FETAL CEREBRAL OXYGENATION MEASURED BY NEAR-INFRARED SPECTROSCOPY SHORTLY BEFORE BIRTH AND ACID-BASE STATUS AT BIRTH

Objective: To test the hypothesis that the mean cerebral oxygen satura tion measured by near-infrared spectroscopy shortly before delivery co rrelates with fetal acid-base status in umbilical cord blood. Methods: A specially designed optical probe was inserted through the dilated c ervix and placed against the fetal head during labor in 41 women. Chan ges in cerebral oxyhemoglobin and deoxyhemoglobin concentrations were measured continuously, and the mean cerebral oxygen saturation was det ermined over a 10-minute period within 30 minutes of delivery. Umbilic al arterial and venous blood acid-base status was assessed immediately after birth and then correlated to the values for mean cerebral satur ation. Results: Values for mean cerebral oxygen saturation could be de termined in 33 fetuses. Umbilical cord artery and vein pH (r = 0.82 an d r = 0.79, respectively) showed significant positive correlations (P < .001), whereas base deficit (r = -0.73 and r = -0.71) and carbon dio xide pressure (r = -0.68 and r = -0.63) showed significant negative co rrelations (P < .001) with mean cerebral oxygen saturation measured wi thin 30 minutes before birth. There was also a significant positive co rrelation between umbilical vein oxygen pressure and mean cerebral oxy gen saturation (r = 0.51, P < .01). Conclusion: Fetal umbilical blood gas and acid-base status at birth showed significant correlations with mean cerebral oxygen saturation measured shortly before delivery. Low values for saturation were related to both respiratory and metabolic acidemia.