Systems and methods for measuring and tracking wound volume

1 . A method of operating a negative pressure wound therapy apparatus comprising:

periodically activating a negative pressure source to maintain negative pressure in a fluid flow path connecting the negative pressure source to a wound covered by a wound dressing between a low negative pressure setpoint and a high negative pressure setpoint, the high negative pressure setpoint being associated with higher level of negative pressure than the low negative pressure setpoint;

determining a change in a volume of the wound based on a time duration between a first time at which the high negative pressure setpoint has been established and a second time at which the high negative pressure setpoint has been reestablished in the fluid flow path, the second time being subsequent to the first time; and

providing indication of the change in the volume of the wound,

wherein the method is performed by a controller of the negative pressure wound therapy apparatus.

2 . The method of claim 1 , further comprising:

monitoring the change in the volume of the wound over a duration of time; and

providing indication of progress of healing of the wound based on the change in the volume of the wound monitored over the duration of time.

3 . The method of claim 1 , further comprising determining the change in the volume of the wound based on a difference between the first time and the second time divided by the second time.

4 . The method of claim 1 , further comprising:

determining that negative pressure in the fluid flow path satisfies the high negative pressure setpoint; and

deactivating the negative pressure source responsive to determining that negative pressure in the fluid flow path satisfies the high negative pressure setpoint.

5 . The method of claim 1 , further comprising:

determining that negative pressure in the fluid flow path satisfies the low negative pressure setpoint; and

activating the negative pressure source responsive to determining that negative pressure in the fluid flow path satisfies the low negative pressure setpoint.

6 . The method of claim 1 , wherein determining the change in the volume of the wound is performed without determining a rate of leak in the fluid flow path.

7 . The method of claim 1 , wherein the fluid flow path is configured to not include any openings configured to admit fluid into the fluid flow path at a controlled leak rate.

8 . A method of operating a negative pressure wound therapy apparatus comprising:

determining a volume of a wound based on a first plurality of negative pressure measurements in a fluid flow path connecting a negative pressure source to the wound covered by a wound dressing and a rate of flow of fluid in the fluid flow path, the first plurality of negative pressure measurements being made at a first plurality of times, the first plurality of negative pressure measurements comprising first and second negative pressure measurements made, respectively, at first and second times, the second time being subsequent to the first time, and the second negative pressure measurement corresponding to pressure that is more negative than the first negative pressure measurement; and

providing indication of the volume of the wound,

wherein the method is performed by a controller of the negative pressure wound therapy apparatus.

9 . The method of claim 8 , further comprising, by the controller:

monitoring a change in the volume of the wound over a duration of time; and

providing indication of progress of healing of the wound based on the change in the volume of the wound monitored over the duration of time.

10 . The method of claim 8 , wherein determining the volume of the wound is performed using a product of the rate of flow of fluid in the fluid flow path and a difference between the second and first times divided by a difference between the second and first negative pressure measurements.

11 . The method of claim 10 , wherein the product is scaled by at least one of an ambient temperature or gas constant.

12 . The method of claim 8 , further comprising:

determining a leak rate in the fluid flow path; and

determining the volume of the wound based on the first plurality of negative pressure measurements in the fluid flow path made at the first plurality of times and an adjusted rate of flow of fluid in the fluid flow path, the adjusted rate of flow of fluid in the fluid flow path being determined based on subtracting the leak rate from the rate of flow of fluid in the fluid flow path.

13 . The method of claim 12 , further comprising:

determining the leak rate in the fluid flow path based on the volume of the wound and a second plurality of negative pressure measurements in the fluid flow path made at a second plurality of times, the second plurality of negative pressure measurements including third and fourth negative pressure measurements made, respectively, at third and fourth times, the fourth time being subsequent to the third time, and the fourth negative pressure measurement corresponding to pressure that is more positive than the third negative pressure measurement.

14 . The method of claim 13 , wherein determining the leak rate is performed using a product of the volume of the wound and a difference between the fourth and third negative pressure measurements divided by a difference between the fourth and third times.

15 . The method of claim 14 , wherein the difference between the fourth and third times is scaled by at least one of an ambient temperature or gas constant.

16 . The method of claim 8 , wherein determining the volume of the wound is performed without determining a rate of leak in the fluid flow path.

17 . The method of claim 8 , further comprising:

determining a first leak rate in the fluid flow path based on the volume of the wound;

determining a second leak rate in the fluid flow path using a flow meter or based on a level of activity of the negative pressure source; and

verifying that the volume of the wound has been accurately determined based on a determination that the first leak rate matches the second leak rate.

18 . The method of claim 8 , further comprising, by the controller:

determining a leak rate in the fluid flow path based on the volume of the wound; and

verifying that the volume of wound has been accurately determined based on a determination that first leak rate matches a known leak rate in the fluid flow path.

19 . The method of claim 8 , further comprising, by the controller:

periodically activating the negative pressure source to maintain negative pressure in the fluid flow path between a low negative pressure setpoint and a high negative pressure setpoint, the high negative pressure setpoint being associated with higher level of negative pressure than the low negative pressure setpoint.

20 . The method of claim 19 , wherein periodically activating the negative pressure source to maintain negative pressure in the fluid flow path between the low negative pressure setpoint and the high negative pressure setpoint comprises:

at a first time, determining that negative pressure in the fluid flow path satisfies the low negative pressure setpoint and activating the negative pressure source responsive to determining that negative pressure in the fluid flow path satisfies the low negative pressure setpoint; and

at a second time, determining that negative pressure in the fluid flow path satisfies the high negative pressure setpoint and deactivating the negative pressure source in response to determining that negative pressure in the fluid flow path measured satisfies the high negative pressure setpoint.