title: Lateral temperature spread of monopolar, bipolar and ultrasonic instruments for robot-assisted laparoscopic surgery.
abstract: OBJECTIVE
  To assess critical heat spread of cautery instruments used in robot-assisted laparoscopic (RAL) surgery.
  
  
  METHODS
  Thermal 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.
  
  
  RESULTS
  Monopolar 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.
  
  
  CONCLUSIONS
  All 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.
authors.affiliation: Division of Urology, University Hospital Zurich, Zurich, Switzerland.
authors.forename: Lukas J
authors.initials: LJ
authors.lastname: Hefermehl
authors.forename: Remo A
authors.initials: RA
authors.lastname: Largo
authors.forename: Thomas
authors.initials: T
authors.lastname: Hermanns
authors.forename: Cédric
authors.initials: C
authors.lastname: Poyet
authors.forename: Tullio
authors.initials: T
authors.lastname: Sulser
authors.forename: Daniel
authors.initials: D
authors.lastname: Eberli
mesh_terms: D000818:Animals; D002417:Cattle; D004564:Electrocoagulation / Q000009:adverse effects / Q000295:instrumentation*; D005205:Fascia / Q000473:pathology*; D000071938:Fasciotomy; D006358:Hot Temperature / Q000009:adverse effects*; D010535:Laparoscopy / Q000009:adverse effects / Q000295:instrumentation*; D012371:Robotics / Q000295:instrumentation*; D013814:Thermal Conductivity; D014464:Ultrasonic Therapy / Q000009:adverse effects / Q000295:instrumentation*
keywords: bipolar; cautery; harmonic; monopolar; robotic; thermal spread; tissue damage