What is the crest factor in electrosurgery?

The crest factor (CF) is defined by the ability of an ESU to coagulate without cutting and centres on the idea of shrinking the top layer of tissue which seals and prevents blood loss from the capillaries without causing further thermal damage or tissue necrosis. The CF ranges from 1.4 for a pure sine wave to around a value of 10 for coagulation.

For waveforms with a continuous current setting or pure sinewave (100% on), the CF is defined as the ratio betweem peak voltage and RMS.

CF = Vp/VRMS

For the other waveforms, the crest factor is defined as the ratio between peak-to-peak voltage and 2 x the RMS voltage.

CF = Vpp/2 x VRMS