A system is disclosed for delivering insufflation gas to a body cavity of a patient during an endoscopic surgical procedure, which includes an insufflation conduit for delivering a continuous flow of insufflation gas to the body cavity at a flow rate through a flow path that communicates with a pneumatically sealed trocar which prevents over-pressurization of the body cavity, and an insufflator for driving gas flow through the insufflation conduit at a driving pressure, wherein the system can be configured so that either the gas flow rate through the insufflation conduit or the driving pressure required to maintain the specified flow rate can vary depending upon body cavity pressure.