Trans-abdominal monitoring of fetal arterial blood oxygenation using pulseoximetry

Pulse oximetry (oxygen saturation monitoring) has markedly improved medical care in many fields, including anesthesiology, intensive care, and newborn intensive care. In obstetrics, fetal heart rate monitoring remains the sta ndard for intrapartum assessment of fetal well being. Fetal oxygen saturati on monitoring is a new technique currently under development. It is potenti ally superior to electronic fetal heart rate monitoring (cardiotocography) because it allows direct assessment of both the fetal oxygen status and fet al tissue perfusion. Here we present the analysis for determining the most optimal wavelength selection for pulse oximetry. The wavelengths we chose a s the most optimal are the first in the range of 670-720 nm and the second in the range of 825-925 nm. Further, we discuss the possible systematic err ors during our measurements and their contribution to the obtained saturati on results. We present feasibility studies for fetal pulse oximetry, monito red noninvasively through the maternal abdomen. Our preliminary experiments show that the fetal pulse can be discriminated from the maternal pulse and thus, in principle, the fetal arterial oxygen saturation can be obtained. We present the methodology for obtaining these data, and discuss the depend ence of our measurements on the fetal position with respect to the optode a ssembly. (C) 2000 Society of Photo-Optical Instrumentation Engineers. [S108 3-3668(00)00604-3].