Title:
VALVED BLOOD SAMPLING NEEDLE ASSEMBLY
United States Patent 3874367
Abstract:
A needle assembly for facilitating the collection of a blood sample from a patient into an evacuated collection container while alleviating the danger of flow of fluid from the collection container into the patient during and after collection of the blood sample. The assembly includes a housing, a forward penetrating end for insertion into the patient, a rearward end for coupling with an evacuated collection container, a continuous passageway therethrough, and a resilient elastomeric valve member on the assembly normally in position to close the passageway between the patient and the rearward end and adapted to be responsive to a predetermined decrease in pressure in the rearward end to deform and automatically open the passageway when an evacuated container is coupled with the rearward end. Thereafter, the valve is responsive to a predetermined increase in pressure in the rearward end of the assembly to automatically return to the closed position and prevent flow of fluid from the rear end of the assembly to the patient.
US Patent References:
Sterile article package and method of making the same
Grossman - August 1965 - 3203545
Sterile container
Bennett et al. - February 1966 - 3235069
Push control valve for instant deflation of blood pressure instruments
Berliner - June 1966 - 3254671
APPARATUS FOR TAKING MULTIPLE SAMPLES
Russo et al. - February 1970 - 3494352
BLOOD SPECIMEN COLLECTION ASSEMBLY
Hughes - January 1971 - 3557778
Sterile article package and method of making the same
Grossman - August 1965 - 3203545
Sterile container
Bennett et al. - February 1966 - 3235069
Push control valve for instant deflation of blood pressure instruments
Berliner - June 1966 - 3254671
APPARATUS FOR TAKING MULTIPLE SAMPLES
Russo et al. - February 1970 - 3494352
BLOOD SPECIMEN COLLECTION ASSEMBLY
Hughes - January 1971 - 3557778
Application Number:
05/267559
Publication Date:
04/01/1975
Filing Date:
06/29/1972
View Patent Images:
Export Citation:
Assignee:
Becton, Dickinson and Company (East Rutherford, NJ)
Primary Class:
Other Classes:
604/237, 600/577
International Classes:
A61B5/145; A61B5/15; A61B5/14; A61M5/00
Field of Search:
128/2F,2G,2R,DIG.5,276,218NV,274,221,35V 206/63.2R
US Patent References:
Primary Examiner:
Howell, Kyle L.
Attorney, Agent or Firm:
Kane, Dalsimer Kane Sullivan And Kurucz
Claims:
I claim
1. A needle assembly for facilitating the collection of a blood sample from a patient into an evacuated collection container while preventing flow of fluid from the collection container into the patient during and after collection of the blood sample comprising:
2. The invention in accordance with claim 1 wherein the rear end of the housing has a threaded outer surface portion for interengagement with the holder for an evacuated collection container.
1. A needle assembly for facilitating the collection of a blood sample from a patient into an evacuated collection container while preventing flow of fluid from the collection container into the patient during and after collection of the blood sample comprising:
2. The invention in accordance with claim 1 wherein the rear end of the housing has a threaded outer surface portion for interengagement with the holder for an evacuated collection container.
Description:
BACKGROUND OF THE INVENTION
In the blood sampling field, there are several well known systems. One of the more commonly used systems is the collection of blood from a vein through a needle assembly into an evacuated container. The evacuated container provides the pressure differential necessary to facilitate flow and collection of the blood through the needle assembly into the container.
Improvements have been made in recent years to the basic evacuated container system for blood sampling such as by the provision of a valve on the assembly to automatically open and close the flow path through the assembly as evacuated containers are coupled in succession with the assembly. In this manner a multiplicity of samples can be collected in a multiplicity of containers with only one venipuncture required.
Frequently the evacuated containers contain chemical materials, useful in the clinical laboratory tests to be conducted after mixing with the patient's blood. However, these chemical materials may be harmful to a patient if any were to flow from the evacuated container into the patient's blood system. For example, some evacuated containers are partially filled with protein culture medium, and the possibility exists that if any of this protein material were carried back into the patient, such foreign protein might cause anaphylactic shock. Therefore, it would be extremely desirable to utilize a system for blood sampling which employs evacuated containers in a manner such as in the systems described above and which would alleviate the danger of back flow of fluid into the patient during and after the fluid sampling process. It would be of great advantage to have an inexpensive oneway valve which is responsive to a change in pressure and which does not require a substantial force to cause it to open and one which is sensitive to small pressure differentials in order to insure that an evacuated container is filled to the desired degree before the valve closes. This is particularly true in the blood testing field where various evacuated tubes require a carefully predetermined volume of blood fill in relation to the chemical material already in the evacuated tube so that a predetermined ratio of blood to chemical mixture is present. This assures that ultimate testing is accurate and precise.
With the above thoughts in mind particularly in regard to closely controlled filling requirements and the cost factor involved when considering quantity production of evacuated tubes and needles, any increase in threshold value of pressure differential required to open or close the valve directly increases the inaccuracy of the blood fill. Therefore, valve types requiring as near zero threshold differential pressure to open and close, while at the same time being normally closed, would be extremely valuable and important to the art under consideration.
SUMMARY OF THE INVENTION
With the above background in mind, it is among the primary objectives of the present invention to provide a needle assembly for use with an evacuated container in collecting blood samples wherein a one-way valve means is provided on the needle assembly to prevent the possibility of back flow of chemical materials from the evacuated container into the patient. The valve is designed of a resilient elastomeric self-sealing material to automatically deform and open and permit flow into the evacuated container when the system is utilized under a low pressure differential and to automatically return to the normal closed position preventing flow to and from the forward end of the needle assembly when subjected to flow pressure from the rear end of the assembly to which the evacuated container is connected or exhaustion of the vacuum in an evacuated container utilized in a sampling collection operation.
Thus, a needle assembly is provided for facilitating the collection of a blood sample from a patient into an evacuated collection container while alleviating the danger of flow of fluid from the collection container into the patient during and after collection of the blood sample. The assembly includes a housing with a forward penetrating end including a cannula extending from the housing for penetration into the blood vessel of the patient. The assembly also includes a rearward end extending from the housing and including a cannula and being adapted to be coupled in fluid communication with the interior of an evacuated collection container. Portions of the assembly form a passageway for directing blood from the vein to the collection container when the forward end is in the blood vessel and the rearward end is in the container. Finally, an elastomeric resilient valve member is part of the assembly normally in position to close the passageway between the blood vessel and the rearward end of the assembly and adapted to be responsive to decrease in pressure in the rearward end to deform and automatically open the passageway when the evacuated container is coupled with the rearward end of the assembly. Thereafter, the valve is responsive to a predetermined increase in pressure in the rearward end to automatically return to the closed position and prevent flow of fluid from the rear end of the assembly to the patient.
With the above objectives in mind, reference is had to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings:
FIG. 1 is a partially sectional side elevation view of the needle assembly of the invention shown incapsuled in a sealed container;
FIG. 2 is a side elevation view of the needle assembly of the invention shown in operable position in combination with a holder, an evacuated container, and a needle shield;
FIG. 3 is a fragmentary sectional elevation view thereof with the needle shield removed and the assembly in fluid communication with a blood vessel immediately prior to collection of a sample;
FIG. 4 is an enlarged fragmentary view of the valve portion of the needle assembly as shown in FIG. 3;
FIG. 5 is a fragmentary sectional view of the needle assembly in operable position with the valve portion open and blood being collected in an evacuated container;
FIG. 6 is an enlarged fragmentary view of the valve portion of the needle assembly of FIG. 5 with arrows showing the blood flowing through the needle assembly;
FIG. 7 is an enlarged sectional view of the needle assembly of the invention in operable position in the vein of the patient subsequent to collection of a sample in an evacuated container after the valve portion has reclosed; and
FIG. 8 is an enlarged fragmentary view of the valve portion of the needle assembly of FIG. 7 with the valve having reclosed upon completion of collection of a sample.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
As shown in FIGS. 1, 2 and 3 in particular, needle assembly 20 includes a housing 21 on the forward end of which is mounted a forward venipuncture cannula 22 and on the rear end of which is mounted a second cannula 23.
Housing 21 includes a forward end portion 24 having a passageway 25 therethrough. Mounted in passageway 25 is the rear end portion of venipuncture cannula 22. The cannula is held in position in a convenient manner such as by epoxy 26 as shown.
Forward portion 24 of housing 21 has a tapered frusto conical rear mating end 27 with a hollow interior. The rear end portion of cannula 22 extends rearwardly from passageway 25 into the hollow interior of tapered frusto conical portion 27. The forward end of cannula 22 extends from the forward tip of housing 21 and has a beveled tip 28 for insertion into the vein of a patient. The rear end of cannula 22 has a blunt tip 29 and the end portion adjacent blunt tip which extends from passageway 25 has an elastomeric cap or valve member 30 mounted thereon.
Valve member 30 has a closed rear end and has its open forward end in sealing engagement with cannula 22. Between the rear end of valve 30 and blunt tip 29 of cannula 22, valve 30 has a hollow center 31 in communication with the passageway through cannula 22. Valve 30 is of a self-sealing elastomeric material and contains one or more slits 32 where hollow portion 31 is located. Valve 30 is of a lesser inner diameter than the outer diameter of cannula 22 so that when the sleeve or valve 30 is positioned on cannula 22 it is expanded at the location of contact so as to provide sealing interengagement between the cannula and valve sleeve.
Housing 21 is of a two-part construction with the tapered outer surface of forward portion 24 which forms frusto conical portion 27 in frictional engagement with a tapered inner surface of a rear end 33 of the housing. Rear end 33 includes the hollow cylindrical portion 34 with a tapered inner surface in interengagement with forward end 24 and a rear cylindrical neck 35 having a passageway 36 therethrough. The outer surface 37 of neck 35 is threaded for interengagement with a holder as will be discussed in detail below. As shown, when forward portion 24 and rear portion 33 of housing 21 are interengaged, a chamber 38 is formed therein. Access to chamber 38 is gained through the hollow cannula 22 mounted in passageway 25 or through the hollow cannula 23 which is mounted in passageway 36. Cannula 23 is mounted in a conventional manner such as by epoxy 39. The forward tip of cannula 23 is located intermediate the ends of passageway 36 and the rear tip of cannula 23 extends beyond neck 35 and has a pointed end 40 for penetration into an evacuated container as will be discussed in detail below. As shown, cap or valve 30 is housed within chamber 38 in housing 21.
In reference to FIG. 1, it can be seen how needle assembly 20 is packaged for shipment and storage in a sealed aseptic fashion prior to use. The package is in the form of a hollow capsule 41 of rigid material such as a rigid plastic in a two-part assembly. The forward part 42 covers the forward part of needle assembly 20 and terminates intermediate the ends of housing 33. The rear part 43 covers the rear end of the needle assembly and terminates below the lower end of housing 21. Both the forward part 42 and the rear part 43 of capsule 41 have a closed end distal from one another and an open end proximal to one another for frictional interengagement to form capsule 41 with the needle assembly contained therein. At the point of joinder of portions 42 and 43 of capsule 41 an outer cylindrical mating surface is formed on which is mounted a tamper-proof band 144. As long as band 144 is not disturbed and remains intact, the capsule 41 is unbroken and the assembly 20 contained therein remains in aseptic condition. The rigid nature of capsule 41 alleviates the danger of damage to the assembly during shipment, storage and handling prior to use. Assembly 20 is of a disposable nature so that, if desired, once capsule 41 is opened and assembly 20 is utilized it may be discarded.
In use, tamper-proof band 144 is broken and capsule 41 is opened by removing rear portion 43 from forward portion 42 and from its surrounding relationship with the rear end of assembly 20. Forward portion 42 of capsule 41 is retained in position covering venipuncture cannula 22 to alleviate the danger of contamination thereeof during the preliminary preparation procedures prior to use. Removal of rear end 43 of capsule 41 exposes cannula 23 and neck 35 so that a holder 44 may be extended over cannula 23 and into threaded interengagement with threaded surface 37 of housing 33. In this position as shown in FIG. 2 cannula 23 is located within holder 44.
An evacuated container 45 is then partially inserted within holder 44 to the rear of tip 40 of cannula 23. The evacuated container is of a conventional type having a tubular body 46 terminated in an open end which is capped and sealed by a punctureable self-sealing stopper 47. The assembly is then in condition for the actual blood sampling operation and forward portion or shield portion 42 of capsule 41 can then be removed from frictional interengagement with housing 21 thereby exposing cannula 22. As shown in FIG. 3, tip 28 of cannula 22 is then inserted into vein 48 of a patient. Since valve 30 is closing the rear blunt end 29 of cannula 22, no blood can travel beyond hollow chamber 31 within valve 30 under the influence of venous pressure alone.
Evacuated container 45 is then extended forward until tip 40 of cannula 23 punctures through stopper 47 thereby providing communication between the interior of evacuated tube 45 and central chamber 38 of housing 21. Thereafter, the pressure differential interiorly and exteriorly of valve 30 caused by the vacuum within container 45 automatically opens slits 32 and permits blood to flow from the vein through cannula 22 through slits 32 through chamber 38 and then through cannula 23 into container 45. Flow will continue as long as the pressure differential exists. Therefore, once the vacuum is exhausted within container 45 valve 30 will automatically return to its normal configuration with slits 32 returning to the sealed position thereby shutting off the blood flow adjacent to blunt end 29 of cannula 22. Similarly, should a back pressure build up during the filling operation, the pressure differential will be disturbed and the increased pressure exteriorly of valve 30 will cause slits 32 to be closed and eliminate any danger of fluid flow into valve 30 and consequently into cannula 22 and the patient. As discussed above, this is particularly useful in instances where harmful materials to be used in later chemical analysis may be contained within tube 45 and it is extremely desirable to avoid any of the possibly harmful material entering the patient.
FIGS. 3-8 show the sequence of operations in the taking of a blood sample while alleviating the danger of blood flow or other fluid flow back through the needle into the patient.
FIGS. 3 and 4 show the venipuncture having been made in the vein 48 of a patient. With valve 30 in the closed position, no blood flow due to venous pressure can occur beyond valve 30 in the assembly. The evacuated tube 45 is shown in position for engagement with the rear tip of the needle assembly. Thereafter, in FIGS. 5 and 6 the evacuated tube 45 has been coupled with assembly 20 so that tip 40 of cannula 23 is within the evacuated tube 46. The vacuum causes a pressure differential and reduces the pressure in chamber 38 so that slits 32 open in valve 30 permitting blood to pass through needle assembly 20 into evacuated tube 46 for collection. During this procedure, should any back flow or increased pressure occur to the rear of valve 30 this force will cause slits 32 to return to their relaxed position sealing valve 30 and preventing flow in either direction within the assembly.
When the vacuum has been exhausted in tube 46, the pressure will equalize on both sides of valve 30 and valve 30 will return to its normal relaxed position with slits 32 sealing the passageway through assembly 20. No flow can then occur between tip 28 and tip 40 of the cannulas of assembly 20. The evacuated container 45 can then be removed from the needle assembly as shown in FIGS. 7 and 8 and processed as desired. Subsequent evacuated containers can then be coupled with assembly 20 in a similar manner for the collection of further samples.
The elastomeric material of the valve member permits close control over the opening and closing of the valve. The valve is responsive to deform when subjected to a low threshold of differential pressure. This enables the valve to be extremely accurate in controlling the flow into an evacuated container when a predetermined amount of fluid such as blood is to be collected. As discussed above, this is extremely advantageous in the blood sampling field.
Naturally, there are many other embodiments which fall within the scope of the invention as described and claimed. Thus, the above discussed objectives, among others, are effectively attained.
In the blood sampling field, there are several well known systems. One of the more commonly used systems is the collection of blood from a vein through a needle assembly into an evacuated container. The evacuated container provides the pressure differential necessary to facilitate flow and collection of the blood through the needle assembly into the container.
Improvements have been made in recent years to the basic evacuated container system for blood sampling such as by the provision of a valve on the assembly to automatically open and close the flow path through the assembly as evacuated containers are coupled in succession with the assembly. In this manner a multiplicity of samples can be collected in a multiplicity of containers with only one venipuncture required.
Frequently the evacuated containers contain chemical materials, useful in the clinical laboratory tests to be conducted after mixing with the patient's blood. However, these chemical materials may be harmful to a patient if any were to flow from the evacuated container into the patient's blood system. For example, some evacuated containers are partially filled with protein culture medium, and the possibility exists that if any of this protein material were carried back into the patient, such foreign protein might cause anaphylactic shock. Therefore, it would be extremely desirable to utilize a system for blood sampling which employs evacuated containers in a manner such as in the systems described above and which would alleviate the danger of back flow of fluid into the patient during and after the fluid sampling process. It would be of great advantage to have an inexpensive oneway valve which is responsive to a change in pressure and which does not require a substantial force to cause it to open and one which is sensitive to small pressure differentials in order to insure that an evacuated container is filled to the desired degree before the valve closes. This is particularly true in the blood testing field where various evacuated tubes require a carefully predetermined volume of blood fill in relation to the chemical material already in the evacuated tube so that a predetermined ratio of blood to chemical mixture is present. This assures that ultimate testing is accurate and precise.
With the above thoughts in mind particularly in regard to closely controlled filling requirements and the cost factor involved when considering quantity production of evacuated tubes and needles, any increase in threshold value of pressure differential required to open or close the valve directly increases the inaccuracy of the blood fill. Therefore, valve types requiring as near zero threshold differential pressure to open and close, while at the same time being normally closed, would be extremely valuable and important to the art under consideration.
SUMMARY OF THE INVENTION
With the above background in mind, it is among the primary objectives of the present invention to provide a needle assembly for use with an evacuated container in collecting blood samples wherein a one-way valve means is provided on the needle assembly to prevent the possibility of back flow of chemical materials from the evacuated container into the patient. The valve is designed of a resilient elastomeric self-sealing material to automatically deform and open and permit flow into the evacuated container when the system is utilized under a low pressure differential and to automatically return to the normal closed position preventing flow to and from the forward end of the needle assembly when subjected to flow pressure from the rear end of the assembly to which the evacuated container is connected or exhaustion of the vacuum in an evacuated container utilized in a sampling collection operation.
Thus, a needle assembly is provided for facilitating the collection of a blood sample from a patient into an evacuated collection container while alleviating the danger of flow of fluid from the collection container into the patient during and after collection of the blood sample. The assembly includes a housing with a forward penetrating end including a cannula extending from the housing for penetration into the blood vessel of the patient. The assembly also includes a rearward end extending from the housing and including a cannula and being adapted to be coupled in fluid communication with the interior of an evacuated collection container. Portions of the assembly form a passageway for directing blood from the vein to the collection container when the forward end is in the blood vessel and the rearward end is in the container. Finally, an elastomeric resilient valve member is part of the assembly normally in position to close the passageway between the blood vessel and the rearward end of the assembly and adapted to be responsive to decrease in pressure in the rearward end to deform and automatically open the passageway when the evacuated container is coupled with the rearward end of the assembly. Thereafter, the valve is responsive to a predetermined increase in pressure in the rearward end to automatically return to the closed position and prevent flow of fluid from the rear end of the assembly to the patient.
With the above objectives in mind, reference is had to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings:
FIG. 1 is a partially sectional side elevation view of the needle assembly of the invention shown incapsuled in a sealed container;
FIG. 2 is a side elevation view of the needle assembly of the invention shown in operable position in combination with a holder, an evacuated container, and a needle shield;
FIG. 3 is a fragmentary sectional elevation view thereof with the needle shield removed and the assembly in fluid communication with a blood vessel immediately prior to collection of a sample;
FIG. 4 is an enlarged fragmentary view of the valve portion of the needle assembly as shown in FIG. 3;
FIG. 5 is a fragmentary sectional view of the needle assembly in operable position with the valve portion open and blood being collected in an evacuated container;
FIG. 6 is an enlarged fragmentary view of the valve portion of the needle assembly of FIG. 5 with arrows showing the blood flowing through the needle assembly;
FIG. 7 is an enlarged sectional view of the needle assembly of the invention in operable position in the vein of the patient subsequent to collection of a sample in an evacuated container after the valve portion has reclosed; and
FIG. 8 is an enlarged fragmentary view of the valve portion of the needle assembly of FIG. 7 with the valve having reclosed upon completion of collection of a sample.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
As shown in FIGS. 1, 2 and 3 in particular, needle assembly 20 includes a housing 21 on the forward end of which is mounted a forward venipuncture cannula 22 and on the rear end of which is mounted a second cannula 23.
Housing 21 includes a forward end portion 24 having a passageway 25 therethrough. Mounted in passageway 25 is the rear end portion of venipuncture cannula 22. The cannula is held in position in a convenient manner such as by epoxy 26 as shown.
Forward portion 24 of housing 21 has a tapered frusto conical rear mating end 27 with a hollow interior. The rear end portion of cannula 22 extends rearwardly from passageway 25 into the hollow interior of tapered frusto conical portion 27. The forward end of cannula 22 extends from the forward tip of housing 21 and has a beveled tip 28 for insertion into the vein of a patient. The rear end of cannula 22 has a blunt tip 29 and the end portion adjacent blunt tip which extends from passageway 25 has an elastomeric cap or valve member 30 mounted thereon.
Valve member 30 has a closed rear end and has its open forward end in sealing engagement with cannula 22. Between the rear end of valve 30 and blunt tip 29 of cannula 22, valve 30 has a hollow center 31 in communication with the passageway through cannula 22. Valve 30 is of a self-sealing elastomeric material and contains one or more slits 32 where hollow portion 31 is located. Valve 30 is of a lesser inner diameter than the outer diameter of cannula 22 so that when the sleeve or valve 30 is positioned on cannula 22 it is expanded at the location of contact so as to provide sealing interengagement between the cannula and valve sleeve.
Housing 21 is of a two-part construction with the tapered outer surface of forward portion 24 which forms frusto conical portion 27 in frictional engagement with a tapered inner surface of a rear end 33 of the housing. Rear end 33 includes the hollow cylindrical portion 34 with a tapered inner surface in interengagement with forward end 24 and a rear cylindrical neck 35 having a passageway 36 therethrough. The outer surface 37 of neck 35 is threaded for interengagement with a holder as will be discussed in detail below. As shown, when forward portion 24 and rear portion 33 of housing 21 are interengaged, a chamber 38 is formed therein. Access to chamber 38 is gained through the hollow cannula 22 mounted in passageway 25 or through the hollow cannula 23 which is mounted in passageway 36. Cannula 23 is mounted in a conventional manner such as by epoxy 39. The forward tip of cannula 23 is located intermediate the ends of passageway 36 and the rear tip of cannula 23 extends beyond neck 35 and has a pointed end 40 for penetration into an evacuated container as will be discussed in detail below. As shown, cap or valve 30 is housed within chamber 38 in housing 21.
In reference to FIG. 1, it can be seen how needle assembly 20 is packaged for shipment and storage in a sealed aseptic fashion prior to use. The package is in the form of a hollow capsule 41 of rigid material such as a rigid plastic in a two-part assembly. The forward part 42 covers the forward part of needle assembly 20 and terminates intermediate the ends of housing 33. The rear part 43 covers the rear end of the needle assembly and terminates below the lower end of housing 21. Both the forward part 42 and the rear part 43 of capsule 41 have a closed end distal from one another and an open end proximal to one another for frictional interengagement to form capsule 41 with the needle assembly contained therein. At the point of joinder of portions 42 and 43 of capsule 41 an outer cylindrical mating surface is formed on which is mounted a tamper-proof band 144. As long as band 144 is not disturbed and remains intact, the capsule 41 is unbroken and the assembly 20 contained therein remains in aseptic condition. The rigid nature of capsule 41 alleviates the danger of damage to the assembly during shipment, storage and handling prior to use. Assembly 20 is of a disposable nature so that, if desired, once capsule 41 is opened and assembly 20 is utilized it may be discarded.
In use, tamper-proof band 144 is broken and capsule 41 is opened by removing rear portion 43 from forward portion 42 and from its surrounding relationship with the rear end of assembly 20. Forward portion 42 of capsule 41 is retained in position covering venipuncture cannula 22 to alleviate the danger of contamination thereeof during the preliminary preparation procedures prior to use. Removal of rear end 43 of capsule 41 exposes cannula 23 and neck 35 so that a holder 44 may be extended over cannula 23 and into threaded interengagement with threaded surface 37 of housing 33. In this position as shown in FIG. 2 cannula 23 is located within holder 44.
An evacuated container 45 is then partially inserted within holder 44 to the rear of tip 40 of cannula 23. The evacuated container is of a conventional type having a tubular body 46 terminated in an open end which is capped and sealed by a punctureable self-sealing stopper 47. The assembly is then in condition for the actual blood sampling operation and forward portion or shield portion 42 of capsule 41 can then be removed from frictional interengagement with housing 21 thereby exposing cannula 22. As shown in FIG. 3, tip 28 of cannula 22 is then inserted into vein 48 of a patient. Since valve 30 is closing the rear blunt end 29 of cannula 22, no blood can travel beyond hollow chamber 31 within valve 30 under the influence of venous pressure alone.
Evacuated container 45 is then extended forward until tip 40 of cannula 23 punctures through stopper 47 thereby providing communication between the interior of evacuated tube 45 and central chamber 38 of housing 21. Thereafter, the pressure differential interiorly and exteriorly of valve 30 caused by the vacuum within container 45 automatically opens slits 32 and permits blood to flow from the vein through cannula 22 through slits 32 through chamber 38 and then through cannula 23 into container 45. Flow will continue as long as the pressure differential exists. Therefore, once the vacuum is exhausted within container 45 valve 30 will automatically return to its normal configuration with slits 32 returning to the sealed position thereby shutting off the blood flow adjacent to blunt end 29 of cannula 22. Similarly, should a back pressure build up during the filling operation, the pressure differential will be disturbed and the increased pressure exteriorly of valve 30 will cause slits 32 to be closed and eliminate any danger of fluid flow into valve 30 and consequently into cannula 22 and the patient. As discussed above, this is particularly useful in instances where harmful materials to be used in later chemical analysis may be contained within tube 45 and it is extremely desirable to avoid any of the possibly harmful material entering the patient.
FIGS. 3-8 show the sequence of operations in the taking of a blood sample while alleviating the danger of blood flow or other fluid flow back through the needle into the patient.
FIGS. 3 and 4 show the venipuncture having been made in the vein 48 of a patient. With valve 30 in the closed position, no blood flow due to venous pressure can occur beyond valve 30 in the assembly. The evacuated tube 45 is shown in position for engagement with the rear tip of the needle assembly. Thereafter, in FIGS. 5 and 6 the evacuated tube 45 has been coupled with assembly 20 so that tip 40 of cannula 23 is within the evacuated tube 46. The vacuum causes a pressure differential and reduces the pressure in chamber 38 so that slits 32 open in valve 30 permitting blood to pass through needle assembly 20 into evacuated tube 46 for collection. During this procedure, should any back flow or increased pressure occur to the rear of valve 30 this force will cause slits 32 to return to their relaxed position sealing valve 30 and preventing flow in either direction within the assembly.
When the vacuum has been exhausted in tube 46, the pressure will equalize on both sides of valve 30 and valve 30 will return to its normal relaxed position with slits 32 sealing the passageway through assembly 20. No flow can then occur between tip 28 and tip 40 of the cannulas of assembly 20. The evacuated container 45 can then be removed from the needle assembly as shown in FIGS. 7 and 8 and processed as desired. Subsequent evacuated containers can then be coupled with assembly 20 in a similar manner for the collection of further samples.
The elastomeric material of the valve member permits close control over the opening and closing of the valve. The valve is responsive to deform when subjected to a low threshold of differential pressure. This enables the valve to be extremely accurate in controlling the flow into an evacuated container when a predetermined amount of fluid such as blood is to be collected. As discussed above, this is extremely advantageous in the blood sampling field.
Naturally, there are many other embodiments which fall within the scope of the invention as described and claimed. Thus, the above discussed objectives, among others, are effectively attained.