Cardiovascular Depression during Halothane Anesthesia in Infants

Hemodynamic changes during three techniques for induction of halothane anesthesia were studied in 90 healthy infants aged 5 to 26 weeks who were randomly divided into three groups of 30 patients each. In group I, anesthesia was induced using halothane in concentrations that were increased to 3%. In group II, atropine, 0.02 mg/kg, was given intramuscularly before induction, followed by induction as in group I. In group III, halothane in concentrations that were increased to 1.25% was followed by intramuscular succinylcholine, 2 mg/kg, 90 seconds after the start of induction. In all three groups N2O 3 L/min and O2 2 L/min were employed using a non-rebreathing system. Heart rate (HR) and blood pressure (BP) were recorded at 1 -minute intervals for 20 minutes. HR decreased 30% in group 1,18% in group II (p < 0.01), and 29% in group III. BP decreased 50% in group I (p < 0.01), 34% in group II, and 33% in group III. During halothane induction in infants, bradycardia can be minimized with preoperative atropine; the degree of hypotension can be diminished with either preoperative atropine or the use of intramuscular succinylcholine combined with lower concentrations of halothane.