Method and Device for Intraoperative Determination of Drag Coefficient Values of Different Medical Instruments in the Use of a Medical Fluid Pump

Abstract

Disclosed is a method for determining and controlling the internal body pressure during a medical procedure that includes controlling the output of a fluid pump by means of an estimated pressure value, wherein resistance coefficients ζ 1 and ζ 2 of a medical instrument required for the estimation of the pressure value are determined by evaluating a pressure behavior during pump start up.

What is claimed is: 
     
         1 . A method for determining and controlling the internal body pressure during a medical procedure comprising the steps of:
 pumping fluid using a pumping device through a feed line into a body cavity, wherein the pumping device is controlled by a controller and wherein the feed line contains at a patient's end, an exchangeable medical instrument through which the pumping of the fluid into the body cavity takes place,   providing a second line through which fluid can flow out of the body cavity,   providing a pressure sensor and measuring a pressure in the feed line using the pressure sensor, wherein the pressure measured by the pressure sensor is an input variable of a mathematical estimation system, which mathematically describes a state space,   estimating the actual pressure in the body cavity using the mathematical estimation system; and   controlling the output of the pump by means of the estimated value, wherein resistance coefficients ζ 1  and ζ 2  of a medical instrument required for the estimation of the pressure are determined by that when starting the pump, a pressure behavior is evaluated for a certain time, therefrom a characteristic curve is determined, and the characteristic curve is stored in a memory device of the pump.   
     
     
         2 . The method of  claim 1 , further including the step of: determining the resistance coefficients ζ 1  and ζ 2  by starting the pumping device twice. 
     
     
         3 . The method of  claim 1 , wherein determining the resistance coefficients ζ1 and ζ2 of the medical instrument takes place pre- or intraoperatively. 
     
     
         4 . The method of  claim 1 , wherein the mathematical estimation system is configured in the manner of a Kalman filter. 
     
     
         5 . The method of  claim 1 , wherein the fluid is a gas or a liquid. 
     
     
         6 . A medical apparatus for supplying fluids into body cavities, comprising:
 a controllable fluid pump for fluid into a body cavity through a feed line,   a memory device,   a pressure sensor for measuring a pressure in the feed line,   a medical instrument connected to a patient end of the feed line through which the pumping of the fluid into the body cavity takes place,   wherein the pressure measured by the pressure sensor is an input variable of a mathematical estimation system, which mathematically describes a state space, which estimates an actual pressure in the body cavity and controls the output of the pump by means of this estimated value, and   wherein the resistance coefficients ζ 1  and ζ 2  of the medical instrument required for the estimation of the pressure are determined by that when starting the pump, the pressure behavior is evaluated for a certain time, therefrom a characteristic curve is determined, and the characteristic curve is stored in the memory device of the pump.   
     
     
         7 . A medical apparatus for supplying fluids into body cavities, comprising:
 a controllable fluid pump, a memory device, a feed line, a pressure sensor for measuring pressure in the feed line, and a medical instrument connected to the feed line at a patient end,   wherein the pressure measured by the pressure sensor is an input variable of a mathematical estimation system, which mathematically describes a state space, which estimates an actual pressure in a body cavity and controls the output of the pump by means of this estimated value,   wherein the resistance coefficients ζ 1  and ζ 2  of the medical instrument required for the estimation of the pressure are determined by that when starting the pump, a pressure behavior is evaluated for a certain time, therefrom a characteristic curve is determined, and the characteristic curve is stored in the memory device which includes at least one microprocessor, at least one memory and at least one software.   
     
     
         8 . The medical apparatus of  claim 7 , wherein at least one memory contains data with the resistance coefficients of at least one instrument characteristic curve. 
     
     
         9 . The medical apparatus of  claim 7 , wherein the apparatus is an insufflator. 
     
     
         10 . The medical apparatus of  claim 7 , wherein the apparatus is a liquid pump for arthroscopy, urology, hysteroscopy, laparoscopy, or for examinations of the backbone. 
     
     
         11 . The medical apparatus of  claim 7 , wherein the apparatus is a liquid pump with integrated conveyer and suction pump.