HEMOFILTRATION SYSTEM AND METHOD BASED ON MONITORED PATIENT PARAMETERS, SUPERVISORY CONTROL OF HEMOFILTRATION, AND ADAPTIVE CONTROL OF PUMPS FOR HEMOFILTRATION

• US 20100038317A1
• Filed: 10/19/2009
• Published: 02/18/2010
• Est. Priority Date: 04/30/1999
• Status: Active Grant

• Current Assignee: Children's Hospital & Medical Center
• Original Assignee: Children's Hospital & Medical Center
• Inventors: Morales, Efrain O., Hemasilpin, Nat, Bissler, John J., Polycarpou, Marios M.
• Granted Patent: US 7,857,976 B2
• Time in Patent Office: Days
• US Class Current: 210/650
• CPC Class Codes: A61M 1/16 with membranes
• CPC Class Codes: A61M 1/1603 Regulation parameters
• CPC Class Codes: A61M 1/1605 Physical characteristics of the dialysate fluid
• CPC Class Codes: A61M 1/1611 Weight of the patient
• CPC Class Codes: A61M 1/1615 using measurements made at different flow rates
• CPC Class Codes: A61M 1/1643 with weighing of fresh and used dialysis fluid
• CPC Class Codes: A61M 1/1647 with flow rate measurement of the dialysis fluid, upstream and downstream of the dialyser
• CPC Class Codes: A61M 1/34 Filtering material out of the blood by passing it through a membrane, i.e. hemofiltration or diafiltration
• CPC Class Codes: A61M 1/341 by measuring the filtrate rate or volume
• CPC Class Codes: A61M 1/3413 Diafiltration
• CPC Class Codes: A61M 1/342 Adding solutions to the blood, e.g. substitution solutions for preventing coagulation A61M1/3672
• CPC Class Codes: A61M 1/3434 with pre-dilution and post-dilution
• CPC Class Codes: A61M 1/3437 downstream of the filter, e.g. post-dilution with filtrate
• CPC Class Codes: A61M 1/3441 Substitution rate control as a function of the ultrafiltration rate
• CPC Class Codes: A61M 1/3451 the difference in weight between both ultra-filtrate and substitution reservoir being used as control signal
• CPC Class Codes: A61M 1/3496 Plasmapheresis; Leucopheresis; Lymphopheresis A61M1/3472 takes precedence
• CPC Class Codes: A61M 1/3607 Regulation parameters
• CPC Class Codes: A61M 1/3623 Means for actively controlling temperature of blood
• CPC Class Codes: A61M 1/3639 Blood pressure control, pressure transducers specially adapted therefor
• CPC Class Codes: A61M 2205/3331 Pressure; Flow
• CPC Class Codes: A61M 2205/3334 : Measuring or controlling the flow rate
• CPC Class Codes: A61M 2205/3344 : Measuring or controlling pressure at the body treatment site
• CPC Class Codes: A61M 2205/3393 : by weighing the reservoir
• CPC Class Codes: A61M 2205/50 : with microprocessors or computers
• CPC Class Codes: G05B 13/0275 : using fuzzy logic only
• CPC Class Codes: Y10S 210/929 : Hemoultrafiltrate volume measurement or control processes

Abstract

A multipurpose hemofiltration system and method are disclosed for the removal of fluid and/or soluble waste from the blood of a patient. The system continuously monitors the flow rates of drained fluid, blood, and infusate. When necessary, the pumping rates of the infusate, drained fluid and blood are adjusted to remove a preselected amount of fluid from the blood in a preselected time period. A supervisory controller can monitor patient parameters, such as heart rate and blood pressure, and adjust the pumping rates accordingly. The supervisory controller uses fuzzy logic to make expert decisions, based upon a set of supervisory rules, to control each pumping rate to achieve a desired flow rate and to respond to fault conditions. An adaptive controller corrects temporal variations in the flow rate based upon an adaptive law and a control law.

Claims

1. A hemofiltration system for fluid removal from blood of a patient, comprising:

a pump capable of pumping a liquid selected from the group consisting of infusate, drained fluid, and blood in the hemofiltration system;

a sensor for measuring a flow rate of fluid in the hemofiltration system generated by the pump, the flow rate sensor providing flow rate data signals correlated to the fluid flow rate;

a supervisory controller operably connectable to the pump in the hemofiltration system and operably connected to the flow rate sensor; and

a monitor for measuring at least one patient parameter, the patient parameter monitor providing patient parameter data signals correlated to the at least one patient parameter,

wherein the supervisory controller is operably connected to the monitor, the supervisory controller;

receiving the flow rate data signals and patient parameter data signals,

analyzing the flow rate data signals utilizing fuzzy logic having at least one supervisory rule and a width of at least one membership function in the fuzzy logic dependent upon a desired ultrafiltration rate, and

providing an output signal for the at least one pump to adjust, as necessary, on a periodic basis, the flow rate of liquid generated by the pump for regulating fluid removal from the patient'"'"'s blood.

2. The hemofiltration system of claim 1, wherein said at least one patient parameter monitor is selected from the group consisting of a blood pressure monitor providing blood pressure data signals, a heart rate monitor providing heart rate data signals, and combinations thereof.

3. The hemofiltration system of claim 2, wherein the hemofiltration system is an ultrafiltration system and the at least one predetermined supervisory rule is selected from the group consisting of:

a) If heart rate is high and blood pressure is normal or low, then decrease ultrafiltration and wait a first predetermined time,

b) If blood pressure is low and heart rate is normal or high, then decrease ultrafiltration and wait a second predetermined time,

c) If blood pressure is low and heart rate is low, then provide the user a choice between a decrease or increase of the ultrafiltration rate and wait a third predetermined time,

d) If blood pressure is high and heart rate is high for a fourth predetermined time, then provide the user with a choice between a decrease or increase of the ultrafiltration rate,

e) If blood pressure is high and heart rate is low for a fifth predetermined time, then increase ultrafiltration,

f) The lowest possible value of ultrafiltration is a predetermined minimum rate per hour and the highest possible value of the ultrafiltration rate is a predetermined percentage above that of a predetermined maximum ultrafiltration rate,

g) If an increase in ultrafiltration occurs such that the filtered fraction is greater than a predetermined filtered fraction, then increase the blood pump flow such that the filtered fraction equals the predetermined filtered fraction.

4. The hemofiltration system of claim 2, wherein the sensor is selected from the group consisting of a flowmeter and a weight scale.

5. The hemofiltration system of claim 1, further comprising:

a second sensor for measuring the flow rate of fluid generated by a second pump, the second flow rate sensor providing second flow rate data signals correlated to the fluid flow rate,

wherein the supervisory controller is further operably connectable to the second pump and operably connected to the second flow rate sensor, the controller receiving the second flow rate data signals and analyzing the signals utilizing fuzzy logic based on at least one predetermined supervisory rule and the controller then providing an output signal for the second pump to adjust, as necessary on a periodic ongoing basis, the flow rate of fluid generated by the second pump.

6. The hemofiltration system of claim 5, further comprising:

a third sensor for measuring the flow rate of fluid in the hemofiltration system generated by a third pump, the third flow rate sensor providing third flow rate data signals correlated to the fluid flow rate,

wherein the supervisory controller is further operably connectable to the third pump and operably connected to the third flow rate sensor, the controller receiving the third flow rate data signals and analyzing the signals utilizing fuzzy logic based on at least one predetermined supervisory rule and the controller then providing an output signal for the third pump to adjust, as necessary on a periodic ongoing basis, the flow rate of fluid generated by the third pump.

7. The hemofiltration system of claim 6, further comprising:

a fourth sensor for measuring the flow rate of fluid in the hemofiltration system generated by a fourth pump, the fourth flow rate sensor providing fourth flow rate data signals correlated to the fluid flow rate,

wherein the supervisory controller is further operably connectable to the fourth pump and operably connected to the fourth flow rate sensor, the controller receiving the fourth flow rate data signals and analyzing the signals utilizing fuzzy logic based on at least one predetermined supervisory rule and the controller then providing an output signal to the fourth pump to adjust, as necessary on a periodic ongoing basis, the flow rate of fluid generated by the fourth pump.

8. The hemofiltration system of claim 1, further comprising:

an adaptive controller operably connectable to the pump and to said flow rate sensor, the adaptive controller receiving said flow rate data signals, using an adaptive law to generate a set of controller parameters for correcting time-dependent deviations of the flow rate of the respective fluid from a predetermined blood flow rate, and using a control law to generate an output signal from the set of controller parameters for adjusting the pumping rate of fluid generated by the pump to achieve the predetermined blood flow rate, said adaptive controller then providing the output signal for the pump on a periodic ongoing basis.

9. A method of controlling a pump in a hemofiltration system for removing fluid from blood of a patient, the method comprising:

pumping a fluid selected from the group consisting of infusate, drained fluid, and blood either to or from a filer in the hemofiltration system using the pump;

measuring a flow rate of the fluid to generate flow rate signals correlated with the measured fluid flow rate;

measuring a patient parameter to generate patient parameter signals utilizing a fuzzy logic inference system having at least one supervisory rule and a width of at least one membership function in the fuzzy logic dependent upon a desired ultrafiltration rate; and

controlling a pump speed of the pump in response to the analysis of the flow rate signals and the patient parameter signals for regulating fluid removal from the patient'"'"'s blood.

10. The method of claim 9, wherein the hemofiltration system is an ultrafiltration system, the method further comprising:

selecting the at least one predetermined supervisory rule from the group consisting of;

a) If heart rate is high and blood pressure is normal or low, then decrease ultrafiltration and wait a first predetermined time,

b) If blood pressure is low and heart rate is normal or high, then decrease ultrafiltration and wait a second predetermined time,

c) If blood pressure is low and heart rate is low, then provide the user a choice between a decrease or increase of the ultrafiltration rate and wait a third predetermined time,

d) If blood pressure is high and heart rate is high for a fourth predetermined time, then provide the user with a choice between a decrease or increase of the ultrafiltration rate,

e) If blood pressure is high and heart rate is low for a fifth predetermined time, then increase ultrafiltration,

f) The lowest possible value of ultrafiltration is a predetermined minimum rate per hour and the highest possible value of the ultrafiltration rate is a predetermined percentage above that of a predetermined maximum ultrafiltration rate,

g) If an increase in ultrafiltration occurs such that the filtered fraction is greater than a predetermined filtered fraction, then increase the blood pump flow such that the filtered fraction equals the predetermined filtered fraction.

11. The method of claim 9, further comprising:

measuring a flow rate of fluid generated by a second pump with a second sensor, the second flow rate sensor providing second flow rate data signals correlated to the fluid flow rate, and

controlling a pump speed of the second pump in response to the analysis of the flow rate signals from the second flow rate sensor and the patient parameter signals for regulating fluid removal from the patient'"'"'s blood.

12. The method of claim 11, further comprising:

measuring a flow rate of fluid generated by a third pump with a third sensor, the third flow rate sensor providing third flow rate data signals correlated to the fluid flow rate, and

controlling a pump speed of the third pump in response to the analysis of the flow rate signals from the third flow rate sensor and the patient parameter signals for regulating fluid removal from the patient'"'"'s blood.

13. The method of claim 12, further comprising:

measuring a flow rate of fluid generated by a fourth pump with a fourth sensor, the fourth flow rate sensor providing fourth flow rate data signals correlated to the fluid flow rate, and

controlling a pump speed of the fourth pump in response to the analysis of the flow rate signals from the fourth flow rate sensor and the patient parameter signals for regulating fluid removal from the patient'"'"'s blood.

14. The method of claim 9, further comprising:

receiving said flow rate data signals by an adaptive controller operably connectable to the pump and to the flow rate sensor;

using an adaptive law to generate a set of controller parameters for correcting time-dependent deviations of the flow rate of the respective fluid from a predetermined blood flow rate;

using a control law to generate an output signal from the set of controller parameters;

adjusting the pumping rate of fluid generated by the pump to achieve the predetermined blood flow rate; and

periodically providing the output signal for the pump by the adaptive controller on an ongoing basis.