Method and apparatus for ultrafiltration measurement in a two pump dialysis system

• US 4,596,550 A
• Filed: 01/27/1984
• Issued: 06/24/1986
• Est. Priority Date: 09/24/1982
• Status: Expired due to Fees

• Current Assignee: Baxter Travenol Laboratories Incorporated One Baxter Parkway Deerfield Illinois 60015
• Original Assignee: Baxter Travenol Laboratories Incorporated
• Inventors: Troutner, Vernon H.
• Primary Examiner(s): Coven, Edward M.
• Application Number:
  US06/574,791
• Time in Patent Office: 879 Days
• Field of Search: 604/4, 604/5, 604/6, 604/27-31, 604/34, 604/51, 604/66-67, 604/153, 604/118, 128/DIG. 13, 210/321.2, 210/321.3
• US Class Current: 604/6.05
• CPC Class Codes: A61M 1/30 Single needle dialysis ; Reciprocating systems, alternately withdrawing blood from and returning it to the patient, e.g. single-lumen-needle dialysis or single needle systems for hemofiltration or pheresis
• CPC Class Codes: A61M 1/303 having a reservoir for treated blood to be returned
• CPC Class Codes: A61M 1/306 Pressure control, e.g. using substantially rigid closed or gas buffered or elastic reservoirs
• CPC Class Codes: A61M 1/308 Volume control, e.g. with open or flexible containers, by counting the number of pump revolutions, weighing
• CPC Class Codes: A61M 2205/50 with microprocessors or computers
• CPC Class Codes: Y10S 128/13 Infusion monitoring

Abstract

A blood flow system for processing blood has two phases of operation, an arterial phase and a venous phase. During the arterial phase, the system is filled with blood through operation of an arterial blood pump. When a predetermined blood pressure level in the system has been attained, the arterial blood pump is inactivated and a venous blood pump removes blood from the system for a given number of pump turns. By accurately monitoring both arterial and venous pumps operating cycles, ultrafiltration volume and rate may be determined.

Claims

1. In a dual pump blood processing system for a patient wherein an arterial pump fills blood processing means with blood from the patient and a venous pump removes a known volume of blood from said blood processing means between said arterial and venous pumps and returns said blood to the patient, said arterial and venous pumps being alternately operated to fill and remove blood in response to control means, apparatus for performing ultrafiltration measurements comprising:

(a) first means associated with said arterial pump for providing first signals responsive to the volume pumped by said arterial pump;

(b) second means associated with said venous pump for providing second signals responsive to the volume pumped by said venous pump;

(c) first and second signal connecting means for communicating said first and second signals to said control means and wherein said control means calculates the ultrafiltration volume in response to said first and second signals.

2. The apparatus as set forth in claim 1 wherein said control means further calculates the ultrafiltration rate based on the ultrafiltration volume and the elapsed time.

3. The apparatus as set forth in claim 1 wherein said first and second means comprises a slot encoder and said control means comprises a microprocessor with display means.

4. A low pressure blood processing system for a patient comprising:

means for withdrawing blood from said patient;

a first arterial blood pump having an input coupled to said withdrawing means and an output at which a flow of blood is provided when said pump is activated;

means for processing blood having an input coupled to the output of said arterial blood pump and an output at which a flow of processed blood is produced;

a second venous blood pump having an input coupled to the output of said blood processing system, and an output;

means, coupled to the output of said venous blood pump, for returning processed blood to said patient, wherein said blood processing system exhibits a given blood capacity when full;

a monitor coupled to said blood processing system for detecting the attainment of said given blood capacity;

blood pump control means, coupled to said pumps and said monitor, for activating said venous blood pump upon detection of said given blood capacity, and for activating said arterial blood pump after said venous blood pump has been activated for a given number of operating cycles;

first means associated with said arterial blood pump and connected to said control means for providing to said control means first signals responsive to the volume of blood pumped by said arterial pump;

second means associated with said venous blood pump and connected to said control means for providing to said control means second signals responsive to the volume of blood pumped by said venous pump; and

wherein said control means displays ultrafiltration information in response to said first and second signals.

6. The blood processing system of claim 4, wherein said processing means comprises a dialyzer for performing hemodialysis, and said system further comprises a flexible blood accumulator coupled between said dialyzer and said second venous blood pump, said accumulator exhibiting a known blood capacity when full, and said first and second means include a slot encoder and said ultrafiltration information includes ultrafiltration volume and ultrafiltration rate.

8. The blood processing system of claim 6, wherein said monitor comprises a pressure transducer coupled between said dialyzer and said venous blood pump for measuring venous blood pressure.

10. The blood processing system of claim 6, wherein said first and second means detect operating cycles of said arterial and venous blood pumps respectively, and communicate said operating cycle information to said control means which calculates volume of blood pumped by each pump based on each pump'"'"'s known volume per cycle pumping characteristics.

5. A low pressure blood processing system for a patient comprising:

means for withdrawing blood from said patient;

a first arterial blood pump having an input coupled to said withdrawing means and an output at which a flow of blood is provided when said pump is activated;

means for processing blood having an input coupled to the output of said arterial blood pump and an output at which a flow of processed blood is produced;

a second venous blood pump having an input coupled to the output of said blood processing system, and an output;

means, coupled to the output of said venous blood pump, for returning processed blood to said patient;

a pressure monitor coupled to said blood processing system for detecting the blood pressure therein;

blood pump control means, coupled to said pumps and said monitor, for activating said venous blood pump when said detected blood pressure of said blood processing system attains a given threshold, and for activating said arterial blood pump after said venous blood pump has been activated for a given number of operating cycles;

first means associated with said arterial blood pump and connected to said control means for providing to said control means first signals responsive to the volume of blood pumped by said arterial pump;

second means associated with said means blood pump and connected to said control means for providing to said control means second signals responsive to the volume of blood pumped by said venous pump; and

wherein said control means displays ultrafiltration information in response to said first and second signals.

7. The blood processing system of claim 5, wherein said processing means comprises a dialyzer for performing hemodialysis, and said system further comprises a flexible blood accumulator coupled between said dialyzer and said second venous blood pump, said accumulator exhibiting a known blood capacity when full, and said first and second means include a slot encoder and said ultrafiltration information includes ultrafiltration volume and ultrafiltration rate.

9. The blood processing system of claim 7, wherein said monitor comprises a pressure transducer coupled between said dialyzer and said venous blood pump for measuring venous blood pressure.

11. The blood processing system of claim 7, wherein said first and second means detect operating cycles of said arterial and venous blood pumps respectively and communicate said operating cycle information to said control means which calculates volume of blood pumped by each pump based on each pump'"'"'s known volume per cycle pumping characteristics.

12. A method of determing ultrafiltration volume in a hemodialysis system which includes a dialyzer, an arterial blood pump coupled to pump a known volume of blood per pump operating cycle between a patient and an input of the dialyzer, and a venous blood pump coupled to pump a known volume of blood per pump operating cycle between an output of the dialyzer and the patient, said method comprising the steps of:

(a) activating said arterial blood pump while said venous pump is inactive until the blood pressure in the system between said blood pumps attains a given relatively low level,

(b) counting the number of operating cycles performed by said arterial pump during activation;

(c) activating said venous blood pump while said arterial pump is inactive for a predetermined number of operating cycles; and

(d) calculating the ultrafiltration volume in response to the number of operating cycles performed by said arterial and venous blood pumps.

13. A method of operating a hemodialysis system which includes a dialyzer, an arterial blood pump coupled to pump blood between a patient and an input of the dialyzer, and a venous blood pump coupled to pump a known volume of blood per pump operating cycle between an output of the dialyzer and the patient, said method comprising the steps of:

(a) activating said arterial blood pump while said venous pump is inactive and the blood pressure at said output of said dialyzer remains substantially equal to atmospheric pressure and, when said blood pressure at the output of said dialyzer increases a predetermined, relatively small amount, above atmospheric pressure;

(b) counting the number of turns performed by said arterial pump during activation;

(c) activating said venous blood pump while said arterial pump is inactive for a predetermined number of pump turns; and

(d) calculating the ultrafiltration volume in response to the number of turns and fractions thereof of said arterial and venous pumps.