Doppler ultrasonographic evidence of intrapartum brain-sparing effect in fetuses with low oxygen saturation according to pulse oximetry.

Objective: This study was undertaken to verify by means of Doppler ultrasonography and simultaneous fetal pulse oximetry the redistribution of fetal blood flow in favor of the brain during intrapartum hypoxemia.
Study Design: During labor 11 term fetuses with abnormal heart rate patterns and arterial oxygen saturation <30% and 14 control term fetuses with normal oxygen saturation were simultaneously monitored by pulse oximetry and Doppler ultrasonography. The results were compared with the Student t test.
Results: The blood flow velocity in the middle cerebral artery was significantly higher in the presence of reduced oxygen saturation, implying lower pulsatility and resistance indices (P <.001). The reduction of blood flow in the umbilical artery was not significant (P =.61).
Conclusion: Simultaneous intrapartum pulse oximetry and Doppler ultrasonography proved that reduced arterial oxygen saturation (<30%) is associated with profound changes in fetal hemodynamics and could be tolerated for only a limited period, which should be the subject of further studies.