Closed loop dialysis treatment using adaptive ultrafiltration rates
A method of performing closed-loop dialysis treatment during hemodialysis is provided. The method involves determining an initial ultrafiltration rate and setting an ultrafiltration pump of a dialysis system to the determined ultrafiltration rate. A series of measurements and calculations are made to ensure that a rate of change of blood volume during treatment follows a specified profile. A threshold may be used to keep the rate of change of blood volume tracking the profile. Patient fluid dynamics may be measured in real-time and used to determine the ultrafiltration pump rate.
1. A method for performing closed-loop dialysis treatment, comprising:
determining, by a dialysis system, an initial ultrafiltration rate and setting an ultrafiltration pump to the determined initial ultrafiltration rate;
measuring, by the dialysis system, a total blood volume change based on the initial ultrafiltration rate;
determining, by the dialysis system, a benchmark blood volume threshold for the measured total blood volume change based on a target change in blood volume, a currently elapsed treatment time for the closed-loop dialysis treatment, a time duration associated with the closed-loop dialysis treatment, and a start time for the closed-loop dialysis treatment;
setting, by the dialysis system, the ultrafiltration pump to a new pump rate based on comparing the determined benchmark blood volume threshold with the measured total blood volume change; and
stopping, by the dialysis system, the closed-loop dialysis treatment based on the target change in blood volume.
2. The method of claim 1 , wherein measuring the total blood volume change comprises periodically sampling the total blood volume change at a sampling rate to determine a plurality of measured total blood volume changes, wherein each of the plurality of measured total blood volume changes is associated with a different elapsed treatment time, and
wherein determining the benchmark blood volume threshold comprises determining a new benchmark blood volume threshold for each of the plurality of measured total blood volume changes.
3. The method of claim 2 , wherein setting the ultrafiltration pump to the new pump rate comprises cycling the ultrafiltration pump between a minimum pump rate associated with the ultrafiltration pump and the initial ultrafiltration rate based on the determined new benchmark blood volume threshold for each of the plurality of measured total blood volume changes.
4. The method of claim 1 , further comprising:
determining a hysteresis associated with the ultrafiltration pump, and
wherein setting the ultrafiltration pump to the new pump rate is based on comparing the measured total blood volume change with the hysteresis and the determined benchmark blood volume threshold.
5. The method of claim 1 , further comprising:
prior to measuring the total blood volume change, measuring a second total blood volume change; and
setting the ultrafiltration pump to a minimum pump rate based on comparing a second benchmark blood volume threshold with the second total blood volume change,
wherein setting the ultrafiltration pump to the new pump rate comprises setting the ultrafiltration pump from the minimum pump rate back to the initial ultrafiltration rate based on comparing the determined benchmark blood volume threshold with the measured total blood volume change.
6. The method of claim 1 , further comprising:
prior to measuring the total blood volume change, measuring a second total blood volume change; and
setting the ultrafiltration pump to a minimum pump rate based on comparing a second benchmark blood volume threshold with the second total blood volume change,
wherein setting the ultrafiltration pump to the new pump rate comprises:
setting, based on comparing the determined benchmark blood volume threshold with the measured total blood volume change, the ultrafiltration pump from the minimum pump rate to an ultrafiltration rate that is above the minimum pump rate and different from the initial ultrafiltration rate.
7. The method of claim 1 , wherein stopping the closed-loop dialysis treatment is based on a cumulative change in blood volume reaching the target change in blood volume.
8. The method of claim 1 , wherein stopping the closed-loop dialysis treatment is based on a total dialysis treatment time elapsing.
9. The method of claim 1 , wherein:
the target change in blood volume is associated with a first time interval of a treatment profile;
the treatment profile indicates at least two separate time intervals comprising the first time interval associated with the target change in blood volume and at least one other time interval associated with at least one other target change in blood volume; and
determining the benchmark blood volume threshold for the measured total blood volume change comprises determining a waypoint change in blood volume based on the target change in blood volume and the first time interval.
10. The method of claim 9 , further comprising:
measuring a second total blood volume change within a second time interval of the at least one other time interval;
determining a second waypoint change in blood volume based on the second time interval and a second target change in blood volume of the at least one other target change in blood volume, wherein the target change in blood volume is different from the second target change in blood volume; and
setting the ultrafiltration pump to a second pump rate based on comparing the second waypoint change in blood volume with the measured second total blood volume change.
11. A dialysis system for performing closed-loop dialysis treatment, comprising:
an ultrafiltration pump;
a processor; and
a non-transitory computer-readable storage medium having processor-executable instructions stored thereon, wherein the processor-executable instructions, when executed by the processor, facilitate:
determining an initial ultrafiltration rate and setting the ultrafiltration pump to the determined initial ultrafiltration rate;
measuring a total blood volume change based on the initial ultrafiltration rate;
determining a benchmark blood volume threshold for the measured total blood volume change based on a target change in blood volume, a currently elapsed treatment time for the closed-loop dialysis treatment, a time duration associated with the closed-loop dialysis treatment, and a start time for the closed-loop dialysis treatment;
setting the ultrafiltration pump to a new pump rate based on comparing the determined benchmark blood volume threshold with the measured total blood volume change; and
stopping the closed-loop dialysis treatment based on the target change in blood volume.
12. The dialysis system of claim 11 , wherein measuring the total blood volume change comprises periodically sampling the total blood volume change at a sampling rate to determine a plurality of measured total blood volume changes, wherein each of the plurality of measured total blood volume changes is associated with a different elapsed treatment time, and
wherein determining the benchmark blood volume threshold comprises determining a new benchmark blood volume threshold for each of the plurality of measured total blood volume changes.
13. The dialysis system of claim 12 , wherein setting the ultrafiltration pump to the new pump rate comprises cycling the ultrafiltration pump between a minimum pump rate associated with the ultrafiltration pump and the initial ultrafiltration rate based on the determined new benchmark blood volume threshold for each of the plurality of measured total blood volume changes.
14. The dialysis system of claim 11 , wherein the processor-executable instructions, when executed by the processor, further facilitate:
determining a hysteresis associated with the ultrafiltration pump, and
wherein setting the ultrafiltration pump to the new pump rate is based on comparing the measured total blood volume change with the hysteresis and the determined benchmark blood volume threshold.
15. The dialysis system of claim 11 , wherein the processor-executable instructions, when executed by the processor, further facilitate:
prior to measuring the total blood volume change, measuring a second total blood volume change; and
setting the ultrafiltration pump to a minimum pump rate based on comparing a second benchmark blood volume threshold with the second total blood volume change,
wherein setting the ultrafiltration pump to the new pump rate comprises setting the ultrafiltration pump from the minimum pump rate back to the initial ultrafiltration rate based on comparing the determined benchmark blood volume threshold with the measured total blood volume change.
16. The dialysis system of claim 11 , wherein the processor-executable instructions, when executed by the processor, further facilitate:
prior to measuring the total blood volume change, measuring a second total blood volume change; and
setting the ultrafiltration pump to a minimum pump rate based on comparing a second benchmark blood volume threshold with the second total blood volume change,
wherein setting the ultrafiltration pump to the new pump rate comprises: setting, based on comparing the determined benchmark blood volume threshold with the measured total blood volume change, the ultrafiltration pump from the minimum pump rate to an ultrafiltration rate that is above the minimum pump rate and different from the initial ultrafiltration rate.
17. The dialysis system of claim 11 , wherein:
the target change in blood volume is associated with a first time interval of a treatment profile;
the treatment profile indicates at least two separate time intervals comprising the first time interval associated with the target change in blood volume and at least one other time interval associated with at least one other target change in blood volume; and
determining the benchmark blood volume threshold for the measured total blood volume change comprises determining a waypoint change in blood volume based on the target change in blood volume and the first time interval.
18. A non-transitory computer-readable storage medium having processor-executable instructions stored thereon, wherein the processor-executable instructions, when executed by a processor, facilitate:
determining an initial ultrafiltration rate and setting an ultrafiltration pump to the determined initial ultrafiltration rate;
measuring a total blood volume change based on the initial ultrafiltration rate;
determining a benchmark blood volume threshold for the measured total blood volume change based on a target change in blood volume, a currently elapsed treatment time for the closed-loop dialysis treatment, a time duration associated with the closed-loop dialysis treatment, and a start time for the closed-loop dialysis treatment;
setting the ultrafiltration pump to a new pump rate based on comparing the determined benchmark blood volume threshold with the measured total blood volume change; and
stopping the closed-loop dialysis treatment based on the target change in blood volume.
19. The method of claim 1 , wherein determining the benchmark blood volume threshold is based on the following equation:
benchmark
%
Δ
BV
=
Treatment
Length
Current
Time
-
Start
Time
×
target
%
Δ
BV
,
where the benchmark % ΔBV is the benchmark blood volume threshold, the target % ΔBV is the target change in blood volume, the Treatment Length is the time duration associated with the closed-loop dialysis treatment and indicates a total treatment length for the closed-loop dialysis treatment, a Current Time is the currently elapsed treatment time for the closed-loop dialysis treatment, and a Start Time is the start time for the closed-loop dialysis treatment.
20. The method of claim 1 , wherein determining the benchmark blood volume threshold is based on the following equation:
Waypoint
%
Δ
BV
=
n
Current
Time
-
Start
Time
×
target
%
Δ
BV
(
n
)
,
where the Waypoint % ΔBV is the benchmark blood volume threshold at a time interval, n is the time duration associated with the closed-loop dialysis treatment and indicates the time interval, the target % ΔBV(n) is the target change in blood volume at the time interval, a Current Time is the currently elapsed treatment time for the closed-loop dialysis treatment, and a Start Time is the start time for the closed-loop dialysis treatment.