The effects of hypotensive anaesthesia on otoacoustic emissions: a prospective, randomized, double-blind study with objective outcome measures

The aim of the present study was to compare pre- and post-operative otoacoustic emission examinations of patients who experienced surgery under hypotensive anaesthesia using distortion product otoacoustic emission (DPOAE) and transient evoked otoacoustic emission (TEOAE). Forty-one patients, admitted to our tertiary centre for nasal valve surgery, were prospectively and randomly assigned into two groups. Hypotensive group included 20 patients, while control group included 21 patients. All investigators and patients were blinded to anaesthesia assignment throughout the course of the study. DPOAEs and TEOAEs were performed before surgery and repeated after 15 days in both groups. In control group, DPOAE-DP1 levels per frequency increased significantly in the post-operative period when compared with the preoperative values in all patients. However, DPOAE-DP1 levels decreased significantly in hypotensive group. Similarly, DPOAE-SNR levels per frequency decreased significantly in hypotensive group. In conclusion, we have observed that under the influence of hypotensive general anaesthesia, the amplitudes of OAEs are affected