Intravenous nitroglycerin to relieve intrapartum fetal distress related to uterine hyperactivity: a prospective observational study.

During a 1-yr period, we evaluated prospectively the use of nitroglycerin (NTG) to relieve severe intrapartum fetal distress related to uterine hyperactivity. Sixty to ninety micrograms of NTG were injected intravenously (i.v.) within 2-5 min after onset of severe fetal distress after oxygen administration, left lateral decubitus, and discontinuation of any ongoing oxytocin infusion (62%) had failed to resolve the fetal heart rate abnormality. A second dose (60 or 90 micrograms) was used 2-3 min later as required. NTG was completely effective in 22 cases (fetal distress resolution within 4-5 min with restoration of normal uterine activity) and partially but sufficiently effective in the remaining 2 cases (fetal distress resolution within 4-5 min with residual mild uterine hyperactivity). However, a second dose was required for nine parturients (38%). Six parturients (25%) developed hypotension 2 min after the first NTG injection, with a mean nadir of 93.2 mm Hg (minimum 85 mm Hg). Hypotension was always rapidly reversed with a small single dose of ephedrine (4.5-6 mg). In conclusion, we found small doses (60-180 micrograms) of IV NTG to be associated with resolution of severe fetal distress related to uterine hyperactivity along with negligible side effects.