Abstract 55: Cerebral Autoregulatory Curves in Postpartum Individuals With and Without Preeclampsia

Abstract

Introduction: Risk of maternal stroke is higher in patients with preeclampsia (PEC), with the highest risk seen in those with chronic hypertension with superimposed preeclampsia (siPEC). Most strokes occur postpartum. Changes in cerebral autoregulation (CA) could contribute to elevated postpartum stroke risk. We describe CA curves in postpartum patients with no hypertension, PEC and siPEC. Methods: We prospectively recruited postpartum patients with and without PEC and measured 10-minute continuous mean arterial pressure (MAP) and cerebral blood flow velocity (CBFV) with finger plethysmography and transcranial Doppler within 1 week of delivery. We generated polynomial S-curves to derive limits of CA, CA plateaus (defined as slope < 0.15), and mean and minimum slopes between CA limits. We calculated Pearson correlation coefficients (Mx) between normalized MAP and CBVF; Mx > 0.3 indicates high MAP-CBFV correlation, suggesting impaired CA. Results: CA curves were produced from 71 patients (28% normotensive, 42% PEC, 30% siPEC). Group means for MAP were higher in those with PEC and siPEC (normotensive 72 mmHg, PEC 88, siPEC 87 [p=0.001]). CA was preserved in all groups, with Mx nadirs below 0.3 (Figure). The normotensive group demonstrated a wide, flat plateau in the S-curve (minimum slope 0.02). In the PEC group, we observed a narrower and slightly steeper autoregulatory plateau (minimum slope 0.05). The siPEC group displayed the narrowest and steepest plateau (minimum slope 0.15). Conclusion: In conclusion, in our sample of postpartum patients with normotension, PEC and siPEC, we observed a gradient in CA plateau range and slope. Compared with the normotensive group, the PEC and siPEC groups had progressively narrower and steeper CA plateaus, suggesting a more limited CA range and diminished CA efficacy. Future studies should investigate whether sustained MAP outside CA limits contributes to adverse maternal outcomes, particularly in those with siPEC.