Surgery – Blood drawn and replaced or treated and returned to body
Reexamination Certificate
2001-03-22
2004-01-27
Paik, Sang Y. (Department: 3744)
Surgery
Blood drawn and replaced or treated and returned to body
C604S043000, C604S264000
Reexamination Certificate
active
06682498
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to medical methods. More particularly, the present invention provides improved methods, apparatus, and kits for establishing access to a patient's vascular system for hemodialysis and other extracorporeal blood treatments.
Access to a patient's vascular system can be established by a variety of temporary and permanently implanted devices. Most simply, temporary access can be provided by the direct percutaneous introduction of a needle through the patient's skin and into a blood vessel. While such a direct approach is relatively simple and suitable for relatively short procedures, such as intravenous feeding, intravenous drug delivery, and the like, they are not suitable for hemodialysis, hemofiltration, or other extracorporeal procedures that must be repeated periodically, often for the lifetime of the patient.
For hemodialysis and other extracorporeal treatment regimens, a variety of transcutaneous catheters and implantable ports have been proposed over the years. Transcutaneous catheters, such as the Tesio catheter available from Med Comp and the Perm-Cath™ available from Quinton, comprise a single catheter tube having a distal end placed in a vein in an in-dwelling manner and a proximal end which extends through the skin and which is available for connection to a hemodialysis or other blood treatment system.
Implantable ports, in contrast, are entirely subcutaneous and connect to a vein or an artery by a subcutaneous “connecting” cannula. Access to the port is achieved by percutaneous placement of a needle or other connecting tube. Such ports typically comprise a needle-penetrable septum to permit percutaneous penetration of the needle. Recently, several valved-port designs have been proposed, where percutaneous introduction of a needle or other access tube into the port opens the valve to permit flow to or from the cannula which connects to the blood vessel.
While both port-access and transcutaneously implanted cannula systems have enjoyed varying levels of success, they continue to suffer from certain disadvantages and limitations. For example, placement of both the port-access and transcutaneously implanted cannula systems has been problematic. Methods and systems for establishing vascular access have been described in related co-pending applications Ser. Nos. 09/333,828; 09/333,728; and 08/856,641, now U.S. Pat. No. 5,931,829, assigned to the assignee of the present application. Typically, such systems place a draw catheter, to draw blood out of the body, proximally of a return catheter, which returns treated blood to the body. Both catheters may be placed through the superior vena cava with the draw catheter tip in the superior vena cava and the return catheter tip extending to a junction between the superior vena cava and the right atrium. However, such access protocols can occasionally result in recirculation of returned treated blood back into the draw catheter. Additionally, such access methods permit only limited blood flow rates. Such limited blood flow rates are problematic since they prolong the duration of the associated extracorporeal blood treatment protocol, such as hemodialysis, hemofiltration, plasmapheresis, apheresis, and the like. Moreover, limited flow rates may cause possible catheter blockage or plugging resulting from fibrin sheath or thrombosis formation over the distal end of the catheter.
For these reasons, it would be desirable to provide improved methods for establishing access to a patient's vascular system for hemodialysis and other extracorporeal blood treatments. In particular, it would be desirable if such improved methods could provide enhanced flow rates without increasing a lumen diameter of the catheters, reduce instances of fibrin sheath or thrombosis formation, and minimize the recirculation of already treated blood. It would be further desirable if such improved methods were useful with both port-access and transcutaneous access systems for hemodialysis, hemofiltration, and other extracorporeal treatment systems. At least some of these objectives will be met by the methods of the present invention described hereinafter.
2. Description of the Background Art
U.S. Pat. No. 5,718,692 describes a double catheter assembly where each catheter has side holes at its distal end. U.S. Pat. Nos. 5,562,617 and 5,041,098 are exemplary of implantable systems employing cannulas extending between a port and a blood vessel for providing extracorporeal circulation. U.S. Pat. Nos. 5,417,656 and 5,281,199 show implantable ports which are connected to vascular cannulas via a transition region (FIG. 1A) and to a multiple branch cannula (FIG. 21). U.S. Pat. No. 4,892,518 shows an implanted port with a transition region extending to a cannula. U.S. Pat. Nos. 5,234,406 and 5,215,530 show two-piece catheters having a distal portion which can be placed percutaneously. The '406 patent discloses a large diameter proximal portion to enhance the flow rate of anesthetics to the subarachnoid region of the spine. U.S. Pat. Nos. 5,203,771 and 4,181,132 show implantable connectors which provide for percutaneous access to implanted shunts.
Related co-pending applications, assigned to the assignee of the present application, include Ser. Nos. 09/630,362; 09/333,828; 09/333,728; 09/238,523; 08/942,990, now U.S. Pat. No. 6,007,516; 08/856,641, now U.S. Pat. No. 5,931,829; 08/745,903, now U.S. Pat. No. 5,755,780; 08/724,948, now U.S. Pat. No. 6,053,901; 08/634,634, now U.S. Pat. No. 5,713,859; 08/539,105, now U.S. Pat. No. 5,807,356; and 60/036,124.
The full disclosures of each of the U.S. patents and co-pending applications listed above are hereby incorporated herein by reference.
SUMMARY OF THE INVENTION
The present invention provides improved methods for establishing vascular access to a patient's body lumen or other target location, particularly coronary blood vessels and cavities, for performing extracorporeal treatment on circulating blood. Exemplary extracorporeal treatment procedures include hemodialysis, hemofiltration, hemodiafiltration, plasmapheresis, apheresis, and the like. In particular, the present invention provides improved methods and kits which enhance extracorporeal blood flow rates, reduce instances of fibrin sheath or thrombosis formation, and minimize recirculation effects. The present invention is most advantageous with access systems comprising a pair of implantable ports connected to a pair of connecting catheters, usually a draw catheter and a return catheter. Specifically, one of the connecting catheters will be intended as a “draw” catheter for removing blood from the patient's vasculature while the other of the catheters will be intended as a “return” catheter for returning treated blood to the patient.
According to a first aspect of the present invention, methods for recirculating blood to a patient generally comprise placing a draw catheter so that a distal tip thereof is positioned in a right atrium of the patient's heart. A return catheter is placed so that a distal tip thereof is positioned in a superior vena cava. Extracorporeal blood flow from the draw catheter to the return catheter may be established. Such methods are particularly useful in that they enhance extracorporeal blood flow rates by placing the draw catheter in the right atrium so that the pressure in the right atrium assists to draw increased volumes of blood through the draw lumen. Such high volume extracorporeal treatment protocols typically provide extracorporeal blood flow rates above 200 ml/minute, usually rates above 300 to 350 ml/minute, and preferably rates above 400 ml/minute or higher. Moreover, the increased blood flow resulting from the increase in pressure (provided by the right atrium) serves to wash a distal tip of the draw catheter which in turn reduces the occurrence of fibrin sheath or thrombosis formation from completely occluding the tip of the catheter, and thereby reducing the risk of trauma.
The placement steps prefer
Paik Sang Y.
Townsend and Townsend / and Crew LLP
Vasca, Inc.
Zec Filip
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