Emissões otoacústicas evocadas transientes em neonatos durante a sucção/deglutição

Abstract

Objective: To verify if the noise caused by sucking and swallowing mechanisms interferes in the quality of transient evoked otoacoustic emissions (TEOAE) in neonates with and without risk indicators for hearing loss by comparing the responses without sucking with situations of non-nutritive sucking, breast-feeding nutritive sucking and bottle-feeding nutritive sucking. Methods: a study carried out with 53 neonates (13 with risk indicators for hearing loss), evaluated with TEOAE, at rest and in three different cases: non-nutritive sucking, breast-feeding nutritive sucking and bottle-feeding nutritive sucking. Results: Studying the different types of sucking, it was found that the greater incidence of failure occurred at the frequency of 2000 Hz for all the three types of sucking. An increase in the noise intensity was observed in all frequencies during the capture of TEOAE in the left ear in all types of sucking studied. At 1400, 2000, 2800, and 4000 Hz, the signal to noise ratio decreased in the left ear during sucking. In breast-feeding nutritive sucking, the noise levels were lower at 1400 Hz and the signal to noise ratio was higher at the same frequency as well as at 2000 Hz. When neonates were compared regarding the presence or not of risk indicators for hearing loss, the seconds during non-sucking situation showed higher amplitude of TEOAE at the frequencies of 700, 1000, 2000, and 4000 Hz, and at 1000 and 4000 Hz during sucking. In both groups, a decrease in the amplitude of TEOAE and in the noise at 700 Hz during sucking was observed. At the other frequencies, the noise level increased in the sucking situation. There was no change in the signal to noise ratio between the conditions of sucking and nonsucking at 700 and 1000 Hz. At 1400 Hz, the sucking impaired the signal to noise ratio causing absence of response. At 2000, 2800, and 4000 Hz, the signal to noise ratio remained greater than 6 dB. Conclusions: The evaluation of TEOAE during sucking can be performed in neonates with and without risk indicators for hearing loss, since the criteria of presence/absence are achieved in at least three frequencies studied.