Electrosurgical Units: Evaluation Criteria and Test Methods

September 17, 2014 | Evaluations & Guidance


General-purpose electrosurgical units (ESUs) are used in a variety of procedures, and they should deliver a predictable and consistent surgical effect in various and changing tissue environments. In addition, they are expected to operate safely, easily, and with minimal maintenance. The following test methods have been devised to analyze these devices in terms of performance and safety, human factors design, and other criteria.

A general-purpose ESU should offer a broad range of output modes, with output power and waveform characteristics that meet the needs of a wide variety of surgical applications. The unit should also operate safely and should be able to effectively communicate its operating and monitoring status to staff.

We analyze the waveform and measure the power output accuracy of each mode. We use a Pico Technology PicoScope Model 3204 PC oscilloscope to measure root mean square (RMS) voltage from a Solar Electronics RF current probe (Type 6741-1 1.50 ampere/volt conversion factor) and Ohmite noninductive resistors. Power accuracy is assessed at the rated load resistance specified by the manufacturer for the particular mode of operation (a resistance of 300 or 500 Ω, depending on the unit and mode). The amount of radio-frequency (RF) power delivered is calculated using the following formula (where P is power...

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