Entry force and intra-abdominal pressure associated with six laparoscopic trocar-cannula systems: a randomized comparison.

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.

Incision characteristics associated with six laparoscopic trocar-cannula systems: a randomized, observer-blinded comparison.

OBJECTIVE: Laparoscopic trocar-cannula systems of different design but similar internal diameter result in incisions of varying dimensions. Such variations might affect the incidence of incisional complications, such as dehiscence and hernia. We developed a system to measure associated fascial defects and then used the techniques to compare the defects resulting from different trocar-cannula systems. METHODS: This was a randomized, observer-blinded study. Six laparoscopic trocar-cannula systems of similar diameter (12 mm) were tested (two pyramidal, two blunt conical, and two cutting-dilating) using a white swine model. All systems were inserted into each of 12 subjects, with location designated by random allotment (total 72 insertions). The fascial defects were exposed and then directly measured for incisional length and area by an observer blinded to the system used. Means of each outcome variable (incisional length and area) were compared using factorial analysis of variance. RESULTS: The values for mean incisional areas were as follows: cutting-dilating 28.73 mm2 and 31.09 mm2, pyramidal 18.25 mm2 and 26.75 mm2, and blunt conical 10.00 mm2 and 12.33 mm2. Mean maximal incisional lengths were similar among all trocar-cannula systems. CONCLUSION: Blunt conical trocar-cannula systems resulted in significantly smaller fascial defects compared with the widely used pyramidal and the two cutting-dilating trocar-cannula systems tested. These differences have potential clinical implications. For example, smaller fascial defects could reduce risk of incisional hernia and dehiscence.