Entry Force and Intra-abdominal Pressure Associated With Six Laparoscopic Trocar-Cannula Systems

In Brief Objective In trocar-cannula systems, increased entry force could result in loss of operator control, a potential cause of serious visceral and vascular injuries. We developed a system to measure entry force and intraperitoneal pressure to evaluate and compare trocar-cannula systems. Methods Six laparoscopic trocar-cannula systems of similar diameter (12 mm) were tested (two pyramidal, two cutting-dilating, and two blunt conical) using a white swine model. All six systems were inserted into each of 12 subjects with location designated by random allotment (72 insertions). During each insertion, intraperitoneal pressure and entry force were measured using a system consisting of a gas-gas transducer, a 50-lb load cell, and a multichannel data acquisition board. Mean entry force and intraperitoneal pressure were compared using mixed-model analysis of variance. Results Mean entry force measurements were as follows: pyramidal 9.01 lb and 13.48 lb, cutting-dilating 9.94 lb and 16.46 lb, and blunt conical 19.15 lb and 31.91 lb. Intraperitoneal pressure changes generally reflected measured entry force. Conclusion The system successfully measured both entry force and resultant intraperitoneal pressure. Pyramidal trocar-cannula systems required the lowest force for entry. These differences in entry force have potential clinical implications related to the risk of visceral and vascular injury. Intraperitoneal pressure measurement could be used as a surrogate for insertional force measurement. A system designed to evaluate insertional force of laparoscopic trocar-cannula systems found that pyramidal-tipped trocars required the lowest insertional force.