The Effect of Residual Neuromuscular Blockade on the Speed of Reversal with Sugammadex

BACKGROUND: Sugammadex is a modified gamma cyclodextrin compound which encapsulates rocuronium resulting in rapid reversal of residual neuromuscular blockade. We performed a post hoc analysis of data from a multicenter study designed to mimic standard clinical practice which would test the hypothesis that the presence (versus the absence) of a twitch response to neuromuscular stimulation at the time of reversal drug administration would influence the speed and completeness of the reversal effect of sugammadex. METHODS: One-hundred-seventy-one consenting patients undergoing general anesthesia with a volatile-based anesthetic technique were enrolled in a multicenter observational study. All patients received rocuronium, 0.6 mg/kg IV for tracheal intubation and maintenance boluses of 0.15 mg/kg IV as needed during surgery. The degree of rocuronium-induced blockade was assessed during anesthesia using a TOF-Watch (R)-SX acceleromyograph to record the train-of-four (TOF) responses on a laptop computer from induction of anesthesia until the TOF ratio returned to >= 0.9 after completion of the surgical procedure. The patients received sugammadex, 4 mg/kg IV, for reversal of neuromuscular blockade >15 min after the last dose of rocuronium. Recovery data were compared in patients with either no (0) (n = 89) or >= 1 twitch (n = 82) in response to TOF stimulation at the time of reversal drug administration. RESULTS: The patients without a twitch response were more likely to be female (60%, vs 40%) and had a shorter time interval between the last bolus dose of rocuronium and the administration of the reversal drug (31 18 v's 45 23 min, P < 0.05). The time to achieve a TOF ratio of 0.9 was prolonged in the 0 twitch group compared with the >= 1 twitch response group (173 +/- 162 vs 104 +/- 73 s, P < 0.05). Overall, 84% of the patients in the 0 twitch group recovered to a TOF of 0.9 in <= 5 min compared to 91% of the patients in the group with >= 1 twitch (P < 0.05). The times to achieve a TOF of 0.9 varied from 0.8 to 22.3 and 0.7 to 8.5 min in the 0 twitch and >= 1 twitch groups, respectively. CONCLUSION: Reversal of rocuronium-induced neuromuscular blockade by sugammadex was influenced by the degree of residual blockade at the time the reversal drug was administered. Despite the wide variability, reversal of the TOF ratio to 0.9 occurred <= 5 min in more than 80% of the patients regardless of the number of twitches at the time of reversal drug administration.