The feasibility of spectrophotometric measurements of arterial oxygen saturation from the fetal scalp utilizing noninvasive skin-reflectance pulse oximetry.

In in-vivo animal experiments, the authors evaluated the feasibility of measuring arterial oxyhemoglobin saturation (SaO2) noninvasively during simulated delivery conditions with a skin-reflectance pulse oximeter sensor attached to the fetal scalp. The optical reflectance sensor consisted of three pairs of red and infrared light-emitting diodes and a concentric array of six identical photodiodes. Two prototype sensor assemblies, incorporating different means of attachment to the scalp, were evaluated. Each sensor was interfaced to a commercial Datascope ACCUSTAT transmittance pulse oximeter, adapted to perform as a reflectance pulse oximeter. This method, once successfully developed, could potentially be used in combination with other fetal monitoring techniques to elucidate the role of noninvasive pulse oximetry in reducing fetal morbidity and mortality.