Effects of dexmedetomidine and esmolol on otoacoustic emissions during controlled hypotensive anesthesia: randomized clinical trial

Purpose: The aim of this study was to investigate the ability of esmolol and dexmedetomidine to achieve controlled hypotension on cochlea by measuring otoacoustic emission and stapedius reflex. Methods: In this prospective, double-blind pilot study, patients scheduled for elective tympanoplasty, rhinoplasty and endoscopic sinus surgery operation were randomly assigned to two groups, and received either dexmedetomidine (n=23) or esmolol (n=24) during surgery to maintain a mean arterial blood pressure between 55 and 65 mmHg. Distortion product otoacoustic emission tests (DPOAE) were performed 24 hours before and after the operation and during surgery (in the 20th and 40th minutes of the operation). Results: In the intra-group comparison, a statistically significant decrease was present at t20 (2,000 and 4,000 Hz frequency band) and t40 (1,000 and 1,500 Hz) according to the baseline value in the dexmedetomidine group (n=23); in the esmolol group (n=24), a statistically significant decrease (relative to the baseline value) was also detected at t20 and t40 for the 1,000 Hz frequency band. No damage was found on stapes reflexes with the infusion of these drugs. Conclusions: Infusion of dexmedetomidine and esmolol decreased DPOAE levels during the operations, but DPOAE levels returned to normal in the postoperative period, and had no effect on stapes reflexes. Studies with larger groups of patients are needed to confirm these results in tympanoplasty and other surgeries.