Insufflation device with intelligent control of smoke evacuation
The present invention relates to an insufflator with integrated smoke evacuation. By virtue of a novel control method of the evacuation volumetric flow rate, the following advantages are achieved. First, a reduction of the pressure in the cavity due to the evacuation is prevented. An empirically determined safety factor is determined, which results in the evacuation volumetric flow rate not exceeding the maximum possible insufflation volumetric flow rate. Second, the exchange volumetric flow rate is limited. It is limited such that the sum of the currently calculated leakage and the evacuation volumetric flow rate does not exceed a defined value. Thus, stress on the patient due to unnecessarily high exchange volumetric flow rates and the associated cooling and drying processes is prevented.
1 . An insufflator for providing gas to a patient cavity during minimally invasive surgery, comprising:
a) a gas connection configured to receive a gas supply and provide the gas supply to a pressure and flow rate regulating unit equipped with a flow rate measuring unit, a proportional valve and a pressure sensor, the pressure and flow rate regulating unit configured to be controlled by a controller;
b) a supply line configured to receive the gas supply from the pressure and flow rate regulating unit, the supply line connected to a first trocar for providing pressurized gas to the patient cavity;
c) a second trocar connected to an exhaust line which is operatively connected to an evacuation device configured to remove flue gas from the patient cavity;
d) a second flow rate measuring unit operatively positioned in a flow path between the evacuation device and the second trocar, the second flow rate measuring unit configured to measure an evacuation volumetric flow rate;
e) the controller operatively connected to the pressure and flow rate regulating unit and the evacuation device; wherein the controller is configured to control the evacuation device so as to adjust the evacuation volumetric flow rate based at least in part on a defined maximum volumetric supply flow rate and a determined leakage volumetric flow rate;
wherein the insufflator is configured to:
a. determine a maximum possible insufflation volumetric flow rate based on a flow resistance characteristic, wherein the maximum possible insufflation volumetric flow rate is determined using a mathematical model that is a Kalman filter or a Luenberger observer;
b. determine the determined leakage volumetric flow rate, wherein the determined leakage volumetric flow rate is determined by a mathematical observer model;
c. multiply the maximum possible insufflation volumetric flow rate with a safety factor to determine a reduced maximum insufflation volumetric flow rate,
d. determine a maximum allowed evacuation volumetric flow rate by subtraction of the determined leakage volumetric flow rate from the reduced maximum insufflation volumetric flow rate;
e. define the defined maximum volumetric supply flow rate, being the reduced maximum insufflation volumetric flow rate;
f. determine whether the defined maximum volumetric supply flow rate is exceeded based on the maximum allowed evacuation volumetric flow rate and the determined leakage volumetric flow rate; and
g. limit and reduce the maximum allowed evacuation volumetric flow rate if the defined maximum volumetric supply flow rate is exceeded.
2 . The insufflator as recited in claim 1 , wherein the pressure sensor is positioned within the pressure and flow rate regulating unit.
3 . The insufflator according to claim 1 , wherein the safety factor used for determining the reduced maximum insufflation volumetric flow rate is between about 0.6 and 0.9.
4 . The insufflator according to claim 1 , wherein the defined maximum volumetric supply flow rate is between about 10 and 20 lpm.
5 . The insufflator according to claim 1 , wherein the insufflator is further configured to cyclically repeat at least some of a-g in order that the maximum allowed evacuation volumetric flow rate can continuously be adapted to changes in leakage or changes in the flow resistance characteristic.
6 . The insufflator according to claim 5 , wherein the insufflator is further configured to cyclically repeat at least some of a-g every second.