Abstract
Background. Sensorineural hearing loss after procedures including extracorporeal circulation and hypothermia is greater than general population. Mild hypothermia has a protective role on cochlea; however, deep hypothermia may result in cochlear injury. This research aimed at assessing auditory function in children after open heart surgery in relation to different hypothermic techniques. Subjects and Methods. Forty children with acyanotic heart diseases who underwent open heart surgery were included: group I: twenty patients subjected to mild hypothermia (33° to 37°C), group II: twenty patients subjected to moderate hypothermia (28° to 32°C). Audiological assessment included basic evaluation and otoacoustic emissions. Results. Both groups had distortion-product otoacoustic emissions (DPOAEs) amplitude >3 dB SPL at all frequencies. However, group II showed lower amplitude at overall and at high frequencies (4.416–8.837 KHz) than group I. Transient evoked otoacoustic emissions (TEOAEs) showed partial pass in three patients of group I (15%) and in 15 patients of group II (75%). Moreover, group II showed statistical significant reduction in overall TEOAEs amplitude as well as at high frequencies (2–4 KHz). Conclusions. Patients exposed to moderate hypothermic technique had subtle cochlear dysfunction. Otoacoustic emissions should be used for early detection of subtle cochlear dysfunction in operated cardiac children.
Highlights
The risk of sensorineural hearing loss after surgical procedures including extracorporeal circulation and hypothermia is estimated at 0.14% in the literature, a rate six times greater than the risk in general population [1]
In cardiopulmonary bypass most patients are subjected to one of two techniques regarding body temperature either mild technique in which body temperature ranges from 32◦ to 37◦C or moderate hypothermic technique in which body temperature ranges from 28◦ to 32◦C [2]
Few studies revealed that hypothermia has a protective role on the cochlea and could prevent its damage during long-lasting operations performed in extracorporeal circulation [3]
Summary
The risk of sensorineural hearing loss after surgical procedures including extracorporeal circulation and hypothermia is estimated at 0.14% in the literature, a rate six times greater than the risk in general population [1]. Extracorporeal circulation with deep hypothermia may result in cochlear cells injury [4]. Otoacoustic emissions (OAEs), described by Kemp in 1978 [5], arise apparently in the outer hair cells (OHCs) and possibly represent the rapid contractions of this cell group. They are acoustic phenomena of cochlear nature, which reverberate through the ossicles in the middle ear and are transmitted to the ear canal, where they can be captured through a microphone [5]. Sensorineural hearing loss after procedures including extracorporeal circulation and hypothermia is greater than general population. Otoacoustic emissions should be used for early detection of subtle cochlear dysfunction in operated cardiac children
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