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Lateral Position Brachial Plexus Injury — FRCA Final MCQ

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ModerateAnaesthetic Equipment & SafetyLateral Position Brachial Plexus InjuryFRCA Final

A 35-year-old man (ASA I, 75 kg) is undergoing arthroscopic shoulder surgery in the lateral decubitus position. The shoulder is in 70° of forward flexion and 30° of abduction with 5 kg of longitudinal traction. Which brachial plexus injury mechanism is most relevant?

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Correct answer: D — Compression between clavicle and first rib from head positioning

In the lateral decubitus position for shoulder surgery, the non-operative (dependent) arm is at risk of brachial plexus compression between the clavicle and first rib from the weight of the torso. The operative arm is at risk of traction injury if excessive traction force is applied (>5 kg is associated with increased risk) or if the arm is positioned in extreme abduction or flexion. An axillary roll placed under the chest wall (not in the axilla) protects the dependent brachial plexus from compression.

Reference: AAGBI – 2018 – Perioperative peripheral nerve injury; RCOA – 2023 – Positioning injuries