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TOF Ratio 0.9 Extubation Threshold — FRCA Final MCQ

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ModerateGeneral AnaesthesiaTOF Ratio 0.9 Extubation ThresholdFRCA Final

A 42-year-old woman (ASA I, 68 kg) is recovering from an elective laparoscopic cholecystectomy performed under general anaesthesia. In recovery, her NMB monitoring (at adductor pollicis) shows a TOF ratio of 0.85. Can she be safely extubated?

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Correct answer: B — Only if she can perform a 5-second head lift

A TOF ratio ≥0.9 at the adductor pollicis is the accepted threshold for safe extubation (RCOA, ESA, ASA guidelines). A ratio of 0.85 indicates clinically significant residual neuromuscular block, which is associated with: impaired pharyngeal function (aspiration risk), upper airway obstruction, reduced hypoxic ventilatory response, and subjective weakness. At TOF 0.85, the patient may appear to breathe normally but has impaired protective airway reflexes. Sugammadex (if aminosteroid NMBA used) or additional neostigmine (if TOF count is 4 with fade) should be administered and TOF ratio rechecked.

Reference: RCOA – 2023 – Neuromuscular monitoring guidelines; Naguib M – 2018 – Residual neuromuscular block