Simulation of patient drain phase in peritoneal dialysis

1. A method of modeling a patient's peritoneal dialysis drain phase comprising:

determining a constant flowrate for the patient residing in a particular patient position;

modeling a first segment of a drain phase curve as having the constant flowrate;

modeling a second segment of a drain phase curve as having a decaying exponential flowrate;

incorporating a switching component into the first and second segments so that (i) at a first time the first segment is active while the second segment is inactive and (ii) at a second time the first segment is inactive while the second segment is active; and

programming a computer to use the modeled first and second drain phase segments for at least one of: (i) determining a drain time for an automated peritoneal dialysis (“APD”) machine, (ii) determining a dwell time for the APD machine, (iii) determining a drain time for a continuous ambulatory peritoneal dialysis therapy, (iv) setting a low flowrate alarm in the APD machine, (v) setting a minimum drain volume percentage in the APD machine, (vi) determining a dwell time for use in kinetically modeling a patient, and (vii) preventing overfilling of the patient.

2. The method of claim 1 , which includes determining the constant flowrate empirically.

3. The method of claim 1 , wherein the particular patient position is one of standing, sitting or lying down.

4. The method of claim 1 , which includes determining a time of transition from the first segment to the second segment for the switching component empirically.

5. The method of claim 1 , which includes a patient specific constant used with the decaying exponential flowrate empirically.

6. The method of claim 1 , which includes entering at least one of the drain time, dwell time and low flowrate alarm setting into the APD machine.

7. The method of claim 6 , wherein the APD machine uses gravity for drain or pumps to drain.

8. The method of claim 1 , which includes using the model to ensure that the drain flowrate does not fall below a certain level during therapy.

9. A model of a patient's peritoneal dialysis drain phase produced via the method of claim 1 .

10. A method of modeling a patient's peritoneal dialysis drain phase comprising:

modeling a first segment of a drain phase curve as having a linear decrease in drain volume from the patient residing in a particular patient position;

modeling a second segment of a drain phase curve as having an exponentially decaying decrease in drain volume from the patient;

incorporating a switching component into the first and second segments so that (i) at a first time the first segment is active while the second segment is inactive and (ii) at a second time the first segment is inactive while the second segment is active; and

programming a computer to use the modeled first and second drain phase segments for at least one of: (i) determining a drain time for an automated peritoneal dialysis (“APD”) machine, (ii) determining a dwell time for the APD machine, (iii) determining a drain time for a continuous ambulatory peritoneal dialysis therapy, (iv) setting a low flowrate alarm in the APD machine, (v) setting a minimum drain volume percentage in the APD machine, (vi) determining a dwell time for use in kinetically modeling a patient, (vii) preventing overfilling of the patient, and (viii) determining a time at which the patient's drain volume is calculated to drop to a certain level as a drain phase duration for therapy.

11. The method of claim 10 , which includes entering the time at which the patient's drain volume is calculated to drop to a certain level as a drain phase duration for therapy into the APD machine.

12. The method of claim 10 , which includes using the method to ensure that the certain level of drain volume removed over the drain phase duration is below a minimum drain volume level or percentage.

13. The method of claim 10 , which includes using the method to ensure that the drain phase flowrate does not fall below a minimum level over the drain phase duration.

14. The method of claim 10 , wherein the particular patient position is one of standing, sitting or lying down.

15. An apparatus for modeling a patient's peritoneal dialysis drain phase comprising:

a computer; and

a non-transitory computer readable medium modified to yield an instantaneous drain volume remaining in a patient, V D , which is equal to [V D0 −Q max *t]*Φ+[V D0 *e −αt ]*(1−Φ), wherein

V D0 is an initial patient drain volume;

Q max is a starting flowrate;

Φ is a switching component;

α is a decaying exponential constant; and

t is time, and

wherein the computer executes the computer readable medium and outputs the instantaneous drain volume.

16. The apparatus of claim 15 , wherein V D0 is estimated from a fill volume plus an expected amount of ultrafiltrate removed from the patient over a previous dwell phase.

17. The apparatus of claim 15 , wherein Q max is at least one of (i) patient specific, (ii) patient drain position specific, and (iii) determined empirically.

18. The apparatus of claim 15 , wherein Φ is either 1 or 0 depending on time t.

19. The apparatus of claim 18 , wherein Φ switches from 1 to 0 at a time t or a volume V D that is determined empirically.

20. The apparatus of claim 15 , wherein α is at least one of (i) patient specific and (iii) determined empirically.

21. The apparatus of claim 15 , wherein the computer readable medium is further modified to use V D to at least one of: (i) determine a drain time for an automated peritoneal dialysis (“APD”) machine; (ii) determine a dwell time for the automated peritoneal dialysis (“APD”) machine; (iii) determine a drain time for a continuous ambulatory peritoneal dialysis therapy; (iv) set a low flowrate alarm in an APD machine; (v) set a minimum drain volume percentage in the APD machine; (vi) determine a dwell time for use in kinetically modeling a patient; and (vii) prevent overfilling of the patient.