Histamine release during the administration of atracurium or vecuronium in children.

The histamine releasing potential of equivalent bolus doses of atracurium 0.6 mg kg-1 or vecuronium 0.12 mg kg-1 was evaluated in 20 children anaesthetized with halothane. Blood samples were obtained before, and at 2 and 5 min after the administration of the neuromuscular blocker. The twitch response to 0.15 Hz was also evaluated. None of the 10 patients receiving vecuronium had a significant increase in plasma histamine concentration. In two of the 10 children receiving atracurium, the plasma histamine concentration increased markedly, but without any apparent clinical manifestations. Recovery of neuromuscular function (to 95% twitch height) after vecuronium 0.12 mg kg-1 was faster than after atracurium 0.6 mg kg-1 (P less than 0.02).