Craniofacial tissue oxygen saturation is associated with blood pH using an examiner's finger-mounted tissue oximetry in mice.

Although fetal scalp blood sampling is an examination to assess fetal acidosis during the intrapartum period, it has not been widely used by obstetricians because of its invasiveness. We have developed a small, portable oximetry with a sensor attached to the examiner's finger. Our previous report using this oximetry concluded that fetal head tissue oxygen saturation (StO 2 StO2 ) correlated with umbilical cord artery blood pH. We investigated whether the association between StO 2 StO2 and blood pH in mice could be validated using this oximetry. Eleven the Institute for Cancer Research (ICR) mice were measured using a near-infrared spectroscopy probe at the craniofacial site in a closed polyethylene bag while changing the oxygen concentration. A total of nine blood samples were collected and analyzed for pH. The StO 2 StO2 and tissue blood pH showed a strong positive correlation (r=0.90 r=0.90 and P=0.0009 P=0.0009 ). The StO 2 StO2 and total hemoglobin index also showed a positive correlation (r=0.84 r=0.84 and P=0.0049 P=0.0049 ). Thus, the results of the present study support those of our previous report on clinical cases and allow examiners to easily check the status of fetal acidosis. Fetal management using this oximetry might gain popularity with obstetricians in the near future.