Comparison of cisatracurium-induced neuromuscular block at the masseter and adductor pollicis muscle

Adequate relaxation of the masseter muscle is important during endotracheal intubation and for the patency of a patient's airway during recovery from anaesthesia. We evaluated onset and recovery from cisatracurium-induced neu romuscular block at the masseter and adductor pollicis muscles. Thirty pati ents were randomly allocated to receive either 0.1 or 0.15 mg kg(-1) cisatr acurium. The evoked response was measured at both muscles using acceleromyo graphy. Onset time was significantly shorter at the masseter muscle than at the adductor pollicis (0.1 mg kg(-1) cisatracurium: 155 +/- 52 vs. 229 +/- 44 s; 0.15 mg kg(-1) cisatracurium: 105 +/- 24 vs. 174 +/- 35 s). Followin g 0.1 mg kg(-1) cisatracurium, recovery to a TOP-ratio of 0.7 was faster at the masseter compared to the adductor pollicis (P < 0.05). In the 0.15 mg kg(-1) cisatracurium group recovery of T-1 to 75% of control and to a TOF-r atio of 0.7 occurred sooner at the masseter (P < 0.05). We conclude that on set and recovery from cisatracurium neuromuscular block occurs more rapidly at the masseter than at the adductor pollicis. It appears unlikely that re sidual paralysis is present at the masseter once neuromuscular function at the adductor pollicis has completely recovered.