Happy 2021! We just published our fourth chapter of the Cutting Edge. Dr Bart van Goethem and others discuss electro-, cryo-, and laser surgery.
In electrosurgery or diathermy, heat is generated in the patient’s tissue due to an electric current, with the aim of using this heat for hemostasis or for making incisions. Electric current is the flow of free charge carriers – electrons and ions – from a positive electrode (the source) to a negative electrode or ground.
Electrosurgery requires an electrosurgical generator that changes the standard 50 or 60 Hz, low frequency electrical current into a useable high frequency 200 kHz to 5 MHz current. Since the neuromuscular system becomes refractory to electrical stimulation beyond a frequency of 100 kHz, there is minimal stimulation when using these high frequencies. The spectrum mentioned falls within the electromagnetic spectrum of low radiofrequency bands (AM broadcast signals 550-1550 kHz). Some units go as high as 3-4 megahertz (MHz) and occur in the range between AM and FM radio broadcasting. These are referred to as radio wave radiosurgery units (Figure 1).
When heat is applied to a biological system, the effect is temperature-related and also dependent on application time. Between 38-60°C, tissues will warm and weld without obvious visual signs. At 60-65°C irreversible damage resulting from coagulation necrosis and protein denaturation is visible as blanching. At 65-90°C protein denaturation resulting in white/greyish discoloration occurs. At 90-100°C tissues dry and show puckering. Above 100°C solid tissue vaporization results in steam and smoke, and temperatures of 350-450°C result in immediate carbonization and char formation.
The use of electrosurgical equipment has some inherent risks. Most operating room fires are caused by the use of electrosurgical equipment. Regular checks of insulation and grounding pads should therefore be performed. Smoke generated by these devices contains many carcinogenic compounds. A smoke evacuation system is therefore highly recommended.
Click on the Cutting Edge chapter for more info!!