Patent ID: 7510542

Claim:
A method for determining and controlling the pressure at a surgical work site during an endoscopic surgical procedure utilizing a fluid inflow pump, inflow tubing and an inflow cannula for conveying fluid from a fluid source to the surgical work site, a fluid outflow pump, outflow tubing and an outflow cannula for conveying fluid from the work site to a drain, the method further utilizing a pressure feedback control loop intended to maintain fluid pressure at the surgical work site at a pressure set point by adjusting pressure and flow parameters to maintain the pressure at the work site at or near the set point pressure, the method comprising the steps of: providing a first pressure determining means comprising a first pressure sensor near the inflow pump to measure pressure at the output of the inflow pump; providing a second pressure determining means comprising a second pressure sensor at the surgical work site to measure actual pressure at the surgical work site; providing a third pressure determining means comprising a pressure inferring system to calculate the pressure at the surgical work site using known and measurable pressure and fluid flow characteristics; determining whether said second pressure determining means comprising a pressure sensor at the surgical work site is present and operational; if said second pressure sensor is present and operational, selecting said second pressure sensor as the source of the value for the pressure at the surgical work site to be used in the feedback control loop; and if said second pressure sensor is not present and operational, selecting either said first or third pressure determining means as the source of the value for the pressure at the surgical work site to be used in the feedback control loop.