A prospective study was undertaken using a range-gated, pulsed Doppler velocimeter to study flowpressure relationships in the anterior cerebral artery. Serial velocity and pressure studies were performed with each infant serving as his or her own control. The hypothesis tested was that ill preterm infants sustaining subependymal/intraventricular hemorrhage would have absent autoregulation. The hypothesis has been tested in 88 studies on 32 infants. Of 32 infants studied, 15 were judged to be pressure passive; nine of these children bled. The other 17 infants were not pressure passive; eight of these children bled ( P .05). From these studies, it may be concluded that the pressure passive state is not the final common link in the genesis of subependymal/intravertricular hemorrhage. Pulsed Doppler ultrasound may provide an extremely useful noninvasive technique for studing both the arterial and venous sides of the cerebral circulation.
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