title: Parameters of fetal pulmonary vascular health: baseline trends and response to maternal hyperoxia in the second and third trimesters.
abstract: OBJECTIVE
  Several parameters, including branch pulmonary artery (PA) diameter and Doppler-derived PA acceleration-to-ejection time ratio (AT/ET), peak late-systolic/early-diastolic reversed flow (PEDRF) and pulsatility index (PI) response to maternal hyperoxia, have been used to investigate fetal pulmonary health. Lower AT/ET, increased PEDRF and lack of PI response to hyperoxia have been observed in fetuses with severe lung hypoplasia and are considered markers of pulmonary vascular resistance. We sought to further define the evolution of PA diameter and Doppler parameters and their response to maternal hyperoxia in healthy fetuses.
  
  
  METHODS
  Fifty-four prospectively recruited women with healthy pregnancy underwent fetal echocardiography from 18-36 weeks of gestation. After baseline branch PA diameter and Doppler assessment, oxygen (8-10 L/min) was administered by non-reservoir facemask for 10 min and PA Doppler parameters were reassessed.
  
  
  RESULTS
  Branch PA diameters and AT/ET increased linearly with gestational age, while PEDRF increased quadratically (P < 0.001 for all) and PA-PI did not change. In response to maternal hyperoxia, although most fetuses demonstrated a significant decrease in PI for both branch PAs (right PA, P = 0.025; left PA, P = 0.040) ≥ 30 weeks, significant variability was observed in PI response with 31% of cases demonstrating either no response or a slight decrease. No other parameter demonstrated a measurable change in response to maternal hyperoxia.
  
  
  CONCLUSIONS
  From the mid-trimester, fetal branch PA diameters and AT/ET increase linearly and PEDRF increases quadratically, whereas PI remains unchanged. Although maternal hyperoxia triggers a significant decrease in PA-PI after 30 weeks, variability in this response may reduce its utility in clinical practice. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.
authors.affiliation: Fetal and Neonatal Cardiology Program, Department of Pediatrics, Division of Cardiology, Women's & Children's Health Research Institute and Mazankowski Heart Institute, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Y
authors.initials: Y
authors.lastname: Yamamoto
authors.affiliation: Fetal and Neonatal Cardiology Program, Department of Pediatrics, Division of Cardiology, Women's & Children's Health Research Institute and Mazankowski Heart Institute, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: A
authors.initials: A
authors.lastname: Hirose
authors.affiliation: Fetal and Neonatal Cardiology Program, Department of Pediatrics, Division of Cardiology, Women's & Children's Health Research Institute and Mazankowski Heart Institute, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: L
authors.initials: L
authors.lastname: Howley
authors.affiliation: Fetal and Neonatal Cardiology Program, Department of Pediatrics, Division of Cardiology, Women's & Children's Health Research Institute and Mazankowski Heart Institute, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: W
authors.initials: W
authors.lastname: Savard
authors.affiliation: Department of Obstetrics and Gynecology, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: V
authors.initials: V
authors.lastname: Jain
authors.affiliation: Fetal and Neonatal Cardiology Program, Department of Pediatrics, Division of Cardiology, Women's & Children's Health Research Institute and Mazankowski Heart Institute, University of Alberta, Edmonton, Alberta, Canada.|Department of Obstetrics and Gynecology, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: L K
authors.initials: LK
authors.lastname: Hornberger
mesh_terms: D000328:Adult; D015150:Echocardiography, Doppler / Q000379:methods; D005260:Female; D005333:Fetus / Q000196:embryology / Q000503:physiopathology; D005865:Gestational Age; D064368:Healthy Volunteers; D006801:Humans; D018496:Hyperoxia / Q000000981:diagnostic imaging / Q000196:embryology / Q000503:physiopathology*; D011247:Pregnancy; D011249:Pregnancy Complications, Cardiovascular / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology*; D011262:Pregnancy Trimester, Second / Q000502:physiology*; D011263:Pregnancy Trimester, Third / Q000502:physiology*; D011446:Prospective Studies; D011651:Pulmonary Artery / Q000000981:diagnostic imaging / Q000196:embryology / Q000503:physiopathology*; D016216:Ultrasonography, Prenatal / Q000379:methods; D014655:Vascular Resistance / Q000502:physiology
keywords: Doppler; lung growth; maternal hyperoxia; pulmonary artery