Changes in cerebral perfusion pressure in puerperal women with preeclampsia

Abstract

Objective: To determine the variation in the estimated maternal cerebral perfusion and cerebrovascular resistance (the resistance area product) in the puerperium. Methods: The maternal middle cerebral artery was evaluated by transcranial Doppler ultrasound in ten women 2 days before labor, in 21 women in early labor and at 24 and 48 hours postpartum, and in 6 women at 1 week postpartum. Cerebral blood flow velocities were determined. Women were diagnosed initially with mild preeclampsia. Estimated cerebral perfusion pressure was V mean/[V mean − V diastolic] [BP mean − BP diastolic]. Because the diameter of the vessels could not be measured directly, an index of resistance was calculated: the resistance area product = BP mean/velocity mean. We calculated an index of cerebral blood flow to be estimated cerebral perfusion pressure divided by resistance area product. Our study had a power of 80% to detect a 16-cm/second increase in middle cerebral blood flow velocity. Results: Estimated maternal cerebral perfusion was maintained for up to 1 week postpartum. Cerebrovascular resistance did not change in the puerperium. Cerebral blood flow index (±standard deviation) was significantly increased at 1 week postpartum compared with early labor levels (28.3 ± 6.9 versus 46.7 ± 15.6, respectively) ( P < .05). Conclusion: Cerebral blood flow 1 week postpartum increased significantly over early labor values. These persistent changes in the cerebral vasculature might put patients at risk for seizures up to 1 week postpartum.