[Cerebral blood flow dynamics in fetus].

In order to obtain quantitative data concerning the changes of fetal cerebral blood flow occurring in relation to hypoxia and acidemia, we evaluated correlations between fetal blood gases and blood flow velocity waveforms in fetuses. A total of 24 Doppler examinations were carried out to investigate the waveforms of middle cerebral and umbilical arteries in 17 intrauterine growth retardation (IUGR) fetuses. Within 24 hours after blood flow measurements, cordocentesis was performed and umbilical venous blood gases and pH were determined. There was a significant positive correlation between the gestationally adjusted resistance index value [delta SD (RI)] for middle cerebral artery and PO2 or pH, while a negative correlation was noted between the middle cerebral artery delta SD (RI) and PCO2. The umbilical artery delta SD (RI) and pH showed a negative correlation, but there was no correlation between the umbilical artery delta SD (RI) and PCO2 or PCO2. In the presence of partly compensated respiratory acidosis, the delta SD (RI) for middle cerebral artery was still high, while that for umbilical artery did not increase although PO2 was reduced. These findings suggest that blood flow changes in fetal middle cerebral and umbilical arteries are different in IUGR. Middle cerebral artery blood flow may respond directly to changes in PO2. Furthermore, fetal acid-base disorders may modify the relationship between blood flow changes and fetal PCO2.