Wound therapy system with wound volume estimation

Abstract

A wound therapy system includes a negative pressure circuit configured to apply negative pressure to a wound, a pump fluidly coupled to the negative pressure circuit and operable to control the negative pressure within the negative pressure circuit, a pressure sensor configured to measure the negative pressure within the negative pressure circuit or at the wound and a controller communicably coupled to the pump and the pressure sensor. The controller is configured to execute a pressure testing procedure including applying a pressure stimulus to the negative pressure circuit, observe a dynamic pressure response of the negative pressure circuit to the pressure stimulus using pressure measurements recorded by the pressure sensor, and estimate a wound volume of the wound based on the dynamic pressure response.

What is claimed is: 
     
         1 . A wound therapy system comprising:
 a negative pressure circuit configured to apply negative pressure to a wound;   a canister containing instillation fluid for delivery to the wound;   a pump operable to deliver the instillation fluid to the wound;   a pressure sensor configured to measure the negative pressure within the negative pressure circuit or at the wound; and   a controller communicably coupled to the pump and the pressure sensor, the controller configured to:
 execute a pressure testing procedure to estimate a wound volume of the wound; 
 determine a volume of instillation fluid to deliver to the wound based on the estimated wound volume; and 
 operate the pump to deliver the volume of instillation fluid to the wound. 
   
     
     
         2 . The wound therapy system of  claim 1 , wherein the controller is configured to determine the volume of instillation fluid to deliver to the wound by multiplying the estimated wound volume by a fluid instillation factor. 
     
     
         3 . The wound therapy system of  claim 2 , wherein the fluid instillation factor is less than one such that less than the total wound volume is filled with the instillation fluid. 
     
     
         4 . The wound therapy system of  claim 2 , wherein the fluid instillation factor is between approximately 0.2 and approximately 0.8. 
     
     
         5 . The wound therapy system of  claim 1 , wherein the negative pressure circuit comprises a wound dressing sealable to skin surrounding the wound. 
     
     
         6 . The wound therapy system of  claim 5 , wherein the negative pressure circuit comprises tubing fluidly connecting the canister with the wound dressing. 
     
     
         7 . The wound therapy system of  claim 1 , wherein the controller is configured to operate the pump to establish the negative pressure within the negative pressure circuit. 
     
     
         8 . The wound therapy system of  claim 1 , wherein the pressure testing procedure comprises:
 operating the pump to establish the negative pressure within the negative pressure circuit; and   applying a pressure stimulus to the negative pressure circuit after the negative pressure has been established within the negative pressure circuit.   
     
     
         9 . The wound therapy system of  claim 1 , further comprising a valve coupled to the negative pressure circuit and operable to controllably vent the negative pressure circuit. 
     
     
         10 . The wound therapy system of  claim 9 , wherein the pressure testing procedure comprises:
 opening the valve to allow airflow into the negative pressure circuit for a predetermined amount of time; and   closing the valve after the predetermined amount of time has elapsed.   
     
     
         11 . The wound therapy system of  claim 10 , wherein the pressure testing procedure comprises:
 waiting for another predetermined amount of time after closing the valve; and   repeating the opening, closing, and waiting steps until the negative pressure reaches a threshold pressure value.   
     
     
         12 . The wound therapy system of  claim 10 , wherein the pressure testing procedure comprises operating the pump while the valve is closed to mitigate air leakage into the negative pressure circuit. 
     
     
         13 . The wound therapy system of  claim 10 , wherein the pressure testing procedure comprises:
 applying a pressure stimulus to the negative pressure circuit;   observing a dynamic pressure response of the negative pressure circuit to the pressure stimulus using pressure measurements recorded by the pressure sensor; and   estimating the wound volume of the wound based on the dynamic pressure response.   
     
     
         14 . The wound therapy system of  claim 13 , wherein the dynamic pressure response of the negative pressure circuit is characterized by a depth of purge parameter defined as a difference between:
 a measured value of the negative pressure before the valve is opened; and   a measured value of the negative pressure while the valve is open.   
     
     
         15 . The wound therapy system of  claim 13 , wherein the dynamic pressure response of the negative pressure circuit is characterized by a rebound parameter defined as a difference between:
 a measured value of the negative pressure after the valve is closed; and   a measured value of the negative pressure while the valve is open.   
     
     
         16 . The wound therapy system of  claim 13 , wherein the dynamic pressure response of the negative pressure circuit is characterized by a delta parameter defined as a difference between:
 a measured value of the negative pressure before the valve is opened; and   a measured value of the negative pressure after the valve is closed.   
     
     
         17 . The wound therapy system of  claim 13 , wherein the dynamic pressure response of the negative pressure circuit is characterized by a leak rate parameter defined as a rate at which the negative pressure changes while the valve is closed. 
     
     
         18 . The wound therapy system of  claim 13 , wherein estimating the wound volume based on the dynamic pressure response comprises:
 determining values for one or more parameters that characterize the dynamic pressure response; and   applying the values of the one or more parameters as inputs to a model that defines a relationship between the one or more parameters and the wound volume.   
     
     
         19 . The wound therapy system of  claim 18 , wherein the model that defines the relationship between the one or more parameters and the wound volume is a polynomial approximation model. 
     
     
         20 . The wound therapy system of  claim 18 , wherein the model that defines the relationship between the one or more parameters and the wound volume is a neural network. 
     
     
         21 . The wound therapy system of  claim 18 , wherein the controller is configured to generate the model that defines the relationship between the one or more parameters and the wound volume by:
 executing a training procedure comprising applying the pressure stimulus to training circuit having a known volume;   observing a dynamic pressure response of the training circuit to the pressure stimulus using pressure measurements recorded by the pressure sensor; and   associating the known volume with the dynamic pressure response of the training circuit.   
     
     
         22 . The wound therapy system of  claim 21 , wherein generating the model further comprises:
 repeating the training procedure for a plurality of known volumes;   observing the dynamic pressure response of the training circuit for each of the plurality of known volumes; and   generating a correlation between the plurality of known volumes and the dynamic pressure response of the training circuit.   
     
     
         23 . The wound therapy system of  claim 21 , wherein the controller is configured to:
 execute the pressure testing procedure to estimate the wound volume at a plurality of times during wound treatment; and   determine healing progression based on changes in the wound volume during wound treatment.