In this study, a novel thermal management system (TMS) is developed for the minimization of thermal spread created by a monopolar electrosurgical device, the most commonly used surgical instrument. The phenomenon of resistive heating of tissue is modeled using the finite-element method (FEM) to analyze the electrical potential and temperature distributions in biological tissue subjected to heat generation during monopolar electrosurgery. Ex vivo experiments are used to validate the FEM by comparing the model predicted and experimentally measured temperatures. The predicted FEM maximum temperature 1.0 m adjacent to the electrode is within 1% of the experimentally measured maximum temperature using a standard monopolar pencil electrode. A TMS consisting of adjacent cooling channels produces coagulation volumes 80% that of standard monopolar procedures while maintaining comparable temperatures in the targeted tissue below the electrode. In vivo temperatures using a device incorporating a TMS at distances of 2 and 3 m adjacent to the electrode edge are maintained below temperatures known to damage tissue.

No abstract

A monopolar electrosurgical device is the most commonly used energy-based surgical instrument. Monopolar devices are primarily applied to incise, ablate, dissect, and coagulate tissue by transferring electrical energy to the tissue in the form of heat generation through resistive heating. The substantial amount of heat created by the monopolar device has been shown to spread throughout the tissue, creating unintended tissue damage, which can lead to nerve thermal damage and loss of normal bodily functions. Due to this fact, energy-based devices have had a limited use in surgical procedures performed near neurovascular bundles. The extent to which the generated heat raises the temperature of the surrounding tissue is referred to as the device’s thermal spread. In this study, ex vivo and in vivo experiments have shown that a novel thermal management system (TMS) can reduce the amount of thermal spread created by a typical monopolar device, thus eliminating the thermal collateral tissue damage typically caused during a monopolar procedure. The incorporation of a TMS consisting of adjacent cooling channels reduces the thermal spread of the device, as illustrated in a reduction as high as 50% in the maximum temperature recorded during an in vivo experimental procedure. The design of the TMS was aided by finite element modeling (FEM). The phenomenon of monopolar resistive heating was modeled to analyze the temperature distributions in biological tissue subjected to heat generation by a commonly used monopolar electrosurgical device. The mathematical model was verified by comparing the model’s predicted temperature distribution with experimental results. Ex vivo experiments were performed with liver tissue heated by a monopolar pencil electrode. The experimental data for 1 mm distance from the electrode are seen to fit within 1% of the predicted temperature values by the FEM simulation.

This study develops a thermal management system for the most commonly used energy-based surgical instrument: the monopolar electrosurgical device. Monopolar electrosurgery, using the same principle as the electrical discharge machining, is widely used to cut or remove tissue by sparks during surgical operations. This study develops a thermal management system consists of cooling channels placed around the active electrode to reduce the thermal damage to the tissue. Finite element modeling (FEM) was performed to analyze temperature distribution in biological tissue subject to heat generation by a commonly used monopolar electrosurgical device. The mathematical model was verified by comparing FEM predicted temperature distribution with experimental measurements. Exvivo experiments were performed with bovine liver tissue heated by a monopolar pencil electrode. The experimental data for 1 mm distance from the electrode is seen to fit within 1% of the predicted temperature values by the FEM simulation. The accuracy of the model decreases at further distances from the electrode. The inaccuracies are believed to be due to unaccounted temperature-dependent thermal conductivity. The addition of the cooling channels shows a reduction of the radial thermal damage of the tissue in both FEM simulations and ex-vivo experimental procedures.