Intraoperative hemodynamic effects of oxytocin and carbetocin in elective cesarean sections

Introduction and Aim: Numerous scientific studies have explored the safety and efficacy of oxytocin, a commonly preferred agent for the prophylaxis of postpartum hemorrhage, particularly focusing on its hemodynamic side effects. In recent years, various investigations have also been conducted on carbetocin, a synthetic analog of oxytocin. The primary objective of this study is to evaluate the intraoperative hemodynamic effects of two uterotonic agents, oxytocin and carbetocin, used to prevent hemorrhage during elective cesarean deliveries, along with their impacts on intraoperative blood loss, the need for additional uterotonics, and uterine tone. Materials and Methods: This study was designed to be conducted at the Faculty of Medicine, Van Yüzüncü Yıl University, on ASA II patients aged between 18 and 40 years who were scheduled for elective cesarean section. All patients were informed about the study during the preoperative assessment. A total of 100 patients were enrolled, randomized into two groups of 50 each, using a single-blind closed-envelope method. Standard general anesthesia was administered to all participants. Each patient received an equal volume of fluid (270 mL of 0.9% NaCl) over 30 minutes. Following delivery and clamping of the umbilical cord, one group received 0.6 IU of oxytocin diluted in 20 mL of 0.9% NaCl via slow infusion over one minute, while the other group received 100 mcg of carbetocin diluted in 20 mL of 0.9% NaCl over 30–60 seconds. Intraoperative hemodynamic parameters (heart rate, systolic arterial pressure, diastolic arterial pressure, mean arterial pressure, and peripheral oxygen saturation), the need for additional uterotonics, and uterine tone were recorded at baseline (prior to administration) and at 1, 5, and 10 minutes following uterotonic administration. The total amount of intraoperative blood loss was calculated and recorded by measuring aspirated blood volume, sponge weight, and estimated blood loss within the surgical field. Results: No significant differences were observed between the groups regarding age, weight, BMI, smoking status, or ASA score. However, height was found to be significantly lower in the carbetocin group (p<0.05). There were no statistically significant differences between the groups in heart rate, systolic, or diastolic blood pressure measurements at baseline, 1, 5, 10, 15, 20, 25, and 30 minutes after uterotonic administration. Mean arterial pressure measured at the 1st minute was significantly lower in the carbetocin group (p<0.05). Uterine tone at the 1st and 5th minutes was higher in the carbetocin group, whereas similar results were observed between the groups at the 10th minute (p<0.05). Additional uterotonic use was required in 13 patients in the oxytocin group and 5 patients in the carbetocin group, with the need for additional uterotonics being significantly lower in the carbetocin group (p<0.05). Furthermore, intraoperative blood loss was significantly lower in the carbetocin group (p<0.05). X Conclusion: Carbetocin, which has gained increasing attention in recent years for the prevention of postpartum hemorrhage, demonstrates hemodynamic effects comparable to oxytocin. Moreover, due to its longer half-life allowing for single-dose administration, its ability to achieve more effective uterine tone, and the associated reduction in the need for additional uterotonics and intraoperative blood loss, carbetocin stands out with notable clinical advantages.