Effets de 0,4 mg de nitroglycérine sublinguale sur le relâchement utérin de parturientes à terme

Abstract

Objectives: to measure the effect of 0.4mg of sublingual nitroglycerin spray on uterine activity in normal spontaneous or oxytocin-induced term labor and to evaluate the maternal and fetal side effects.Methods: at Centre Hospitalier Universitaire de Sherbrooke, 21 term pregnancies in labor, consented to have an intrauterine pressure catheter during the active phase (dilatation ≥ 4cm). The groups were: spontaneous labor (n = 6) receiving 0.4 mg sublingual nitroglycerin with dicontinuation of oxytocin perfusion during 30 minutes. A control group on oxytocin (n = 8) was studied where oxytocin perfusion was stopped during 30 minutes without receiving nitroglycerin. Maternal blood pressure and fetal heart rate were recorded 20 minutes before and over 60 minutes after the administration of nitroglycerin and/or the arrest of oxytocin perfusion. The frequency of uterine contractions. Montevideo units and the area under the curve of the contractions were calculated in 10 minutes windows before and after the administration of nitroglycerin and/or the arrest of oxytocin perfusion. P<0.05 was considered statistically significant.Results: the uterine activity during spontaneous labor showed a 20 percent reduction for the area under the curve after the administration of O.4mg nitroglycerin at 10-20 minutes (p = 0.06), without significant changes for the frequency of uterine contractions and Montevideo units. In stimulated or induced labor, the area under the curve decreased by 40 percent (p < 0.001) from 10 to 30 minutes after the administration of nitroglycerin and/or the arrest of the oxytocin perfusion, without any difference between the groups with or without nitroglycerin. No maternal or fetal side effects were observed.Conclusion: there was no clinically significant uterine relaxation in normal spontaneous labor with 0.4 mg of sublingual nitroglycerin spray. In stimulated or induced labor, the uterine activity was significantly decreased following the arrest of the oxytocin perfusion from 10 to 30 minutes without any additional relaxation with the concomitant use of nitroglycerin. At this concentration, there were no maternal or fetal side effects. For an obstetrical emergency in active labor at term, 0.4 mg nitroglycerin is ineffective to obtain a clinically significant uterine relaxation.