CA1183021A - Syringe device for physiological fluid sampling - Google Patents

Abstract

ABSTRACT

This invention relates to a device for collecting a sample of physiological fluid such as a blood sample so that subsequent analysis may be made for diagnostic purposes. In many such applications, including blood pH and blood gas analysis, it is desirable that the sample be taken in a manner wherein potentially contaminating gases contained in the device are removed while the sample is taken. The present invention incorporates structure to vent unwanted gases and at the same time is configured to be adaptable for use with various analytical laboratory machines in order to avoid the necessity of transferring the sample from one container to another prior to analysis. Accordingly, the sampling device according to the present invention provides a means for selectively isolating a blood sample from contaminant gases.

Description

SYRlNGE Dl.\/lCr: I:OR l'~lYSIOl,()Cl(,AI. I~l.l)ID S/~MI'LING
BA(:KGI~OUND Ol~ Tll~ INVI~'I`ITION

This invcntion rc-lates to a device for collecting a s~lmplc of physiological fluid such as a blood samplc so that subsequent analysis may hc madc for 5. diagnostic purposcs. In many such applications, including blood pll and blood gas analysis, it is desirable that the sarnple be takcn in a rnanner wherein potentially contaminating gases contained in the device arc rrmoved while the sample is taken. Tlle present invention incoryorates structure to vent unwanted gases and at the same tirne i9 configured to be adaptable for lO. use with various analytical laboratory machines in order to avoid the necessity of transferring the sample from one container to another prior to analysis. Accordingly, the sampling device according to the present invention provides a means for selectively isolating a blood sample from contaminant gases.

15. As noted, the present invention is useful in blood gas analysis and is constructed specifically to enhance the ease and accuracy of this process.
The value of blood gas analysis has long been recognized by the rnedical community, but several problems have been present in utilizing blood gas analysis as a diagnostic tool. Such analysis requires a sample of known 20. volume which i5 pure from contaminants which would rende} the results of the analysis suspect. Typical contaminants which often introduce error in analysis are atmospheric air, other gases or fluids, and some solid materials Isolation of the sample from these contaminants is therefore crucial. ~here a blood sample is taken and is subsequently transferred from one container 25. to another prior to analysis, there is an incrcased chance for introduction of these contaminants. Thus, it is desiraole that the analysis take place ~ith the blood remaining in the sampling cartridge.

Another problem that has been confronted in blood gas analysis, which typically requires artcrially collected blood, is that the blood cannot be .

pcrm~ttcd to clot. To thiA cnd, prior art dcviccs hnvc ~rccon(lltionecl tho contalncr into whicil the blood snmple is rcceived with an antl-coagu]aht solution a]though the dilutcnt of thc solution may, itself, cause contaml~
nation of the samplc. Somc prior art techniqles include the ln-roduction 5. of crystalline heparin whether as a singlc crystal or as El crystallinc coatin~ on the intcrior wall of the cartridge so that this prohle~n is alleviated.

Tle prior art has recognized thesc probl ~ns and llas proposed vnrious structures to minimize thcm. For example, ~.S. Patent No. 4,133,304, issued 10. 9 January 1979 to EMDE Corporation, the assignee of the present invention, dis-closes an apparatus which pe~lits the collection of a blood sample so that it is isolated within a capillary cartridge of standard volume with this cartrldge being coated with a crystalli~e heparin to prevent clotting of the blood sample.
As the sample is drawn into the cartridge through a hypodermic needle, contaminant 15. gases which may be present in the cartridge are vented through the opposite end of the cartridge which is sealed by a resiliPnt member but through which a fiber extends to provide an exhaust passageway for the gas. When the capillary cartridge is filled, the technician removes the fiber so that the resilient seal collapses to seal the blood sample within the cartridge. While this is 20. an exceptionally good device for taking the sample, it has a restriction in that only one sample volume may be obtained so that several different sizes of the sampling device must be produced and stocked to provide versatility of sample vol-lmes .

~nother device which uses crysta]line heparin is described in U.S.

25, Patent No. 4,~06,768, issued 10 June 1980- This syringe dcvice is similar to a standard hypodermic syringe, having a piston-like scaling mcmber positioned in a cylindricnl body and a plunger connected to this sealing mclnber. The only departure of this devise from the standard syringe is the provision of a plastic thread which is connected to the plunger and which 30. extends bctween the wall of the main body of the syringe and the scaling membcr so ns to br~ak thc he1-mctic flcal Lh~rcb~twccn. Til$s dcvlce ;Illowo the plunger to bc sct at a required volumc, anù, ns blood fills thc syringe~ contam;nant ~ascs escape through thc bloken scal bctwccn the side wall of the syrlngc and the sealing mcmbcr. Whcn thc syrlnge ls 5. filled with blood, the pl-lnger is rotated to withdraw the thrcad so that a seal may be re-established. Scveral problcms have becn noted in this dcvice, however, in that operat;on requires a fairly col~plex pro~
cedure, including the alignment of the hypodcrmic ncedle bcvel with the plnstic line breaking the seal of the sealing m~nber. An additional lO. problem results in the leakage of blood through the brokcn scal port:ion both while the line is in place and after the wit:hdrawal of the plastic line.

Therefore, it is desirable to provide an apparatus which permits the collecting of samples of various selected volumes by a single unit while at 15. the same time isolating the sample fro1n contaminants without leakage. The presene device acco1nplishes this by having a movable sealing member through which contaminant gases may escape but which automatically seals upon contact with a liquid such as blood or other physiological fluid.

SUMMARY OF THE INVENTION

20. It is an object of the prescnt invention to provide a device for sampling physiological fluids, such as blood, wherein contaminant gases are vented from the sampling chan1ber as a sample is taken.

It is anotl)er object of the present invention to provide a device for sampling physiological fluids such as blood wherein a sample of a 25. variable prc-selected volume may be collected and which auto~atically scals upon contact with the physiological fluid after contaminant gascs are rrmoved from the sampling device.
.

It ls yet nnottler object of t~le prencAt: invellt:ioll to ~)rovicle a device for collection of pllysLologlcal fluids whe{eLn a ch.lmb~r of varylng volume is defined by a movable sealing m~nber tllroup,h wlhlch contall1Lnan~
gases may be exhausted yet which seals against re-entry of those ~ases 5. upon contact wlth the physiological fluid.

A still further objest of the present invention is to provide for the collection of arterial blood by means of a device whcrein contamLnant gases are automatically expelled from a collection chcm~ber of variable volume which is insensitive to ro-tational orlentation and ~hio}l i.ncludes 10. an anti-coagulant to prevent clotting of the arterial blood.

To accompli.sh these and other objects, the present invention broadly includes a housing member or main body having one end matable with a hypo-dermic needle and in fluid communication with the needle. A movable end wall is mounted in the interior of the ho~sing member so that it may b~
15. positioned to define a chamber of pre-selected but variable volume. Sealing means is associated with the end wall for maintaining an hermetic seal completely around its perimeter against the interior side wall of the housing member. One ~r more exhaust passageways are formed in the movable end wall with these passageways containing a liquid reactive materlal which 20. will substantially seal the passageways on contact with a liquid. When the sample is being drawn, fluids in the fo-rm of gaseous contaminants are evacuated through the passageways, but, as the liquid blood comes in contact with the end wall and its associated passageways, the liquid reactive means in the passageway seals the passage~ay so as to prevent contaminant 25. gases from re-entering the chamber to contaminate the blood sample. In this manner, a pure sample is obtained.

In the preferred embodiment of the present invention, the main housing member is cylindrical in shape and closed at one end except for an axial bore extending through the closed end. An attac~lent means such as an - ~ 30. axially projecting nub is provided on the exterior of the closed end so that a hypodermic needle may be attached there~o with the hypodermic needle being in fluid communication with the .in-teri.or of the housing Member. The movable end wall is defined by a cup-shaped member which receives the tip of a plunger, and the sealing member-plunger assembly is placed axially in the housing member. The plunyer extend.s through an opening in the housing member opposite its closed end to be exteriorly accessible to the user of the device. Since the plunger is manuall.y movable, an opera-tor can selectively pos.ition the sealing member to acljust the voll~e of the sample chamber which is defined by the end wall of the sealing msmber and the closed end wall of the housing member.
In order to vent contaminant gases, a plurality of passageways extend longitudinally through the sealing member so that the chamber of variable volume communicates with the external atmosphere. The passageways are equi-angularly spaced around the common longitudinal axis of the sealing member and the housing member. A liquid reactive material, such as a fiber, completely fills each of the passageways so that, upon contact with a liquid, the fibers swell to substantially seal the passageways.
In operation, the hypodermic needle is attached to the syringe device, the sealing member is adjus-ted for the desired volume, and -the needle inserted into the body. ~s the sample fluid fills the chamber of variable volume, unwanted gases are expelled through the passage-ways past the fibrous materials so that they may exit the chamber. However, as the liquid sample comes in contact with the fibrous material in the passageways, the passageways are sealed by the swelling of the fibers so that gases may not re-enter the chamber to contaminate the sample fluid.
By providing a plurality of exhaust passageways, and preferably three or more such passageways, the effect of the rotational orientation of the sealing member is minimized since there will always be one passageway oriented near the extreme vertical portion of that chamber when the housing member is at small angle to the horizon.
Other object.s,advantages and features of the present invention will . sd ~ -5-become more readily appreciatcd alld understood whc!n t~qken togeLher with the following detalled dcscription in conJurlctlon wltll the accc)mpanylng drawings in which:

BRIEF DIASC~IPTI()N OF ~IE DRAWINGS

5, Figure 1 is a side view in elevcltion of the physiological fluid sampling device according to the preferred embodimen~t of the present invent ion;

Figure 2 is a side view in elevation of the interior tip of the plunger member according to the preferred embodiment of the present invention;

10. Figure 3 is a side view in elevation of the sealing member according to the preerrecl embocliment of the present invention;

Figure 4 is a cross-sectional view of the plunger member talcen about lines 4-4 of Figure 2;

Figure 5 is a bottom-plan view of the plunger m.ember taken about lines 15. 5-5 of Figure 2;

Figure 6 is a cross sectional view oE the pref erred cmbodiment of the present invention showing the sealing member and plunger tip mounted in thc housing member according to the preferred embodiment of the present invention;

Figure 7 is a side view in elevation of the first alternate embodi;.:ent 20. of the plunger tip of the present invention;

Figure 8 is a eross-sectional view taken about lines 8-8 o Figure 7;

Figure 9 is a bottom-plan view taken about lines 9 9 of Figure 7;

i ~r~ .
;3S,3",,~ 3 Eigure 10 is a .s:Lde v:lew in elevlt-loll of thc f:i.r6t nlternate embodiment of the seal:ing m~tnber of the preserlt invelltlon;

Figure 11 is a bottom-plan view of the sealing member shown in Figure 10;

5. Figure ].2 is a side vlew in cross-section showing the pl.unger tip and sealing member of the first alternate embodi~ent of the preserlt invention mounted in the housing me~nber;

Figure 13 is a side-plan view of a plunger tip accordi.ng to a second alternate embodiment of the present invention;

10. Figure 14 is a bottom-plan view taken about line 14-14 of Figure 13;

Figure 15 is a side view in elevation of the sealing ~ember according to the second alternate embodiment of the present invention;

Figure 16 is a bottom-plan view talcen about line 16-1.6 of Figure 15;

Figure 17 is a side view ln cross section of the sealing member taken 15. about lines 17-17 of Figure 16;

Figure 18 is a side view in cross section of the plunger tip and sealing member mounted in the housing member according to the second alter-nate embodiment of the present invention.

~ETAI~ED DESCRIPTION OF ~IE P~EFERR~D EMBODIMENT

20. The present invention is directed to a device or apparatus for sampling physiological fluids and is particularly useful for sampling arterial blood for purposes of providing a specimen for arterial blood .

-gas analysi8 and blood pll arl~lysls . It should be ~Ipprec l;!tcd, howcver, tl).lt the present lnvention is fiuitahlc ~or collectinE, other typer: of physlologlcal specimens and is not limited to thc sampling of artcrial blood. The samyllrlg is done so that a pre-selected volume Or blc-od is reccived by Lhe device, 5. although this volume i9 variable according to the preferred ~nbodiment of the present invcntion, with unwanted contaminant gases being ventcd froLn the device as the sample is talcell in ordcr to obtain a En~re sample for analysi.s.

The preferred embodiment of the present invention is showrl in Figure ]
wherein sampling device 10 has a main housirlg 12, constructed of glass or 10. plastic, which is graduated in units of volume as is known in the medical art.
One end of housing :12 is substantially closed by end wall 14, and a nub 16 is provided to attach a hypodermic needle 20 housing 12 in fluid communication with the interior thereof. Specifically, hypodermic needle 20 has a sleeve 22 which receives nub 16 so that fluid entering the hypodermic needle can 15. pass through bore 18 into the interior of housing 12. Housing 12 is provided with an open end 24 opposite end wall 14, and a plunger 26 extends through opening 24 so that it has a portion positioned exteriorly of housing 12 with plunger 26 being axially movable into and out of housing 12. Preferably, housing 12 is cylindrical with a surrounding side wall 28 which is coated 20. with sodium or lithium heparin in crystalline form to prevent blood clotting as discussed in U~S. Patent No. 4 ,133 ,304 . End wall 14 and side wall 28 define an open cavity 30 in the interior of housing 12. Plunger 26 extends, therefore, into this cavity. A piston mamber 32 is mounted in cavity 30 and is axially slidable in housing l2. Accordingly, piston member 32 divides 25. cavity 30 to def ine a chamber 34 . Chamber 34 thus has a variable voluoe depending upon the selectable axial position of piston manber 32 in cavity 30.

Preferrably~ piston manber 32 i5 formed of a resilient material, such as n~bber, in a generally cylindrical configuration and acts as a -seal-Lng member for ch2ul)ber 34. A cnvlty 36, h<1ving a mr~ut:h 55, Is formed in the interior of piston mcmbrr 32 to rcceive .-n end portion or mounting m~nber 50 of plunger 26. Piston mcl11ber 32 has a pair of radially outwardly extcnding shoulders 38 and 40. When piston member 32 iB positioned 5. within cavity 30, shoulders 33 and 40 abut side wall 28 on the intcrior of housing 12 completely around the perimeteT of piston rnc1nber 32 to form an hermetic seal between piston member 32 and side wall 28. Since s11oulders 38 and 40 project radially outwardly from the n2ain body oI piston m~nber 32, a small chamber 42 is def ined between the piston mel11ber 3Z and side wall lo. 28 with chamber 42 being in the shape of a cylindrical shell.

The construction of plunger 26 is shown in greater detail in Figure 2, 4 and 5 wherein it should be appreciated that plunger 26, in the preferred embodiment, is formed of a plastic material and has an elongated main body which terminates at one end in a flat disc 46 and at 15. the opposite end in a flat~disc 48, which is slightly smalier than disc 46.
The main body of plunger 26 is formed of four vanes 44 which are connected at a common longitudinal edge ana which extend radially outwardly at right angles to one another. Discs 46 and 48 are thus perpendicular to the longitudinal axis of plunger 26 defined by the junction of vanes 44.

20. A mounting member 50 in the form of a flat circular plate is mounted to a disc 48 by means of four smaller vanes 52 which extend radially out-wardly from the common longitudinal axis o vanes 44. Mounting member 50 is oriented generally parallel to disc 48 and serves to mount piston member 32 to the end of plunger 26. Specifically, mounting member 50 is 25. matably received by cavity 36 formed in piston member 32 and is resiliently retaioed thereon by means of a radially inwardly projecting shoulder 54 which surrounds the interior surface of cavity 36 of piston 32 adjacent shoulder 40. Accordingly, shoulder 55 has an axial thickness slightly smaller than the lenpth of vanes 52, and cavity 36 is shaped to conveniently 30. receive mounting member 50.

.

_g_ D~

From the ahove, it aho~lld bc npprccla-cd that plitun m~qt~bcr 32 1B
~cially movable within cavity 30 by mcans of manual operation oE plungcr 26 Thus, a chamber 34 of v~riable volumc i5 formed, B5 noLcd, and shouldcrs 38 and 40 always remain in an hermctically sealed relationship with the intcrior 5~ surfacc of side wall 38.

As a physiological fluid enters chamber 34 it is dcsirable that con-taminant gases bc pcrmitted to exit chamber 34. To this end, at Icaat one exhaust passageway is provided through plston membcr 32 and around the cnd of plunger 26 as defined by plate 50, vancs 52, and disc 48. Specifically, in the 10. preferred embodiment, a pair of exhaust passageways are fonlled for vcnting contaminant gases from chamber 34 ~ As is shown in Figure 2, 4 ? and 5, disc 48 has a pair of holes 56 positioned 180 apart and plate 50 has a pair of channels 58 formed longitudinally in its clrcumferential edge so that each channel 58 is respectively aligned with a hole 56. Piston member 32 has a lS. pair of ports 60 formed in its end wall 62 in communication with cavity 36.
Accordingly, chamber 34 is in fluid communication with cavity 30 so that contaminant gases may pass through port 60 into cavity 36 after which they may pass through channels 58 around plate 50. The gases are thcn vented to the external atmosphere by passing through holes S6 formed in disc 48 and into 20. cavity 30.

~ ince it is important, for the scope of this invention, that contaminant gases not be permitted to re-enter chamber 34 after it is filled with the physiological fluid, it is necessary that the cxhaust passageways be sealable upon the filling of chamber 34 with the fluid, which, in the case of physio-25. logical fluids, is in the fonn of a liquid material, such as blood. To this end, a liquid reactive material is positioned in the fluid passageways, which material reacts on contact with liquid to substantially seal the passagewa In the preferred embodiment of the present invention, the liquid reactive material is definPd by a thread 64 which is positioned in each of thcse 30, passageways. As may be seen in Figure 6, a pair of threads 64 are cach 3~ 7~

tnounted to extend betwe~n cav-Lty 30 and chambc!r 34. In 90 dolng, each thread 64 extends through a rec;pectlve hole 56, around shoulder 64 and throtlgh a respective channcl 58 so that lt may thcn pass through port 60 in end wall 62 to terminate in chamber 34. ~hus, each thread 64 completely bypasses thc 5. plunger tip to enable thc ventin6 of gase9 from chamber 34. Each threa(l 64 performs a dual function~ First, each thread 64 act9 to maintain its respecLJve port 60 open and to provide a gas vent path. Second, upon contact with the liquid blood, the fibrous ti~read swclls to seal ports 60, and, corIespondingly~
end wall 62 is sealed to prevent re-elltry of contEullinan~ gases.

10. The operation of the preferred embodiment of the present invention may now be more fully appreciated. Specifically, the user of sampling syringe 10, such as a doctor or other medically trained person, first connects a hypodermic needle assembly 20 and 22 to nub 16 so that hypodermic needle 20 may be inserted in the appropriate location from which the physiological fluid 15. sample is to be talcen~ Plunger 26 is then manually moved so that piston 32 connected thereto is axially slid in housing 12 to a selected location corres-ponding to the volume of physiological fluid to be talcen. This volume, of course, corresponds to the volume of chamber 34 defined by end wall 14, side wall 28 and end wall 62 which is variable depending upon the position of piston 20. member 32 in housing 12. The hypodermic needle 20 may then be inserted into tbe pztient's body such that the pressure of the physiologica] fluid will cause chamber 34 to begin filling. As chamber 34 fills with the physio-logical fluid in liquid form, air or other contaminant gases contained in chamber 34 are exhausted through ports 60 and around the plunger tip as 250 described above so that they nay escape through cavity 30 to the external atmosphere. Upon contact of the physiological fluid, threads 64 swell to seal ports 60 thereby preventing the re-entry of contaminant gases into chamber 34 and thus provide a pure sample of physiological fluids to be tested, The hypodermic needle 20 may then be withdrawn from the patient's body and 30~ inserted into a standard needle sealer, such as a rubber stopper (not shown) as is known in the art.

~n alternate ~qnbodiment of ii~e plullgcr tlp nsseqllbly al1d the piston ~ember ii5 shown in Figures 7 tilrougll 12. ~hile -ln mcmy ways the structurc shown in Figures ~ through 12 is similar to that discusse(l wll:h respect to the preferred embodiment shown in Figures 1-6, tl-is first alLernate 5. embodiment provides a di~ferent arrangement for and number of the exhaust passageways which permit the venting of gas from chamber 34 to the external enviromnent.

Speclfically, as shown in Figures 7, 8, and 9, plunger 126 is made up of four main vanes 144 positioned in a manner similar to that described 10. with respect to the preferred embodiment. Plunger 126 terrninates in a flatdisc 148 which is oriented perpendicularly to vanes 144 and a second sct of smaller vanes 152 are attached to disc 148 and support a flat mounting member 150 also in a manner similar to that described with respect to the preferred embodiment. Whereas the preferred embodiment provided a pair 15. of holes 56 which were axially spaced 180 apart from one another, the alternate embodiment shown in Figure 8 provides four channels 156 which are cut radially inward into the disc 148 and are spaced equiangularly around its circumference so that they are 90 apart from one another. Likewise, a plurality of channels 158 are longitudinally cut into the edge of mounting 20. member 150 so that there is a respective channel 158 matched with a channel 156. Channels 158 correspond to channels 58 of the preferred embodiment discussed above.

Piston member 132, according to this alternate embodiment, is formed correspondingly to piston member 32 of the preferred embodiment, 25. except that piston 132 is provided with ports 160 which are equal in number to the number of channels 156 and channels 158. Thus, in the alternate embodiment shown in Figures 10, 11, and 12, piston member 132 is provided with four such ports 160 which are adapted to form part of the exhaust passageways or vents for contaminant gases. The structure 30. of piston member 132 is shown in greater detail in Figure 10 where it ~12--shnuld be appreclaecd that pl~ngcr 132 is Kcncr~lly cup-5h;~pcd "lavinK a surrounding side wal.l and a conic nose or end wall 162 wlth ports 160 bclng drilled through cnd wall 162. Accordingly, pis~on lo~ber 132 hns an intcrnal cavity 136 with an open mouth 155 which is adapted to rcceivc mounting 5. member 150 in a manner dcsczibed below. Piston m~ber 132 has a pair of radially outwardly-projecting shoulders 138 and 140 which are axially spaced apArt from one another and a radially inward]y projecting shoulder 154 near an end piston member 132 opposite end wall 162.

Figure 12 shows plunger 126 and piston ~ember 132 positioned in 10. cylindrical housing 112 comparable to that shown in Figure 6 of the preferred embodiment. Here, piston member 132 is mounted in housing 112 such that shoulder 138 and 140 form an hermetic seal completely around the interior side wall of housing 112. Mounting member 150 is passed througll mouth 155 and is received in cavity 136 of piston member 132 with shoulders 154 being 15- positioned between mounting member 150 and disc 148 to resiliently retain mounting member 150 in cavity 136. Liquid reactive material in the form of a plurality of threads 164 extends through each port 160 and are wound through channels 158, past vanes 152, and through channels 156 to projece into cavity 130 wllich is exposed eo the external environment. In this 20. manner, an exhaust or vent passageway is formed so that contaminant gases can pass from cavity 134 through piston member 132 and then bei:vented into cavity 130. Threads 164 provide a liquid reactive maeerial such ~hat, upon contact with physiological fluids, threads 16~ will swell to seal ports 160 so that contaminant gases cannot re-enter the sample of physiological 25. fluids so taken into chamber 134.

A third embodiment of the prcsent inveneion is shown in Figures 13-18 with this cmbodimene departing in several aspeces from ehe embodimelles show~ in Figures 1-12. Particularly, Figure 13 shows plunger 226 compriscd of four vanes 244 which are connected at a common vertex and extend radially 30. outwardly fro~ one another. Vanes 244 tcrminate in a flat disc 248 mountcd at n right angle thcrcto, nnd n post 252 i-; ax~nlly moIlnted to disc 248.
Post 252 supports a mounting melllbcr 250 wllich is gencrnl]y cylindrlcal but which has a frustoconical nose 251. A-; discusscd In gre~ter detail below, disc 248 is provided with three holes 256 which arc equiang~llarly 5. spaced around its periuneter adjacent its edge, and mounting member 250 is provided with a slot 258 cut longitudinnlly thereill to a depth corresponding to the radius of post 252.

A piston member 232 is shown in Figures 15, 16, and 17, and has Q
generally cylindrical, cup-shaped confi~ration. T~articularly, piston 10. member 232 has an interior cavity 236 and a radially inwardly projecting shoulder 2S4 adiacent mouth 255 of cavity 236. Cavity 236 is adapted to receive mounting member 250 with shoulders 254 resiliently retaining piston member 232 on mounting member 250. Piston member 232 has a pair of radially outwardly projecting shoulders 238 and 240 which are axially spaced from 15. one another at opposite ends of piston member 232, and a closed end wall 262 having a conic nose. Shoulder 238 is adjacent end wall 262 with shoulder 240 being at an end of piston 232 opposite end wall 262. End wall 262 is provided with three ports 260 therethrough with ports 260 extending from the exterior of piston member 232 into cavity 236. Ports 260 are 20. equiangularly spaced about the axis of piston member 232 as shown in Pigure 16 with there being three such ports 260 in this embodiment of the present invention.

The mounting of piston member 232 onto plunger 226 is shown in greater detail in Figu~e 18 where it should be appreciated that the plunger and 25. piston member asst~nbly is adapted to be positioned in a generally cylind-rical housing 212 in a manner similar to that described with respect to housing 12 of syringe 10 according to the preferred embodiment of the present invention. As is shown in Figure 18, housing 212 terminates in an end wall 214 which is provided with an axially extended nub 216 which 30. has a bore 218 therethrough. Nub 216 is adapted to secure a hypodermic -14 - ~

needle onto end wall 214 so that fl-lld communical lon is eatnl)lisilc(l frcnn the hypoder;nic nee(lle thro~lgh bore 218 into chamber 234 which i: dCfilled bet~!7ecn end wall 214 of housing 212 and end wall 262 of piston mcmber 232, Piston m~nber 232 is positioned ~o be ax lal]y slidable in llousing ~12 5. with shoulders 238 and 240 defining an hermetic seal complctely around thc interior side wall 223 of housing 212. J~ccordin~ly, side wall 228, shouldcr 23E~, and shoulder 240 form a chambcr 242 in the sll.lpe of a gerle~ lly cylindrical shell with end wall 262 therefore defining a movable end wall for chamber 234. As sloted, mounting member 250 is matal>ly received in 10. ca*lty 236 and is retained therein by means of shoulder 254 which has an axial thickness slightly smaller than the axial length of post 252 with mouth 255 havislg a slightly greater diameter than ~ost 252. In this manner, the end of piston 232 adjacent shoulder 240 abuts disc 248 of plunger 226.

As is shown in Figures 17 and 18, ports 260 receive a thread 264 which 15. is doubled over upon itself so that its two free ends 266 extend into cavity236 with the folded mid-portion extending slightly outwardly from end wall 262. This configuration is desired for ease of manufacture, but accomplishes the same purpose as threads o4 and 164 of the first two embodiments of the present invention as described above. Sepcifically, the tip of plunger 20. 226 defined by disc 248, post 252 and mounting member 250 are configured so that there is sufficient play to avoid a seal between piston member 232 and the tip of plunger 226. In this manner, then, three exhaust passageways are defined by ports 260, slot 258 and holes 256 so that contaminant gases may escape from chanber 234 through end wall 262 and 25. into cavity 230 as chamber 234 fills with a sample physiological fluid.
Of course, since cavity 230 is open to the external atmosphere, the contaminant gases can be released. To this end, it is necessary that there be sufficient room around the mounting member 250 and post 252 such that the gases can so escape. Notch 258 helps facilltate escape 30. of the contaminant gases through mounting member 250. - Threads 264, in a ~L~

manncr simllar to threacls 6~ and 164 are formed of a 1;quid reactivc rnfltorlsll such that, as the physiological fluid contacts eact- of thrcads 2G~, cach thread 264 swells to substantinlly soal its respectlve ports 260 rrom passage of contaminant gases so that contaminant gascs mny not rc-enter 5. chamber 234 once it is filled with thc physlological fluitl.

The operation of the sampling devices shown and descr-ibed with respcct to the second and third cmbodimcnts of thc present invention i5 the samc as the operation o the preferred cmbodiment. ~lowevcr, it should be appreciated that since physiological samples are oftcn taken with the syringe 10 oriellted 10. at a small acute angle relative to the horizon and with the beveled tip of the hypodermic needle upward, it is helpful to have a sampling device that is ins~nsitive to rotational orientation. In past devices, this orientation has been critical where only one exhaust passageway, of whatever nature, has been provided. While orientation of the pores 60 is somewhat sensitive 15. with respect to the embodiment of the present invention shown in Figures 1-6, the second two embod:iments substantially eliminate the problem by providing either three ports as shown in Figure 13-18 or four ports as shown in Figures 7-12 since there is always a port oriented near the uppermost portion of a respective chamber 134 or 234 regardless of tl-e rotational positioning 20. of the piston member in its respective housing. It should be appreciated, however, that it is within the scope of the present invention to provide any number of ports in the piston member so long as the requisite liquid reactive material be provided in those ports to substantially seal them upon contact with a physiological fluid.

25. ~nbodiments of the present invention have been sho~Jn and described with a degree of particularity to enable a complete and full understanding of those embodiments. llowever, lt should be understood that the present invention involves invcntive concepts def ined in the appcnded claims, and these invcntive concepts are not intended to be limited except insofar as 30. the prior art requires. This physiological fluid sampling syringe may takc other fonn~ and iF, su~cel)tib].c to variou3 chanl,c3 i.n (letail without departing from the principles of thls k~ventlon.

Claims (27)

WE CLAIM:

1. An arterial blood sampling device adapted for use with a hypodermic needle comprising:

a housing member including a surrounding sidewall, an end member, said end member having a bore there through and an open end opposite said end member, including mounting means for mounting a hypodermic needle to said housing member in fluid communication with said bore;

a movable end wall member positioned in said housing member and movable axially therein, said movable end wall, said side wall and said end member defining a chamber of variable volume in fluid communication with said bore; said end wall having an axial passageway therethrough in fluid communication with said chamber;

sealing means associated with said end wall for maintaining an hermetic seal between said end wall and said side wall; and liquid reactive means in said passageway for substantially sealing said passageway on contact with liquid.

2. An arterial blood sampling device according to claim 1 wherein said liquid reactive means includes a fibrous material positioned in said passageway.

3. An arterial blood sampling device according to claim 2 wherein said liquid reactive means is a thread having a portion thereof protruding from said endwall member into said chamber.

4. An arterial blood sampling device according to claim 1 including a plunger member mounted to said moveable end wall member and extending through said open end to the exterior of said housing member in an axial direction.

5. An arterial blood sampling device according to claim 4 wherein said plunger having an attachment nub on its internal end, said end wall member having a cavity formed therein for matably receiving said nub, said nub having a channel in fluid communication with said passageway.

6. An arterial blood sampling device according to claim 1 wherein said movable end wall member is formed of a resilient material, said liquid reactive means including a fibrous material threaded through said end wall.

7. An arterial blood sampling device according to claim 1 wherein said end wall has a plurality of passageways formed at equiangularly spaced positions about tile axis of said housing member, there being liquid reactive means positioned in each said passageway for substantially sealing each respective passageway on contact with liquid.

8. An arterial blood sampling device according to claim 1 including an anti-coagulant material in said chamber.

9. An arterial blood sampling device according to claim 8 wherein said surrounding sidewall interior surface is coated with said anti-coagulant material.

10. An arterial blood sampling device according to claim 1 further including a plunger member mounted to said movable endwall and extending exteriorly of said housing, said housing being cylindrical, and said end wall member being a generally cylindrically shaped plug formed of a resilient material and having a pair of radially extending circumferential lips at opposite ends thereof, said plug having a cavity formed in one end for matably receiving the interior end of said plunger, said lips maintaining an hermetic seal with said housing.

11. A syringe device adapted for use with a hypodermic needle, comprising:
a hollow body member having a surrounding sidewall, an open end and a closed end opposite said open end, said closed end having a bore therethrough and means for securing said hypodermic needle to the exterior of said body member in fluid communication with said bore;
a sealing member positioned in the interior of said body member, said sealing member having sealing means for maintaining an hermetic seal with said sidewall and being axially movable in said body member, said sealing member, said sidewall and said closed end defining a chamber of variable volume;
a handle member extending through said open end and operatively connected to said sealing member whereby said sealing member may be selectably positioned axially along the interior of said body member;
said sealing member having a gas vent passageway therethrough for per-mitting exhaust of gas from said chamber through said sealing member; and liquid reactive means in said vent passageway for substantially sealing said passageway on contact with a liquid for preventing exhaust of gas from said chamber.

12. An arterial blood sampling device according to claim 11 wherein said scaling member being generally cup-shaped having an open cavity and a closed endwall, said handle member having an exterior end adapted to be manually gripped by a user, an interior end comprising a flat plate oriented in a plane perpendicular to the longitudinal axis of said handle member, adapted to be matably received by said cavity and a post interconnecting said mounting member and said flat plate.

13. An arterial blood sampling device according to claim 12 wherein said gas vent passageway comprising a bore through said closed endwall, a longitudinal channel in said mounting member and an opening in said plate.

14. An arterial blood sampling device according to claim 11, there being a plurality of gas vent passageways through said sealing member, each said gas vent passageway comprising a bore through said closed endwall, a longitudinal channel in said mounting member and an opening in said plate, said gas vent passageways being equiangularly spaced about the axis of said sealing member.

15. An arterial blood sampling device according to claim 14 wherein said liquid reactive means in each said gas vent passageway includes a fiber thread extending through said bore in said endwall, through said channel and through said opening.

16. A syringe device according to claim 11 wherein said sealing member having a cavity in a first end facing said open end, an endwall opposite said first end, and a radially inwardly projecting shoulder surrounding said cavity adjacent said first end, said handle member having a mounting member on its interior tip, said shoulder resiliently retaining said mounting member in said cavity.

17. An arterial blood sampling device according to claim 12 wherein said sealing means includes a pair of radially outwardly extending resilient shoulders surrounding the perimeter of said sealing member at axially spaced-apart locations from one another.

18. A syringe device adapted for use with a hypodermic needle in sampling physiological fluids, comprising:
a generally tubular housing member having an open end, a closed end opposite said open end, and a surrounding sidewall;
connection means on said closed end for connecting said hypodermic needle to the exterior of said housing member closed end, said closed end having a bore therethrough adapted for fluid communication with said hypedermic needle;

a plunger member extending through said open end and having a portion exterior of said housing member adapted for manual gripping and having a portion interior of said housing member terminating in a mounting member;
a cup-shaped sealing member positioned in the interior of said housing member and having an endwall and a surrounding sidewall forming a cavity in said scaling member adapted to mateably receive said mounting member, and having sealing means on the exterior of said surrounding sidewall of the sealing member for maintaining an hermetic seal between said sealing member and interior surface of said tubular housing member's surrounding sidewall;
said sealing member being axially slideable in said housing member so that the surrounding sidewall and the closed end of said housing member and said endwall of said scaling member define a chamber of variable volume, said endwall having a passageway therethrough in fluid communication with said chamber and said cavity for permitting gases to flow between the chamber and the exterior of said housing member through said sealing member; and liquid reactive means in said passageway for substantially prohibiting flow of gases through said passageway upon contact with a liquid.

19. An arterial blood sampling device according to claim 18 wherein said liquid reactive means includes a fiber thread extending through said passage and having a first end terminating in said chamber and a second end termi-nating in said cavity.

20. An arterial blood sampling device according to claim 19 wherein said mounting member has a longitudinal channel formed therein.

21. An arterial blood sampling device according to claim 19 wherein said plunger includes a flat plate on its interior end and an axial post projecting from said plate, said mounting member attached to said post and having a larger cross-section than said post, said channel having a bottom surface coextensive with the surface of said post adjacent said channel and extending the length of said mounting member.

22. An arterial blood sampling device according to claim 21 wherein said plate has an opening therethrough.

23. An arterial blood sampling device according to claim 19 wherein said thread is folded on itself so that its free ends are adjacent one another to define said second end and the folded end defining said first end.

24. An arterial blood sampling device according to claim 18, there being a plurality of passageways in the endwall of said sealing member and spaced equiangularly about its longitudinal axis, each said passageway in fluid communication with said chamber and said cavity for permitting gases to flow therebetween, and liquid reactive means in each said passageway for substantially prohibiting the flow of gases therethrough upon contact with a liquid.

25. An arterial blood sampling device according to claim 24 wherein said liquid reactive means includes a fiber thread.

26. An arterial blood sampling device according to claim 25 wherein there are three said passageways, each said passageway formed at an acute angle to said axis and having an opening into said chamber located adjacent the edge of endwall of said sealing member.

27. An arterial blood sampling device according to claim 25 wherein said mounting member has a longitudinal channel radially formed therein.