A train-of-four ratio of 0.9 may not certify adequate recovery after sugammadex.

摘要

Until recently, a train-of-four (TOF) ratio of 0.7 measured at the adductor pollicis muscle had been accepted to be an index showing sufficient recovery from neuromuscular block.1 The index can consistently estimate the recovery of respiratory muscle function that ensures safe tracheal extubation and spontaneous ventilation. However, as supported by several studies, a TOF ratio of 0.9 has been becoming a new benchmark for patient's safety. The patients with a TOF ratio <0.9 have great potential to be exposed to persistent hypoxia2 and pulmonary aspiration3 because even a mild neuromuscular block reduces ventilatory response to hypoxia by an impaired discharge from carotid body chemoreceptors, pharyngeal function and resting tonus in the upper esophageal sphincter muscle.