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.

[Study on the feature of cortical auditory evoked potential under different auditory tasks in cochlear implant children].

Objective: To investigate the variation regularity and influencing factors of cortical auditory evoked potential (CAEP) evoked by pure tone, syllable and tone stimuli in cochlear implant (CI) children. Methods: Cortical auditory evoked potential (CAEP) responses were collected from 46 CI children in the sound field. Pure tones with frequencies of 1 kHz and 2 kHz were used as the standard and the deviant respectively in the pure tone stimulation condition. The Chinese Mandarin tokens/ba/-/pa/and/ba1/-/ba4/pairs were used as the stimuli respectively in the syllable and tone stimulation condition. The latency, amplitude and presence rate of P1 and mismatch negative(MMN) were obtained and the correlation between the difficulty of auditory task, the age of hearing month, the duration of severe-profound hearing loss, the wearing history of hearing aid before CI, the hearing threshold of the better ear before CI and the latency and amplitude of P1 and MMN were analyzed. All statistical analyses and figures were conducted using SPSS 25.0. Results: The P1 presence rate of pure tone, syllable and tone group was 100% (17/17), 100% (13/13) and 75.0% (12/16), respectively, with significant difference (χ²=8.214, P=0.016). There was significant difference between pure tone group and tone group (χ²=4.836, P=0.028), but no significant difference between pure tone group and syllable group, syllable group and tone group. The MMN presence rate of pure tone, syllable and tone group was 94.1% (16/17), 84.6% (11/13) and 62.5% (10/16), respectively, but no significant difference among the three groups with different auditory tasks(χ²=0.066, P=0.066). No significant difference was observed among the three groups of different auditory tasks in the latency and amplitude of P1 and MMN. Multiple linear regression analysis showed that the latency of P1 was positively correlated with the difficulty of auditory task and the hearing threshold of the better ear before CI, and negatively correlated with hearing age and the history of hearing aid before CI. The latency of MMN was positively correlated with the difficulty of auditory task, and negatively correlated with hearing age. Conclusions: The P1 presence rate of pure tone auditory task is significantly higher than that of tone auditory task. The difficulty of auditory task, hearing age, the history of hearing aid before CI, and the hearing threshold of the better ear before CI has significant effects on the P1 latency. The difficulty of auditory task and hearing age has significant effects on the MMN latency.