Application of Near-Infrared Spectroscopy During Fetal Cardiac Surgery

BackgroundNear-infrared spectroscopy (NIRS) has been shown to provide reliable noninvasive monitoring of regional oxygenation in a variety of clinical settings. We set out to test its feasibility as a monitor of fetal and placental oxygenation during fetal cardiac surgery.Materials and MethodsSix ovine fetuses from 98–110 ds gestation were placed on fetal bypass for 30 min and followed post-bypass for 2 h. A NIRS probe (MI INVOS 5100B; Somanetics, Troy, MI) was placed on the pregnant uterine horn during and after fetal surgery. NIRS values were compared with blood gas values obtained by direct sampling from umbilical circulation.ResultsNIRS values positively correlated with umbilical venous oxygen saturation (R2 = 0.891, P < 0.01) and partial oxygen pressure values (R2 = 0.810, P < 0.01). NIRS values also correlated to a lesser extent with umbilical venous pH and pCO2, and fetal arterial pH, pO2, and oxygen saturation.ConclusionsThis is the first report of application of NIRS in the setting of fetal surgery. NIRS permits noninvasive assessment of placental oxygen saturation and pO2. This technology is a simple and useful tool for real-time monitoring of oxygen delivery to the fetus during maternal–fetal cardiac interventions and of overall well-being of the fetal-placental unit.