VARIATION IN CEREBRAL PERFUSION-PRESSURE WITH DIFFERENT HYPERTENSIVE STATES IN PREGNANCY

OBJECTIVE: Our purpose was to compare the estimated maternal cerebral perfusion pressure and an index of vascular resistance, the resistance area product, in nonpregnant women with hypertensive pregnant women. STUDY DESIGN: The maternal middle cerebral artery was evaluated by tra nscranial Doppler ultrasonography in 17 nonpregnant women, 17 pregnant normotensive patients, 20 pregnant patients with chronic hypertension , and 21 pregnant patients with pre-eclampsia (defined by The American College of Obstetricians and Gynecologists criteria) and cerebral blo od flow velocities were determined. We calculated estimated cerebral p erfusion pressure as [Estimated cerebral perfusion pressure = V mean/( V mean = V diastolic) (Mean blood pressure - Diastolic blood pressure) ] modified from Aaslid et al, 1986. Because the diameter of the vessel s could not be measured directly an index of resistance, the resistanc e area product, was calculated. Resistance area product = Mean blood p ressure/mean velocity (Evans et al, 1988). We calculated an index of c erebral blood flow (Cerebral blood flow index) = Estimated cerebral pe rfusion pressure/resistance area product. RESULTS: Women who were chro nically hypertensive and those with pre-eclampsia showed a significant increase in estimated cerebral perfusion pressure and resistance area product compared with nonpregnant and pregnant normotensive women. An estimate of cerebral blood flow (cerebral blood flow index) in nonpre gnant women showed that pregnancy resulted in a nonsignificant 18% inc rease in cerebral blood flow. CONCLUSIONS: Women with chronic hyperten sion and pre-eclampsia behave similarly by demonstrating significant i ncreases in cerebral perfusion pressure (estimated cerebral perfusion pressure) and cerebrovascular resistance (resistance area product) com pared with normotensive and nonpregnant women. Pregnant patients have a minimal increase in cerebral blood flow (18%).