The maternal cardiovascular effect of carbetocin compared to oxytocin in women undergoing caesarean section.

OBJECTIVE: To compare haemodynamic changes, measured noninvasively using the USCOM monitor, after combined spino-epidural anaesthesia and after administration of two different uterotonic drugs, oxytocin and carbetocin, in a population of pregnant women during elective caesarean delivery. METHODS: Haemodynamic measurements were obtained with the USCOM system, by positioning a probe at maternal suprasternal notch (SSN) until the aortic valve flow's profile was optimally identified. Evaluations of the haemodynamic profile were obtained in seven different moments: before anaesthesia; during skin incision; 60, 180 and 300s after administration of uterotonic drug, at closure of the uterus, at closure of the skin. Doses of uterotonic drugs were: Oxytocin 5UI in 500cc NaCl eV, Carbetocin 100mcg in bolus eV. Main measured parameters were: heart rate, mean blood pressure, stroke volume, cardiac output and total vascular resistance. RESULTS: We enrolled 32 pregnant women. Patients were randomized in two groups: oxytocin and carbetocin. A reduction in mean blood pressure, a reduction of total vascular resistance and an increase of cardiac output and of stroke volume were seen, while heart rate values remained stable in both treatment groups. No statistically significant differences were found. DISCUSSION: Administration of carbetocin is associated with a substantial global haemodynamic stability in patients undergoing elective caesarean section without any difference with oxytocin. This observation allows us to consider carbetocin comparable to oxytocin, with minimum haemodynamic impact on the maternal circulation. This minimal effect on global haemodynamic stability might extend the use of this uterotonic drug in patients at high haemorrhagic risk with preeclampsia.