The Ontogeny of Cerebrovascular Pressure Autoregulation in Premature Infants
Our objective was to quantify cerebrovascular autoregulation as a function of gestational age (GA) and across the phases of the cardiac cycle. One hundred eighty-six premature infants, with a GA range of 23–33 weeks, were monitored using umbilical artery catheters and transcranial Doppler insonation of middle cerebral artery flow velocity (FV) for 1-h sessions over the first week of life. Autoregulation was quantified as a moving correlation coefficient between systolic arterial blood pressure (ABP) and systolic FV (Sx); mean ABP and mean FV (Mx); diastolic ABP and diastolic FV (Dx). Autoregulation was compared across GAs for each aspect of the cardiac cycle. Systolic FV was pressure-passive in infants with the lowest GA, and Sx decreased with increased GA (r = −0.3; p < 0.001). By contrast, Dx was elevated in all subjects, and showed minimal change with increased GA (r = −0.06; p = 0.05). Multivariate analysis confirmed that GA (p < 0.001) and the “closing margin” (p < 0.01) were associated with Sx. Premature infants have low and almost always pressure-passive diastolic cerebral blood FV. Conversely, the regulation of systolic cerebral blood FV by autoregulation was manifested in this cohort at a GA of between 23 and 33 weeks.
KeywordsCerebrovascular pressure autoregulation Arterial blood pressure Closing margin Prematurity
Dr Kaiser was supported by the National Institutes of Health (1K23NS43185, RR20146, and 1R01NS060674) and the University of Arkansas for Medical Sciences (UAMS) Translational Research Institute (1UL1RR029884). The technical assistance of Natalie C. Sikes and Melanie J. Mason, and the support of the UAMS neonatologists, NICU nurses, respiratory therapists, and ultrasound technicians, are gratefully appreciated.
Conflict of Interest Statement
There is no potential conflict of interest, real or perceived.
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