Relationship between cerebrovascular dysautoregulation and arterial blood pressure in the premature infant

Objective:To evaluate cerebrovascular autoregulation as a function of arterial blood pressure (ABP) in the critically ill, premature infant.Study Design:A prospective observational pilot study was conducted in two tertiary care Neonatal Intensive-Care Units. Premature infants (n23, 30 weeks estimated gestational age with invasive ABP monitoring) were enrolled and received routine care while undergoing continuous autoregulation monitoring, using the cerebral oximetry index (COx). The COx is a moving, linear correlation coefficient between cortical reflectance oximetry and ABP. COx values were stratified as a function of ABP for individual subject recordings and for the cohort.Result:The mean duration of autoregulation monitoring was 3.2 days (median: 2.97, range: 0.61-3.99). A total of 10 of 23 (43%) developed intraventricular hemorrhage and 1 of 23 (4%) developed periventricular leukomalacia by head ultrasound. No association was found between neurologic injury and percentage of the monitoring periods with autoregulation impairment (defined as COx0.5). Lower ABP was associated with dysautoregulation (higher COx values, P0.01). The percentage of time with impaired autoregulation was greater with lower ABP (P0.013, Spearman r0.51).Conclusion:All infants studied had periods with intact and periods with impaired cerebrovascular autoregulation, measured with the COx. Low ABP was associated with impaired autoregulation.