[A Randomized Controlled Trial on the Effect of Earmuffs on Intermittent Hypoxia and Bradycardia in Preterm Infants]

Irregular breathing causing hypoxia and bradycardia is a common problem of preterm infants but its pathophysiology is incompletely understood. Agitation provoked by environmental noise may play a role. We wanted to know if earmuffs can at least halve the rate of intermittent hypoxia in premies.

In this randomized controlled trial 31 infants (14 male; median [min.-max.] birth weight and gestational age: 1 323 g [560-1 990] and 30(1/7) weeks [25(5/7)-33(0/7)]) had the effect of earmuffs on the frequency of pulse oximeter desaturations (SpO(2) <80%) and bradycardia events (<80 beats per minute) tested, documented via a standard home monitor. Infants were measured 2 h each with or without earmuffs; the sequence of intervention was randomised. Measurement conditions were kept constant while a noise meter recorded sound pressure levels at a 1 Hz sampling rate.

Median sound pressure level was 46.8 dB(A). In a pre-study, ear muffs yielded a sound reduction by 7.2 dB. 19 infants had a total of 474 desaturations. The median (25.-75. percentile) number of desaturations was 1 (1-10.5) without, and 1 (1-10) with earmuffs. The amount of infants with at least one desaturation was equal in both treatment protocols. Only 7 bradycardias occurred.

The earmuffs had, in a rather quiet environment, no effect on intermittent hypoxia in these infants.