title: Umbilical blood flow velocity waveforms in different maternal positions and with epidural analgesia.
abstract: Umbilical blood flow velocity waves were measured in the fetuses of healthy parturients in early active labor to assess the influence of different maternal positions (N = 16) and of epidural analgesia (N = 16). The ratio of systolic peak to diastolic trough (S/D) of the umbilical blood flow velocity wave is reflective of vascular resistance distal to the point of measurement on the fetal side of the placenta. Umbilical blood flow velocity wave S/D ratios were significantly higher in the supine than in either lateral position indicating that umbilical artery vascular resistance is increased when the mother lies supine. After epidural blockade, the S/D ratios were unchanged in three and lowered to varying degrees in 13 parturients indicating that this method of pain relief beneficially affects umbilical artery vascular resistance.
mesh_terms: D000767:Anesthesia, Epidural; D000773:Anesthesia, Obstetrical; D001783:Blood Flow Velocity; D005260:Female; D005312:Fetal Blood / Q000502:physiology*; D005323:Fetal Monitoring / Q000379:methods; D006801:Humans; D007743:Labor, Obstetric; D008431:Maternal-Fetal Exchange; D011187:Posture; D011247:Pregnancy; D014465:Ultrasonics; D014463:Ultrasonography; D014469:Umbilical Arteries / Q000502:physiology; D014655:Vascular Resistance