Volatile induction and maintenance of anesthesia using laryngeal mask airway in pediatric patients

formed parental consent, 60 children, aged 2 to 8 years, American Society of Anesthesiologists (ASA) class I– II, who were scheduled for minor urogenital surgery were enrolled in this prospective, randomized study. Automated noninvasive blood pressure, ECG, and SpO2 were monitored using a Criticare System 1100 monitor (Criticare System, Waukesha, WI, USA). Respiratory gases were monitored by infrared spectroscope S/5 (Datex-Ohmeda, Helsinki, Finland). Anesthesia was induced by mask with a mixture of O2/N2O by a pediatric Bain system at a fresh gas flow of 6 l·min 1. In both the halothane and the sevoflurane groups (group H and group S, respectively), inspired gas concentrations were increased in stepwise fashion; halothane in 0.5% increments, up to a maximum of 5%; and sevoflurane in 1% increments, up to a maximum of 7%. As soon as consciousness was lost, an intravenous catheter was inserted, after eyelash and protective airway reflexes were lost, and the percent concentration of inhaled anesthetic was decreased to keep hemodynamic stability; then the child was ventilated at that concentration of inhaled anesthetic for another 1min. The LMA was chosen depending on the child’s weight, and placed in the hypopharynx. Simultanously, end-tidal concentrations of the inhaled anesthetics and the percentage concentration of the vaporizer dial were recorded. Neuromuscular blocking drugs were not given. Ventilation was controlled to maintain normocapnia, and fresh gas flow was kept high enough to prevent rebreathing. Anesthesia maintenance was done with a total of 1 minimum alveolar concentration (MAC) of the volatile agent and 50% N2O in oxygen in order to provide hemodynamic stability and LMA tolerance until the end of the surgery. Analgesia was provided by 2μg·kg 1 i.v. fentanyl before skin incision. At the end of the surgery, all anesthetic agents were discontinued, 100% O2 was administered, and the LMA was removed in the operating room when the patient was fully awake.