Cardiovascular effects of inhalation induction with isoflurane in infants.

We evaluated hemodynamic changes during inhalation induction of isoflurane anesthesia in 60 healthy infants aged 5-26 weeks who were randomly divided into two groups of 30 patients each. In group 1 anesthesia was induced using isoflurane in concentrations that were increased to 3.5%. In group 2, 0.02 mg/kg of atropine was given intramuscularly before induction of anesthesia, as in group 1. In both groups, N2O (3 L/min) and O2 (2 L/min) were administered using a nonrebreathing system. Heart rate (HR) and blood pressure (BP) were recorded at 1-min intervals for 20 min. HR decreased 32% in group 1 and 20% in group 2; BP decreased 40% in group 1 and 38% in group 2. During isoflurane induction in infants, both HR and BP are depressed. Premedication with atropine minimizes the depression of HR, but does not affect the change in BP.