Effect of nicotine sulfate on the hemodynamics and acid base balance of chronically instrumented pregnant sheep

Abstract

The maternal and fetal effects of nicotine sulfate (15 mg/10 min) upon the hemodynamics and acid-base balance were evaluated in 9 intravenous infusions to 5 chronically instrumented pregnant sheep preparations of 97-117 days of gestation. Experiments were performed from 2 to 11 days postoperatively. Maternal (n = 9) and fetal (n = 8) arterial blood samples were simultaneously drawn at 0, 10, 30 and 60 min from the start of infusion. Maternal arterial pH transiently increased from 7.47 +/- 0.01 to 7.51 +/- 0.01 units (p less than 0.01) at 10 min. Maternal arterial base deficit simultaneously fell from -2.41 +/- 1.3 to -0.3 +/- 1.1 mEq/l (p less than 0.01). Maternal blood pressure increased during the infusion from 90.8 +/- 3.8 to 118.7 +/- 5.6 mm Hg (p less than 0.005) at 10 min, remaining elevated at 30 min. Maternal heart rate transiently rose from 97 +/- 6 to 107 +/- 6 beats/min (p less than 0.01) at 1 min, returning to control levels by 10 min. 10 min into infusions a decrease in uterine blood flow was recorded as 28.7 +/- 9.0% (p less than 0.02) below preinfusion values. A gradual recovery to -8.5 +/- 2.9% ws observed (p less than 0.025) at 60 min. Fetal blood pressure also decreased transiently from 52.6 +/- 2.3 to 50.2 +/- 2.0 mm Hg (p less than 0.05) during the infusion. Fetal arterial PCO2 fell from 41.1 +/- 3.1 to 37.2 +/- 2.5 mm Hg (p less than 0.05) at 10 min. A transient increase was seen in fetal heart rate from 197 +/- 12 to 215 +/- 15 beats/min (p less than 0.05) at 30 min. No significant changes were seen in fetal arterial PO2 and O2% saturation of hemoglobin. All maternal and fetal values except uterine blood flow returned to preinfusion levels by 60 min.