Deep neuromuscular block improves the surgical conditions for laryngeal microsurgery

Adequate neuromuscular block is required throughout laryngeal microsurgery. We hypothesized that the surgical conditions would improve under a deeper level of rocuronium-induced neuromuscular block. Seventy-two patients undergoing laryngeal microsurgery were randomly allocated to either the 'post-tetanic counts 1-2' (PTC1-2) group or the 'train-of-four counts 1-2' (TOFcount1-2) group according to the level of neuromuscular block used. Two different doses of rocuronium (1.2 or 0.5 mg kg(-1)) were used after anaesthetic induction, and two respective targets of neuromuscular block (post-tetanic counts a parts per thousand currency sign2 or train-of-four count of 1 or 2) were used. Surgical conditions were assessed by the surgeon using a five-point rating scale (extremely poor/poor/acceptable/good/optimal), and clinically acceptable surgical conditions were defined as those which were rated acceptable, good, or optimal. The occurrence of vocal cord movement and postoperative adverse events was assessed. The surgical conditions were significantly different between the PTC1-2 and TOFcount1-2 groups (extremely poor/poor/acceptable/good/optimal: 0/2/1/7/26 and 3/10/2/14/7, respectively, P < 0.001). The incidence of clinically acceptable surgical conditions was significantly higher in the PTC1-2 group than in the TOFcount1-2 group (94 vs 64%, P=0.003). The percentage of patients who exhibited vocal cord movement was significantly lower in the PTC1-2 group than in the TOFcount1-2 group (3 vs 39%, P < 0.001). The incidence of postoperative adverse events was not significantly different except for the less frequent occurrence of mouth dryness in the PTC1-2 group (P=0.035). Deep neuromuscular block (post-tetanic count of 1-2) surgical conditions in patients undergoing laryngeal microsurgery improves. Clinical trial registration: NCT01980069.