Electromyographic assessment of neuromuscular block at the gastrocnemius muscle

We have assessed neuromuscular block electromyographically at the gastrocnemius muscle and compared it with that at the abductor digiti minimi muscle in 60 adult patients undergoing cervical spine surgery under general anaesthesia. All patients were in the prone position. After vecuronium 0.2 mg kg-1, times to onset of neuromuscular block at the gastrocnemius and abductor digiti minimi muscles were mean 147 (SD 24) and 145 (14) s, respectively (ns). Times to return of the first response of the post-tetanic count (PTC1) at the gastrocnemius and abductor digiti minimi muscles were 27.7 (5.6) and 37.0 (5.9) min, respectively (P = 0.0001). Times to return of the first response of the train-of-four (TOF) at the gastrocnemius and abductor digiti minimi muscles were 41.0 (9.1) and 49.9 (8.7) min, respectively (P = 0.01). Recovery of PTC, T1/T0 and TOF ratio at the gastrocnemius muscle were significantly faster than at the abductor digiti minimi muscle.