The ontogeny of cerebrovascular pressure autoregulation in premature infants

Objective: To quantify cerebrovascular autoregulation as a function of gestational age (GA) and across the phases of the cardiac cycle. Study design: The present study is a hypothesis-generating re-analysis of previously published data. Premature infants ( n =179) with a GA range of 23 to 33 weeks were monitored with umbilical artery catheters and transcranial Doppler insonation of the middle cerebral artery for 1-h sessions over the first week of life. Autoregulation was quantified by three methods, as a moving correlation coefficient between: (1) systolic arterial blood pressure (ABP) and systolic cerebral blood flow (CBF) velocity (Sx); (2) mean ABP and mean CBF velocity (Mx); and (3) diastolic ABP and diastolic CBF velocity (Dx). Comparisons of individual and cohort cerebrovascular pressure autoregulation were made across GA for each aspect of the cardiac cycle. Results: Systolic, mean and diastolic ABP increased with GA ( r =0.3, 0.4 and 0.4; P