Electrosurgery Support

Advice and support for users of Rigel’s electrosurgical analyzers

Get the most out of your Rigel electrosurgical analyzers and find the answers to your questions with our FAQs.

Electrosurgery FAQs

How to test electrosurgical units?

Performance testing of electrosurgical units (ESUs) relies predominantly on three crucial tests.
HF Power tests measure the output current, voltage, wattage and crest factor using a series of variable loads. Checks are almost always carried out on available modes and maximum power. The performance schedule from the manufacturer will state which loads are required, plus any additional power levels. Specifications for output power are usually around +/-10%.

Modern ESU analysers have built in variable load resistances with automated power test procedures. An ESU performance maintenance schedule can be programmed into the analyser for ease of use and uniform testing.

HF leakage current tests ensure that the ESU is limiting the amount of stray capacitive leakage. It must be tested in all available modes and under fault conditions. Tests are carried out from the active and dispersive electrodes in monopolar mode, and from both electrodes in bipolar mode. They ensure that if a failure in any electrode were to occur, leakage should be shielded effectively from the patient. The IEC 60601 standard states that leakage should not exceed 150mA to earth ground through a 200 Ω load.

Return electrode monitoring tests ensure that the alarms sound and ESU deactivates when the impedance of the patient plate exceeds specified values. The resistance limits are stated in the performance schedule by the manufacturer. Typically, there are low resistance (≈ 10 Ω) and high resistance (≈ 250 Ω) alarm limits.

Why test electrosurgical units?

The proper performance of ESUs is vital in ensuring the safety of patients and the management of hazards related to high frequency (HF) electrical current. ESUs must adhere to the performance and safety parameters of IEC 60601-2-2, which will be stated in the manufacturer’s service manuals. Regular testing at periodic intervals ensures that these units adhere to these requirements and are safe to use.
ESUs are a common and vital piece of equipment in operation rooms. Due to its prevalence and high risk, it’s essential that performance and safety of these devices can be verified.

HF performance measurements include current, voltage, crest factor and power. Power measurements ensure that the device output is accurate over a wide range of load resistances. There are variety of waveforms that require testing via both monopolar and bipolar electrodes.
High frequency leakage test of electrosurgical generators is specified as a requirement in the standard but may not be including in preventative maintenance schedule by the manufacturer. The test ensures that the ESU circuitry is properly limiting the amount of capacitive leakage of high frequency current. This is due to electrical current having a tendency to stray at frequencies exceeding 400 kHz, which leads to decreased functionality and potential thermal patient injury.

REM was a critical function developed when skin burns were prevalent. In monopolar mode, active electrodes provide high density energy in the form of high frequency current to the site. Neutral electrodes provide a pathway for the high frequency current delivered to the patient back to the ESU. A wide electrode surface area and low contact impedance reduces the current density, allowing current to dissipate whilst minimalizing tissue heating and reducing the risk of burns. The REM technique uses split electrodes to monitor patient impedance. An alarm will sound and the ESU will deactivate once impedance exceeds specified impedance limits.

What is electrosurgery?

Electrosurgical units (ESUs) are a crucial piece of equipment in operation rooms, used in 85% of all surgeries. These units use high frequency currents to generate heat and manipulate human tissue. Electrosurgery testing ensures patient safety, due to the high risks that are associated with high frequency electrical current and the human body. Periodic testing is an IEC 60601-2-2 requirement and manufacturers typically recommend 6-12 month test intervals. The procedure typically involves electrical safety tests, visual inspections and performance tests.
The performance procedure usually consists of output power measurement tests, high frequency measurement tests and return electrode monitoring tests.

Power measurement tests include several parameters to ensure that each mode is performing as it should. Electrosurgery is provided through cutting currents, coagulation currents or a blend of both. Cutting is an uninterrupted sinusoidal waveform with high average power and high current density. Coagulation currents are intermittent bursts of sine waves which drive the current through the tissue with relatively low current. With this in mind, it’s essential that power measurements include voltage peaks, output currents and crest factors.
ESUs use high frequencies exceeding 400 kHz, which is the range where electrical current tends to stray. This can lead to decreased functionality and potential thermal injury to the patient. These high frequency leakage limits are specified in IEC 60601. Leakage tests must be carried out under different fault condition to ensure full patient safety.

The return electrodes function is to dissipate current from the patient, ideally over a wide surface area. Return electrode monitoring (REM) was developed to ensure patient safety from burns, by ensuring adequate contact between the patient and the return electrode. REM technology relies on split electrodes, whereby the resistance of the return electrodes site is consistently monitored. Testing of the REM function ensures that when impedance increases beyond a set threshold, the electrosurgical unit alarms and deactivates.

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