Effects of various concentrations of O2 and umbilical cord occlusion on fetal breathing and behavior

J Appl Physiol (1985). 1990 Apr;68(4):1597-604. doi: 10.1152/jappl.1990.68.4.1597.


To test the hypothesis that continuous fetal breathing could be induced by hyperoxemia alone or by hyperoxemia and umbilical cord occlusion, even in the absence of a rise in arterial PCO2 (PaCO2), we studied 18 chronically instrumented fetal sheep on 34 occasions using our window model (18). After a resting cycle (1 low-voltage followed by 1 high-voltage electrocortical activity epoch), the fetal lung was distended via an endotracheal tube using mean airway pressure of approximately cmH2O. Inspired N2, 17% O2, and 100% O2 were given to the fetus during one cycle each. While 100% O2 was given, the umbilical cord was occluded (balloon cuff).(ABSTRACT TRUNCATED AT 250 WORDS)

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Behavior, Animal / drug effects
  • Constriction
  • Fetus / physiology*
  • Gestational Age
  • High-Frequency Ventilation
  • Oxygen / administration & dosage
  • Oxygen / blood
  • Oxygen / pharmacology*
  • Respiration / drug effects*
  • Sheep
  • Umbilical Cord / physiology*


  • Oxygen