No abstract

IntroductIon: Very early preterm infants (VPIs) are exposed to unpredictable noise in neonatal intensive care units. Their ability to perceive moderate acoustic environmental changes has not been fully investigated. rESuLtS: Physiological values of the 598 isolated sound peaks (sPs) that were 5-10 and 10-15 dB slow-response a (dBa) above background noise levels and that occured during infants' sleep varied significantly, indicating that VPIs detect them. exposure to 10-15 dBa sPs during active sleep significantly increased mean heart rate and decreased mean respiratory rate and mean systemic and cerebral oxygen saturations relative to baseline. dIScuSSIon: VPIs are sensitive to changes in their nosocomial acoustic environment, with a minimal signal-to-noise ratio (sNR) threshold of 5-10 dBa. These acoustic changes can alter their well-being. MEtHodS: In this observational study, we evaluated their differential auditory sensitivity to sound-pressure level (sPL) increments below 70-75 dBa equivalent continuous level in their incubators. environmental (sPL and audio recording), physiological, cerebral, and behavioral data were prospectively collected over 10 h in 26 VPIs (Ga 28 (26-31) wk). sPs emerging from background noise levels were identified and newborns' arousal states at the time of sPs were determined. changes in parameters were compared over 5-s periods between baseline and the 40 s following the sPs depending on their sNR thresholds above background noise. V ery early preterm infants (VPIs) are exposed to nosocomial environmental stimuli that differ from the stimuli they encounter in utero. This new "naturalistic" milieu, especially loud noise, may interfere with their neurodevelopment and growth (1-4). This has led to specific recommendations for permissible noise criteria levels in the neonatal intensive care unit (NICU) (5-7). These recommendations were based primarily on the evaluation of the effects of noise on the developing auditory system and well-being of newborns. Most studies were experimental. Preterm newborns were exposed to 5 s of high artificial sound (8,9), including sound-pressure levels (SPLs) ranging from 80 to 100 dB (8) and to warbling tones of 100 dB (9). The most prevalent responses were an increase in heart rate (HR) (8,9) proportional to the SPL of the stimulus and a tendency toward a decrease in respiratory rate (RR) (9). Few studies have evaluated the impact of noise in the NICU on newborns' physiological stability. Unfortunately, some of these studies measured the effect of acoustic environments quite different from those in the contemporary NICU (10) or did not include preterm infants (11) or VPIs (10). Moreover, some yielded questionable results because of study design, nonreporting of background noise, and the absence of a well-defined study population (e.g., inclusion of newborns with a wide range of gestational age, GA) (12). Despite these limitations, these studies showed that a high level of environmental noise, >70-75 dB slow response A (dBA) equivalent continuous leve...

No abstract