Comparison of two radiofrequency-based hemostatic devices: saline-linked bipolar vs. cooled-electrode monopolar

Abstract

Purpose To characterize the coagulation zones created by two radiofrequency (RF)-based hemostatic devices: one comprised an internally cooled monopolar electrode and the other comprised externally irrigated bipolar electrodes (saline-linked).Materials and methods RF-induced coagulation zones were created on ex vivo and in vivo porcine models. Computer modeling was used to determine the RF power distribution in the saline-linked device.Results Both external (irrigation) and internal cooling effectively prevented tissue sticking. Under ex vivo conditions in ‘painting’ application mode, coagulation depth increased with the applied power: 2.8 − 5.6 mm with the 3-mm monopolar electrode, 1.6 − 6.0 mm with the 5-mm monopolar electrode and 0.6 − 3.2 mm with the saline-linked bipolar electrodes. Under in vivo conditions and using spot applications, the 3-mm monopolar electrode created coagulation zones of similar depth to the saline-linked bipolar electrodes (around 3 mm), while the 5-mm monopolar electrode created deeper coagulations (4.5 − 6 mm) with less incidence of popping. The presence of saline around the saline-linked bipolar electrodes meant that a significant percentage of RF power (50 − 80%) was dissipated by heating in the saline layer. Coagulation zones were histologically similar for all the tested devices.Conclusions Both external (irrigation) and internal cooling in hemostatic RF devices effectively prevent tissue sticking and create similar coagulation zones from a histological point of view. Overall, saline-linked bipolar electrodes tend to create shallower coagulations than those created with an internally cooled monopolar electrode.

Keywords

• Cooled electrode
• hemostatic device
• radiofrequency
• saline-linked
• thermal ablation