PULSE OXIMETRY AND NEAR-INFRARED SPECTROSCOPY DURING LABOR - INTERPRETATION OF SUB PARTU MEASUREMENTS

Pulse oximetry and Near Infrared Spectroscopy (NIRS) are both optical methods which have been made applicable to the fetus during labour in order to improve the assessment of fetal oxygen supply and well being. 317 pulse oximetry measurements showed that postpartum pH, Base Exces s, PO2 are significantly negatively resp. pCO2 is positively correlate d to the time, during which arterial oxygen saturation (SpO2) is below a critical threshold of 30%. The 1' APGAR-score is also influenced by the duration of SpO2 values below 30%. Near Infrared Spectroscopy sem iquantitatively measures cerebral concentration changes of oxigenized, desoxigenized and total hemoglobin as well as that of cytochrome aa3 which is the key enzyme of the intracellular respiratory chain. In an analysis of 1350 contractions during 42 deliveries decelerations type 1 and 2 differed from normal CTG by a significantly deeper drop of oxi genized and total hemoglobin in the brain on top of contractions. Unti l the following contraction oxigenized and total hemoglobin remained d eeper below their original levels in case of decelerations type 2 than in case of normal CTG or type 1 decelerations. Simultaneous registrat ion of pulse oximetry and NIRS revealed an increase of cerebral blood volume in case of low arterial oxygen saturation (SpO2 < 30%) which ma y be interpreted as ''brain sparing effect''.