Increased Blood Pressure Variability is Associated with More Time Spent Outside Personalized Limits of Cerebral Autoregulation in Postpartum Preeclampsia

Background: Preeclampsia is associated with altered cerebral autoregulation (CA) and cerebrovascular injury, including intracranial hemorrhage and cerebral oedema, which are major causes of postpartum maternal mortality. Impaired autoregulation increases susceptibility to cerebral hypoperfusion or hyperperfusion. Preeclampsia is also associated with sympathetic hyperreactivity resulting in increased blood pressure variability (BPV). We investigated whether higher BPV in postpartum patients with preeclampsia correlated with more time spent outside the personalized limits of CA. Methods: This is a preliminary analysis of observational data collected through the Protecting Maternal Brains from Injury and Stroke study (ClinicalTrials.gov identifier: NCT05726279), an ongoing, nonrandomized, nonmasked pilot clinical trial that includes observational and interventional arms. Eligible patients were admitted for treatment of severe preeclampsia within 6 weeks after delivery. We continuously measured mean arterial blood pressure (MAP) using finger plethysmography and regional oxygen saturation with near infrared spectroscopy for up to 24 h. We calculated BPV as the standard deviation of MAP over the monitoring period. We correlated change in regional oxygen saturation with change in MAP to generate individual autoregulatory curves. The upper and lower MAPs, where curves crossed a correlation coefficient of ≥ 0.3, were considered limits of CA. We computed a Pearson correlation (R value) between BPV and percentage of time outside limits of CA. Results: We analyzed data from 19 participants, all of whom were in the observational arm of the trial. The median monitoring time was 16.0 h (interquartile range 5.7–19.5). Higher BPV correlated with more time spent outside limits of CA (R = 0.71, p < 0.001), including above the upper limit (R = 0.56, p = 0.012) but not below the lower limit (R = 0.31, p = 0.200). Conclusions: Higher BPV in postpartum patients with preeclampsia correlated with more time outside the personalized limits of CA. High BPV may identify patients at higher cerebrovascular risk. Future studies should correlate BPV with maternal outcomes in preeclampsia.