Haemodynamic depression by halothane is age‐related in paediatric patients

Abstract

The hypothesis that young infants are more sensitive to the haemodynamic depressant effects of halothane compared with older children was tested. One hundred and sixty unpremedicated, ASA physical status I or II paediatric patients without cardiac or pulmonary disease were divided into five age groups: term neonates, 1-6 months, 6-24 months, 2-6 years and 6-12 years. Anaesthetic induction was achieved with halothane in oxygen and air via mask. Vecuronium 0.1 mg.kg-1 was administered intravenously. During normocapnic manual ventilation by mask, endtidal halothane concentration was maintained at either 2xage-specific MAC (Method I) or 1.7% (Method II) in 20 patients in each age group for 10 min. In both Method I and Method II, systolic and mean blood pressure of term neonates and infants aged 1-6 months decreased significantly (P < 0.01) compared with other age groups. The results of this study demonstrate that neonates and young infants are more susceptible to haemodynamic depression during halothane anaesthesia than are older children, confirming clinical experience.

The halothane era in pediatric anesthesia: The convergence of a cardiac depressant anesthetic with the immature myocardium of infancy

“…SBP was recorded at baseline and at age‐appropriate 2 MAC halothane at a steady state after enough time to allow myocardial uptake of halothane. The results demonstrated that SBP decreased 30% in neonates and infants up to 6 months of age and 12%–15% in older children aged greater than 6 months to 12 years 11 . (Figure 4) Thus, these clinical studies demonstrated important hemodynamic depression by halothane in neonates and infants that significantly improved after 6 months of age, suggesting that functional myocardial maturation is attained by about 6 months.…”

Anesthetic Drugs in Congenital Heart Disease

“…15,16 Thus, at equipotent minimum alveolar concentrations of halothane or desflurane, the infant exhibits a greater decrease in MAP than does the older child. 17,18 The volatile anesthetics also cause a decrease of SVR that contributes to a decrease of MAP, with the effect of isoflurane being somewhat greater than that of sevoflurane or halothane in children with CHD and of desflurane in adults undergoing thoracotomy. 14,19 Evidence exists that volatile anesthetics also decrease PVR.…”

“…15,16 Thus, at equipotent minimum alveolar concentrations of halothane or desflurane, the infant exhibits a greater decrease in MAP than does the older child. 17,18…”

Outstanding contribution to pediatric anesthesiology: An interview with Dr. Robert H. Friesen

“…Animal research at the time demonstrated that the cardiovascular depression associated with halothane was more severe in newborn animals than older ones, presumably because the immature myocardium was more sensitive to depression confirming the observation of an increased incidence of cardiac arrest in infants undergoing halothane general anesthesia . In a prospective study, Friesen demonstrated for the first time that at equipotent doses of halothane, blood pressure depression was greater in neonates and infants less than 6 months of age than in older children . Additional prospective studies of halothane induction of anesthesia in infants documented a mean decrease in blood pressure of 50% that could be attenuated by pretreatment with atropine to maintain heart rate .…”