Exposure to nitrous oxide may increase airway inflammation during sevoflurane anesthesia

Background: The purpose of this study was to examine whether nitrous oxide increases the inflammatory reaction in the airway in patients undergoing minor surgery.

Methods: Twenty patients were divided into two groups at random. The patients were anesthetized by either sevoflurane with air (Group A: n=10) or sevoflurane with nitrous oxide (Group G: n=10). In addition, all patients were mechanically ventilated. Epithelial lining fluid (ELF) specimens were obtained by bronchoscopic microsampling method at both the beginning and end of surgery. The concentrations of interleukin (IL)-6 and IL-8 in the ELF were measured by enzyme immunometric assay(ELISA).

Results: Significant differences were observed in the IL-8 concentrations in the ELF of the G group at the end of surgery in comparison with those seen at the beginning of surgery in the G group (P < 0.05), and at the end of surgery in the A group (P < 0.05). The IL-6 levels were not measured in either group.

Conclusions: The pulmonary immunologic function changed progressively during anesthesia, surgery and positive pressure mechanical ventilation. The data from this study suggest that the immune ability of the lung may possibly change due to the administration of nitrous oxide. As a result, our findings suggest that the postoperative inflammatory reaction in the lung may increase when sevoflurane plus nitrous oxide are used during general anesthesia.