Otoacoustic emission and its application in anesthesia.

Objective: An otoacoustic emission (OAE) is a low-level sound emitted by the cochlea. OAEs are able to objectively evaluate the auditory perception and reflect the functional status of the auditory system. With the characteristics of non-invasiveness, high reliability, and easy manipulation, OAEs have gained wide popularity in clinical audiology and anesthesiology. This review aims to summarize the application of OAE in anesthesia.
Materials and Methods: This study collected data from the databases Web of Science-Clarivate Analytics, PubMed, and Google Scholar in English, covering research in the last 40 years. The keywords were defined as anesthesia, cochlea, OAEs, distortion product otoacoustic emissions, transient evoked otoacoustic emissions, bispectral index, auditory evoked potentials, and depth of anesthesia. Documents that matched defined keywords were selected and reviewed.
Results: Research showed that the types and doses of anesthetic drugs impacted OAEs. Ketamine-based anesthesia has a greater effect on OAE sensitivity over time compared to isoflurane. A higher dose of ketamine-xylazine significantly reduced the amplitude of OAEs. According to those characteristics, OAEs could be used as an objective evaluation method for the effect of anesthetics and have great potential to be applied for anesthetic drug dose control during surgery. OAEs also have been used to detect the cochlear function during anesthesia, which may cause irreversible damage to the cochlea.
Conclusions: Studies reported that OAEs have been used in anesthesia. However, the existing studies have mainly focused on the influence of anesthetic types or dosages on OAEs. Considering the characteristics of OAEs, such as a convenient measurement, less susceptibility to interference, and fast detection speed, the application of OAE has a great potential in the anesthesia field.