THE EFFECTS OF INTRAVENOUS AND EPIDURAL SUFENTANIL IN THE CHRONIC MATERNAL-FETAL SHEEP PREPARATION

This study examines the placental transfer and hemodynamic and acid-ba se changes after intravenous (IV) and epidural administration of sufen tanil in the chronically instrumented maternal-fetal sheep preparation . A dose of 50 mu g sufentanil was injected either IV or epidurally in to seven ewes. Neither IV nor epidural injection of sufentanil affecte d maternal mean arterial pressure (MMAP), uterine blood flow (UBF), ma ternal heart rate (MHR), fetal mean arterial pressure (FMAP), fetal he art rate (FHR), or blood gases and acid-base status in mother and fetu s, After TV administration, a peak sufentanil level of 1.28 ng/mL +/- 0.285 (SD) was detected in maternal plasma. A peak plasma level of 0.0 37 ng/mL +/- 0.041 (SD) was attained in the fetus. A constant maternal -fetal concentration ratio of 5.5 from 15-60 min after the TV injectio n was found. After epidural injection a mean peak plasma level of 0.05 9 ng/mL +/- 0.042 (so) was reached in the mother 25 min after injectio n. Sufentanil levels were undetectable in fetal plasma after epidural injection into the mother. Because placental transfer of sufentanil is small, the maternal and fetal cardiovascular and acid-base effects ar e minimal in the pregnant ewe.