Comparison of neuromuscular blockade in the diaphragm and the hand

Neuromuscular blockade was recorded in the diaphragm and in the adductor pollicis muscle using unilateral supramaximal stimulation of phrenic and ulnar nerves and measurement of the mechanical effect of each. After administration of atracurium 0.4-0.5 mg kg-1 to 10 patients, both onset and recovery of neuromuscular blockade in the diaphragm occurred before that in adductor pollicis and there was a linear relationship between recovery in diaphragm and adductor pollicis. After administration of vecuronium 0.08-0.1 mg kg-1 to a further 10 patients, paralysis occurred in the diaphragm before adductor pollicis in all except one patient, in whom it occurred simultaneously. Reappearance of adductor pollicis twitch occurred in six patients after all four twitches had returned in the diaphragm, but the rate of recovery of twitch height in the diaphragm was more rapid than in adductor pollicis in every patient.