382 Umbilical cord gas abnormalities in the presence of a nuchal cord

Abstract

The clinical significance of nuchal cord (NC) at the time of delivery is unclear. Studies have found that NC is associated with lower umbilical artery (UA) pH however, the mechanism for acidemia remains unclear. Since fetal hypercarbia proceeds respiratory acidosis, we tested the hypothesis that UA pCO2 is elevated in neonates with NC at time of delivery. This is a secondary analysis of a prospective cohort study of women with full term singleton pregnancies admitted in labor or for induction of labor at an institution with universal umbilical cord gas policy. We compared patients with NC at time of delivery to those without NC. Women were excluded if they did not have validated UA gases, had a major fetal anomaly, or had an intrauterine fetal demise. The primary outcome of the study was UA pCO2. Secondary outcomes were other components of UA gas and neonatal morbidity (neonatal death, seizures, hypoxic-ischemic encephalopathy, respiratory distress, hypothermia protocol, hypotension requiring pressors, and suspected sepsis). Baseline characteristics were compared utilizing chi-square or Fisher’s exact test or the Student’s. UA gas parameters were compared using Kruskall-Wallis test. Multivariable logistic regression was utilized to adjust for confounders. Of the 8580 study participants, 7608 had validated umbilical cord gases. The incidence of NC in the population was 24.15% (n=1837). UA pCO2 was higher in those with NC than without (58 mmHg [53, 64] v. 55 mmHg [50, 60], p<0.01), Table 1. There was a greater odds of hypercarbia in the NC group (pCO2 >65mmHg, aOR 2.01 (95% CI 1.76, 2.30), p<0.01), Table 2. Additionally, the NC group was more likely to be acidemic (pH < 7.1, p<0.01) and have a pO2 < 20 mmHg (aOR 1.57, (95%CI 1,40, 1.76) p<0.01). There was no difference in composite neonatal morbidity between the groups. NC is associated with an increased risk of hypercarbia and acidemia. However, this is not associated with increased risk of neonatal morbidity.View Large Image Figure ViewerDownload Hi-res image Download (PPT)