CEREBRAL BLOOD-FLOW VELOCITY IN NORMAL, FULL-TERM NEWBORNS IS NOT RELATED TO DUCTAL CLOSURE

Objective. - To correlate changes in blood flow velocity in the anterior and middle cerebral arteries with closure of the ductus arteriosus in normal, full-term newborns during the first 2 days following delivery. Design. - Survey. Setting. - Large community hospital. Participants. - Twenty-three normal, full-term neonates. Selection Procedures. - Volunteer sample. Interventions. - None. Measurements and Results. - We measured blood flow velocity in the anterior and middle cerebral arteries, cardiac output, and patency of the ductus arteriosus using pulsed Doppler, M-mode, and real-time ultrasound. The initial examination was performed at (mean +/- SD) 7.6 +/- 2 hours and the second examination was performed at 30 +/- 3 hours. The systolic, diastolic, and mean blood flow velocity in the anterior and middle cerebral arteries increased significantly from day 1 to day 2. Cardiac output did not change significantly (252 +/- 49 vs 279 +/- 69 cm3/kg per minute). Thirteen newborns on day 1, but only two newborns on day 2, had echocardiographic evidence of a patent ductus arteriosus. Newborns whose ductus was already closed on day 1 had similar increases in blood flow velocity in the anterior and middle cerebral arteries from day 1 to day 2 compared with newborns whose ductus had closed from day 1 to day 2. Conclusion. - The normal increase in blood flow velocity in the anterior and middle cerebral arteries in the first 2 days following delivery is not related to changes in cardiac output or ductal closure.