Volatile anesthetics depress spontaneous ventilation in a dose-dependent manner with variations in effects among different drugs. The goal of this prospective study was to assess respiratory changes during spontaneous ventilation using desflurane/O (2/N)2 O anesthesia in two groups of children. Both groups were undergoing minor surgery and consisted of children < 2 yr old (Group I) and children > 2 yr old (Group II). They were examined at 0.5, 1, and 1.5 minimum alveolar anesthetic concentration desflurane anesthesia. Induction of anesthesia was performed via a face mask and a mixture of O2/N2 O (40:60) with halothane. At lease 20 min after stopping halothane, the respiratory variables were recorded on desflurane anesthesia. Tidal volume and minute ventilation decreased significantly (P <0.05) as desflurane increased from 0.5 to 1.5 MAC in both groups. At 1.5 MAC, the respiratory rate was greater in Group II than in Group I (P <0.05). In both groups, the increase in end-tidal CO2 was significant at 1.5 MAC versus 1 and 0.5 MAC (P <0.05). Apnea, i.e., no respiratory movement for 20 s, occurred at 1.5 MAC in one patient in each group. The respiratory duty cycle did not change in any of the groups. Both indices of paradoxical respiration-amplitude index and delay index-did not change. Implications: Desflurane induces respiratory depression at concentrations higher than 1 minimum alveolar anesthetic concentration mainly due to a decrease in tidal volume. Therefore, desflurane at high concentrations should be used cautiously in infants and children with spontaneous ventilation.
(Anesth Analg 1998;87:1052-5)