Comparison of haemodynamic effects of intravenous carbetocin and oxytocin during caesarean section under subarchanoid block

Context: Uterine atony is the commonest cause for postpartum haemorrhage in majority of cases. Oxytocin remains the first-line uterotonic agent but, is associated with significant cardiovascular effects like hypotension and tachycardia after intravenous administration. Carbetocin, a synthetic heat-stable oxytocin analogue combines the safety and efficacy profile of oxytocin with the sustained uterotonic activity. Aims: The aim of this study was to compare intravenous oxytocin and carbetocin for haemodynamic responses during caesarean section under subarachnoid block. Settings and Design: Randomized controlled trial. Methods and Material: We performed a prospective randomized, controlled study on 142 pregnant patients undergoing elective cesarean section under subarachnoid block. Patients were randomly assigned to receive either 3U of intravenous oxytocin followed by infusion of 10U/hour for 4 hours or 100 μg intravenous carbetocin after the delivery of anterior shoulder. Heart rate and mean intra-arterial blood pressures were recorded at every 15 s during the study period of 5 min. Statistical Analysis Used: Data were analyzed using Student's unpaired test, Chi-squared test, and Fischer's exact test. A P < 0.05 was considered statistically significant. Results: Oxytocin produced clinically significant tachycardia (>20%) with peak effects over 180 s after injection (P < 0.0001). It also demonstrated a significant decrease in mean arterial pressure within 30 s of bolus injection and hypotension persisted throughout the study period (P < 0.0001). Carbetocin produced no significant changes in heart rate and mean blood pressure responses. The requirement of additional uterotonics and total intraoperative blood loss were similar among both the groups. Conclusions: Intravenous carbetocin is better tolerated without significant haemodynamic adverse effects in comparison to oxytocin during cesarean section.