Residual Heat of Laparoscopic Energy Devices – How Long Must the Surgeon Wait Until Touching Additional Tissue

Henry Govekar, MD, Thomas N Robinson, MD, Greg V Stiegmann, MD, Francis T McGreevy, BSEE. University of Colorado School of Medicine

Introduction: Energy devices are essential laparoscopic tools. Residual heat is defined as the increased instrument temperature after energy activation is completed. The purpose of our study was to determine how long a surgeon needs to wait prior to touching additional tissue without causing injury using four common laparoscopic energy sources.
Methods: Thermal imaging quantified instrument and tissue temperature ex vivo using monopolar, bipolar tissue fusion, ultrasonic and argon laparoscopic devices. To simulate real-life operative usage, each instrument was activated for 5 seconds 4 consecutive times with 5 second pauses between fires. Thermal conductivity to bovine liver tissue was measured at 2.5, 5, 10 and 20 seconds following the final activation. Results reported as mean ± standard deviation.
Results: Maximum increase in instrument tip temperature was: monopolar (81±18ºC), bipolar tissue fusion (46±19ºC), ultrasonic (172±63ºC) and argon beam (1±1ºC); (p<0.05 for all comparisons). Temp increase of liver tissue resulting due to thermal conductivity from instrument tip was:

Conclusions: Peak instrument temperature was greatest in the ultrasonic device, followed by monopolar, bipolar tissue fusion then argon. Ultrasonic energy tips heated tissue >20ºC for all time points (even for the 20 second rest period). In contrast, all other energy source’s tissue conductivity was <20ºC from baseline by 5 seconds. These practical findings may alter a surgeon’s usage of these common energy devices.

Session: SS10
Program Number: S049

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