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Opioid-Induced Rigidity — FRCA Final MCQ

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HardGeneral AnaesthesiaOpioid-Induced RigidityFRCA Final

A 35-year-old woman (ASA I, 55 kg) is having an elective tonsillectomy. At induction, after administration of propofol and remifentanil, her jaw is noted to be completely rigid preventing mouth opening. No suxamethonium has been given. What is the most appropriate next step?

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Correct answer: C — Administer rocuronium 1.2 mg/kg and ventilate via facemask while waiting for onset

Opioid-induced rigidity (wooden chest syndrome) is a recognised complication of rapid IV administration of potent synthetic opioids (fentanyl, alfentanil, remifentanil, sufentanil), causing generalised skeletal muscle rigidity including the chest wall and jaw. It can prevent ventilation. Treatment: administer a neuromuscular blocking agent (rocuronium 1.2 mg/kg for rapid onset, or suxamethonium if rocuronium is unavailable) to overcome the rigidity and allow ventilation and intubation. This is not masseter spasm from MH and suxamethonium is not contraindicated here, though rocuronium is preferred.

Reference: RCOA – 2023 – Final FRCA curriculum: opioid pharmacology; Bailey PL – 1990 – Opioid-induced rigidity