PEA Arrest Reversible Causes — FRCA Final MCQ

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ModerateAnaesthetic Equipment & SafetyPEA Arrest Reversible CausesFRCA Final

A 42-year-old man (ASA II) has a witnessed cardiac arrest in the anaesthetic room during IV cannulation (before any drugs have been given). The ECG shows sinus rhythm at rate 80 but there is no pulse. This is pulseless electrical activity. Given the temporal relationship to venepuncture, the most likely cause in the 4H/4T framework is:

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Correct answer: E — Hypovolaemia

PEA cardiac arrest occurring in an otherwise healthy patient before any drug administration is unusual. In this setting, the most likely reversible cause is a vasovagal/anaphylactoid event progressing to arrest, or an undiagnosed underlying cardiac condition. However, within the 4H/4T framework and given the anaesthetic setting, hypovolaemia (from unrecognised haemorrhage or severe dehydration) is statistically most common overall. Given no drugs were administered, toxins are excluded. The correct approach is systematic: address the 4Hs (Hypoxia, Hypovolaemia, Hypo/hyperkalaemia, Hypothermia) and 4Ts (Tension pneumothorax, Tamponade, Toxins, Thromboembolism).

Reference: Resuscitation Council UK – 2021 – ALS guidelines; RCOA – 2023 – Perioperative cardiac arrest