Evaluation of ear function after cardiopulmonary bypass with otoacoustic emissions: a pilot study

Objectives: During extracorporeal circulation (ECC) there is a great hemodynamic stress with possible impact on the microcirculation, including cochlear one. Previous studies have evaluated the effect of ECC on inner ear with contrasting results. The aim of this study is to evaluate possible modifications of the outer hair cells (OHC) function after open heart surgery (OHS) under ECC with transient evoked (TEOAEs) and distortion product otoacoustic emissions (DPOAEs). Methods: Ten patients (5 F and 5 M), undergoing OHS with ECC, were subjected to an audiological assessment pre- and postoperatively. We compared the pre-operative and post-operative mean auditory thresholds, mean TEOAEs reproducibility and amplitude, and mean DPOAEs amplitude. Student's t-test was used to compare different values. Results: No significant differences were found between pre- and post-operative audiological assessment both in hearing level and in otoacoustic emissions. Conclusion: OHC function seems to be not affected by hemodynamic stress induced by ECC. Further studies on a larger scale will be necessary to confirm our preliminary data.