Dose - response for Atropine and Heart Rate in Children during Inhalation Anesthesia

Bahk, Jae Hyon; Yang, Mi Kyung; Lim, Seung Woon; Kim, Seong Deok

Abstract

We determined the dose-response for atropine and heart rate in 114 healthy children anesthetized with N2O-O2-1 MAC halothane, enflurane or isoflurane. After induction of anesthesia, atmpine in does of 5, 10, 20 and 30 ug/kg was administered successively by rapid intravascular infusion with a time interval to each subject. The effects of atropine on heart rate and systolic blood pressure were compared among anesthetic groups and dosage groups, and a dose-response curve for peak heart rate was constructed in each anesthetic group. The heart rate increased in all cases following atropine medication. Among the dosage group of 5 ug/kg, the heart rate was significantly highest in children receiving isoflurane anesthesia (p<0.05). Among 10 and 20 ug/kg, the heart rate was significantly lowest in enflurane group. In 30 ug/kg, the heart rate was not different in eaeh anesthetic group. In each dosage group, the systolic blood pressure was significantly lowest in isoflurane gorup (p<0.05). In children anesthetized with halothane. 50% maximal response corresponded to 7.8 ug/kg, and 90% maximal response corresponded to 16.5 ug/kg. In enflurane group, 50% maximal response corresponded to 9.5 ug/kg, and 90% maximal response corresponded to 23.0 ug/kg. In isoflurane group, 50% maximal response corresponded to 7.5 ug/kg, and 90% maximal response corresponded to 18.3 ug/kg. Based on these data we conclude that 10 ug/kg of atopine is minimally required to increase heart rate by 50% of peak heart rate in children anesthetized with N2O-O2-1 MAC halothane, enflurane or isoflurane and that this also increases systolic blood pressure.