Studies of circulation and acid-base balance in pregnant sheep: I. The effect of aminophylline infusion.

The maternal and fetal effects of aminophylline on hemodynamics and acid-base and blood gas balances were evaluated by 11 infusions to four chronically catheterized sheep at 114-142 days' gestation. Maternal and fetal arterial blood samples were drawn for baseline determination at 15-minute intervals. Mean maternal and fetal pH levels and heart rates increased significantly. Respiratory alkalosis was indicated by a concomitant fall in mean maternal carbon dioxide pressure. We conclude that aminophylline infusion (5.6 mg/kg of body weight/15 min) to pregnant sheep may cause maternal and fetal tachycardia and alkalosis, with a possible increase in uterine blood flow, but no changes in fetal blood gas status or blood pressure.