• Broens Suzanne J L SJL From the Department of Anesthesiology, Leiden University Medical Center, Leiden, The Netherlands., Martijn Boon, Chris H Martini, Marieke Niesters, Monique van Velzen, Aarts Leon P H J LPHJ, and Albert Dahan.
• From the Department of Anesthesiology, Leiden University Medical Center, Leiden, The Netherlands.
• Anesthesiology. 2019 Sep 1; 131 (3): 467-476.

What We Already Know About This TopicThe ventilatory response to hypoxia is a critical reflex that is impaired by neuromuscular blocking drugs. However, the degree to which this reflex is restored after reversal of blockade is unknown.What This Article Tells Us That Is NewDespite full reversal of neuromuscular blockade at the thumb using different drug classes, this hypoxic chemoreflex is not fully restored.BackgroundThe ventilatory response to hypoxia is a life-saving chemoreflex originating at the carotid bodies that is impaired by nondepolarizing neuromuscular blocking agents. This study evaluated the effect of three strategies for reversal of a partial neuromuscular block on ventilatory control in 34 healthy male volunteers on the chemoreflex. The hypothesis was that the hypoxic ventilatory response is fully restored following the return to a train-of-four ratio of 1.MethodsIn this single-center, experimental, randomized, controlled trial, ventilatory responses to 5-min hypoxia (oxygen saturation, 80 ± 2%) and ventilation at hyperoxic isohypercapnia (end-tidal carbon dioxide concentration, 55 mmHg) were obtained at baseline, during rocuronium-induced partial neuromuscular block (train-of-four ratio of 0.7 measured at the adductor pollicis muscle by electromyography), and following reversal until the train-of-four ratio reached unity with placebo (n = 12), 1 mg neostigmine/0.5 mg atropine (n = 11), or 2 mg/kg sugammadex (n = 11).ResultsThis study confirmed that low-dose rocuronium reduced the ventilatory response to hypoxia from 0.55 ± 0.22 (baseline) to 0.31 ± 0.21 l · min · % (train-of-four ratio, 0.7; P < 0.001). Following full reversal as measured at the thumb, there was persistent residual blunting of the hypoxic ventilatory response (0.45 ± 0.16 l · min · %; train-of-four ratio, 1.0; P < 0.001). Treatment effect was not significant (analysis of covariance, P = 0.299) with chemoreflex impairment in 5 (45%) subjects following sugammadex reversal, in 7 subjects (64%) following neostigmine reversal, and in 10 subjects (83%) after spontaneous reversal to a train-of-four ratio of 1.ConclusionsDespite full reversal of partial neuromuscular block at the thumb, impairment of the peripheral chemoreflex may persist at train-of-four ratios greater than 0.9 following reversal with neostigmine and sugammadex or spontaneous recovery of the neuromuscular block.

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