The incidence of postoperative residual curarization following the use of intermediate-acting muscle relaxants and related factors.

PURPOSE To evaluate the incidence of residual curarization (RC) and related risk factors in the early and late postoperative periods in patients receiving general anesthesia with intermediate-acting muscle relaxants. METHODS Two-hundred and eight American Society of Anesthesiologists class I and II patients, aged 18-70 years, who underwent general anesthesia with intermediate-acting muscle relaxants, were included. Heart rate, blood pressure, oxygen saturation, tympanic temperature were recorded for each patient who was transported to the recovery room, every 10 minutes by a trained nurse. To define the efficacy of residual muscle relaxants, neuromuscular monitoring was performed, and Train of Four (TOF) ratios < 90% were regarded as RC whereas ratios ≥ 90% were considered as adequate neuromuscular recovery in early and late recovery periods. Age, duration of anesthesia, repeated doses, reversal and types of intermediate-acting neuromuscular blockers were evaluated as risk factors for RC. Logistic Regression Analysis was performed to define the risk factors for RC in early and late periods. RESULTS The RC rate was 10.6% in the early recovery period, and short duration of anesthesia, repeated doses and lack of reversal use were the risk factors for RC. However, RC rate was 2.9% in the late recovery period, and the only risk factor was repeated doses. CONCLUSION Reversal use was shown to reduce residual effects of intermediate-acting muscle relaxants in early recovery period, whereas risk of RC in 30 min in PACU was shown to increase with repeated doses of muscle relaxants.