Prospective Randomized Trial to Determine Whether Inhalational Anesthetics Have Any Effects on Hearing Function

Abstract

Objective: The purpose of this study was to investigate and compare the effects of inhalation anesthetics (sevoflurane and isoflurane) on hearing function by using an audiometric test battery. Design: A prospective, randomized, double-blind, clinical trial. Setting: University hospital. Patients: Fifty-three adult patients (American Society of Anesthesiologists I-II) scheduled for sinonasal surgery with intratracheal general anesthesia were enrolled in the study. The patients were premedicated with diazepam intramuscularly. Propofol 2 mg/kg (Diprivan, AstraZeneca, Wilmington, DE) was given intravenously (IV) for induction of general anesthesia. After endotracheal intubation with vecuronium IV (1 mg/kg), in group 1 (n = 27) sevoflurane 2% and in group 2 (n = 26) isoflurane 1.2% were used to maintain general anesthesia. All patients received nitrous oxide during maintenance. Main Outcome Measures: The patients' hearing function was measured before anesthesia and 24 hours after surgery by means of pure-tone audiometry, high-frequency pure-tone audiometry, and transient evoked otoacoustic emissions (TEOAEs) by the same clinician. Results: There were no statistically significant differences between the demographic data and the hemodynamic and respiratory parameters of the groups. No significant differences were found between groups in hearing thresholds of conventional pure-tone audiometry and extended high frequency (p > .05). For TEOAE responses, no statistically significant differences were determined between pre- and postoperative measurements (p > .05). Conclusion: It was audiometrically demonstrated that general anesthesia did not affect the hearing function in any of the patients undergoing sinonasal surgery. These findings encourage the use of sevoflurane or isoflurane as a safe agent without any ototoxic effects in otorhinolaryngologic surgery with general anesthesia.