The effects of rapacuronium on histamine release and hemodynamics in adultpatients undergoing general anesthesia

Neuromuscular blocking drugs may have variable effects on heart rate (HR) a nd blood pressure. Rapacuronium is a rapid-acting, steroidal-derived neurom uscular blocking drug whose hemodynamic effects have not been characterized . We studied the effects of 1, 2, and 3 mg/kg rapacuronium on histamine rel ease, HR, and blood pressure in 47 ASA physical status II or III adult pati ents after the induction of anesthesia with etomidate/fentanyl/N2O. Plasma histamine concentrations were measured before induction and immediately bef ore and 1, 3, and 5 min after the rapid administration of rapacuronium. Mea n arterial pressure (MAT) decreased after rapacuronium administration, but there were no significant differences among the groups for changes in HR or MAP, and there was no correlation between changes in MAP or HR and increas es in histamine levels. There were no changes in HR or MAP among five patie nts who had significant (greater than or equal to 1 ng/mL) increases in his tamine from baseline. Seven patients had bronchospasm without increases in plasma histamine levels. Rapacuronium 2-3 mg/kg increased plasma histamine levels. However, clinically significant histamine-related sequelae did not occur in this population with 1- to 3-mg/kg doses of rapacuronium, and card iovascular changes were not directly correlated with histamine release. Rap acuronium administration can produce hypotension via mechanisms that do not seem to be related to histamine release. Implications: Rapacuronium, a new steroidal-derived muscle relaxant, may release histamine and produce sligh t changes in blood pressure and heart rate after administration.