Randomized comparison of intravenous terbutaline vs nitroglycerin for acute intrapartum fetal resuscitation

OBJECTIVE: The purpose of this study was to compare terbutaline and nitroglycerin for acute intrapartum fetal resuscitation. STUDY DESIGN: Women between 32-, 42 weeks' gestation were assigned randomly to 250 mu g of terbutaline or 400 mu g nitroglycerin intravenously for nonreassuring fetal heart rate tracings in labor. The rate of successful acute intrapartum fetal resuscitation and the maternal hemodynamic changes were compared. Assuming a 50% failure rate in the terbutaline arm, we calculated that a total of 110 patients would be required to detect a 50% reduction in failure in the nitroglycerin group ( 50% to 25%), with an alpha value of .05, a beta value of .20, and a power of 80%. RESULTS: One hundred ten women had nonreassuring fetal heart rate tracings in labor; 57 women received terbutaline, and 53 women received nitroglycerin. Successful acute resuscitation rates were similar ( terbutaline 71.9% and nitroglycerin 64.2%; P =.38). Terbutaline resulted in lower median contraction frequency per 10 minutes ( 2.9 [ 2575 percentile, 1.7- 3.3] vs 4 [ 25- 75 percentile, 2.5- 5]; P <.002) and reduced tachysystole ( 1.8% vs 18.9%; P =.003). Maternal mean arterial pressures decreased with nitroglycerin ( 81- 76 mm Hg; P =.02), but not terbutaline ( 82- 81 mm Hg; P = .73). CONCLUSION: Although terbutaline provided more effective tocolysis with less impact on maternal blood pressure, no difference was noted between nitroglycerin and terbutaline in successful acute intrapartum fetal resuscitation.