Single needle dialysis

Abstract

Method and apparatus for extracorporeally dialyzing the blood of a patient with only a single venipuncture including withdrawing blood from the patient through the venipuncture and forcing the blood along an arterial path to a dialyzer. Blood emerging from the dialyzer is then conducted along a venous path again to the venipuncture. The pressure is monitored in the extracorporeal system to trigger occluding devices which alternately open and close the arterial and venous paths so that undialyzed blood is taken from the patient and dialyzed blood is injected into the patient. The apparatus includes clamps actuated by a pressure monitor to alternately obstruct the arterial and venous paths. A blood pump may be controlled to operate as one of the clamps. In an alternative embodiment, blood is circulated at a comparatively high flow rate throughout the system. A clamp is provided in one of the arterial or venous lines, said clamp being controlled by a pressure monitor. When the clamp is closed, a pressure differential is developed between the extracorporeal system and the patient so that a volume of blood is exchanged between the system and the patient.

What is claimed and desired to be secured by United States Letters Patent is: 
     
       1. A method of dialyzing the blood of a patient with a single cannula dialysis system having a dialyzer, a blood pump acting thereon and openable clamp comprising the steps of: cannulating the patient by placing a single cannula into the bloodstream of the patient;   providing an extracorporeal bifurcated flow path in communication with the cannula, the flow path having an arterial branch, a venous branch and the blood dialyzer interposed therebetween;   continuously pumping the blood in the arterial branch toward the dialyzer with a pump acting upon the arterial branch;   creating two pressure zones by situating the openable clamp along the length of the venous branch, the first pressure zone defined by the portion of the flow path downstream from the pump and upstream from the clamp so as to include the dialyzer and the second pressure zone being defined by the portion of the flow path upstream from the pump and downstream from the clamp so as to include the patient cannula;   developing increased pressure in the first zone and simultaneously decreasing pressure in the second zone by closing the clamp and continuously pumping blood in the arterial line so as to draw blood from the patient; and thereafter   equalizing the pressure between the zones by opening the clamp thereby permitting blood to be transferred to the patient.   
     
     
       2. A method of dialyzing the blood of a patient with a single cannula dialysis system having a dialyzer, a blood pump acting thereon and openable clamp comprising the steps of: cannulating the patient by placing a single cannula into the bloodstream of the patient;   providing an extracorporeal bifurcated flow path in communication with the cannula, the flow path having an arterial branch, a venous branch and the blood dialyzer interposed therebetween;   continuously pumping the blood in the arterial branch toward the dialyzer with a pump acting upon the arterial branch;   creating two pressure zones by situating the openable clamp in the arterial line upstream from the pump, the first pressure zone being defined by the portion of the flow path downstream from the pump and upstream from the clamp so as to include both the patient cannula and the dialyzer and the second pressure zone being defined by the portion of the flow path upstream from the pump and downstream from the clamp;   developing increased pressure in the first zone by continuously pumping the blood while closing the clamp thereby increasing the pressure in the first zone to inject blood into the patient; and   equalizing the pressure between the zones by opening the clamp and permitting blood to be transferred from the patient to the flow path. .Iadd. 3. A method of dialyzing the blood of a patient with a single cannulation in a system including a pump and a hemodialyzer connected together in a series configuration, and a single hollow cannula having a bifurcated conduit connected thereto to provide an arterial branch and a venous branch, coupled respectively to opposed ends of the series connected pump and hemodialyzer, wherein the interconnected conduit, pump and hemodialyzer define a closed system connected to the single hollow cannula, comprising the steps of:   cannulating the blood vessel of a patient with the single cannula through which blood is withdrawn from and returned to the patient through said system in alternate phases of successive cycles of operation;   pumping blood from the patient to the hemodialyzer through the arterial branch, while preventing the return of blood to the patient through the venous branch;   sensing pressure in the closed system;   automatically occluding blood flow through the arterial branch to stop the withdrawal of blood from the patient in response to the sensing of a predetermined first pressure level in the closed system, while permitting the return of blood to the patient through the venous branch; and, alternately,   automatically occluding blood flow through the venous branch to stop the return flow of blood to the patient in response to the sensing of a predetermined second pressure level in the closed system, while permitting blood withdrawal from the patient through the arterial branch, so that blood is alternately withdrawn and returned to the patient in alternate phases of each successive cycle of operation of the system in response to the sensing of the predetermined first and second pressure levels. .Iaddend. .Iadd. 4. A method of dialyzing the blood of a patient with a single cannulation in a system including a pump and a hemodialyzer connected together in a series configuration, and a single hollow cannula having a bifurcated conduit connected thereto to provide an arterial branch and a venous branch, coupled respectively to opposed ends of the series connected pump and hemodialyzer, wherein the interconnected conduit, pump and hemodialyzer define a closed system connected to the single hollow cannula, comprising the steps of:   cannulating the blood vessel of a patient with the single cannula through which blood is withdrawn from and returned to the patient in alternate phases of successive cycles of operation;   pumping blood from the patient to the hemodialyzer through the arterial branch, while preventing the return of blood to the patient through the venous branch;   sensing pressure in the closed system downstream of the pump;   automatically occluding blood flow through the arterial branch to stop the withdrawal of blood from the patient in response to the sensing of a predetermined first pressure level in the closed system, while permitting the return of blood to the patient through the venous branch; and, alternately,   automatically occluding blood flow through the venous branch to stop the return flow of blood to the patient in response to the sensing of a predetermined second pressure level in the closed system, wherein the first pressure level is higher than said second level, while permitting blood withdrawal from the patient through the arterial branch, so that blood is alternately withdrawn and returned to the patient in alternate phases of each successive cycle of operation of the system in response to the sensing of the predetermined first and second pressure levels..Iaddend.