Humidification reduces coughing and breath-holding during inhalation induction with isoflurane in children

Purpose: Inhalation induction using isoflurane is associated with airway irritability, coughing, breath-holding and laryngospasm. These complications are more common in children. This study was designed to determine if humidification of isoflurane in oxygen/nitrous oxide would reduce respiratory complications and hypoxic episodes at induction. Methods: Fifty-nine unpremedicated children, aged three months to 12 yr, were enrolled in the study and randomised to receive either humidified isoflurane (n = 27, Group A), or non-humidified isoflurane (n = 32, Group B). All inductions of anaesthesia were with isoflurane 4% in 50% oxygen/nitrous oxide. Subjects were observed for the occurrence of breath-holding, coughing, larygospasm, bronchospasm, secretions, and hiccoughs. The severity of each complication was graded on a scale of 0-3. The need to administer 100% oxygen and/or succinylcholine was also identified. Results: Coughing (33% vs 53%) was more frequent in Group B (P < 0.05). Coughing severity scores (13 vs 36) and breath-holding severity scores (8 vs 19) were also greater in Group B (P < 0.05). A change in FIO2 was required more frequently in Group B (4% vs 16%). Although there was a high incidence of laryngospasm in both groups (52% vs 59%), no other differences were identified, breath-holding (26% vs 31%), secretions (30% vs 31%), hiccough (11% vs 12.5%) (P > 0.05). Conclusion: Humidification of inspired isoflurane reduces the frequency and severity of coughing, the severity of breath-holding, and the need to increase supplemental inspired oxygen concentration, when isoflurane is used for inhalation induction of anaesthesia in children. Humidification has no effect, however, on the frequency and severity of laryngospasm, or on the frequency of occurrence of arterial oxygen desaturation.