Dialysis control system and method

Claim 1

A method of dialyzing the blood of a patient in an extracorporeal hemodialyzer, the steps of: cannulating a blood vessel of a patient with a single hollow cannula, the cannula being bifurcated extracorporeally into an arterial branch and a venous branch, the hemodialyzer being situated therebetween; closing the venous branch for a first variable time increment and simultaneously aspirating blood out of the patient blood vessel through the arterial branch toward the dialyzer until blood in the venous branch reaches a predetermined elevated pressure; closing the arterial branch and opening the venous branch for a second predetermined time increment, the second time increment being less than the first, so that the elevated pressure causes the blood in the venous line to be conducted to the patient at a flow rate which is greater than the rate at which the same quantity of blood is withdrawn from the patient.

Claim 2

A method of dialyzing the blood of a patient in an extracorporeal hemodialyzer, the steps of: cannulating a blood vessel of a patient with a single hollow cannula, the cannula being bifurcated extracorporeally into an arterial branch and a venous branch, the hemodialyzer being situated therebetween; closing the venous branch for a first variable time increment and simultaneously aspirating blood out of the patient blood vessel through the arterial branch toward the dialyzer until blood in the venous branch reaches a predetermined elevated pressure; closing the arterial branch and opening the venous branch for a second predetermined time increment, the second time increment being less than the first, so that the elevated pressure causes the blood in the venous line to be conducted to the patient at a flow rate which is greater than the rate at which the same quantity of blood is withdrawn from the patient.

Claim 3

A method of controlling an extracorporeal hemodialysis sytem comprising an arterial line conducting blood away from a patient, a venous line conducting blood toward the patient, a dialyzer situated between the arterial and venous lines and a blood pump for unidirectionally displacing the blood, the steps of: aspirating blood from the patient through the arterial line at a flow rate which will not collapse blood-conducting conduit; closing the venous line while continuing to aspirate the blood until a predetermined elevated pressure is reached in the venous line; thereafter opening the venous line and essentially simultaneously closing the arterial line for a predetermined time increment to inject the blood under pressure into the patient; and insuring that the duration of a venous line opening is less than the duration of the arterial line opening.

Claim 4

A method of controlling an extracorporeal hemodialysis sytem comprising an arterial line conducting blood away from a patient, a venous line conducting blood toward the patient, a dialyzer situated between the arterial and venous lines and a blood pump for unidirectionally displacing the blood, the steps of: aspirating blood from the patient through the arterial line at a flow rate which will not collapse blood-conducting conduit; closing the venous line while continuing to aspirate the blood until a predetermined elevated pressure is reached in the venous line; thereafter opening the venous line and essentially simultaneously closing the arterial line for a predetermined time increment to inject the blood under pressure into the patient; and insuring that the duration of a venous line opening is less than the duration of the arterial line opening.

Claim 5

A system for controlling the dialysis of blood comprising an arterial line conducting blood away from a patient, a venous line conducting blood toward the patient, and a dialyzer situated between the arterial line and venous line, the improvement comprising: means for pumping blood unidirectionally from the patient through the open arterial line at a pressure which will not collapse blood-conducting conduit; means for closing the venous line while the blood is being pumped until a predetermined elevated blood pressure is reached in the venous line, said closing means comprising pressure-responsive control means adjustable to maintain the closure of the venous line independent of time; means for opening the venous line and essentially simultaneously closing the arterial line, said opening means comprising time-responsive control means adjustable to maintain the venous line open independent of pressure in the line for a predetermined time increment to inject the blood under pressure to the patient, the duration of the closure of the arterial line being less than the duration of the venous line closure.

Claim 6

A system for controlling the dialysis of blood comprising an arterial line conducting blood away from a patient, a venous line conducting blood toward the patient, and a dialyzer situated between the arterial line and venous line, the improvement comprising: means for pumping blood unidirectionally from the patient through the open arterial line at a pressure which will not collapse blood-conducting conduit; means for closing the venous line while the blood is being pumped until a predetermined elevated blood pressure is reached in the venous line, said closing means comprising pressure-responsive control means adjustable to maintain the closure of the venous line independent of time; means for opening the venous line and essentially simultaneously closing the arterial line, said opening means comprising time-responsive control means adjustable to maintain the venous line open independent of pressure in the line for a predetermined time increment to inject the blood under pressure to the patient, the duration of the closure of the arterial line being less than the duration of the venous line closure.

Claim 7

A system for controlling the dialysis of blood comprising an arterial line conducting blood away from a patient, a venous line conducting blood toward the patient, and a dialyzer situated between the arterial line and the venous line, the improvement comprising: means for pumping blood unidirectionally from the patient through the open arterial line at a pressure which will not collapse blood-conducting conduit; means for closing the venous line while the blood is being pumped, said closing means comprising a first independently variable control means maintaining closure of the venous line until a predetermined blood pressure is reached in the system; means for opening the venous line and essentially simultaneously closing the arterial line, said opening means comprising a second independently variable control means allowing accumulated pressure of the blood to inject the blood to the patient for a predetermined time increment, the duration of the closure of the arterial line being greater than the duration of the venous line closure.

Claim 8

A system for controlling the dialysis of blood comprising an arterial line conducting blood away from a patient, a venous line conducting blood toward the patient, and a dialyzer situated between the arterial line and the venous line, the improvement comprising: means for pumping blood unidirectionally from the patient through the open arterial line at a pressure which will not collapse blood-conducting conduit; means for closing the venous line while the blood is being pumped, said closing means comprising a first independently variable control means maintaining closure of the venous line until a predetermined blood pressure is reached in the system; means for opening the venous line and essentially simultaneously closing the arterial line, said opening means comprising a second independently variable control means allowing accumulated pressure of the blood to inject the blood to the patient for a predetermined time increment, the duration of the closure of the arterial line being greater than the duration of the venous line closure.