Cerebral Autoregulation Dynamics in Premature Newborns

Publisher Website
Google Scholar
Abstract
Background and Purpose Autoregulation of cerebral blood flow is easily disrupted, and loss of this normal physiological reflex may worsen the neurological outcome for patients undergoing intensive care. We studied the response of cerebral blood flow velocity to changes in mean arterial blood pressure. Methods Cerebral blood flow velocity was measured with Doppler ultrasonography in one middle cerebral artery for 5-minute periods in 33 babies of gestational age Results Whereas the regression method allowed the classification of only 51 of 106 records, the coherent average method classified 101 of 106 (95.3%) of the records available. For 51 records that were classified by both methods, there was agreement in 42 cases (82.3%). The coherent average of all records classified as having an active autoregulation showed cerebral blood flow velocity returning to baseline much earlier than blood pressure, suggesting that autoregulation was taking place within 1 to 2 seconds. This pattern was absent in records in which autoregulation was classified as absent. Conclusions Computerized coherent averaging of the cerebral blood flow velocity response to spontaneous blood pressure transients offers a promising new method for noninvasive bedside assessment of autoregulation in patients undergoing intensive care. The time course for autoregulation, when present, is in agreement with that reported in adults.