ST Depression in Preeclampsia Women Receiving Oxytocin during Cesarean Section: A Randomized Controlled Trial

Abstract

Background: Electrocardiogram changes suggestive of myocardial ischemia, ST depressions, have been reported to be associated with oxytocin administration in healthy women undergoing cesarean section in regional anesthesia. We investigated whether there was a difference in the occurrence of ST depressions on electrocardiograms in preeclamptic women randomized to five or ten units of oxytocin during cesarean section with regional anesthesia. Methods: Double-blind randomized controlled trial. Twenty-five women with preeclampsia delivered by cesarean section under spinal anesthesia were allocated to 5 or 10 units of oxytocin, given as an intravenous bolus. A Holter monitor was used to record electrocardiograms. Non-invasive blood pressure and heart rate were monitored. The main outcome measure was depression of the ST segment on electrocardiogram related to oxytocin bolus; the secondary outcomes were changes in mean arterial pressure and heart rate related to oxytocin bolus. Results: ST depressions associated with oxytocin administration occurred in two women (8%), one in each group. The decrease in mean arterial pressure from baseline to 2 minutes after the oxytocin bolus differed within groups, with 12 mmHg in the five unit group and 16 mmHg in the ten unit group (p<0.01). The increases in mean heart rate from baseline to 2 minutes after the oxytocin bolus did not differ. Conclusion: ST depressions on electrocardiograms were uncommon in patients with preeclampsia undergoing cesarean section in regional anesthesia, although the hemodynamic changes associated with an oxytocin bolus were substantial.