Open patient fluid management method and system

• US 4,769,134 A
• Filed: 12/13/1985
• Issued: 09/06/1988
• Est. Priority Date: 11/20/1985
• Status: Expired due to Fees

• Current Assignee: Althin Medical, Inc.
• Original Assignee: C.P. Medical Corporation
• Inventors: Allan, Jonathan M., Guinn, Perry W.
• Primary Examiner(s): SPEAR JR, FRANK
• Application Number:
  US06/808,828
• Time in Patent Office: 998 Days
• Field of Search: 210/929, 210/87, 210/321.3, 210/90, 210/646, 210/188, 210/321.65
• US Class Current: 210/87
• CPC Class Codes: A61M 1/16 with membranes
• CPC Class Codes: A61M 1/1639 linked by membranes
• CPC Class Codes: A61M 1/1649 with pulsatile dialysis fluid flow
• CPC Class Codes: Y10S 210/929 Hemoultrafiltrate volume measurement or control processes

Abstract

An open, volumetrically regulated patient fluid management system and method are disclosed. Fresh fluid is metered into a patient fluid exchange unit by a first metering device and spent fluid is drawn out by a pump. A back pressure regulator is provided across the pump to maintain its output pressure at a constant value. To the output of the pump are connected a second metering device and an open drain circuit. The second metering device meters out of the patient fluid exchange unit a predetermined quantity of spent fluid. The open drain circuit drains any fluid pumped by the pump, but not removed by the second metering device, to a drain open to atmospheric pressure. When the dialysis unit is deenergized, fluid in the dialyzer returns rapidly to atmospheric pressure by virtue of the open path through the open drain circuit, pump and back pressure regulator to the dialyzer.

Claims

1. An open method of patient fluid management utilizing a semipermeable membrane apparatus, said apparatus including a semipermeable membrane device with an input port and an output port, the apparatus further including a first volumetric metering means operable to transfer a fixed volume of fluid from its input to its output per operational cycle, a second volumetric metering means operable to transfer a fixed volume of fluid from its input to its output per operational cycle, an input circuit disposed between the first volumetric metering means and the input port of the membrane device and an output circuit disposed between the output port of the membrane device and the second volumetric metering means, said method comprising the steps of:

operating the first volumetric metering means to transfer a first volume of fresh fluid from a source of fresh fluid into the input circuit;

transferring a second volume of fresh fluid from the input circuit to the membrane device input port;

transferring a third volume of fluid between a patient and the membrane device;

transferring a fourth volume of spent fluid from the output port of the membrane device to the output circuit;

operating the second volumetric metering means to transfer a fifth volume of the spent fluid from the output circuit to a drain; and

continuously allowing the excess, if any, of the net fluid volume transferred into the membrane device, over the net fluid volume transferred out of the membrane device, to flow to an open drain circuit outlet that is open to atmospheric pressure, thereby maintaining an open system.

2. The method of claim 1 which further comprises allowing said excess to flow to the open drain circuit outlet from either said input circuit, said output circuit, or both.

3. The method of claim 1 in which the transferring steps occur substantially simultaneously.

4. The method of claim 1 which further includes controlling the rate of fluid flow to the open drain circuit outlet.

5. The method of claim 1 which further includes indicating directly and continuously the rate of fluid flow to the open drain circuit outlet.

6. The method of claim 1 which further includes collecting said excess fluid from the open drain circuit outlet.

7. The method of claim 6 in which the collecting step includes indicating directly and continuously the amount of the fluid collected.

8. The method of claim 1 in which transferring a fourth volume includes:

pumping the spent fluid from the output port of the membrane device to a designated point; and

regulating the pressure at the designated point by returning a variable amount of the spent fluid from the designated point to the output port.

9. The method of claim 1 in which:

transferring a fourth volume includes pumping the spent fluid through a pump from the output port of the membrane device to a pump output and regulating the pressure at the pump output by returning a controllable amount of the fluid from the pump output to the membrane device output port through a back pressure regulator under the influence of the pressure difference across the pump, and which further includes the steps;

collecting said excess fluid in a container open to atmospheric pressure;

controlling the rate of said excess fluid flow to the container;

indicating directly and continuously the rate of fluid flow to the container; and

indicating directly and continuously the quantity of fluid in the container.

10. The method of claim 1 in which the patient fluid management comprises ultrafiltration, wherein:

the third volume of fluid is transferred from the patient to the membrane device; and

the fourth volume is greater than or equal to the second volume.

11. The ultrafiltration method of claim 10 in which the fifth volume is equal to the first volume.

12. The method of claim 1 in which the patient fluid management comprises fluid infusion, wherein:

the third volume of fluid is transferred from the membrane device to the patient; and

the fourth volume is less than or equal to the second volume.

13. An open patient fluid management system for use with a semipermeable membrane device comprising:

first volumetric metering means having an input coupled to a source of fresh fluid and an output coupled to an input of the membrane device, for metering a first volume of fresh fluid into the membrane device during an operational cycle;

membrane means for transferring a second volume of fluid between the patient and the membrane device during said operational cycle;

pump means having an input coupled to an output of the membrane device for withdrawing a third volume of spent fluid from the membrane device to a pump means output during said operational cycle;

second volumetric metering means having an input coupled to the pump means output and having an output coupled to a first drain, for metering a fourth volume of fluid from the pump means output to the first drain during said operational cycle;

open drain means having an input coupled to the output of the pump means and an output coupled to a second drain open to atmospheric pressure, for passing continuously any excess of the third volume of fluid over the fourth volume to the second drain, whereby an open system is maintained.

14. The system of claim 13 in which the second drain comprises a container and includes means for indicating directly and continuously the amount of fluid in the container.

15. The system of claim 13 in which the open drain means includes flow control means having an input coupled to the output of the pump means and an output coupled to the second drain, for controlling the flow of excess fluid to the second drain.

16. The system of claim 13 in which the open drain means includes a flow indicator means interposed between the output of the pump means and the second drain for indicating directly and continuously the flow of the excess fluid to the second drain.

17. The system of claim 13 in which the pump means includes back pressure regulator means for regulating the pressure at the output of the pump means.

18. The system of claim 13 in which:

the pump means includes a back pressure regulator means for regulating the pressure at the output of the pump means;

the open drain means includes a flow control means for controlling the flow of fluid to the second drain and a flow indicator means for indicating directly and continuously the rate of said flow; and

the second drain includes a container and means for indicating directly and continuously the amount of fluid in the container.

19. The system of claim 18 in which:

the first and second metering means comprise cross connected, double acting diaphragm pumps;

the open drain means includes a pressure regulator;

the flow control means comprises a first variable size orifice; and

the flow indicator means comprises a rotameter.

20. A system for passing fluid through a semipermeable membrane device comprising:

first and second twin chambered pump means, each having an affluent chamber and an effluent chamber separated by a movable diaphragm, each such chamber having an input port and an output port, for metering dialysate into and out of the membrane device;

a plurality of controllable valve means connected to said chamber ports for controlling the flow of dialysate into or out of the respective chamber, said valve means being operable to controllably open and close the ports with which they are associated;

the input port of each affluent chamber being coupled through one of said valve means to a source of fresh fluid;

the output port of each affluent chamber being coupled through one of said valve means to an input of the membrane device;

the input port of each effluent chamber being coupled through one of said valve means to an output of the membrane device; and

the output port of each effluent chamber being coupled through one of said valve means to a spent fluid output circuit;

electronic control means for configuring the plurality of valve means into at least two operational states;

in the first operational state the valve means being operated to open the following first set of ports;

the input port of the first pump means affluent chamber, the output port of the first pump means effluent chamber, the output port of the second pump means affluent chamber, and the input port of the second pump means effluent chamber, and to close the remaining second set of ports;

in the second operational state the valve means being operated to close the first set of ports and to open the second set of ports; and

electronic clock means for causing the electronic control means to alternate periodically between the first and second states.

21. The system of claim 20 in which:

the electronic control means is also capable of configuring the plurality of valve means into a third operational state in which all of the valve means are closed; and

the clock means is operable to cause the electronic control means to configure the valves in said third operational state during a transition period between the first and second operational states and also between the second and first operational states.