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High pressures are generated at the tip of laparoscopic graspers
J A Cartmill1, A J Shakeshaft, W R Walsh
1University of Sydney Department of Surgery, Nepean Hospital, Penrith, NSW, Australia.
The Australian and New Zealand Journal of Surgery
|February 25, 1999
Summary
Laparoscopic graspers generate high tip pressures on tissue, increasing significantly with grasp angle. These forces are independent of load and handle pressure, highlighting critical interface mechanics.
Area of Science:
- Biomedical Engineering
- Surgical Instrumentation
- Tissue Mechanics
Background:
- The interaction between surgical instruments and tissue is not well understood.
- Accurate characterization of forces at the tissue-instrument interface is crucial for safe and effective surgical procedures.
Purpose of the Study:
- To investigate the forces generated at the tip of laparoscopic graspers.
- To determine the effect of varying grasp angles on tissue pressure.
- To analyze the pressure distribution at the tissue-instrument interface during grasping.
Main Methods:
- A thin film pressure transducer was utilized.
- The transducer was placed between the jaws of eight different laparoscopic instruments and simulated tissue.
- Forces and pressures were measured across a range of grasp angles (0 to 135 degrees).
Main Results:
- Pressure was predominantly concentrated at the instrument tip.
- Localized pressures increased from 210 kPa to 650 kPa as the grasp angle increased from 0 to 135 degrees.
- Significant variations in pressure increase (up to eightfold) were observed across different instruments with changing angles.
Conclusions:
- Laparoscopic graspers generate substantial tip pressures.
- Increasing the angle of incidence between the grasper and tissue leads to higher pressures.
- The observed pressure changes are independent of applied load and handle pressure, emphasizing the geometric effect of the grasp angle.