Abstract
When surgery is performed without cardiac arrest, an artificial heart-lung machine is used to replace the functions of the heart and lungs. One of these functions is vent suction. One of its functions is to suction blood in the cardiac cavity to prevent myocardial overextension. However, if the tip of the suction part sticks to the myocardium, it cannot fulfill this function and excessive negative pressure is generated. In addition, it is not easy to measure negative pressure directly due to problems such as infection. The principle of suction is the restorative force generated by the pump head squeezing the circuit in a roller pump. When the negative pressure in the suction circuit increases, the force that holds the inner diameter of the circuit inside acts to weaken the restoring force, and the circuit does not return to its original diameter. By measuring the decrease in the restoring force, we attempt to detect excessive negative pressure in the vent suction circuit.
