삼출성 중이염에 대한 아산화질소의 영향

Background and Objectives: The nitrous oxide (N₂O) is a widely used anesthetic gas and has been known to incr eases middle ear pressure during anesthesia. The positive pressure induced by the nitrous oxide may be sufficient to open the eustachian tube and to evacuate the fluid from the middle ear. In this study, we attempted to evaluate the influence of N₂O on the patients with middle ear effusion. We assumed that N₂O increased the middle ear pressure to evacuate the fluid from the middle ear. On the other hand, other anesthetic agents might not influence the middle ear pressure to evacuate the fluid from the middle ear cavity. Materials and Method: We reported 243 operated ears (175 patients) who underwent myringotomy and ventilation tube insertion from January 1995 to March 1998 in Daedong Hospital. We evaluated their type of anesthesia, impedance audiometry findings, microscopic findings of the tympanic membrane during surgery, concomitant nasal symptom, rate of recurrence. Results: The percentage of absence of fluid during surgery was higher in the group of anesthesia with N₂O than that of without N₂O. Patients who underwent anesthesia with N₂O showed 31.1% disappearance rate of the fluid, whereas, patients without N₂O anesthesia showed only 5.6% disappearance rate. The number of patients who had middle ear effusion with concomitant nasal symptoms were 125 patients. Patients who underwent anesthesia with N₂O showed 38.5% disappearance rate of the fluid whereas, patients without N₂O anesthesia showed only 5.0% disappearance rate. Conclusion: Anesthesia with nitrous oxide showed a great tendency of disappearance of middle ear effusion than without nitrous oxide. (J Clinical Otolaryngol 1999;10:36-40)