Fetal heart rate changes after fetal intravascular treatment with pancuronium bromide

Because of recurrent needle dislodgement secondary to fetal movement, we have altered our intravascular transfusion technique by replacing maternal premedication (meperidine and diazepam [group 1]) with fetal intravascular infusion of pancuronium bromide (Pavulon [group 2]), a nondepolarizing neuromuscular blocking agent. Baseline fetal heart rate, number of accelerations, and variability were assessed before and after transfusion in both groups. Whereas there were no changes after transfusion in the former group, those fetuses who received pancuronium bromide demonstrated a dramatic abolishment of accelerations and decrease in variability, with the heart rate pattern often appearing "sinusoidal-like." These alterations in fetal heart rate were temporary changes that reverted to normal once the fetus "awakened" from the neuromuscular blockade. We speculate that these changes in fetal heart rate are secondary to the interaction of the reported hypertensive and vagolytic effects of pancuronium bromide.