Variations in optical absorption spectra of adult and fetal hemoglobins and its effect on pulse oximetry.

One of the concerns clinicians have relates to the interpretation of noninvasive pulse oximeters in newborns since at birth high levels of fetal hemoglobin (HbF) is present in the blood. Accurate in vivo studies of pulse oximeters in infants with predominantly HbF cannot be easily performed. Therefore, the objective of this in vitro study was to determine whether the presence of high levels of HbF in the blood can significantly affect the accuracy of noninvasive pulse oximeters. It is evident from our results that there is no perceptible difference in the 650-1000 nm wavelength region, which is commonly used in pulse oximetry, between the optical absorption spectra of hemolyzed whole adult and fetal blood. Our observations are in good agreement with in vivo studies published by other investigators showing considerable correlations between SpO2 measured by a pulse oximeter and SaO2 values analyzed in vitro by an IL 282 CO-Oximeter.