Ventricular Function in Children during Halothane Anesthesia

Abstract

The effect of halothane on ventricular function in normal children was studied with the aid of echocardiography, which offers a noninvasive method ot obtain these measurements safely. Healthy children (13) ranging in age from 19 mo.-12 yr (mean = 6 yr), undergoing elective non-cardiac surgical procedures, were studied. Secobarbital, 4 mg/kg and morphine, 0.1 mg/kg, were administered i.m. 1 h prior to induction of general anesthesia. Echocardiographic measurements were obtained while the patients breathed room air (control) and following nitrous oxide, 60%, and concentrations of halothane ranging from 0.5-2%. Increasing inspired concentrations of halothane significantly altered ventricular function in a dose-dependent fashion. At halothane, 2%, systolic blood pressure, pulse rate and cardiac output decreased to 82, 94 and 72% of control values, respectively. Measurements of ventricular performance, ejection fraction (EF), left ventricular enddiastolic volume (LVEDV) and mean normalized rate of circumferential fiber shortening (Vcf) showed parallel decreases. Following atropine, 0.02 mg/kg, i.v., improvement in cardiac output and all rate-dependent variables was observed. Although Vcf improved by 18%, other indices of myocardial performance (EF, LVEDV, PEP/LVET) still showed depression. Halothane may significantly decrease ventricular function in children undergoing surgical procedures. The accompanying decrease in cardiac output was completely offset by the administration of atropine.