Very preterm infants (VPI) are exposed to atypical and intense light levels in the Neonatal Intensive Care Unit. We conducted this prospective observational study to better understand very preterm infants’ responses to light level variations in their incubator and to evaluate the determinants of their reactivity.
Methods A total of 27 VPI were studied in their incubator during 10 h. We analysed their physiological responses: Heart rate (HR), respiratory rate (RR), systemic saturation (SaO2), regional cerebral saturation (rSO2) and fractional oxygen extraction (FOE) following variations (10 to 50 lux, > 50 lux above baseline) of their light level environment, measured concomitantly on the same time scale.
Results A total of 332 light level changes were identified and analysed. An increase in HR (+3.8 [-2.6;12.6] bpm), RR (+6 [-1.5;26] cycles/min) and rSO2 (+1.1 [-0.5;3.9]%) and a decrease of FOE (-1.4 [-4;-0.2]%) were observed when the light level increase more than 50 lux above the background light level (all p < 0.05). Below 50 lux variation, only RR (-8.4 cycles per minute [-28;-0.4]) and FOE (-0.7% [-0.6;0.2]) decreased (p < 0.05). Characteristics of the population did not seem to interfere with the VPI’s responses in contrast to the initial degree of illumination (the higher the ambient baseline light level, the higher the reactivity).
Conclusion VPI react to small variations of their environment’s illumination suggesting that they are able to detect light levels changes in the range recommended by the American Association of Paediatrics. The ambient baseline illumination can alter their responses.