Evaluation of awakening and recovery characteristics following anaesthesia with nitrous oxide and halothane fentanyl or both for brief outpatient procedures in infants.

This study compared recovery characteristics and postoperative ventilatory function when halothane, fentanyl or combination of halothane and fentanyl in addition to N2O were used for intraoperative anaesthesia in term infants undergoing hernia repair as outpatients. Sixty-six full term ASA PS I infants ages 1-12 months were studied. All received inhalation induction with N2O, O2 and halothane, followed by intravenous atropine and atracurium, tracheal intubation, and controlled ventilation. For anaesthesia maintenance, patients were randomized into one of three groups. Group I received 70% N2O, 30% O2 and halothane. Group II received 70% N2O, 30% O2, halothane and 2 micrograms.kg-1 fentanyl. Group III received 70% N2O, 30% O2 and 10 micrograms.kg-1 fentanyl. Awakening times were similar in all three groups, however, Group I patients had significantly shorter recovery and discharge times than those of Group II and III. None of the patients experienced postoperative apnoea or periodic breathing. One patient in Group III experienced two brief episodes of bradycardia not associated with apnoea or arterial desaturation (SpO2 > 90% for greater than 30 s). Decreased SpO2 occurred less frequently in Group I (5.9%) compared to Group II (22.7%) and Group III (19.0%) patients, however, the group differences were not significant. Transcutaneous CO2 (TcCO2) values were not statistically different among the three groups. Pain scores were initially lower in Groups II and III, but at 120 min the differences were not significant. Postoperative apnoea was not observed in this study. SpO2 < 90% and TcCO2 > 9 kPa (70 mmHg) was more common in infants receiving 2 and 10 micrograms.kg-1 fentanyl than in infants receiving halothane and nitrous oxide anaesthesia. Infants < 3 months old did not have a higher incidence of SpO2 < 90% or significantly higher TcCO2 values when compared to infants > 3 months old. Fentanyl in doses used in this study did not prolong awakening time but did prolong recovery and discharge times in outpatient infants.