Postoperative residual block after intermediate‐acting neuromuscular blocking drugs

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Abstract
The frequency and duration of postoperative residual neuromuscular block on arrival of 150 patients in the recovery ward following the use of vecuronium (n = 50), atracurium (n = 50) and rocuronium (n = 50) were recorded. Residual block was defined as a train‐of‐four ratio of <0.8. An additional group of 10 patients received no neuromuscular blocking drugs during anaesthesia. The incidence of postoperative residual neuromuscular block was 64%, 52% and 39% after the use of vecuronium, atracurium and rocuronium, respectively. Similar numbers of patients were not able to maintain a sustained head or leg lift for 5 s on arrival in the recovery ward. The mean [range] times to attaining a train‐of‐four ratio of ≥0.8 after arrival in the recovery ward were 9.2 [1–61], 6.9 [1–24] and 14.7 [1.5–83] min for vecuronium, atracurium and rocuronium, respectively. None of the 10 patients who did not receive neuromuscular blocking drugs had train‐of‐four ratios <0.8 on arrival in the recovery ward. It is concluded that a large proportion of patients arrive in the recovery ward with a train‐of‐four ratio <0.8, even with the use of intermediate‐acting neuromuscular blocking drugs. Although the residual block is relatively short lasting, it may occasionally be prolonged, requiring close observation and monitoring of such patients in the recovery ward.