Cerebral autoregulation in premature infants during the first 96 hours of life and relationship to adverse outcomes.

Objective: To test the hypothesis that impaired cerebral autoregulation (ICA) increases the susceptibility of premature infants to adverse outcomes, we determined the relationship of ICA and cerebral reactivity (CR) measured in the first 96 hours of life to the outcome of grade 3 or 4 intraventricular haemorrhage (IVH) and/or death within 1 month.

Setting: Single-centre level IV neonatal intensive care unit.

Patients: Neonates 24-29 weeks' gestation less than 12 hours old with invasive blood pressure monitoring.

Design: Cerebral saturations and mean arterial blood pressure were recorded every 30 s for 96 hours. For each 10 min epoch, the correlation coefficient (r) was calculated for mean arterial blood pressure versus cerebral saturations. The epoch was considered to have ICA if r>0.5 and CR if r<0.

Results: Sixty-one subjects were included. During the first 96 hours, ICA occurred 17.6% and CR occurred 41% of recorded time. In those without adverse outcomes, ICA decreased and CR increased by postnatal day (p<0.05). Adjusted for birth weight and gestational age, those with IVH and those who died spent more time with ICA and less time with CR (p<0.05) over the entire recording period. Those with IVH had 1.5-fold increase in time with ICA on day 2 (p=0.021), and decrease in time with CR on day 3 (p=0.036). Compared with survivors, non-survivors spent more time with ICA on days 3 and 4 (p<0.005), and less with CR on day 3 (p=0.032).

Conclusion: ICA and CR vary by postnatal day and these patterns are associated with adverse outcomes.