Cerebral hemodynamics during arousals in preterm infants

Aims: To evaluate potential changes of cerebral blood volume related to arousals in preterm infants.

Methods: Polygraphic recordings were performed in 38 preterm infants (18 female, 20 male). The infants' gestational age at birth was 32.0±2.3 weeks, postconceptional age was 35.1±1.2 weeks and postnatal age at study entry was 24.3±2.9 days, birth weight was 1793±527g and actual weight at study entry was 2011±324g [mean (±standard deviation)]. Cerebral blood volume (CBV) was measured using near infrared spectroscopy. Arousals were scored due to the guidelines of the International Paediatric Work Group on Arousals and categorized as either cortical (CA) or subcortical arousals (SCA).

Results: Altogether, 122 arousals (66 CA, 56 SCA) were scored. According to sleep stage, 77 arousals were analyzed in active sleep, 23 in quiet sleep and 22 in intermediate sleep. Mean duration of arousals was 8.8±0.3 seconds. Cerebral blood volume, cerebral vascular oxygenation and the balance between oxygen delivery and oxygen consumption remained constant during arousals in preterm infants. This was demonstrated for both CA and SCA and was independent of sleep stage.

Conclusions: We found that arousals in preterm infants were not accompanied by any significant changes in CBV. Therefore the impact of physiological changes induced by arousals seems to be too small to result in significant CBV changes in preterm infants.