Intraventricular hemorrhage in extremely low birth weight infants: frequency and duration of impaired cerebrovascular reactivity.

Abstract

Extremely low birth weight (ELBW) infants are born with limited functional cerebral autoregulation. The postnatal transitional period is often marred by hemodynamic instability with highest risk for developing intraventricular hemorrhage (IVH). To determine if the frequency and duration of impaired cerebrovascular reactivity during the first 72 postnatal hours is associated with development of IVH in ELBW infants. Preterm infants of birth weight 401-1000 g were studied during the first 72 h of life. Continuous regional cerebral oximetry monitoring by near-infrared spectroscopy was used to calculate the tissue oxygenation-heart rate reactivity index (TOHRx), which was further segmented and categorized into distinct periods during which TOHRx remained exclusively positive or negative. Fifty-eight infants with a mean gestational age of 25.8 weeks and birth weight of 738 g were included. IVH was detected in 33% of neonates. Infants without IVH had predominantly negative TOHRx values whereas infants with high grade IVH (Grade 3-4) had predominantly positive TOHRx values. Infants who developed IVH had greater frequency of positive TOHRx measurements with more prolonged periods of positivity. ELBW infants who developed IVH were observed to have more frequent and longer periods of impaired cerebrovascular reactivity than those without IVH. We introduced a novel method to analyze cerebral autoregulation indices to capture magnitude and duration of impaired cerebrovascular reactivity. Distinct TOHRx patterns based on frequency and duration are identifiable and related to IVH severity. More frequent and longer periods of impaired cerebrovascular reactivity were observed in correspondence with increasing IVH severity. Our study highlights the potential for TOHRx to serve as an early indicator of cerebrovascular health. Our results support the importance of early monitoring of cerebrovascular reactivity in ELBW infants and may guide future development of interventions to reduce IVH incidence and severity.