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Anaes TopicsElectricity, diathermy & theatre safety

Anaes · Electricity, diathermy & theatre safety

Electricity, diathermy & theatre safety

Also known as Surgical diathermy · Electrosurgery · Electrosurgical unit · Macroshock · Microshock · Surgical fire · Line isolation monitor

The electrical safety in the operating theatre covers the risks of the electric shock (the macroshock and the microshock), the diathermy (the electrosurgery) physics, and the fire and the explosion risk. The framework rests on five exam-critical ideas: the macroshock (the whole-body current through the skin) and the microshock (the tiny current delivered directly to the heart); the protective measures (the earthing, the line isolation monitor, the residual current device); the diathermy physics (the monopolar and the bipolar, the cutting and the coagulation currents); the pacemaker and the implanted-device interaction; and the surgical fire (the fire triangle of the fuel, the oxidiser, and the ignition).

medium8 referencesUpdated 26 July 20269 min readVerification in progress

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Red flags

  • The monopolar diathermy is contraindicated in the patient with a cardiac pacemaker or an ICD unless precautions are taken — the current can traverse the device, cause the electromagnetic interference, induce the ventricular fibrillation, or inhibit the pacing. Use the bipolar diathermy where possible, keep the return plate and the active electrode well away from the device, and consult the device team.
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Red flags

  • The monopolar diathermy is contraindicated in the patient with a cardiac pacemaker or an ICD unless precautions are taken — the current can traverse the device, cause the electromagnetic interference, induce the ventricular fibrillation, or inhibit the pacing. Use the bipolar diathermy where possible, keep the return plate and the active electrode well away from the device, and consult the device team.
The one-line answer

Electrical safety in theatre rests on three things: do not shock the patient (macroshock from the mains, microshock to a catheterised heart), do not burn them (the diathermy return plate and the fire triangle), and do not interfere with their devices or monitors. Diathermy uses high-frequency current — above about 300 kilohertz — that cuts and coagulates without tetany; monopolar traverses the body to a return plate, bipolar stays between the forceps tips. The killers are monopolar near a pacemaker, a misplaced return plate, and an airway fire — fuel, oxidiser and ignition together.[3][4]

Meet the patient

A 78-year-old with a dual-chamber pacemaker presents for a laparoscopic cholecystectomy. The surgeon asks for monopolar diathermy. The anaesthetist pauses — the current path, the device and the magnet all need to be considered before the pedal is pressed.[5]

The two questions that decide every diathermy decision are the two that keep the patient safe: where will the current go? (monopolar traverses the body to the plate; bipolar stays local) and what three elements are in the field? (fuel, oxidiser, ignition — the fire triangle). Hold those two and the physics below becomes practical.[1][4]

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References8ShowHide
  1. [1]Vilos GA, et al. Electrosurgical generators and monopolar and bipolar electrosurgery J Minim Invasive Gynecol, 2013.PMID 23659748
  2. [2]Link T. Guidelines in Practice: Electrosurgical Safety AORN J, 2021.PMID 34181252
  3. [3]Burgess RC. Electrical safety Handb Clin Neurol, 2019.PMID 31277877
  4. [4]Mortada H, et al. Preventing and Managing Operating Room Fires in Plastic Surgery: A Review of Incidence, Risk Factors, and Recommendations With Case Experiences J Burn Care Res, 2024.PMID 38158891
  5. [5]Chacko S, et al. Diathermy-induced Ventricular Fibrillation J Innov Card Rhythm Manag, 2021.PMID 33654572
  6. [6]Al Baalharith MM, et al. Understanding the safe application of electrosurgery: A cross sectional study of surgeons in KSA J Taibah Univ Med Sci, 2023.PMID 36818175
  7. [7]Zhang S, et al. Prevalence of operating room occupational health cluster: a systematic review and meta-analysis Front Public Health, 2026.PMID 42273630
  8. [8]Karuppal R. It is time for a more cautious approach to surgical diathermy, especially in COVID-19 outbreak: A schematic review J Orthop, 2020.PMID 32425415

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