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Microshock risk — FRCA Primary MCQ

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HardPhysics and Clinical MeasurementMicroshock riskFRCA Primary

A patient with a temporary pacing wire in ICU is connected to several mains-powered devices. Which electrical hazard is particularly important?

Educational content. Not a substitute for clinical judgement or local policy.

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Correct answer: C — Tiny currents applied directly to the myocardium may cause fibrillation

Microshock refers to very small currents delivered directly to the myocardium through intracardiac conductors, which can trigger ventricular fibrillation. Skin resistance protects against some external currents but is bypassed by intracardiac wires. Macroshock is external current through the body and does not require a central venous catheter. Equipment checks and isolation reduce leakage-current risk.

Reference: Dorsch and Dorsch Understanding Anesthesia Equipment; RCoA Primary FRCA Syllabus