Effect of hyperventilation on cerebral blood flow velocity in preeclampticpregnancies: Is there evidence for an altered cerebral vasoreactivity?

The purpose of this study was to investigate cerebral arteriolar vasoreacti vity function in preeclampsia. Preeclamptic (n = 26) and healthy pregnant ( n = 22) women underwent transcranial Doppler sonography of the middle cereb ral artery at rest and after 60 seconds of hyperventilation (HV). Systolic, diastolic, and mean blood Row velocities were recorded. The percentage cha nge of the blood Row velocities after HV was calculated. Mean blood flow ve locity of the middle cerebral artery was higher in preeclamptic women as co mpared with healthy pregnant women. No difference could be detected in perc entage change of middle cerebral artery blood Row velocities after HV betwe en the two groups. There is no evidence of a small-vessel vasoconstriction among preeclamptic patients. The role of vasoconstriction of the large cere bral arteries and vasodilation of the resistance arterioles, as well as a c ombination of these 2 pathomechanisms, in determining cerebral blood flow i n preeclampsia and eclampsia should be investigated in further studies.