RESUMO
OBJECTIVE: To determine the effects of pretreatment with either promethazine or dexamethasone on mivacurium-induced histamine release in children. METHODS: Eighty ASA I-II children (4-10 years of age) scheduled for tonsillectomy and/or adenoidectomy were randomly divided into 4 groups (n = 20 per group) designated as either the rocuronium, mivacurium, dexamethasone (DXM), or promethazine group. Children in the DXM and promethazine groups were treated separately with intramuscular DXM 0.2 mg·kg(-1) or promethazine 0.5 mg·kg(-1) injections 60 min before operation. Radial artery blood samples were collected to quantify plasma histamine concentrations 1 min before and 1, 3, and 5 min after administration of the relaxant. Mean arterial pressure (MAP), heart rate (HR), and skin flushing were recorded at the same time. RESULTS: No significant decreases in plasma histamine concentrations were observed between groups; however, more stable MAP and HR and less skin flushing were observed in DXM group participants compared with individuals in the mivacurium group (P < 0.05). By contrast, children in the promethazine group had significantly decreased plasma histamine concentrations and stable MAP and HR (without a significant increase in HR) compared with patients in mivacurium group. In addition, skin flushing was significantly decreased compared with that observed in the rocuronium group (P < 0.05). CONCLUSIONS: Pretreatment with promethazine significantly decreased mivacurium-induced histamine release in children and provided stable hemodynamics during administration of anesthesia.
