Development of a numerical model of surgical smoke during laparoscopy

Abstract

An accurate understanding of laparoscopic surgical smoke behaviour is essential to enhance the healthcare of patient and operating room staff and to achieve better optical clarity for the surgeon. This work develops a numerical model of surgical smoke behaviour during laparoscopy. A computational fluid dynamics model was created for a rectangular chamber geometry. A “large eddy simulation” (LES) technique was used to solve transport equations, electrosurgery was modelled using a heat-flux boundary condition, and condensation and evaporation models were employed.An experimental study was undertaken to provide the unknown parameters such as surgical smoke generation rate, water evaporation rate, and heat flux at the electrosurgery site in the numerical simulation. The experimental apparatus was composed of a rectangular chamber with two ports; one used for monopolar electrosurgery, and the other for inlet flow. Condensed water on the chamber inner surface, evacuated water vapour and particulate matter, as well as temperature and relative humidity at different locations within the model, were measured.The experiments showed that surgical smoke generated during laparoscopy is composed of 65% water vapour, 11% particulate matter, and 24% volatile matter by mass. It was measured that particulate matter and water vapour were generated at a rate of 1.9 (±0.3) mg/s and 11.7 (±0.6) mg/s (mean ± SD, n = 8), respectively. The numerical model predicted that approximately 31% - 35% of the generated smoke was evacuated from the outlet port as a relatively high speed flow and the remainder was accumulated close to the upper surface due to buoyancy. The CFD model can be used as a predictive tool to investigate the exposure of operating room staff to surgical smoke, particulate matter deposition on the peritoneum surface and tissue desiccation during electrosurgical procedures.