Closed circuit anesthesia in infants and children

A closed-system low-flow technique with enflurane, halothane, or isoflurane as the sole anesthetic was used in three groups of ten children each. Anesthesia was induced by injection into the expiratory limb of a priming standard dose of the liquid anesthetic, followed by additional doses at 15, 30, 60, and 90 sec, and 2, 3, and 4 min. Further injections following the "square root of time" sequence were used for maintenance. Volumes of anesthetics used averaged 3.7 +/- 1.1 ml for enflurane, 2.3 +/- 1.1 ml for halothane, and 3.0 +/- 0.9 ml for isoflurane. These volumes were higher than predicted on theoretical grounds, as was the frequency with which anesthetics had to be injected. Closed-system low-flow anesthesia is a practical, economical, and nonpolluting technique in pediatric patients. Complications associated with isoflurane suggest, however, that isoflurane is not as satisfactory as enflurane or halothane when using this technique in infants and children.