Regulation of vacuum level in a wound treatment apparatus

Abstract

A wound treatment apparatus has a vacuum bandage covering a wound of a patient, a vacuum source coupled to the vacuum bandage, and a controller that operates the vacuum source to apply negative pressure to the wound through the bandage in a controlled manner. The controller is programmed to limit the rate of change of the negative pressure applied to the wound. A caregiver has the ability to change one or more negative pressure setpoint values and the controller of the wound treatment apparatus controls the rate of change of the negative pressure to reduce patient discomfort.

1 . A vacuum wound therapy system for applying negative pressure to a wound of a patient, the system comprising 
 a bandage configured to be placed adjacent the wound,    a negative pressure source,    a regulator coupled to the negative pressures source,    a variable flow orifice coupled to the regulator and having a flow orifice, the negative pressure source being operable to produce a negative pressure that is communicated to the bandage through the regulator and the variable flow orifice,    a controller coupled to the variable flow orifice to control a size of the flow orifice, the regulator being configured to establish a maximum negative pressure communicated to the flow orifice, air being drawn through the regulator by the negative pressure source along a first pneumatic path and the regulator having an air intake through which additional air is drawn by the negative pressure source in the event that the air drawn by the negative pressure source along the first pneumatic path is insufficient.    
   
   
       2 . The system of  claim 1 , wherein the regulator has a port that opens to permit air to be drawn into the air intake of the regulator when a negative pressure established by the variable flow orifice is less than the maximum negative pressure.  
   
   
       3 . The system of  claim 2 , wherein the regulator has an air filter coupled to the port.  
   
   
       4 . The system of  claim 3 , wherein the air filter comprises glass microfibers.  
   
   
       5 . The system of  claim 3 , wherein the air filter has a filtration rating of 25 microns.  
   
   
       6 . The system of  claim 1 , wherein the negative pressure source comprises a vacuum pump.  
   
   
       7 . The system of  claim 6 , wherein the vacuum pump has an outlet and further comprising a filter coupled to the outlet.  
   
   
       8 . The system of  claim 6 , wherein the filter serves as an exhaust muffler for the vacuum pump.  
   
   
       9 . The system of  claim 6 , wherein the vacuum pump  110  is a diaphragm-type compressor.  
   
   
       10 . The system of  claim 1 , further comprising a sound chamber in which the negative pressure source and the regulator are housed.  
   
   
       11 . The system of  claim 10 , wherein the sound chamber is lined with a damping foil.  
   
   
       12 . The system of  claim 1 , further comprising a canister coupled to the bandage, the negative pressure that is communicated to the bandage through the regulator and the variable flow orifice also being communicated through the canister, and the canister being configured to collect exudate drawn from the wound.  
   
   
       13 . The system of  claim 12 , further comprising a pressure transducer to measure the negative pressure at a location between the variable flow orifice and the canister.  
   
   
       14 . The system of  claim 1 , wherein the variable flow orifice comprises a proportional valve and the controller sends a pulse-width-modulated signal to the proportional valve to control the size of the flow orifice.  
   
   
       15 . The system of  claim 1 , wherein the controller controls the size of the flow orifice based on a proportional, integral, derivative control algorithm.  
   
   
       16 . The system of  claim 1 , wherein the controller controls a time rate of change of the negative pressure communicated to the bandage to be less than a predetermined maximum allowable rate.  
   
   
       17 . The system of  claim 1 , further comprising a fluid source to deliver an irrigation fluid to the bandage.  
   
   
       18 . The system of  claim 17 , wherein the fluid source comprises a syringe.  
   
   
       19 . The system of  claim 1 , further comprising a portable housing which carries the negative pressure source, the regulator, the variable flow orifice, and the negative pressure source.  
   
   
       20 . The system of  claim 19 , further comprising a canister coupled to the bandage, the negative pressure that is communicated to the bandage through the regulator and the variable flow orifice also being communicated through the canister, and the portable housing having a cavity in which the canister is insertable.