• Lukas J Hefermehl, Remo A Largo, Thomas Hermanns, Cédric Poyet, Tullio Sulser, and Daniel Eberli.
• Division of Urology, University Hospital Zurich, Zurich, Switzerland.
• BJU Int. 2014 Aug 1; 114 (2): 245-52.

ObjectiveTo assess critical heat spread of cautery instruments used in robot-assisted laparoscopic (RAL) surgery.Materials And MethodsThermal spread along bovine musculofascial tissues was examined by infrared camera, histology and enzyme assay. Currently used monopolar, bipolar and ultrasonic laparoscopic instruments were investigated at various power settings and application times. The efficacy of using an additional Maryland clamp as a heat sink was evaluated. A temperature of 45 °C was considered the threshold temperature for possible nerve damage.ResultsMonopolar instruments exhibited a mean (sem) critical thermal spread of 3.5 (2.3) mm when applied at 60 W for 1 s. After 2 s, the spread was >20 mm. For adjustable bipolar instruments the mean (sem) critical thermal spread was 2.2 (0.6) mm at 60 W and 1 s, and 3.6 (1.3) mm at 2 s. The PK and LigaSure forceps had mean (sem) critical thermal spreads of 3.9 (0.8) and 2.8 (0.6) mm respectively, whereas the ultrasonic instrument reached 2.9 (0.8) mm. Application of an additional Maryland clamp as a heat sink, significantly reduced the thermal spread. Histomorphometric analyses and enzyme assay supported these findings.ConclusionsAll coagulation devices used in RAL surgery have distinct thermal spreads depending on power setting and application time. Cautery may be of concern due to lateral temperature spread, causing potential damage to sensitive structures including nerves. Our results provide surgeons with a resource for educated decision-making when using coagulation devices during robotic procedures.© 2013 The Authors. BJU International © 2013 BJU International.

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