A curved edge moderates high pressure generated by a laparoscopic grasper

Background: Very high pressures are generated at the interface between the tip of laparoscopic graspers and tissue. The pressure profile suggests that the high pressure is due to stress concentration at the edge of the jaw. S tress concentration at an edge can be modified by curving the edge. This st udy sought to determine the effect of a curved edge on pressures generated by the jaw of a laparoscopic grasper. Methods: Pressure generated at the instrument tissue interface was measured by a thin film pressure transducer. The two instruments that we compared w ere identical in every respect except the profile of the jaw edge. One was unmodified; the other had a rounded grasping edge. Load and handle pressure were constant throughout. Tissue pressures generated by the grasper were r ecorded as the angle of load was increased from vertical (0 degrees) to 135 degrees. Results: Localized pressures at the tip of the unmodified instrument reache d a maximum of 1500 kPa. Pressures at the tip of the curved instrument reac hed a maximum of 920 kPa under identical conditions. Conclusion: High pressures generated at the tip of laparoscopic graspers ca n be reduced by rounding the edge of the jaw.