Relationship between maternal arterial and foetal cord carbon dioxide tension and neonatal outcome in critically ill pregnant women at delivery

Background and Aims: No studies have evaluated the relationship between maternal arterial partial pressure of carbon dioxide (mPaCO 2 ) and umbilical cord venous partial pressure of carbon dioxide (PCO 2 ) in critically ill pregnant women at delivery. Based on the studies in healthy pregnant women, an mPaCO 2 target of ≤50 mmHg is a suggested threshold during mechanical ventilation in critically ill parturients. We evaluated the relationship between mPaCO 2 and neonatal cord gases in critically ill parturients at delivery as the primary objective. The relationship between mPaCO 2 and APGAR scores at delivery was also analysed as a secondary objective. Methods: Maternal and neonatal cord gas data at delivery and APGAR scores were obtained by a retrospective chart review of 25 consecutive parturients with severe respiratory compromise who were delivered during mechanical ventilation. Linear regression was used to assess the relationship between mPaCO 2 and umbilical artery and vein PCO 2 and between mPaCO 2 and APGAR scores at 1 and 5 min. Results: There was a positive correlation between mPaCO 2 and neonatal cord venous PCO 2 ( P = 0.013). Foetal venous PCO 2 exceeded predelivery mPaCO 2 by 17.5 (7.5) mmHg. There was an inverse relationship between mPaCO 2 and neonatal APGAR scores at 1 and 5 min ( P = 0.006 and P = 0.007, respectively). Conclusion: Foetal cord venous PCO 2 can be predicted if mPaCO 2 values are known. Unlike in healthy pregnant women, there was an inverse relationship between rising mPaCO 2 levels and neonatal APGAR scores in critically ill pregnant women who had several associated compounding factors.