressure in the downstream segment and for providing an equilibrium signal representative thereof;
resistance means for providing a resistance signal representative of the resistance to fluid flow downstream of the fluid chamber;
processor means for taking the difference between the equilibrium signal and the equalization signal, integrating said difference and scaling the integrated difference by the resistance signal in determining the head pressure, said processor means also for providing a head pressure signal representative of the determined head pressure; and an alarm generator which receives the head pressure signal, compares the received signal to a first threshold and if the head pressure signal is less than the first threshold, provides an occlusion alarm signal.
a fluid line having an upstream segment coupled to the fluid supply for receiving fluid from the fluid supply at head pressure and a downstream segment coupled to the vascular system of the patient;
a fluid chamber comprising a flexible segment of the fluid line disposed between and in fluid communication with the upstream segment and with the downstream segment of the fluid line;
control means for operating on the flexible segment of the fluid chamber to control the pressure of the fluid in the fluid line and for alternately opening the fluid chamber to fluid communication with the upstream segment of the fluid line and with the downstream segment of the fluid line, wherein when opened to the upstream segment, the chamber receives and stores fluid at head pressure and wherein. when opened to the downstream segment, the chamber communicates the fluid stored at head pressure to fluid residing in the downstream segment thereby causing a pressure equalization pulse in the downstream segment;
pressure sensor means for sensing the pressure equalization pulse and for providing an equalization signal representative of the pressure equalization pulse and for sensing equilibrium pressure in the downstream segment and for providing an equilibrium signal representative thereof;
resistance means for providing a resistance signal representative of the resistance to fluid flow downstream of the fluid chamber;
processor means for taking the difference between the equilibrium signal and the equalization signal, integrating said difference and scaling the integrated difference by the resistance signal in determining the head pressure, said processor means also for providing a head pressure signal representative of the determined head pressure; and an alarm generator which receives the head pressure signal, compares the received signal to a first threshold and if the head pressure signal is less than the first threshold, provides an occlusion alarm signal.
52. The apparatus of claim 51 wherein:
the fluid chamber has compliance;
the apparatus further comprising compliance means for providing a compliance signal representative of the compliance of the fluid chamber, and wherein the processor is also for scaling the integrated difference by the compliance signal in determining head pressure.
the fluid chamber has compliance;
the apparatus further comprising compliance means for providing a compliance signal representative of the compliance of the fluid chamber, and wherein the processor is also for scaling the integrated difference by the compliance signal in determining head pressure.
53. The apparatus of claim 52 wherein the processor means further comprises adder means for adding the scaled, integrated difference to said equilibrium signal in determining the head pressure.
54. The apparatus of claim 51 wherein the processor is also for adding the integrated difference to the equilibrium signal in determining head pressure.
55. The apparatus of claim 51 wherein the alarm generator compares the received signal to a second threshold and if the head pressure signal is less than the second threshold, provides an alarm signal indicating that the fluid supply is empty.
56. The apparatus of claim 51 wherein the processor means is also for comparing determined head pressures to each other and for providing a head pressure difference signal representative of the difference between compared head pressures; and the alarm generator receives the pressure difference signal, compares said difference signal to a third threshold and if said difference signal exceeds the third threshold, provides an alarm signal indicating that the fluid supply is empty.
57. The apparatus of claim 56 further comprising:
flow rate means for sensing the flow rate of the fluid and providing a flow rate signal representative of the sensed flow rate;
wherein the processor means is also for receiving the flow rate signal and for comparing the change in the flow rate to the change in head pressure to determine the head pressure difference signal.
flow rate means for sensing the flow rate of the fluid and providing a flow rate signal representative of the sensed flow rate;
wherein the processor means is also for receiving the flow rate signal and for comparing the change in the flow rate to the change in head pressure to determine the head pressure difference signal.
58. The apparatus of claim 51 wherein the processor means is also for receiving the size of the fluid line, the size of the fluid supply and the height of the fluid supply and based on head pressure, said sizes and height, determining the quantity of fluid remaining in the fluid supply.
59. The apparatus of claim 58 further comprising:
flow rate means for sensing the flow rate of the fluid and providing a flow rate signal representative of the sensed flow rate;
wherein the processor means is also for receiving the flow rate signal and based on the received flow rate signal and the quantity remaining in the fluid supply, providing a time remaining signal indicative of the amount of time remaining before the fluid supply is empty.
flow rate means for sensing the flow rate of the fluid and providing a flow rate signal representative of the sensed flow rate;
wherein the processor means is also for receiving the flow rate signal and based on the received flow rate signal and the quantity remaining in the fluid supply, providing a time remaining signal indicative of the amount of time remaining before the fluid supply is empty.
60. The apparatus of claim 51 wherein the fluid pressure control means comprises a peristaltic pump having a plurality of peristaltic means for operating on the flexible segment of the tubing for sequentially occluding the flexible segment wherein said fluid line pumping segment comprises the fluid chamber.
61. The apparatus of claim 51 further comprising valve means for preventing the flow of air into the upstream segment of the fluid line when the fluid supply becomes empty.
62. A method for detecting the condition of a fluid delivery system which includes a fluid line having an upstream segment coupled to a fluid supply and a downstream segment coupled to a fluid receiver, the delivery system having a fluid pressure control means for operating on a flexible segment of the fluid line to control the pressure of the fluid in the fluid line, the fluid upstream of the fluid pressure control means being at head pressure, the method comprising the steps of:
storing fluid at the head pressure in a fluid chamber disposed in fluid communication with the upstream segment and with the downstream segment of the fluid line;
alternately opening the fluid chamber to fluid communication with the upstream segment of the fluid line and with the downstream segment of the fluid line, wherein when opened to the upstream segment, the chamber receives and stores fluid at head pressure and wherein when opened to the downstream segment, the chamber communicates the fluid stored at head pressure to fluid residing in the downstream segment thereby causing a pressure equalization pulse in the downstream segment;
sensing the equilibrium pressure in the downstream segment and providing an equilibrium signal representative thereof and also sensing the pressure equalization pulse and providing an equalization signal representative of the pressure equalization pulse; and processing the equalization signal to determine the head pressure including the steps of taking the difference between the equilibrium signal and the equalization signal and integrating the difference in determining the head pressure.
storing fluid at the head pressure in a fluid chamber disposed in fluid communication with the upstream segment and with the downstream segment of the fluid line;
alternately opening the fluid chamber to fluid communication with the upstream segment of the fluid line and with the downstream segment of the fluid line, wherein when opened to the upstream segment, the chamber receives and stores fluid at head pressure and wherein when opened to the downstream segment, the chamber communicates the fluid stored at head pressure to fluid residing in the downstream segment thereby causing a pressure equalization pulse in the downstream segment;
sensing the equilibrium pressure in the downstream segment and providing an equilibrium signal representative thereof and also sensing the pressure equalization pulse and providing an equalization signal representative of the pressure equalization pulse; and processing the equalization signal to determine the head pressure including the steps of taking the difference between the equilibrium signal and the equalization signal and integrating the difference in determining the head pressure.
63. The method of claim 62 further comprising the steps of determining the resistance to fluid flow downstream of the fluid chamber and providing a resistance signal representative of said resistance;
wherein the step of processing further comprises the step of scaling the integrated difference by the resistance signal in determining head pressure.
wherein the step of processing further comprises the step of scaling the integrated difference by the resistance signal in determining head pressure.
64. The method of claim 62 further comprising the step of determining the compliance of the material forming the fluid chamber; and wherein the step of processing further comprises the step of scaling the integrated difference by the compliance in determining head pressure.
65. The method of claim 62 wherein the step of processing comprises the steps of scaling the integrated difference and adding the scaled, integrated difference to the equilibrium signal in determining head pressure.
66. The method of claim 62 wherein the step of processing further comprises providing a head pressure signal representative of the determined head pressure; and further comprising the step of comparing the head pressure signal to a first threshold and providing an occlusion alarm signal if the head pressure is less than the first threshold.
67. The method of claim 62 wherein the step of processing further comprises providing a head pressure signal representative of the determined head pressure; and further comprising the step of comparing the head pressure signal to a second threshold and providing an empty supply alarm signal if the head pressure is less than the second threshold.
68. The method of claim 62 wherein the processing step further comprises the steps of comparing determined head pressures to each other and providing a head pressure difference between compared head pressures; and further comprising the step of comparing said difference signal to a third threshold and providing an alarm signal indicating that the fluid supply is empty if said difference signal exceeds the third threshold.
69. The apparatus of claim 51 further comprising:
flow rate means for sensing the flow rate of the fluid and providing a flow rate signal representative of the sensed flow rate;
wherein the processor means is also for receiving the flow rate signal and for comparing the change in the flow rate to the change in head pressure to determine the head pressure difference signal.
flow rate means for sensing the flow rate of the fluid and providing a flow rate signal representative of the sensed flow rate;
wherein the processor means is also for receiving the flow rate signal and for comparing the change in the flow rate to the change in head pressure to determine the head pressure difference signal.
70. The apparatus of claim 69 wherein the processor means is also for receiving the size of the fluid line, the size of the fluid supply and the height of the fluid supply and based on head pressure, said sizes and height, determining the quantity of fluid remaining in the fluid supply.
71. The apparatus of claim 70 further comprising:
flow rate means for sensing the flow rate of the fluid and providing a flow rate signal representative of the sensed flow rate;
wherein the processor means is also for receiving the flow rate signal and based on the received flow rate signal and the quantity remaining in the fluid supply, providing a time remaining signal indicative of the amount of time remaining before the fluid supply is empty.
flow rate means for sensing the flow rate of the fluid and providing a flow rate signal representative of the sensed flow rate;
wherein the processor means is also for receiving the flow rate signal and based on the received flow rate signal and the quantity remaining in the fluid supply, providing a time remaining signal indicative of the amount of time remaining before the fluid supply is empty.
72. The method of claim 62 further comprising the step of preventing the flow of air into the upstream segment of the fluid line when the fluid supply becomes empty.
73. A fluid line condition detection apparatus (10) coupled between a fluid supply (12) and the vascular system of a patient (14), the apparatus comprising a fluid line having an upstream segment (16) coupled to the fluid supply (12) receiving fluid from the fluid supply (12) at head pressure (54) and a downstream segment (18) coupled to the vascular system of the patient (14); a fluid chamber (44) in the form of a flexible segment (44) coupled in fluid communication with the upstream and downstream segments (16, 18); fluid pressure control means (20) operating on the flexible segment (44) of the fluid line to control the pressure of the fluid in the fluid line and alternately opening the fluid chamber (44) to fluid communication with the upstream segment (16) of the fluid line and with the downstream segment (18) of the fluid line, wherein when opened to the upstream segment (16), the chamber (44) receives and stores fluid at head pressure (54) and wherein when opened to the downstream segment (18), the chamber (44) communicates the fluid stored at head pressure (54) to fluid residing in the downstream segment (18) thereby causing a pressure equalization pulse in the downstream segment (18);
pressure sensor means (22) sensing the pressure equalization pulse and providing an equalization signal representative of the pressure equalization pulse and sensing equilibrium pressure in the downstream segment (18) and providing an equilibrium signal representative thereof; resistance means (66) providing a resistance signal representative of the resistance to fluid flow downstream of the fluid chamber (44);
processor means (57), and an alarm generator (36), the apparatus (10) being characterized by:
said flexible segment (44) having a predetermined effective compliance;
said processor means (57) taking the difference (60) between the equilibrium signal and the equalization signal, integrating (62) said difference with respect to time and multiplying the integrated difference by the reciprocal of the product of the resistance signal and the compliance, whereby the head pressure (54) is achieved by adding (70) the equilibrium pressure to the above-mentioned product, said processor means (57) also providing a head pressure signal representative of the determined head pressure; and said alarm generator (36) receiving the head pressure signal, comparing the received signal to a first threshold (74), and if the head pressure signal is less than the first threshold (74), providing an occlusion alarm signal.
pressure sensor means (22) sensing the pressure equalization pulse and providing an equalization signal representative of the pressure equalization pulse and sensing equilibrium pressure in the downstream segment (18) and providing an equilibrium signal representative thereof; resistance means (66) providing a resistance signal representative of the resistance to fluid flow downstream of the fluid chamber (44);
processor means (57), and an alarm generator (36), the apparatus (10) being characterized by:
said flexible segment (44) having a predetermined effective compliance;
said processor means (57) taking the difference (60) between the equilibrium signal and the equalization signal, integrating (62) said difference with respect to time and multiplying the integrated difference by the reciprocal of the product of the resistance signal and the compliance, whereby the head pressure (54) is achieved by adding (70) the equilibrium pressure to the above-mentioned product, said processor means (57) also providing a head pressure signal representative of the determined head pressure; and said alarm generator (36) receiving the head pressure signal, comparing the received signal to a first threshold (74), and if the head pressure signal is less than the first threshold (74), providing an occlusion alarm signal.
74. The apparatus of claim 73 further characterized in that the processor means (57) further comprises adder means (60) adding the integrated difference to said equilibrium signal in determining the head pressure.
75. The apparatus of claim 73 or 74 further characterized in that the alarm generator (36) compares the received signal to a second threshold (16) and if the head pressure signal is less than the second threshold (16), provides an alarm signal indicating that the fluid supply (12) is empty.
76. The apparatus of any one of claims 73 to 75 further characterized in that the processor means (57) also receives the flow rate and compares the change in the flow rate to the change in head pressure to determine the head pressure difference signal.
77. The apparatus of any one of claims 73 to 76 further characterized in that the processor means (57) also receives the size of the fluid line, the size of the fluid supply (12) and the height of the fluid supply (12) and based on head pressure, said sizes and height, determines the quantity of fluid remaining in the fluid supply (12).
78. The apparatus of claim 77 further characterized in that the processor means (57) also receives the flow rate and based on the received flow rate and the quantity remaining in the fluid supply (12), provides a time remaining signal indicative of the amount of time remaining before the fluid supply (12) is empty.
79. The apparatus of any one of claims 73 to 78 further characterized in that the fluid pressure control means (20) comprises a peristaltic pump (20) having a plurality of peristaltic means (46) operating on the flexible segment (44) of the tubing sequentially occluding the flexible segment (44).
80. The apparatus of any one of claims 73 to 79 further characterized by valve means (88) preventing the flow of air into the upstream segment (16) of the fluid line when the fluid supply (12) becomes empty, said valve means (88) having a float valve (88).
81. A method for detecting the condition of a fluid delivery system, utilizing the apparatus of any one of claims 73 to 80, the fluid upstream of the fluid pressure control means (20) being at head pressure, the method being characterized by the steps of:
storing fluid at the head pressure in a fluid chamber (44) disposed in fluid communication with the upstream segment (16) and with the downstream segment (18) of the fluid line;
alternately opening the fluid chamber (44) to fluid communication with the upstream segment (16) of the fluid line and with the downstream segment (18) of the fluid line, wherein when opened to the upstream segment (16), the chamber (44) receives and stores fluid at head pressure and wherein when opened to the downstream segment (18), the chamber (44) communicates the fluid stored at head pressure to fluid residing in the downstream segment (18) thereby causing a pressure equalization pulse in the downstream segment (18);
sensing the pressure equalization pulse and providing an equalization signal representative of the pressure equalization pulse; and processing the equalization signal to determine the head pressure, including the steps of taking the difference between the equilibrium pressure and the equalization signal, integrating the difference with respect to time, and adding the equilibrium pressure in determining the head pressure.
storing fluid at the head pressure in a fluid chamber (44) disposed in fluid communication with the upstream segment (16) and with the downstream segment (18) of the fluid line;
alternately opening the fluid chamber (44) to fluid communication with the upstream segment (16) of the fluid line and with the downstream segment (18) of the fluid line, wherein when opened to the upstream segment (16), the chamber (44) receives and stores fluid at head pressure and wherein when opened to the downstream segment (18), the chamber (44) communicates the fluid stored at head pressure to fluid residing in the downstream segment (18) thereby causing a pressure equalization pulse in the downstream segment (18);
sensing the pressure equalization pulse and providing an equalization signal representative of the pressure equalization pulse; and processing the equalization signal to determine the head pressure, including the steps of taking the difference between the equilibrium pressure and the equalization signal, integrating the difference with respect to time, and adding the equilibrium pressure in determining the head pressure.
82. The method of claim 81 further characterized in that the step of sensing further comprises the steps of sensing equilibrium pressure in the downstream segment (18) and providing an equilibrium signal representative thereof.
83. The method of claim 82 further characterized by the steps of determining the resistance to fluid flow downstream of the fluid chamber (44), providing a resistance signal representative of said resistance and determining the compliance of the material forming the fluid chamber (44); and wherein the step of processing further comprises the step of multiplying the integrated difference by the reciprocal of the product of the resistance signal and the compliance in determining head pressure.
84. The method of claim 81 further characterized in that the step of processing further involves providing a head pressure signal representative of the determined head pressure;
and further involves the step of comparing the head pressure signal to a first threshold (74) and providing an occlusion alarm signal if the head pressure is less than the first threshold (74), the step of processing further involving providing a head pressure signal representative of the determined head pressure; and comparing the head pressure signal to a second threshold (16) and providing an empty supply alarm signal if the head pressure is less than the second threshold (16).
and further involves the step of comparing the head pressure signal to a first threshold (74) and providing an occlusion alarm signal if the head pressure is less than the first threshold (74), the step of processing further involving providing a head pressure signal representative of the determined head pressure; and comparing the head pressure signal to a second threshold (16) and providing an empty supply alarm signal if the head pressure is less than the second threshold (16).
85. The method of claim 81 further characterized in that the processing step further involves the steps of comparing determined head pressures to each other and providing a head pressure difference signal representative of the difference between compared head pressures; and further involves the step of comparing said difference signal to a third threshold (78) and providing an alarm signal indicating that the fluid supply (12) is empty if the difference signal exceeds the third threshold (78).
86. The method of claim 81 further characterized by the step of preventing the flow of air into the upstream segment (16) of the fluid line when the fluid supply (12) becomes empty.
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|---|---|---|---|
| US82386392A | 1992-01-22 | 1992-01-22 | |
| US07/823,863 | 1992-01-22 |
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| CA002087809A Expired - Lifetime CA2087809C (en) | 1992-01-22 | 1993-01-21 | Fluid line condition detection |
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| EP (1) | EP0554716B1 (en) |
| JP (1) | JP3444912B2 (en) |
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-
1993
- 1993-01-20 EP EP93100819A patent/EP0554716B1/en not_active Expired - Lifetime
- 1993-01-20 DE DE69315450T patent/DE69315450T2/en not_active Expired - Lifetime
- 1993-01-21 CA CA002087809A patent/CA2087809C/en not_active Expired - Lifetime
- 1993-01-22 JP JP02734893A patent/JP3444912B2/en not_active Expired - Lifetime
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1994
- 1994-01-24 US US08/185,278 patent/US5356378A/en not_active Expired - Lifetime
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1998
- 1998-11-24 HK HK98112293A patent/HK1011296A1/en not_active IP Right Cessation
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|---|---|
| US5356378A (en) | 1994-10-18 |
| EP0554716A1 (en) | 1993-08-11 |
| DE69315450D1 (en) | 1998-01-15 |
| EP0554716B1 (en) | 1997-12-03 |
| CA2087809A1 (en) | 1993-07-23 |
| HK1011296A1 (en) | 1999-07-09 |
| JP3444912B2 (en) | 2003-09-08 |
| JPH06233818A (en) | 1994-08-23 |
| DE69315450T2 (en) | 1998-05-20 |
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