Hemodialysis system

• US 4,366,051 A
• Filed: 11/19/1976
• Issued: 12/28/1982
• Est. Priority Date: 11/19/1976
• Status: Expired due to Term

• Current Assignee: Halbert Fischel
• Original Assignee: Halbert Fischel
• Inventors: Fischel, Halbert
• Primary Examiner(s): Sadowski, David R.
• Application Number:
  US05/743,222
• Time in Patent Office: 2,230 Days
• Field of Search: 210/321 B, 210/180, 210/186, 210/134, 210/137, 210/188, 210/494 M, 210/22, 210/436, 210/321.1-321.5, 210/96.2, 210/181, 210/195.2, 55/184, 55/200, 55/204, 55/158, 55/189, 21/94, 21/97, 21/56, 137/504, 422/14, 422/26, 422/38
• US Class Current: 210/96.2
• CPC Class Codes: A61M 1/16 with membranes
• CPC Class Codes: A61M 1/1605 Physical characteristics of the dialysate fluid
• CPC Class Codes: A61M 1/1686 by heat
• CPC Class Codes: A61M 2205/18 with alarm
• CPC Class Codes: A61M 2205/3317 Electromagnetic, inductive or dielectric measuring means
• CPC Class Codes: A61M 2205/3324 PH measuring means
• CPC Class Codes: A61M 2205/3331 Pressure; Flow
• CPC Class Codes: A61M 2205/3334 Measuring or controlling the flow rate
• CPC Class Codes: A61M 2205/3368 Temperature

Abstract

A compact self-sterilizable proportioning hemodialysis system alternatively usable with either a coil type or parallel flow artificial dialyzer without material alteration comprises a hydraulic driven dialysate proportioning pump in a positive pressure flow path to provide dialysate in a controlled concentration to a dialysate receiving canister. A coil-type dialyzer within the canister receives dialysate in a recirculating flow from a circulation pump. A venturi in the recirculating flow path provides a negative pressure to pull dialysate through a suction loop, which may alternatively include a parallel flow dialyzer. A conductivity cell, temperature monitor and blood leak detector sample and monitor dialysate from the canister, and to control the dialysate and indicate fault conditions. The system may alternatively function as a recirculating plate-type dialyzer having high dialysis efficiency. In this mode a vortex degasifier recirculating loop and an air separator in the suction loop eliminate entrained gases. Parts of the system may be sterilized by internal means, because the system defines a closed path when certain connections are made. An upright resistive heating steam generator delivers sterilizing steam throughout the liquid flow path which terminates in a pressure relief valve. This increases the steam temperature above the atmospheric water vaporization temperature and maintains the steam at a uniform temperature-pressure equilibrium throughout the flow path. The system requires no central dialysate mixing, yet closely controls the concentration of dialysate utilized.

Claims

1. A compact hemodialysis system including a dialyzer comprising:

canister means having an interior chamber for receiving a dialysate solution and means for draining solution in excess of a selected amount;

a proportioning pump responsive to control signals for feeding dialysate solution to the interior chamber of the canister means, the proportioning pump receiving an inlet water flow and an inlet saline concentrate flow and providing outlet water and concentrate flows in specific proportions comprising a feed rate flow of dialysate solution;

circulation pump means including conduit means coupled to the canister means for delivering dialysate solution to the dialyzer at a rate which may be independent of the feed rate flow;

means for returning the solution through the dialyzer to the canister means, the canister means time averaging variations in concentrate from the proportioning pump to prevent abrupt changes in dialysate properties delivered to the dialyzer and draining off excess from the canister means;

means including conduit means coupled to the circulation pump means and to said canister means for defining a suction loop, the suction loop including negative pressure means for circulating the dialysate solution from the canister means in the suction loop independent of the feed flow from the proportioning pump to the canister means, and wherein the suction loop in addition include means responsive to the dialysate for providing control signals for control of the proportioning pump;

means internal to the hemodialysis system for passing steam throughout the conduit means and the canister means to sterilize the system so that the unit may be used thereafter with different patients without danger of contamination, said means internal to the hemodialysis system comprising a resistive heating element having an exterior casing in the feed flow path, and a cylindrical sleeve about and larger than the casing and means for admitting water at a lower end of the heater between the sleeve and casing and for allowing the escape of saturated steam at the upper end of the heater, the heater being disposed in an upright position so that forced vertical convection drives steam upwardly preventing steam collection and overheating adjacent the heated core surface;

means for shunting exterior couplings of the conduit means to provide a confined pressurizable multi-path volume having a drain outlet, a liquid retaining lower cavity along the flow path and a conduit coupled to the drain outlet from the lower end of the cavity, and pressure release means coupled to the drain oulet for regulating the maximum pressure available in the system to develop a pressure-temperature equilibrium upon generation of adequate steam in the presence of liquid water to sterilize the dialysis system by steam at temperatures substantially in excess of the atmospheric boiling point of water to adequately destroy bacterial and viral germs;

means for enclosing the canister means to enable steam to contact all exposed surfaces of the canister means, said means for enclosing including safety valve means operable at a higher pressure than said means for maintaining pressure;

and

drain valve means in the conduit having a lower operating pressure than the means for maintaining steam at pressure, so that liquid is driven out of the lower cavity through the drain valve means prior to the flow path reaching equilibrium temperature, and thereby allowing complete flow path surface steam penetration.

2. A blood dialysis system for receiving a dialyzer comprising:

canister means including an upwardly open volume for receiving a dialysate;

feed flow means for delivering dialysate to the canister means at a regulated concentration and at feed flow rate;

circulating flow means comprising a positive pressure flow loop and a negative pressure loop for removing dialysate from the canister means at a rate independent of the feed flow rate to supply dialysate to the dialyzer and returning dialysate to the canister means;

means including a plurality of dialysate monitoring devices in the negative pressure loop to aid in maintaining control over dialysate passing through the dialyzer coupled to the circulating flow means;

a circulation pump in the feed flow means;

venturi means coupling the circulation pump to the canister means, and coupled to the negative pressure loop whereby dialysate pumped by the circulation pump to the canister means provides negative pressure at the venturi means for the negative pressure loop;

negative pressure control means coupled in the negative pressure loop, the negative pressure control means including a limiting restriction and means for adjustably bypassing the limiting restriction, the limiting restriction providing a minimum negative pressure available within the negative pressure loop and the adjustable bypass means allowing increased negative pressure within the loop;

air separator means in the negative pressure loop including an inlet and a spaced apart outlet at lower regions thereof;

an internal upstanding flow guide about the inlet and an outer tubular flow guide of greater volume than the internal flow guide to define a downward flow path with dialysate velocity lower than the upward velocity of a substantial proportion of bubbles entrained in the dialysate;

a suction outlet opening in the upper region of the air separator means spaced apart from the inlet for withdrawing a fraction of the dialysate rich in bubbles; and

mesh disposed within the air separator means for collecting and coalescing small bubbles traveling with the dialysate.

3. A self-contained sterilizable hemodialysis system comprising:

canister means for holding a supply of dialysate;

proportioning means coupled to supply dialysate in a feed flow path at a regulated concentration and feed rate to the canister means;

an upright elongated water heater in the feed flow path;

circulation pump means for removing dialysate solution from the canister means at a rate independent of the feed rate in a positive pressure circulation path;

a negative pressure flow path including flow control means coupled to the circulation pump means and the canister means, in which flow path dialysate is drawn through at a controllable rate;

means coupled along the negative pressure flow path for monitoring the concentration of dialysate solution including means providing a signal in response thereto;

means coupled to the proportioning means for adjusting the concentration of dialysate in response to the dialysate monitoring signal;

the system including means for forcing steam generated by the heater through portions of the feed flow path exposed to contamination, the positive pressure circulation path and the negative pressure flow path;

means for receiving either (1) a coil dialyzer in the canister means and in the positive pressure circulation path or (2) a parallel flow dialyzer in the negative pressure flow path;

and

degasifier means adapted to couple into the positive pressure circulation path within the canister means when the system is operated with a parallel flow dialyzer.

4. The invention as set forth in claim 3 above, wherein the degasifier comprises a vortex degasifier arranged to create an angular velocity of from 500 to 1500 radians per minute of the dialysate about a central axis, and including means for withdrawing a minor proportion of dialysate containing a substantial proportion of entrained gases at the central axis.

5. A method for sterilizing hemodialysis apparatus having an interconnecting multibranch liquid flow path including upwardly and downwardly directed passageways containing liquid comprising the steps of:

heating water to generate sufficient steam to pressurize the multibranch liquid flow path;

flowing steam generated by the heating step through the multibranch liquid flow path to be sterilized;

limiting the maximum steam pressure developed therein to establish a pressure-temperature equilibrium to supply steam at the same sterilizing temperature throughout the multibranch liquid flow path; and

bubbling steam through the upwardly directed passageways using the gravitational buoyancy of the bubbles, while forcing steam under pressure through the downwardly directed passageways.

6. The method as set forth in claim 5 above, in which the interconnecting multi-branch flow paths include liquid retaining regions having interior dialysate contacting surfaces, comprising the additional steps of:

evacuating liquid from the liquid retaining regions under pressure less than the equilibrium pressure prior to attaining sterilizing equilibrium temperature; and

thereafter

passing steam through the liquid retaining region to permeate and sterilize the dialysate contacting surfaces of the evacuated liquid retaining region.

7. The method as set forth in claim 6 above, wherein thre multi-branch flow paths include a positive pressure liquid flow path and a negative pressure liquid flow path, each of the positive and negative pressure flow paths having a predetermined liquid flow direction during dialysis wherein the step of flowing steam through the multibranch liquid flow path comprises:

passing steam along the liquid flow direction in the positive pressure liquid flow path; and

passing steam in opposition to the liquid flow direction in the negative pressure liquid flow path.

8. The method as set forth in claim 7 above, wherein the maximum steam pressure is maintained such that temperature equilibrium is achieved at approximately 120°

C., and wherein approximately 50% of the water in the pressurized system is converted to steam.

9. The method as set forth in claim 8 above, wherein the steam pressure is maintained at approximately 15 psi and the water flow rate is approximately 50 ml per minute.

10. A proportioning hemodialysis system for operation with either a coil dialyzer or a parallel flow dialyzer and comprising:

means including controllable proportioning pump means for providing a feed flow;

canister means for maintaining a dialysate bath, coupled to receive the feed flow;

dialysate circulating means coupled to said canister means for maintaining a circulating flow of dialysate, said circulating means including venturi means;

suction loop means coupled to said canister means and said venturi means for maintaining a separate negative pressure flow, said suction loop means including means responsive to dialysate properties for providing a signal to control said proportioning pump means;

controllable heater means coupled in the feed flow;

temperature sensor means coupled in the suction loop means and coupled to control the heater means to regulate dialysate temperature;

whereby (1) a coil dialyzer may be coupled into the circulating flow at said canister means or (2) a parallel flow dialyzer may be coupled into the negative pressure flow; and

a vortex degasifier coupled in the circulation flow when the system incorporates a parallel flow dialyzer, the vortex degasifier including a chamber of circular cross-section about a central axis and having inlet and outlet orifices tangentially disposed relative to the interior periphery of the chamber and spaced apart along the length of the chamber and a gas outlet port disposed adjacent and in facing relation to the central axis of the chamber, and further including means establishing an angular velocity of 500-1500 radians per minute in the dialysate therein.

11. The invention as set forth in claim 10 above, wherein the inlet orifice has a diameter D, wherein the length L of the chamber is between 3 D and 5 D, and including in addition conduit means coupled to the gas outlet port and having an enlarged cross-sectional area, and filamentary dialysate permeable means disposed within said conduit means.