A vascular access device

Abstract: A blood containment arterial access device (10) is provided which includes a thin-walled tube (12) having a lumen (16) which extends from the distal end of the tube (12) to the proximal end of the tube (12). The device (10) includes a transparent viewing cylinder (14) having a proximal end and a distal end. The distal end of the viewing cylinder (14) forms a pressure tight seal with the tube (12) proximal end and further includes a lumen (18) in fluid communication with lumen (16) of tube (12). The viewing cylinder (14) forms an enclosed volume in order to contain blood that enters into the opening of the distal end of the tube (12). A guide wire access (22,24) is located at the proximal end of the viewing cylinder (14). The guide wire access (22,24) allows passage of a guide wire or catheter or other similar structure through the viewing cylinder (14) and into the thin-walled tube (12). The access (22,24) provides a pressure tight seal to prevent release of blood prior to insertion of the catheter or guide wire through the access mechanism (22,24).

Description: This invention relates to a vascular access device for accessing human blood vessels for a multiplicity of purposes including the placement of guide wires, introducer sheaths and catheters. Interventional cardiologists and radiologists currently practice a wide range of procedures that require percutaneous access to the human vascular system. In many of these procedures, percutaneous access occurs at the site of the common femoral artery or vein at the groin for the purpose of passing guide wires and introducer sheaths. Catheters can then be advanced through these sheaths to many places within the human vascular system. One method for performing this procedure utilizes a hollow steel cannula with a separate sharpened stylet needle through its centre which is pushed through skin and then completely through the common femoral artery. The stylet is then removed and the steel cannula is pulled back slowly until blood under arterial pressure squirts vigorously in a pulsating manner out of the cannula's proximal end thus indicating that the cannula's distal end is properly placed within the artery. A guide wire is then placed through the cannula and advanced into the artery, and then the cannula is pulled out. A variety of introducer sheaths and/or catheters can then be advanced over the guide wire and into the arterial system. Another method for accessing arteries is by means of an introducer needle with a sharpened distal end that does not use a stylet needle. This introducer needle is placed through the skin at the groin and advanced until the opening of its sharpened distal end lies within the arterial lumen. When this occurs, blood squirts forcibly in a pulsating manner out of the needle's proximal end. The pulsatile blood flow indicates that the introducer needle is properly located in the artery so that a guide wire can be inserted through the introducer needle followed by the introducer sheaths and catheters to be used for the procedure. The blood squirting out of the cannula at arterial pressure results in a considerable release of blood which can find its way into the eyes, nose, or other openings of health care workers in close proximity to the patient. Besides being messy and causing unnecessary blood loss to the patient, the squirted blood represents a risk to the health care workers who could be exposed to infectious diseases carried in the patient's blood. European patent application EP-A-0 223 451, which is used as a basis for the preamble of claim 1, describes a device for use in the sampling or infusion of liquids from or to the human or animal body comprising a chamber for receiving fluid, a cannula in communication with a chamber, at least one valve means operable in an open condition to connect the chamber with a source or drain of liquid and in a closed condition to seal the chamber therefrom, and chamber venting means allowing the escape of air from the chamber whilst preventing the escape of liquid therefrom. US patent US-A-3,766,916, describes catheter placement units wherein the catheter tube is fixed to a generally Y-shaped transparent central unit. A style needle is provided with a tab to facilitate manipulation of the placement unit and extends through a bore in one arm of the central unit and through a catheter tube. The needle is formed with an opening adjacent the proximal end thereof which communicates the bore of the needle with the bore of the other arm of the central unit to provide visual indication of blood flash-back indicative of successful venipuncture. US patent 4,424,833 describes a moulded one-piece, self-sealing gasket which maintains its seal at all times including during the insertion of a tube such as a catheter as well as after the tube is withdrawn. European patent application EP-A-0 260 393 describes a ventilated valve which serves as a blood barrier in medical leads or channels. An outer end of a channel of a tube like portion which is connected with a lead channel is closed with a hydrophobic filter at its outer end. The ventilated valve is constructed so that the function of the hydrophobic filter retains its function as a blood back-flow control arrangement as a blood stream under pressure from the lead channel does not impinge against the hydrophobic filter but rather against the deflecting element at a central portion. The present invention, as described herein, overcomes the deficiencies of the prior art arterial access devices by offering a simple, inexpensive, easy to use device for inserting guide wires, introducer sheaths or other similar items into the femoral artery without allowing the uncontrolled release of arterial blood, or for that matter into any artery or vein of the human body. According to the invention this is provided by a vascular access device for percutaneous insertion into an artery or vein of a patient and when so inserted providing an access point for the feeding of a catheter, catheter guide wire, introducer sheath or like elongate structure into a said artery or vein penetrated by the device, the device comprising a thin-walled tube open at its distal end, a tubular body portion connected to or integral with the proximal end of the thin-walled tube, said tubular body portion having an internal blood collection chamber in open communication at its distal end with the proximal end of the lumen of the thin-walled tube and having a sealing member at its proximal end forming a closure for said blood collection chamber, said sealing member permitting the said catheter, catheter guide wire, introducer sheath or like elongate structure to be introduced axially through said blood collection chamber and into said artery or vein when the device is positioned therein and means enabling the thin-walled tube to be percutaneously introduced into a said artery or vein, characterised in that: said blood collection chamber forms an axially extending pressure tight enclosure open only to the lumen of the thin-walled tube, said blood collection chamber having air trapped therein when arterial or venal blood flows through the lumen of the thin-walled tube into the collection chamber, the blood continuing to flow until the pressure in that chamber equals the arterial or venal blood pressure, and means enabling the user to detect the variation of pressure in that chamber due to the difference between the diastolic and systolic blood pressure of the patient and thereby to confirm that the tip of the device is correctly positioned within the artery or vein prior to the insertion of said catheter, catheter guide wire, introducer sheath or like elongate member through the sealing member at the proximal end of the tubular body portion of the device and axially through the chamber, the lumen of the thin-walled tube and into the artery or vein. In use, the device is percutaneously introduced into the artery or vein, and which can be achieved in a variety of different ways to be described hereinafter, and following which the systolic/diastolic pressure variation of the blood which passes into and collects in the sealed blood collection chamber can be sensed, again in a variety of different ways to be described hereinafter - e.g. visually in the case of a transparent collection chamber, or tactilely in the case of a flexible diaphragm forming part of the chamber wall exposed to the pulsating pressure of the blood in the chamber. In that way the user can easily sense that the access device is correctly positioned before introducing the catheter or whatever therethrough, all without release of arterial or venal blood from the patient. Various preferred features of the device are described hereinafter, and are set out hereinafter in the subsidiary claims. The invention will be further described with reference to the accompanying drawings, in which: Figure 1 is a longitudinal cross-section of a blood containment arterial access device according to the invention that allows the use of visual observation of pulsating blood to determine that the device is properly placed within an artery; Figure 2 is a longitudinal cross-section of the stylet needle that is used with the device of Figures 1 and 3; Figure 3 is a longitudinal cross-section of another embodiment of a blood containment arterial access device according to the invention which uses a thin diaphragm to allow detection of proper placement in an artery; Figure 4 is a longitudinal cross-section of another blood containment vascular access device according to the invention that uses a sharpened distal end to eliminate that need for a stylet needle that section being taken on line 4-4 of Figure 6; Figure 5 is another partial cross-section through the device of Figure 4 showing a guide wire partially advanced through the device's central lumen, that section being taken on line 5-5 of Figure 6; Figure 6 is a transverse cross-section of the device of Figure 4 taken on line 6-6 of Figure 5; Figure 7 is a plan view of the valve placed inside the end cap of the device shown in Figures 4 and 5; and Figure 8 shows the access device of Figures 4 and 5 being inserted into a femoral artery. Referring to the drawings, Figure 1 is a longitudinal cross-section of a blood containment arterial access device 10 according to this invention having a distal tube 12 onto which is moulded or bonded a transparent viewing cylinder or body portion 14. The tube 12 has a lumen 16 which continues into the lumen 18 of the cylinder 14. The lumen 18 terminates in a chamber 20 which is sealed at the proximal end of the cylinder 14 by a soft elastomeric septum 22 which has an entry hole 24 at its centre. The lumens 16 and 18 have an inside diameter which allows a sliding fit with the needle stylet 30 shown in Figure 2. In use, the stylet 30 would be passed through the entry hole 24 and advanced until its distal point 34 lies distal to the distal end of the tube 12 and its handle 36 is in contact with the proximal end of the viewing cylinder 14. When assembled in this manner, the stylet 30 would penetrate the skin above the femoral artery at the groin and the assembly of the access device 10 and the stylet 30 would then be advanced until their distal ends penetrated through the femoral artery. The stylet 30 would then be removed and the device 10 pulled back until the distal end of the tube 12 entered the lumen of the femoral artery. The blood would then rush through the lumen 16 and into the viewing lumen 18. Once blood enters the distal end of the lumen 16, the volumes of the lumens 16 and 18 and the chamber 20 form a closed, pressure tight volume. The pressure of the blood entering this volume will compress the air in this closed volume until the air pressure is equal to the blood pressure. When the pressure in this closed volume reaches systolic pressure, no additional blood will enter the volume and all the blood will be contained within the blood containment arterial access device 10. As the blood pressure varies between systolic and diastolic, blood will flow into and out of the volume with the pressurized trapped air contracting and expanding accordingly. If, as seen in Figure 1, the dimension L1 = 5.08 cms (2.0 ins) and L2 = L3 = 2.54 cms (1.0 ins) and if the diameter of the lumens 16 and 18 is 1.016 mm (0.040 ins) and the diameter of the chamber 20 is 0.508 mm (0.20 ins), then at a normal diastolic pressure of 10.67 kPa (80 mm Hg) the blood would just reach slightly into the viewing lumen 18. At a normal systolic pressure of 18.67 kPa (140 mm Hg), the blood would just squirt into the chamber 20. By tilting the access device 10 at approximately a 45 degree angle (as seen in Figure 8) and viewing it from above, the physician can watch the blood pulse into and out of the chamber 20 confirming that the distal end of the tube 12 is within the lumen of the femoral artery. Thus the goal of this invention which is the assurance of proper placement of the distal end of the tube 12 within the femoral (or any other accessed) artery while disallowing the uncontrolled release of blood has been accomplished. It should be understood that the purpose of having a smaller diameter of the lumen 18 and a larger diameter for the volume 20 is so that, even at comparatively low diastolic pressures, blood will appear in the lumen 18 while the total length L2 + L3 is minimized. If the diameter of volume 20, were the same as the much smaller diameter of the lumen 18, then the total length of the access device 10 would have to be considerably longer making it more awkward to handle. Furthermore it should be pointed out that the lumen 18 has a minimum diameter that will just pass the guide wire. This minimum diameter design provides a maximum linear displacement of the blood as it pulses within the lumen 18 between diastolic and systolic pressures thus providing optimum visualization. Still further, the viewing cylinder 14 is thick-walled and has a convex outer surface thereby providing an optically magnified image of the small diameter lumen 18 which enhances the observability of the blood that moves back and forth in a pulsatile fashion in the lumen 18. After the correct placement has been ascertained by observation of the blood pulsating within the lumen 18, a guide wire can be inserted through the entry hole 24, and then it will pass through the central incision made in the septum 22 by the needle 32 of the stylet 30. The guide wire is then advanced through the lumens 18 and 16 and finally the guide wire's distal end will enter the femoral artery. The access device 10 can then be removed from the body while leaving the guide wire remaining in place in the arterial lumen. The typical guide wire for this application would have a diameter of 0.965 mm (0.038 ins). The tube 12 and the stylet needle 32 would typically be made from Type 304 stainless steel. The viewing cylinder 14 would typically be made from a transparent plastic such as Lucite (RTM) or Lexan (RTM). The septum 22 would be made from a low durometer latex or silicone rubber such as used for the top of bottles for injectable drugs. The handle 36 of the stylet 30 could be moulded from any mouldable plastic such as PVC. Figure 3 shows an alternative embodiment of the present invention. This pressure sensing arterial access device 40 has a tube 41 which has an interior lumen 42 and a cut-out window 43. Wrapped around the window 43 is a thin-walled elastic diaphragm 44. At the proximal end of the tube 41 is a septum holder 45 into which is placed a soft elastomeric septum 46 having a central hole 47. The method for using this device is as follows: (1) The stylet needle 30 is placed through the septum 46 until its sharpened end 34 extends beyond the distal end of the tube 41. (2) This assembly penetrates through the femoral artery at the groin and the stylet 30 is removed. (3) The device 40 is then pulled back until the distal end of the lumen 42 lies within the lumen of the femoral artery. (4) The pressurized blood rushes into the lumen 42, thus raising the pressure in the volume enclosed by the lumen 42 to the pressure of the blood and causing pulsation of the diaphragm 44. This embodiment differs from that shown in Figure 1 in that instead of visual observation of the confined blood, the physician places a finger over the diaphragm 44 while pulling back on the device 40 until a pulse is felt on the diaphragm indicating that the pressure in the lumen 42 is changing between diastolic and systolic blood pressure. Alternatively, a pulsing movement of the diaphragm could be visually observed. After correct positioning is noted, a guide wire can be passed through the septum 46 through the lumen 42, and into the femoral artery. Both the embodiments of Figures 1 and 3 confine the blood to a very small, comparatively rigid, enclosed volume which has an elastomeric septum at the device's proximal end, which septum is designed to be penetrated first by a needle stylet and then by a guide wire. Figures 4 to 7 inclusive show another embodiment of the present invention in the form of an arterial access device 50 that is designed to be used without a stylet needle. Figures 4 and 5 show the access device 50 with a distal metal tube 51 which has a sharpened distal tip 53. The purpose of the sharpened distal tip 53 is to penetrate through the tissue at the groin and penetrate the proximal wall of the femoral artery but not the distal wall so that the distal opening 58 is placed inside the arterial lumen. The distal opening 58 is the terminus of the lumen 54 (see Figure 4) which is in fluid communication with the viewing lumen 55 of the transparent body portion 56 which lumen 55 is in fluid communication with the proximal chamber 57 of the viewing section 56. Luer type threads 49 are formed at the proximal end of the viewing section 56 in order to mate with a separate Luer end cap 60. The end cap 60 has a generally cylindrical body 61 which has a tapered proximal access hole 63 which leads into a central lumen 62 through which a guide wire can be passed. The outer perimeter of an elastomeric valve 68 is adhesively joined to the interior distal surface of the end cap 60. The valve 68 has a valve poppet 64 (see Figures 4, 5 and 7) which has a cylindrical extension 65 into the lumen 62. The valve 68 including the extension 65, forms an air-tight seal at the proximal end of the chamber 57. After the access device 50 has been placed so that its distal opening 58 is within the arterial lumen, as shown in Figure 8, the blood will rush into the lumens 54 and 55 and the air in the chamber 57 will undergo pulsating compression. At diastolic pressure, the blood extends just proximal to the proximal end of the lumen 54; i.e. into the distal end of the lumen 55. At normal systolic pressures the column of blood extends into the proximal end of the (approximately 2.54 cms (1.0 ins) long) lumen 55, and at higher systolic blood pressures, some blood will enter the conically-shaped distal end of the chamber 57. When the physician sees that the blood is pulsing back and forth sharply within the lumen 55, he knows that the distal opening 58 is well placed within the arterial lumen. Then, as seen in Figure 5, a guide wire 70 can be pushed through the conical opening 63 of the end cap 60, and as the guide wire 70 is further advanced, it forces the valve poppet 64 to open. As seen in Figure 7, the valve poppet generally bends around the dotted line 67. The guide wire 70 is then advanced further through the chamber 57 and into the lumens 55 and 54, and then out the distal opening 58 and into the arterial lumen. The access device 50 including the end cap 60 is then pulled back and out of the body while leaving the guide wire 70 in place. An important feature of this embodiment of the invention is an improved means for the physician to conveniently hold the access device 50 so that it can be readily pushed through as mush as through 6.35 cms (2.5 ins) of the patient's skin and tissue so as to place the opening 58 into the lumen of the femoral artery. This can require several pounds of force. Specifically, Figures 5 and 6 show the flat side surface 59A which can be comfortably grasped by the physician between the thumb and forefinger. The front surface 59B of the bulbous distal end 52 of the viewing section 56 allows the physician to readily provide a high degree of forward thrust without relying on frictional forces of the thumb and forefinger against the side surfaces 59A. This design is clearly superior to a simple, straight steel needle which is in current use which is much more difficult to grasp for thrusting through the skin and tissue. It should also be noted that the flat surfaces 59A have a specific orientation relative to the plane of the opening 58. Specifically, when the surfaces 59A are vertical and the tube 51 is tilted downward at about 45 degrees relative to the longitudinal axis of the femoral artery (see Figure 8), and where the element line 52 touches the device 50 in Figures 4 and 8 and is upward facing toward the physician, then the plane of the opening 58 will be generally perpendicular to the longitudinal axis of the femoral artery. This orientation (as seen in Figure 8) provides the strongest pulsing of the blood into the viewing section 56 and is also the best orientation for placing the guide wire into the arterial lumen. It should also be noted that the surface 59C in Figure 6 is convex, and there is a thick wall, thereby providing optical magnification of the small diameter lumen 55 so as to enhance the ability of the physician to readily observe the pulsatile motion of the blood within the lumen 55. The materials for the embodiment of the invention shown in Figures 4, 5, 6 and 7 would be of the same type as those used for the embodiment shown in Figure 1. When performing percutaneous transluminal coronary angioplasty (PTCA) with a balloon catheter, interventional cardiologists typically place at the groin one sheath into the femoral artery (through which the balloon angioplasty catheter is inserted) and the second sheath is placed to the femoral vein for injecting medications and/or making pressure measurements. The embodiment shown in Figures 4 and 5 can be used for placing these two sheaths, one in the vein and the other in the artery. The method for placing these sheaths is as follows: (1) Using the embodiment shown in Figures 4 and 5, after first cleaning the skin surface with an anti-bacterial solution and then making a small cut at that site with a scalpel, the sharpened point 53 is pushed through the tissue at the groin over the site of the femoral artery. (2) The access device 50 is then pushed forward until the opening 58 of the tube 51 lies within the lumen of the femoral artery. (3) Arterial blood will then rush through the opening 58, into the lumens 54 and 55 and, at higher systolic pressure, into the chamber 57. (4) The blood under arterial pressure will then be able to be seen (with optical magnification) pulsating within the lumen 55 and occasionally spurting into the chamber 57. The physician then has a clear indication that the tube 51 has its distal opening 58 placed properly in the lumen of the femoral artery. (5) When the proper positioning of the access device 50 has been ascertained, a guide wire 70 is inserted through the lumen 62 of the end cap 60 as shown in Figure 5. The guide wire 70 would force the valve poppet 65 to open and then the guide wire 70 would be advanced through the lumens 55 and 54, through the opening 58 and into the arterial lumen. (6) The device 50 can then be pulled out the artery while the guide wire 70 remains in place in the arterial lumen. (7) An introducer sheath would then be inserted over the guide wire into the femoral artery. (8) The guide wire and dilator portion of the introducer sheath would then be removed leaving the sheath in place. (9) The end cap 60 would then be removed from the access device 50 and a syringe would be joined to the proximal end of the device 50 with the syringe's plunger being fully advanced. (10) The sharpened point 53 would then be pushed into the femoral vein while pulling back on the plunger of the syringe so as to create a partial vacuum inside the device 50. (11) When the blood can be seen to reach the chamber 57, the syringe is removed and a guide wire is advanced through the device 50 and into the lumen of the vein. (12) The device 50 is then pulled out of the body while leaving the guide wire in place. (13) An introducer sheath is then advanced over the guide wire and into the lumen of the vein. (14) The sheath's dilator and guide wire are then removed leaving the sheath in place in the vein. To accomplish the placement of one sheath in the femoral artery and a second sheath in the vein, it would be convenient for the interventional cardiologist to have the following items in the form of a single package or kit: (1) An access device 50. (2) End cap 60. (3) One or two guide wires 70. Additionally, it might be advantageous to include: (4) A syringe, and (5) A disposable scalpel. Additionally, one might wish to include two introducer sheaths into the kit. Such a kit would be in the form of a single, sterilized package. Having all these items in a single package would make the placement of the two sheaths required for PTCA quicker, easier and more convenient. It should be understood that the design of Figures 4 and 5 could be used with the stylet needle design of Figure 1. If this were the case, the valve 68 would preferably have a single central hole through which the stylet could pass while maintaining a pressure seal. After the stylet tip 34 (of Figure 2) penetrates through both arterial walls, the stylet 40 would be pulled back until the tip 34 lies within the chamber 57. The access device 50 would then be pulled back until pulsatile blood appeared in the lumen 55. The stylet would then be removed and a guide wire would quickly be inserted through the cap 60 and passed forward into the arterial lumen. It should also be understood that the embodiments of Figures 1 and 3 could be used with a sharpened chisel-like tip as illustrated in Figures 4 and 5 without the use of a stylet. Each of these designs is capable of accomplishing the goal of the present invention, which is to provide a means for inserting a guide wire into an artery and/or vein while providing blood containment. Still further, all of the designs described herein are applicable to any percutaneous vascular access and are not limited to groin access of the femoral artery. Furthermore, these designs could be used for percutaneously or intra-operably accessing human organs such at the spinal column or bladder for acquiring other fluids such as the cerebrospinal fluid (CSF), urine, etc. Various other modifications, adaptions or alternative designs are of course possible in light of the above description without departing from the scope of the invention herein described and hereinafter claimed.

Claims: A vascular access device (10;40;50) for percutaneous insertion into an artery or vein of a patient and when so inserted providing an access point for the feeding of a catheter, catheter guide wire, introducer sheath or like elongate structure into a said artery or vein penetrated by the device, the device comprising a thin-walled tube (12;41;51) open at its distal end, a tubular body portion (14;41;56) connected to or integral with the proximal end of the thin-walled tube, said tubular body portion having an internal blood collection chamber (20;42;57) in open communication at its distal end with the proximal end of the lumen (16;42;58) of the thin-walled tube (12;41;51) and having a sealing member (22;46;68) at its proximal end forming a closure for said blood collection chamber (20;42;57), said sealing member (22;46;68) permitting the said catheter, catheter guide wire, introducer sheath or like elongate structure to be introduced axially through said blood collection chamber and into said artery or vein when the device is positioned therein and means (30;53) enabling the thin-walled tube (12;41;51) to be percutaneously introduced into a said artery or vein, characterised in that: said blood collection chamber (20;42;57) forms an axially extending pressure tight enclosure open only to the lumen (16;42;58) of the thin-walled tube (12;41;51), said blood collection chamber (20;42;57) having air trapped therein when arterial or venal blood flows through the lumen (16;42;58) of the thin-walled tube (12;41;51) into the collection chamber (20;42;57), the blood continuing to flow until the pressure in that chamber equals the arterial or venal blood pressure, and means (14;43;44;55) enabling the user to detect the variation of pressure in that chamber due to the difference between the diastolic and systolic blood pressure of the patient and thereby to confirm that the tip of the device is correctly positioned within the artery or vein prior to the insertion of said catheter, catheter guide wire, introducer sheath or like elongate member through the sealing member (22;46;68) at the proximal end of the tubular body portion (14;41;56) of the device and axially through the chamber (20;42;57), the lumen (16;42;58) of the thin-walled tube (12;41;51) and into the artery or vein. A device according to claim 1, characterised in that the means (30) enabling the thin-walled tube (12;41) to be percutaneously introduced into the artery or vein comprises a stylet needle (30) which, prior to the percutaneous placement of the device in the artery or vein, may be introduced axially into the device (10;40) through said sealing member (22;46) at the proximal end of said tubular body portion (14;41), said needle (30) having length greater than the length of the device, so that when the needle is positioned therein, the sharpened tip (34) of the needle projects from the distal end of said thin-walled tube (12;42), and having an enlarged head (36) at its proximal end enabling the stylet needle to be withdrawn from the device once the device is in position in said artery or vein, thus enabling arterial or venal blood to flow through the lumen of said thin-walled tube into said collection chamber. A device according to claim 2, characterised in that the sealing member (22;46) in the proximal end of the blood collection chamber (20;42) comprises a septum of elastomeric material pierceable by said needle and which automatically seals itself around the needle, and reseals the proximal end of the blood collection chamber when the needle is removed. A device according to claim 1, characterised in that the means (53) enabling the thin-walled tube (51) to be percutaneously introduced into the artery or vein comprise a sharpened tip at the distal end of a rigidly, thin-walled tube, A device according to any one of claims 1-4, characterised in that said tubular body portion (14;56) is transparent, or has a transparent window therein permitting the volume of blood in the collection chamber, and which varies against the trapped air according to the systolic and diastolic pressure, to be seen thereby to confirm that the device has been correctly inserted. A device according to any one of claims 1-4, characterised in that the means (44) permitting the user to confirm that the device has been correctly positioned in the artery or vein comprise a flexible diaphragm (44) in or around a cut-out window (43) of the tubular body portion (41) of the device and through which the variation between the systolic and diastolic pressure of the blood in that collection chamber can be felt by the user. A device according to any one of claims 1, 2, 4 or 5, characterised in that the sealing member in the proximal end of the blood collection chamber (57) comprises a resilient poppet valve (68) having a resilient flap (34) that may be pushed aside by the catheter, catheter guide wire, introducer sheath or like elongated structures as it is introduced through the device and into the artery or vein once the device is positioned therein. A device according to any one of the preceding claims, characterised in that at the junction between the proximal end of the thin-walled tube (51) and the body portion (56) of the device, that body portion has an enlarged head (52) by means of which axial pressure may be applied to the device as it is inserted through the skin into the artery or vein. A device according to claim 8, characterised in that said head (52) has a flattened side or sides (59A). A device according to any one of the preceding claims, characterised in that the cross-sectional diameter and volume of the blood collection chamber (20;57) is greater than the corresponding measurements of the lumen (16;58) located within the thin-walled tube (12;51).

Inventors: FISCHELL DAVID R, FISCHELL ROBERT E, FISCHELL TIM A, FISCHELL, DAVID R.,, FISCHELL, ROBERT E., FISCHELL, TIM A.
Applicants: FISCHELL DAVID R, FISCHELL ROBERT, FISCHELL TIM A, FISCHELL, DAVID R.,, FISCHELL, ROBERT E., FISCHELL, TIM A.
Application year: 1993
Main classification: A61M39
IPC codes: A61M25, A61M39