CA1076831A - External pressure-volume monitor for endotracheal cuff - Google Patents
External pressure-volume monitor for endotracheal cuffInfo
- Publication number
- CA1076831A CA1076831A CA298,216A CA298216A CA1076831A CA 1076831 A CA1076831 A CA 1076831A CA 298216 A CA298216 A CA 298216A CA 1076831 A CA1076831 A CA 1076831A
- Authority
- CA
- Canada
- Prior art keywords
- balloon
- cuff
- cage
- inflation
- endotracheal
- 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
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
- A61M25/00—Catheters; Hollow probes
- A61M25/10—Balloon catheters
- A61M25/1018—Balloon inflating or inflation-control devices
- A61M25/10184—Means for controlling or monitoring inflation or deflation
-
- 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
- A61M16/00—Devices for influencing the respiratory system of patients by gas treatment, e.g. mouth-to-mouth respiration; Tracheal tubes
- A61M16/04—Tracheal tubes
-
- 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
- A61M16/00—Devices for influencing the respiratory system of patients by gas treatment, e.g. mouth-to-mouth respiration; Tracheal tubes
- A61M16/04—Tracheal tubes
- A61M16/0434—Cuffs
-
- 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
- A61M16/00—Devices for influencing the respiratory system of patients by gas treatment, e.g. mouth-to-mouth respiration; Tracheal tubes
- A61M16/04—Tracheal tubes
- A61M16/0434—Cuffs
- A61M16/044—External cuff pressure control or supply, e.g. synchronisation with respiration
-
- 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
- Y10S116/00—Signals and indicators
- Y10S116/08—Inflatable indicator
Abstract
EXTERNAL PRESSURE-VOLUME
MONITOR FOR ENDOTRACHEAL CUFF
James O. Elam ABSTRACT
A monitoring system is comprised of an elastomer balloon housed in a spherical perforated cage which is designed to continuously indicate the state of collapse or expansion of the internal cuff or cuffs of an endo-tracheal tube. This balloon monitor is interconnected in series with the pneumatic channel through which the cuff or cuffs are inflated. The volume of said monitor-ing balloon may be observed visually with reference to its filling the cage enclosure denoting thereby its state of inflation and therefore, also that of the endo-tracheal cuff. Calibration of the balloon monitor pro-vides means of accurately observing both the volume and pressure of air in the system. Therefore, visual in-spection of the monitor indicates by reason of said calibration the prevailing level of pressure in the patient's endotracheal-tube cuff. Since the maintenance of safe cuff pressures results in a normal position of the balloon, in contact with the cage, electrical and electronic means may be arranged appropriately between the balloon and inner surface of the cage to produce a warning signal in the event of cuff overdistension and an alarm signal in the event of cuff collapse.
MONITOR FOR ENDOTRACHEAL CUFF
James O. Elam ABSTRACT
A monitoring system is comprised of an elastomer balloon housed in a spherical perforated cage which is designed to continuously indicate the state of collapse or expansion of the internal cuff or cuffs of an endo-tracheal tube. This balloon monitor is interconnected in series with the pneumatic channel through which the cuff or cuffs are inflated. The volume of said monitor-ing balloon may be observed visually with reference to its filling the cage enclosure denoting thereby its state of inflation and therefore, also that of the endo-tracheal cuff. Calibration of the balloon monitor pro-vides means of accurately observing both the volume and pressure of air in the system. Therefore, visual in-spection of the monitor indicates by reason of said calibration the prevailing level of pressure in the patient's endotracheal-tube cuff. Since the maintenance of safe cuff pressures results in a normal position of the balloon, in contact with the cage, electrical and electronic means may be arranged appropriately between the balloon and inner surface of the cage to produce a warning signal in the event of cuff overdistension and an alarm signal in the event of cuff collapse.
Description
EXTE~AL PRESSURE-VOLUME MONITOR FO~ ENDOTRACHEAL CUFF
James O. Elam BACKGROUND AND SUMMARY
An air-filled endotracheal-tube cuff seals the tracheal tube within the lumen of the trachea to prevent leak during ~ ;
inflation and to prevent entr~ of secretions from the upper airway into the trachea and lungs. Present-day endotracheal `
tubes feature an air inflation channel and small-bore tubing leading to the cuff and a so-called pilot balloon in the proximal segment of said inflation channel to provide external visible proof of the state of cuff inflation. However, current pilot balloons no longer provide this proof. Unfortunately, re-cently marketed cuffed endotracheal tubes have abandoned the original purpose of the pilot balloon by substituting a "miniature" molded bulb which remains normally in expanded posi-tion at zero pressure. The walls of said polymer bulbs are inelastic and are too thick to collapse with cuff deflation and consequently fail to indicate that the patient's ventilator has failed to inflate the lungs.
Therefore, the several purposes of this invention are to -- create a pressure-volume monitor to continuously indicate externally the status of inflation of the endotracheal cuff.
Secondly, to utilize an elastomer for the balloon of said monitor whose thin walls are collapsible and expandable to provide an appreciable change in balloon size with changes in ; internal air pressure, thereby to result in a sensitive and I~ obvious indication of both pressure and volume in the cuff i system without the use of an overflow spill valve. Thirdly, it shall be the purpose of this invention to control the elastomer balloon wall thickness to insure said sensitive response in the appropriate and safe range of cuff pressure, giving obvious evidence of pressures above 15 centimeters of water,
James O. Elam BACKGROUND AND SUMMARY
An air-filled endotracheal-tube cuff seals the tracheal tube within the lumen of the trachea to prevent leak during ~ ;
inflation and to prevent entr~ of secretions from the upper airway into the trachea and lungs. Present-day endotracheal `
tubes feature an air inflation channel and small-bore tubing leading to the cuff and a so-called pilot balloon in the proximal segment of said inflation channel to provide external visible proof of the state of cuff inflation. However, current pilot balloons no longer provide this proof. Unfortunately, re-cently marketed cuffed endotracheal tubes have abandoned the original purpose of the pilot balloon by substituting a "miniature" molded bulb which remains normally in expanded posi-tion at zero pressure. The walls of said polymer bulbs are inelastic and are too thick to collapse with cuff deflation and consequently fail to indicate that the patient's ventilator has failed to inflate the lungs.
Therefore, the several purposes of this invention are to -- create a pressure-volume monitor to continuously indicate externally the status of inflation of the endotracheal cuff.
Secondly, to utilize an elastomer for the balloon of said monitor whose thin walls are collapsible and expandable to provide an appreciable change in balloon size with changes in ; internal air pressure, thereby to result in a sensitive and I~ obvious indication of both pressure and volume in the cuff i system without the use of an overflow spill valve. Thirdly, it shall be the purpose of this invention to control the elastomer balloon wall thickness to insure said sensitive response in the appropriate and safe range of cuff pressure, giving obvious evidence of pressures above 15 centimeters of water,
-2-~; ..
p :~' 1~76831 which is t~e cri`ti~cal cu~f pressure aboYe ~hich tracheal injury~
results. Fourthly, the i`nventi~on shall provIde by direct inspec-tion of balloon size in relation to it contacting the edges of the perforated cage which surrounds said balloon the latter condi-tion serving to identify the specific pressure and volume of the cuff system, such ¢ontainment of the balloon by the cage serving ~, subsequently as a visual reference to discover minute changes in balloon size as long as the patient's trachea remains intubated.
` Finally, the invention shall include means to alert nursing per-sonnel by warning and alarm signals to the hazards related to ~
either excess cuff pressure or leaking collapsed cuffs which may -` in turn result in failure of lung inflation by a mechanical res-- pirator. Attainment of these several features results in pract-ical, inexpensive, durable, mechanical pressure-volume sensor which continually and conveniently reveals the safety and security of the state of inflation of the endotracheal cuff.
This invention replaces the contemporary pilot balloon of only 0.5 to 1.0 milliliter volume with a reliable pressure-vol-ume monitor capable of continuous indication not only of the state of collapse or expansion of the endotracheal cuff but, more import-antly, indicating accurately the level of pressure within said cuff, permitting early discovery by attending personnel of both leakage and excessively high cuff pressure before problems arise. `
The balloon walls of the monitor are appropriately thin elastomer. ~ -The size of the balloon resembles that of the cuff itself, about 20 milliliter volume at 10 centimeters of water and 30 milliliter volume at 20 centimeters of water, this pressure-volume behavior `
being the basis for a sensitive indication of system pressure by virtue of the balloon just contacting the cage edges at 10 centi-meters of water pressure and bulging through the cage windows at 20 centimeters of water. Therefore, the balloon is constructed . . :: ~ . , . .~
~)76~3~l of silicone or KratonT~ rather than RYC, or other inelastic poly-mer. Non-elastic properties of polymers would fail to reveal over-expansion of cuffs. Thus, the contemporary "PVC pilot bal-loons" fail to reveal visible evidence of excessive harmful cuff pressures or of zero pressure. Thus, the pressure-volume monitor of this invention utilizes a balloon with a specific wall thick-:;
ness such that 20 ml of air produces a characteristic internal - pressure. For example, three different balloons of different wall thickness produce pressures of 10 cm of water, 50 cm of water and 200 mm of mercury when filled to occupy the same spac~ within the cage. By attaching the monitoring balloon in series with the inflation channel and cuff system of any cuffed endotracheal tube, one may identify whether the cuff pressure is harmful or benign, and thereby avoid the serious complications arising when high lateral wall pressures are exerted against the wall of the trac-hea. These cited pressures unfortunately cover the-range of cuff pressures typical of currently available endotracheal-tube cuffs, the latter two being harmful.
On the other hand, the safety of the tracheal seal, during lung inflation, dependent upon the integrity of the cuff, part-icularly in patients on mechanical ventilat;on, may be simply and routinely monitored by inspecting the system of this invention.
Nursing personnel may visually inspect the monitor, may palpate with two fingers the balloon's pressure, or may be alerted by pressure sensitive switches in the monitor to a failure of the cuff system.
Accordingly, the invention in its broader aspect compreh-- ends a monitoring accessory for use with a cuffed endotracheal tube which is adapted for connection to a proximal inlet of a cuff inflation channel of the tube. The accessory includes a thin-walled, collapsible-expandable elastic balloon having an injection port and freely communicating with the endotracheal cuff through J
10~683~
the cuff inflation channel of the endotracheal tube. A riid cage havina a pair of spaced end portions ~oined by a plurality of longitudinally extending struts defines a plurality of windows, the windows being disposed about the Periphery of the cage -to provide a volume reference for determining the state of inflation ` of the endotracheal cuff. The cage housing the balloon defines a cavity which has a shape generally conformin~ to the freely in-flated shape of the balloon and has a fixed volume which is fully occupied by the balloon under a normal level of inflation of the endotracheal cuff. The balloon is disposed within the cavity in a manner permitting visual and fingertip percePtion through the windows of any departure from the normal ]evel of inflation of the endotracheal cuff. The monitoring accessory serves as a simple system for continuously monitoring the unseen condition of the endotracheal cuEf.
The foregoing and other aspects and advantages of the invention will be set forth in or are apParent from -the -following description and drawings.
DR~WIN~.S
In the figures:
Figure 1 is a persnective view of the balloon monitor within its surrounding perforated caae with a state of normal inflation of the balloon to fullv occupy the cage an~ contact its longitudinal struts.
Figure 2a is a lateral view of the monitor showing the shape of the four windows in the cage, each sized to admit an adult's finaertip, Figure 2b.
Figure 3 depicts the monitor with the balloon collapsed against the cen-tral thick-wall core tubing and a single orifice at its center, said orifice capable of being occluded hy fingers in order to by-pass inflation of the balloon during inflation or deflation of the endotracheal cuff. Fiaure 3 also depicts the result of air leakage in the cuff system as a result of a defect in the cuff seal or of a prolonaed ~iffusion of air from the cuff.
76t33~
.
This condition illustrates how the monitor may alert attending personnel in a l~fe threatening situation.
Figure 4 is a lateral view of the monitor attached to the proximal end of the cuff inflation tubing of a conventional endo-tracheal tube, the entire pneumatic system inflated to a pressure of 10 centimeters of water resulting in complete and proper fill-ing by the balloon of the space within the cage.
Figure 5 shows a lateral view similar to Figure 4 in which -`
the monitor and cuff system have been over-inflated to result in bulging of the balloon through the oval windows of the cage, thereby indicating harmfully excessive intracuff pressures.
Figure 6 is a lateral view partially in section of an alt-ernative embodiment of the monitor showing micro-switches enlarged for clarity providing an alarm signal or a warning signal in the event of cuff l~nder-inflation or cuff over-inflation.
Figure 7 is a graphic illustration of the pressure-volume relationship of balloons of varying wall thicknesses. -DETAILED DESCRIPTION
Referring to Figure 1, the balloon 10 is constructed of thin elastomer with a configuration and size approximating that ~ ~-of an endotracheal cuff. An ovoid cage 11 is constructed of ri-gid, strong, light-weight metal or plastic, to surround the bal-loon 10 so as to be fully occupied by the balloon at the normal state of inflation with 20 milliliters of air and 10 centimeters of water pressure. The four oval windows 12 in the cage 11 pro-vide for conven:ient inspection of the balloon wall with reference to the fixed volume of the cage 11 and allow fingertip palpation to sense balloon pressure. A central core tube 13 traverses the balloon interior longtudinally with an end-to-end distal end con-sisting of a male fitting 14 to fit into the valved tip on contem-porary tracheal-tube-cuff-inflation channels. At the proximal end of the core tubing 13 a valved standard female inlet 15 is mounted.
,, ~.
7G83~
A small orifice 16 in the core tubing 13 is marked and visible through the transparent balloon wall, to facilitate fingertip occlusion of the orifice during inflation of the cuff, for mom-entary by-pass of the monitoring balloon. Release of said occ-lusion of orifice 16 allows the transfer of air retrograde from the endotracheal-tube cuff to reveal the state of inflation there-of. To attain proper cuff inflat:ion at safe pressure, increments of air are introduced through valved inlet 15 until the balloon 10 fully occupies the cage 11. Respective volumes of 20 milli-liters, 30 milliliters, and 10 milliliters produce an indicationof their magnitude by the size of the balloon 10 as illustrated in the Figures. Corresponding pressures in these states of in-flation are 10 centimeters of water in Figure 4, 17 centimeters of water in Figure 5 and 0 centimeters of water in Figure 3. `
The wall of the elastomer balloon 10, shown collapsed in `
Figure 3, has a wall thickness of three thousandths of an inch - `~
which produces a balloon pressure of 10 centimeters of water (Figure 4) with injection of 20 milliliters. Substitution of an elastomer balloon of equal size with a wall thickness of seven thousandths of an inch provides the monitor with a balloon which identifies 50 centimeters of water pressure upon injection of 20 milliliters of air. A wall thickness of fifteen thousandths of an inch produces a balloon pressure of 350 centimeters of water `~
with injection of 20 milliliters. ~`
Figure 7 illustrates these pressure-volume relationships of balloons of varying wall thicknesses.
'~
.
, , ~6~76~33~
Accordingly, wall thickness determines the specific pressures for a series of monitors for each of which a specific pressure produces full expansion of the monitoring balloon. Therefore, an appropriate group of such monitors with different thicknesses -~
of their respective balloons may be calibrated and specificallylabeled in centimeters of water at normal volume within each cage to monitor specific pressure levels, said group of monitors selected to cover the appropriate ranges of contemporary endo- ;
tracheal cuffs which vary from 10 centimeters to 260 centimeters of water pressure.
For elastomer balloons the accuracy of a number of specimens used in the monitor is reproductible within +5 per cent of the average value. The use of polymer balloons for the monitor is without merit as they fail to exhibit proportional volume changes in pressure.
The balloon monitor supplements the safe care of the intu-bated patient by providing an external visual object for attendingpersonnel to observe to know whether the degree of cuff inflation is satisfactory, whether the cuff has leaked or otherwise lost ; 20 vol~me, or whether, through error, the cuff has been overinflated to result in harmful pressures. Use of this invention may there-fore reduce or eliminate several of the hazards of prolonged tracheal intubation in intensive care patients by providing the means to prevent the common cause of the critical tracheal damage which results from excessive endotracheal cuff pressures and to determine cuff failure which may result in a failure of a mechan-ical ventilator.
Since both prolonged overinflation and temporary underinfla-tion of the endotracheal-tube cuff often results in catastrophic problems or death of ICU patients, means are also described here to provide an alarm signal in the event of cuff ùnderinflation (as shown in Figure 3) and a warning signal for over-inflation ~07683~
(as shown in Fi~gure 5~ of t~e çuEf-~oni~toring balloon system.
Said means as shown in Fi~ure 6 consist of conventional sensi-~ive micro-switches 17 and 18 which respond electrically to pressure contact. The micro-switches 17 and 18 are mounted be-tween the balloon wall and the interior surface of the surrounding cage in the top or bottom of the cage, one micro-switch 17 being arranged to respond to a release of balloon contact against the inner surface of the cage and thereby activate an alarm annun-ciator 19 nearby whereas the other micro-switch 18 is to respond ~ !;
to excess balloon pressure which identifies excessive pressure in the balloon and endotracheal-tube-cuff by activating electrically ;~
a warning annunciator 20 at the nursing station.
While in the foregoing specification a detailed description -of the invention has been set forth for purposes of illustration, variation of the details herein given may be made by those skilled in the art without departing in the spirit and scope of this invention.
' ~ , .
. ~ .
.' _ 9 _
p :~' 1~76831 which is t~e cri`ti~cal cu~f pressure aboYe ~hich tracheal injury~
results. Fourthly, the i`nventi~on shall provIde by direct inspec-tion of balloon size in relation to it contacting the edges of the perforated cage which surrounds said balloon the latter condi-tion serving to identify the specific pressure and volume of the cuff system, such ¢ontainment of the balloon by the cage serving ~, subsequently as a visual reference to discover minute changes in balloon size as long as the patient's trachea remains intubated.
` Finally, the invention shall include means to alert nursing per-sonnel by warning and alarm signals to the hazards related to ~
either excess cuff pressure or leaking collapsed cuffs which may -` in turn result in failure of lung inflation by a mechanical res-- pirator. Attainment of these several features results in pract-ical, inexpensive, durable, mechanical pressure-volume sensor which continually and conveniently reveals the safety and security of the state of inflation of the endotracheal cuff.
This invention replaces the contemporary pilot balloon of only 0.5 to 1.0 milliliter volume with a reliable pressure-vol-ume monitor capable of continuous indication not only of the state of collapse or expansion of the endotracheal cuff but, more import-antly, indicating accurately the level of pressure within said cuff, permitting early discovery by attending personnel of both leakage and excessively high cuff pressure before problems arise. `
The balloon walls of the monitor are appropriately thin elastomer. ~ -The size of the balloon resembles that of the cuff itself, about 20 milliliter volume at 10 centimeters of water and 30 milliliter volume at 20 centimeters of water, this pressure-volume behavior `
being the basis for a sensitive indication of system pressure by virtue of the balloon just contacting the cage edges at 10 centi-meters of water pressure and bulging through the cage windows at 20 centimeters of water. Therefore, the balloon is constructed . . :: ~ . , . .~
~)76~3~l of silicone or KratonT~ rather than RYC, or other inelastic poly-mer. Non-elastic properties of polymers would fail to reveal over-expansion of cuffs. Thus, the contemporary "PVC pilot bal-loons" fail to reveal visible evidence of excessive harmful cuff pressures or of zero pressure. Thus, the pressure-volume monitor of this invention utilizes a balloon with a specific wall thick-:;
ness such that 20 ml of air produces a characteristic internal - pressure. For example, three different balloons of different wall thickness produce pressures of 10 cm of water, 50 cm of water and 200 mm of mercury when filled to occupy the same spac~ within the cage. By attaching the monitoring balloon in series with the inflation channel and cuff system of any cuffed endotracheal tube, one may identify whether the cuff pressure is harmful or benign, and thereby avoid the serious complications arising when high lateral wall pressures are exerted against the wall of the trac-hea. These cited pressures unfortunately cover the-range of cuff pressures typical of currently available endotracheal-tube cuffs, the latter two being harmful.
On the other hand, the safety of the tracheal seal, during lung inflation, dependent upon the integrity of the cuff, part-icularly in patients on mechanical ventilat;on, may be simply and routinely monitored by inspecting the system of this invention.
Nursing personnel may visually inspect the monitor, may palpate with two fingers the balloon's pressure, or may be alerted by pressure sensitive switches in the monitor to a failure of the cuff system.
Accordingly, the invention in its broader aspect compreh-- ends a monitoring accessory for use with a cuffed endotracheal tube which is adapted for connection to a proximal inlet of a cuff inflation channel of the tube. The accessory includes a thin-walled, collapsible-expandable elastic balloon having an injection port and freely communicating with the endotracheal cuff through J
10~683~
the cuff inflation channel of the endotracheal tube. A riid cage havina a pair of spaced end portions ~oined by a plurality of longitudinally extending struts defines a plurality of windows, the windows being disposed about the Periphery of the cage -to provide a volume reference for determining the state of inflation ` of the endotracheal cuff. The cage housing the balloon defines a cavity which has a shape generally conformin~ to the freely in-flated shape of the balloon and has a fixed volume which is fully occupied by the balloon under a normal level of inflation of the endotracheal cuff. The balloon is disposed within the cavity in a manner permitting visual and fingertip percePtion through the windows of any departure from the normal ]evel of inflation of the endotracheal cuff. The monitoring accessory serves as a simple system for continuously monitoring the unseen condition of the endotracheal cuEf.
The foregoing and other aspects and advantages of the invention will be set forth in or are apParent from -the -following description and drawings.
DR~WIN~.S
In the figures:
Figure 1 is a persnective view of the balloon monitor within its surrounding perforated caae with a state of normal inflation of the balloon to fullv occupy the cage an~ contact its longitudinal struts.
Figure 2a is a lateral view of the monitor showing the shape of the four windows in the cage, each sized to admit an adult's finaertip, Figure 2b.
Figure 3 depicts the monitor with the balloon collapsed against the cen-tral thick-wall core tubing and a single orifice at its center, said orifice capable of being occluded hy fingers in order to by-pass inflation of the balloon during inflation or deflation of the endotracheal cuff. Fiaure 3 also depicts the result of air leakage in the cuff system as a result of a defect in the cuff seal or of a prolonaed ~iffusion of air from the cuff.
76t33~
.
This condition illustrates how the monitor may alert attending personnel in a l~fe threatening situation.
Figure 4 is a lateral view of the monitor attached to the proximal end of the cuff inflation tubing of a conventional endo-tracheal tube, the entire pneumatic system inflated to a pressure of 10 centimeters of water resulting in complete and proper fill-ing by the balloon of the space within the cage.
Figure 5 shows a lateral view similar to Figure 4 in which -`
the monitor and cuff system have been over-inflated to result in bulging of the balloon through the oval windows of the cage, thereby indicating harmfully excessive intracuff pressures.
Figure 6 is a lateral view partially in section of an alt-ernative embodiment of the monitor showing micro-switches enlarged for clarity providing an alarm signal or a warning signal in the event of cuff l~nder-inflation or cuff over-inflation.
Figure 7 is a graphic illustration of the pressure-volume relationship of balloons of varying wall thicknesses. -DETAILED DESCRIPTION
Referring to Figure 1, the balloon 10 is constructed of thin elastomer with a configuration and size approximating that ~ ~-of an endotracheal cuff. An ovoid cage 11 is constructed of ri-gid, strong, light-weight metal or plastic, to surround the bal-loon 10 so as to be fully occupied by the balloon at the normal state of inflation with 20 milliliters of air and 10 centimeters of water pressure. The four oval windows 12 in the cage 11 pro-vide for conven:ient inspection of the balloon wall with reference to the fixed volume of the cage 11 and allow fingertip palpation to sense balloon pressure. A central core tube 13 traverses the balloon interior longtudinally with an end-to-end distal end con-sisting of a male fitting 14 to fit into the valved tip on contem-porary tracheal-tube-cuff-inflation channels. At the proximal end of the core tubing 13 a valved standard female inlet 15 is mounted.
,, ~.
7G83~
A small orifice 16 in the core tubing 13 is marked and visible through the transparent balloon wall, to facilitate fingertip occlusion of the orifice during inflation of the cuff, for mom-entary by-pass of the monitoring balloon. Release of said occ-lusion of orifice 16 allows the transfer of air retrograde from the endotracheal-tube cuff to reveal the state of inflation there-of. To attain proper cuff inflat:ion at safe pressure, increments of air are introduced through valved inlet 15 until the balloon 10 fully occupies the cage 11. Respective volumes of 20 milli-liters, 30 milliliters, and 10 milliliters produce an indicationof their magnitude by the size of the balloon 10 as illustrated in the Figures. Corresponding pressures in these states of in-flation are 10 centimeters of water in Figure 4, 17 centimeters of water in Figure 5 and 0 centimeters of water in Figure 3. `
The wall of the elastomer balloon 10, shown collapsed in `
Figure 3, has a wall thickness of three thousandths of an inch - `~
which produces a balloon pressure of 10 centimeters of water (Figure 4) with injection of 20 milliliters. Substitution of an elastomer balloon of equal size with a wall thickness of seven thousandths of an inch provides the monitor with a balloon which identifies 50 centimeters of water pressure upon injection of 20 milliliters of air. A wall thickness of fifteen thousandths of an inch produces a balloon pressure of 350 centimeters of water `~
with injection of 20 milliliters. ~`
Figure 7 illustrates these pressure-volume relationships of balloons of varying wall thicknesses.
'~
.
, , ~6~76~33~
Accordingly, wall thickness determines the specific pressures for a series of monitors for each of which a specific pressure produces full expansion of the monitoring balloon. Therefore, an appropriate group of such monitors with different thicknesses -~
of their respective balloons may be calibrated and specificallylabeled in centimeters of water at normal volume within each cage to monitor specific pressure levels, said group of monitors selected to cover the appropriate ranges of contemporary endo- ;
tracheal cuffs which vary from 10 centimeters to 260 centimeters of water pressure.
For elastomer balloons the accuracy of a number of specimens used in the monitor is reproductible within +5 per cent of the average value. The use of polymer balloons for the monitor is without merit as they fail to exhibit proportional volume changes in pressure.
The balloon monitor supplements the safe care of the intu-bated patient by providing an external visual object for attendingpersonnel to observe to know whether the degree of cuff inflation is satisfactory, whether the cuff has leaked or otherwise lost ; 20 vol~me, or whether, through error, the cuff has been overinflated to result in harmful pressures. Use of this invention may there-fore reduce or eliminate several of the hazards of prolonged tracheal intubation in intensive care patients by providing the means to prevent the common cause of the critical tracheal damage which results from excessive endotracheal cuff pressures and to determine cuff failure which may result in a failure of a mechan-ical ventilator.
Since both prolonged overinflation and temporary underinfla-tion of the endotracheal-tube cuff often results in catastrophic problems or death of ICU patients, means are also described here to provide an alarm signal in the event of cuff ùnderinflation (as shown in Figure 3) and a warning signal for over-inflation ~07683~
(as shown in Fi~gure 5~ of t~e çuEf-~oni~toring balloon system.
Said means as shown in Fi~ure 6 consist of conventional sensi-~ive micro-switches 17 and 18 which respond electrically to pressure contact. The micro-switches 17 and 18 are mounted be-tween the balloon wall and the interior surface of the surrounding cage in the top or bottom of the cage, one micro-switch 17 being arranged to respond to a release of balloon contact against the inner surface of the cage and thereby activate an alarm annun-ciator 19 nearby whereas the other micro-switch 18 is to respond ~ !;
to excess balloon pressure which identifies excessive pressure in the balloon and endotracheal-tube-cuff by activating electrically ;~
a warning annunciator 20 at the nursing station.
While in the foregoing specification a detailed description -of the invention has been set forth for purposes of illustration, variation of the details herein given may be made by those skilled in the art without departing in the spirit and scope of this invention.
' ~ , .
. ~ .
.' _ 9 _
Claims (4)
1. A monitoring accessory for use with a cuffed endotracheal tube adapted for connection to a proximal inlet of a cuff inflation channel of said tube comprising:
a thin-walled, collapsible-expandable elastic balloon, said balloon having an injection port and freely communicating with said endotrachael cuff through said cuff inflation channel of said endotracheal tube; and a rigid cage having a pair of spaced end portions joined by a plurality of longitudinally extending struts defining a plurality of windows, said windows being disposed about the periphery of said cage to provide a volume reference for determining the state of inflation of said endotracheal cuff, said cage housing said balloon therein and defining a cavity having a shape generally conforming to the freely inflated shape of said balloon and having a fixed volume which is fully occupied by said balloon under a normal level of inflation of said endotracheal cuff, said balloon being disposed within said cavity in a manner permitting visual and fingertip perception through said windows of any departure from said normal level of inflation of said endotracheal cuff;
whereby said monitoring accessory serves as a simple system for continuously monitoring the unseen condition of said endotracheal cuff.
a thin-walled, collapsible-expandable elastic balloon, said balloon having an injection port and freely communicating with said endotrachael cuff through said cuff inflation channel of said endotracheal tube; and a rigid cage having a pair of spaced end portions joined by a plurality of longitudinally extending struts defining a plurality of windows, said windows being disposed about the periphery of said cage to provide a volume reference for determining the state of inflation of said endotracheal cuff, said cage housing said balloon therein and defining a cavity having a shape generally conforming to the freely inflated shape of said balloon and having a fixed volume which is fully occupied by said balloon under a normal level of inflation of said endotracheal cuff, said balloon being disposed within said cavity in a manner permitting visual and fingertip perception through said windows of any departure from said normal level of inflation of said endotracheal cuff;
whereby said monitoring accessory serves as a simple system for continuously monitoring the unseen condition of said endotracheal cuff.
2. The monitoring accessory of Claim 1 wherein a central tube extends end-to-end through said balloon and said spaced end portions of said rigid cage, said tube having an orifice intermediate the ends thereof in communication with said balloon, said balloon being transparent and said orifice being visible to facilitate fingertip occlusion thereof through at least one of said windows to permit inflation of said endotracheal cuff prior to said balloon, said central tube including means for connection to said proximal inlet of said cuff inflation channel and means for connection to an external source of air.
3. The monitoring accessory of Claim 1 including a micro-switch placed between the outer surface of said balloon and the inner wall of said cage responsive to under-inflation of said balloon, said micro-switch being connected to a warning or alarm signal.
4. The monitoring accessory of Claim 1 including a micro-switch placed between the outer surface of said balloon and the inner wall of said cage responsive to over-inflation of said balloon, said micro-switch being connected to a warning or alarm signal.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US05/781,177 US4134407A (en) | 1977-03-25 | 1977-03-25 | External pressure-volume monitor for endotracheal cuff |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1076831A true CA1076831A (en) | 1980-05-06 |
Family
ID=25121937
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA298,216A Expired CA1076831A (en) | 1977-03-25 | 1978-03-06 | External pressure-volume monitor for endotracheal cuff |
Country Status (3)
| Country | Link |
|---|---|
| US (1) | US4134407A (en) |
| CA (1) | CA1076831A (en) |
| GB (1) | GB1586992A (en) |
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-
1977
- 1977-03-25 US US05/781,177 patent/US4134407A/en not_active Expired - Lifetime
-
1978
- 1978-03-06 CA CA298,216A patent/CA1076831A/en not_active Expired
- 1978-03-13 GB GB9913/78A patent/GB1586992A/en not_active Expired
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2014009950A1 (en) * | 2012-07-11 | 2014-01-16 | Lunguard Ltd. | Method for monitoring pressures exerted along the length of a biological channel |
| US9848790B2 (en) | 2012-07-11 | 2017-12-26 | Lunguard Ltd. | Method for monitoring pressure exerted along the length of a biological channel |
| WO2014041532A1 (en) * | 2012-09-11 | 2014-03-20 | Lunguard Ltd. | Method for calibrating an expandable means of a medical device and method for monitoring the pressure exerted by the interior wall of a biological channel |
Also Published As
| Publication number | Publication date |
|---|---|
| US4134407A (en) | 1979-01-16 |
| GB1586992A (en) | 1981-03-25 |
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