The effect of neuromuscular blockade on oxygen consumption and blood gases in the fetal lamb.
In seven experiments on five chronically monitored fetal lambs (114 to 136 days' gestation), oxygen consumption, umbilical blood flow, and blood gases were measured before and after temporary paralysis of the fetus by the intravenous injection of gallamine. In two of the experiments, breathing movements were absent in the control, pre-gallamine period, and no change in oxygen consumption (VO2) was observed after the drug. In the other five experiments, breathing activity was present in the control period. After gallamine, Vo2 fell by 17%, as a result of a decline in umbilical oxygen extraction; there was no change in umbilical blood flow. In all experiments, umbilical arterial and venous Po2 values rose after paralysis, by 14% and 18%, respectively. The changes in Po2 values are probably secondary to the fall in fetal oxygen consumption. The data indicate that fetal skeletal muscle activity, in the form of breathing activity and perhaps gross body movements, contributes significantly to total fetal oxygen demands. Conversely, cessation of fetal activity in adverse situations, when oxygen supplies are limited, could aid in maximizing the delivery of the available oxygen to vital organs, such as the heart and brain.
D000818:Animals; D002245:Carbon Dioxide / Q000097:blood; D005260:Female; D005312:Fetal Blood / Q000187:drug effects*; D005318:Fetal Heart / Q000187:drug effects; D005323:Fetal Monitoring; D005333:Fetus / Q000187:drug effects / Q000502:physiology*; D005703:Gallamine Triethiodide / Q000494:pharmacology; D006339:Heart Rate / Q000187:drug effects; D009068:Movement / Q000187:drug effects; D009466:Neuromuscular Blocking Agents / Q000494:pharmacology*; D010100:Oxygen / Q000097:blood; D010101:Oxygen Consumption / Q000187:drug effects*; D010243:Paralysis / Q000139:chemically induced; D011247:Pregnancy; D012756:Sheep; D013997:Time Factors
D009466:Neuromuscular Blocking Agents; D002245:Carbon Dioxide; D005703:Gallamine Triethiodide; D010100:Oxygen