Powered surgical stapling device

Abstract

A medical instrument having a tool assembly including a pair of opposing tissue engaging surfaces for clamping tissue therebetween. The medical instrument includes a housing having a fixed handle and a movable handle mounted to the housing and selectively movable relative to the fixed handle from a first position in spaced relation relative to the fixed handle to a second position closer to the fixed handle to actuate the clamping of tissue. The medical instrument includes a selectively activatable drive assembly including a power source and a motor which is operatively coupled to the movable handle, wherein upon actuation the motor actuates the pair of opposing tissue engaging surfaces. The drive assembly includes a controller configured to variably control the rate at which the motor actuates the pair of opposing tissue engaging surfaces in response to the force exerted on the movable handle.

1 . (canceled) 
     
     
         2 . A drive assembly for use with a surgical device, comprising:
 a motor;   a fixed handle;   a lever movable relative to the fixed handle;   a firing shaft operably coupled to the motor and movable by the lever; and   a controller, wherein the motor is configured to be actuated by the controller at a variably controlled rate in response to a longitudinal motion applied to the firing shaft.   
     
     
         3 . The drive assembly according to  claim 2 , wherein the motor is disposed within a housing. 
     
     
         4 . The drive assembly according to  claim 2 , wherein the controller is configured to variably control a voltage supplied to the motor in response to the longitudinal motion applied to the firing shaft. 
     
     
         5 . The drive assembly according to  claim 2 , wherein the firing shaft is configured to actuate an end effector. 
     
     
         6 . The drive assembly according to  claim 2 , wherein the firing shaft is operatively coupled to the motor via a coupling member. 
     
     
         7 . The drive assembly according to  claim 6 , wherein the coupling member includes a ratchet track having one or more teeth interfacing with a pawl. 
     
     
         8 . The drive assembly according to  claim 2 , further including a power source operatively connected to the motor. 
     
     
         9 . The drive assembly according to  claim 8 , further including a variable resistor coupled to the motor and the power source, the variable resistor controlling a rate at which the firing shaft is longitudinally displaced. 
     
     
         10 . The drive assembly according to  claim 8 , further including a switch assembly coupled to the motor and the power source. 
     
     
         11 . The drive assembly according to  claim 10 , wherein the switch assembly includes a pressure sensor and a switch handle coupled to and movable relative to the fixed handle. 
     
     
         12 . The drive assembly according to  claim 11 , wherein the pressure sensor is a piezoelectric sensor configured to sense pressure applied to the switch handle. 
     
     
         13 . The drive assembly according to  claim 12 , wherein the pressure sensor records pressure applied on the switch handle as sensor signals, the sensor signals being representative of clamping force.