Lauren R Wilson, MD, Nicole T Townsend, MD, Thomas N Robinson, MD. University of Colorado Department of Surgery
The monopolar “Bovie” instrument is ubiquitous. It is used by all surgical specialties on almost all surgical cases. The power delivered by the monopolar generator provides the end-user with a variety of settings to achieve different tissue effects, however patterns of use are unknown. The PURPOSE of this study is to determine the patterns with which surgeons use the monopolar instrument.
We collected retrospective electronic data on consecutive activations of the monopolar instrument from four separate medical centers’ electrosurgical generator units. Outcome variables included generator power in Watts (W), generator mode setting (cut, coagulation [coag], or blend), and duration of activation in seconds (s). Statistical analysis included non-parametric unpaired t-test for continuous variables and chi-square test for dichotomous variables.
6,666 consecutive monopolar instrument activations were analyzed over 39 generator units.
GENERATOR POWER: The most common power setting was 30 Watts (22% of activations, n=1,494) and settings of 25-35W were used 50% of the time (n=3,334). When using coag mode, the average power setting was 39±16W. When using cut mode, the average power was significantly higher at 60W (39±16W v. 60±71W; p<0.0001). Similar to cut mode, average power settings on blend mode were significantly higher at 54W (39±16W v. 54±64W; p<0.0001).
GENERATOR MODE: The most common monopolar mode was coag (high voltage, 6% duty cycle), used 84.8% (n=5,654) of the time, and significantly more frequently than both other modes. In comparison, cut mode (low voltage, 100% duty cycle) was used 10.9% (n=728) of the time, while blend mode (variation in voltage and duty cycle to produce desired clinical effects of coaglation v. cutting) was used only 4.3% (n=284) of the time (5,654 coag activations v. 1,112 non-coag activations; p<0.0001). Although both were used significantly less than coag, cut was used more significantly than blend (cut activations v. blend activations, p<0.0001).
ACTIVATION TIME: Average activation time for coag mode was significantly longer than cut (3±3s v. 2±2s p<0.0001) or blend (3±3s v. 2±2s, p<0.0001) modes. Cut mode and blend mode activation times were not significantly different (2±2s v. 2±2s, p=1.000).
The monopolar instrument is repetitively used on the same power and mode settings. The single power setting of 30 Watts is used 22% of the time with settings of 25-35W used for half of all activations. Coagulation mode is used in 85% of activations. These findings suggest that this instrument, which contains advanced technology with flexible settings, is underutilized by the surgical community. Use of multiple settings can help the surgeon achieve a range of tissue effects, including dessication, fulguration, and vaporization, which can improve tissue cutting and hemostasis. Improved understanding of these patterns of use can identify what additional settings could be used to achieve desired tissue effects. This study may imply that surgeons need additional training in non-standard settings of the monopolar instrument.