Application of Near-Infrared Spectroscopy for the Evaluation of Placental Oxygenation

Abstract

Aims: As the utero-placental circulation have major impact on the fetus, and the placental function can be criti- cal for determining fetal conditions, the placental oxygenation status was investigated. Methods: Near-infrared spectroscopy (NIRS) is a non-invasive technique used for the evaluation of regional tissue oxy- genation in a number of organs. The trans-abdominal NIRS was developed as a non-invasive technique for monitoring placental oxygenation, which was evaluated by the ratio of oxygenated hemoglobin to total hemoglobin (%) (tissue oxy- genation index ,TOI) values. The near-infrared light was confirmed to reach the placenta using the NIRS probe with an in- ter-optode distance of 4.5 cm and the NIRO apparatus (Hamamatsu Photonics, Hamamatsu, Japan). Results: Placental TOI values in pregnant women with pregnancy-induced hypertension and intrauterine fetal growth re- striction were significantly higher than those of pregnant women without complications, although there were no differ- ences of TOI values between the women with threatened preterm delivery and those without complications. Conclusion: Non-invasive monitoring of placental tissue oxygenation assessed by NIRS for the study of utero-placental function may have a high potential for clinical application, particularly in prenatal management.