Pressure sampling systems and methods for negative pressure wound therapy
Systems and methods for controlling a pump system for use in negative pressure wound therapy are described herein. In some embodiments, a method for controlling a pump system includes applying a drive signal to a pump assembly of the pump system, the drive signal alternating between a positive amplitude and a negative amplitude and the drive signal having an offset, and sampling a pressure within a fluid flow path configured to connect the pump system to a wound dressing configured to be placed over a wound during one or more time intervals. Each of the one or more time intervals can occur when the drive signal is approximately at an amplitude equal to one or more sampling amplitudes.
1. A pump system configured for negative pressure wound therapy, the pump system comprising:
a pump assembly configured to be fluidically connected via a fluid flow path to a wound dressing placed over a wound, the pump assembly comprising:
an actuator; and
a diaphragm;
a pressure sensor configured to measure pressure in the fluid flow path; and
a controller configured to control operation of the pump system, the controller further configured to:
apply a drive signal to the pump assembly, the drive signal alternating between a positive amplitude and a negative amplitude and the drive signal having an offset;
determine a plurality of time intervals during which the drive signal is approximately at a sampling amplitude selected for determining pressure in the fluid flow path; and
during application of the drive signal to the pump assembly, sample a plurality of pressures measured by the pressure sensor during the plurality of time intervals and not during other time intervals,
wherein sampling the plurality of pressures during the plurality of time intervals minimizes measurement errors due to pressure fluctuations caused by operation of the actuator of the pump assembly.
2. The pump system of claim 1 , wherein the sampling amplitude comprises a local maxima of the drive signal.
3. The pump system of claim 1 , wherein the sampling amplitude comprises a local minima of the drive signal.
4. The pump system of claim 1 , wherein the sampling amplitude comprises a zero crossing of the drive signal.
5. The pump system of claim 1 , wherein the sampling amplitude comprises an offset crossing of the drive signal.
6. The pump system of claim 1 , wherein the controller is further configured to sample pressure at least twice during a time interval of the plurality of time intervals.
7. The pump system of claim 6 , wherein the controller is further configured to average the pressure samples.
8. The pump system of claim 1 , wherein the controller is further configured to adjust at least one parameter of the drive signal based on the sampled plurality of pressures.
9. A method for controlling a pump system configured for negative pressure wound therapy, the method comprising:
applying a drive signal to a pump assembly of the pump system configured to be fluidically connected via a fluid flow path to a wound dressing placed over a wound, the drive signal alternating between a positive amplitude and a negative amplitude and the drive signal having an offset;
determining a plurality of time intervals during which the drive signal is approximately at a sampling amplitude selected for determining pressure in the fluid flow path; and
while the drive signal is being applied to the pump assembly, sampling a plurality of pressures measured within the fluid flow path during the plurality of time intervals and not during other time intervals,
wherein sampling the plurality of pressures during the plurality of time intervals minimizes measurement errors due to pressure fluctuations caused by operation of the pump assembly, and
wherein the method is performed under control of a controller of the pump system.
10. The method of claim 9 , wherein the sampling amplitude comprises a local maxima of the drive signal.
11. The method of claim 9 , wherein the sampling amplitude comprises a local minima of the drive signal.
12. The method of claim 9 , wherein the sampling amplitude comprises a zero crossing of the drive signal.
13. The method of claim 9 , wherein the sampling amplitude comprises an offset crossing of the drive signal.
14. The method of claim 9 , further comprising sampling pressure at least twice during a time interval of the plurality of time intervals.
15. The method of claim 14 , further comprising averaging the pressure samples.
16. The method of claim 9 , further comprising adjusting at least one parameter of the drive signal based on the sampled plurality of pressures.
17. A pump system configured for negative pressure wound therapy, the pump system comprising:
a negative pressure source configured to be fluidically connected via a fluid flow path to a wound dressing placed over a wound;
a pressure sensor configured to measure pressure in the fluid flow path; and
a controller configured to control operation of the negative pressure source, the controller further configured to:
apply a drive signal to the negative pressure source, the drive signal alternating between a positive amplitude and a negative amplitude;
determine a plurality of time intervals during which the drive signal is approximately at a sampling amplitude selected for determining pressure in the fluid flow path; and
during application of the drive signal to the negative pressure source, sample a plurality of pressures measured by the pressure sensor during the plurality of time intervals and not during other time intervals,
wherein sampling the plurality of pressures during the plurality of time intervals minimizes measurement errors due to pressure fluctuations caused by operation of the negative pressure source.
18. The pump system of claim 17 , wherein the sampling amplitude comprises a local maxima of the drive signal, a local minima of the drive signal, a zero crossing of the drive signal, or an offset crossing of the drive signal.
19. The pump system of claim 18 , wherein the controller is further configured to sample the pressure at least twice during a time interval of the plurality of time intervals.
20. The pump system of claim 19 , wherein the controller is further configured to average the pressure samples.
21. The pump system of claim 20 , wherein the controller is configured to average consecutive pressure samples.