Title: 635 Effect of Medications on Postpartum Cerebral Autoregulation in Preeclampsia with Severe Features
Abstract: Effective cerebral autoregulation (CA) typically maintains constant cerebral blood flow (CBF) within a mean arterial pressure (MAP) range of 50 – 150 mmHg in healthy adults. Impaired CA may contribute to increased risk of cerebrovascular complications in individuals with preeclampsia, due to preeclampsia-associated endothelial and autonomic dysfunction. We characterized CA curves in postpartum individuals treated for preeclampsia with severe features (PSF) and investigated the effects of recent treatment with intravenous magnesium (Mg) and antihypertensives (antiHTN). We prospectively recruited individuals with PSF and measured CA using transcranial doppler (TCD) and finger plethysmography within 1 week of delivery. We constructed polynomial S-curves and calculated Pearson correlation coefficients to describe CA in patients who did and did not receive Mg or antiHTN within 24 hours prior to TCD. A correlation coefficient of > 0.3 indicates high correlation between MAP and CBF velocity, suggesting impaired CA. We included 51 individuals with PSF, of whom 38 (75%) were treated with antiHTN, 3 (6%) were treated with Mg and 7 (14%) were treated with both antiHTN and Mg within the 24 hours prior to CA measurements. The CA S-curve in those recently treated with Mg appeared more linear with a less well-defined plateau, suggesting impaired CA. In the antiHTN group, the S-curve plateau was wider, compared with the non-antiHTN group (Figure). Our results suggest that commonly used treatments for preeclampsia affect CA. Specifically, CA may function more effectively in PSF patients receiving antiHTN in the first week postpartum, compared to those not receiving antiHTN. In contrast, we observed impaired CA in those recently treated with Mg. These findings may have implications for clinical blood pressure management in the postpartum period in patients with PSF. Future studies should explore specific antiHTN medications and their interactions with Mg to better characterize their effects on CA.