Term Newborns with relatively low Tissue Oxygen Saturation Levels soon after Birth are predisposed to Neonatal Respiratory Disorders in Low-risk, Elective Cesarean Sections.

Background: Neonatal respiratory disorders, such as transient tachypnea of the newborn and respiratory distress syndrome, occur frequently after an elective cesarean delivery. Although conventional pulse oximetry is recommended for neonatal resuscitation, it often requires several minutes after birth to obtain a reliable signal. In a previous study, we used novel tissue oximetry equipment to detect fetal and neonatal early tissue oxygen saturation (StO2) before and immediately after vaginal delivery. Therefore, we hypothesized that low neonatal StO2 levels measured by tissue oximetry may lead to neonatal respiratory disorder after a scheduled cesarean delivery. Hence, this study aimed to evaluate the StO2 levels measured by tissue oximetry in neonates with or without a respiratory disorder subsequently diagnosed after an elective cesarean delivery. Materials and methods: We enrolled 78 pregnant Japanese women who underwent an elective cesarean section at ≥36 weeks' gestation. After combined spinal and epidural anesthesia were administered to the mother, fetal StO2 levels were measured by tissue oximetry using an examiner's finger-mounted sensor during a pelvic examination immediately before the cesarean section. We measured the neonatal StO2 levels at 1, 3, and 5 minutes after birth and retrospectively compared the fetal and neonatal StO2 levels with the incidence of subsequent diagnoses of neonatal respiratory disorders. Results: The data of StO2 levels in 35 neonates were collected. Seven neonates (respiratory disorder (RD) group) were subsequently diagnosed with respiratory disorders by neonatal medicine specialists, whereas the 28 remaining neonates (NR group) were not. The median fetal StO2 (interquartile range) of the RD and NR groups was 52.0% (41.8%-60.8%) and 42.5% (39.0%-52.5%), respectively (P = 0.12). The median neonatal StO2 (interquartile range) of the RD and NR groups at 1 minute after birth was 42.0% (39.0%-44.0%) and 46.0% (42.0%-49.0%), respectively (P = 0.091). At 3 minutes after birth, the median neonatal StO2 (interquartile range) of the RD and NR groups was 41.0% (39.0%-46.0%) and 47.0% (44.3%-53.5%), respectively (P = 0.004). Finally, at 5 minutes after birth, the median neonatal StO2 (interquartile range) of the RD and NR groups was 45.0% (44.0%-52.0%) and 54.0% (49.3%-57.0%), respectively (P = 0.007). Conclusions: The StO2 values in the RD group were lower than those in the NR group at 3 and 5 minutes after birth, suggesting that neonates with low StO2 levels soon after birth may be predisposed to clinically diagnosed neonatal respiratory disorders.