title: Umbilical arterial-venous blood gas difference: a novel expression of placental respiratory function.
abstract: We applied the concept of umbilical arterial and venous (A-V) blood gas difference in evaluating placental respiratory function to establish normative values for these relationships. Umbilical A-V cord blood gas samples were obtained in standardized fashion in uncomplicated singleton pregnancies. A-V pO (2) and A-V pCO (2) differences were related to obstetric factors, placental weight, and gestational age. Mean absolute differences in uncomplicated vaginal deliveries between umbilical artery and umbilical vein were: pO (2) 11.4 +/- 7.0 mm Hg and pCO (2) 11.9 +/- 6.8 mm Hg. Values in nonlabor cesarean section cases did not differ significantly from those of cases delivered vaginally. A-V pO (2) differences did not vary significantly across gestation (Pearson's R = 0.05, P = 0.43) and did not correlate with birth weight ( R = 0.06, P = 0.30). A-V pCO (2) differences showed increases with gestational age ( R = 0.15, P = 0.008) and with birth weight ( R = 0.18, P = 0.002). Results similar to those of women delivered vaginally were seen in nonlabor cesarean deliveries. Duration of labor did not impact the A-V blood gas relationship. Umbilical A-V oxygen differences reflect placental respiratory function independent of gestational age, birth weight, duration of labor, and mode of delivery. They are easy to collect and represent a potentially valuable resource for assessment of placental function.
authors.affiliation: Department of Obstetrics, University of Maryland School of Medicine, Baltimore, USA. koji.matsuo@gmail.com
authors.forename: Koji
authors.initials: K
authors.lastname: Matsuo
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Malinow
authors.forename: Chris R
authors.initials: CR
authors.lastname: Harman
authors.forename: Ahmet A
authors.initials: AA
authors.lastname: Baschat
mesh_terms: D000328:Adult; D001784:Blood Gas Analysis; D002245:Carbon Dioxide / Q000097:blood; D005260:Female; D005312:Fetal Blood / Q000737:chemistry*; D005865:Gestational Age; D006801:Humans; D010100:Oxygen / Q000097:blood; D010920:Placenta / Q000502:physiology*; D012189:Retrospective Studies; D014469:Umbilical Arteries / Q000737:chemistry*; D014471:Umbilical Veins / Q000737:chemistry*
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen