Comparison of phenylephrine and mephentermine for preventing oxytocin-induced hemodynamic changes during spinal anaesthesia

Background: Spinal anaesthesia is a safe and reliable regional technique for the caesarean section, offering rapid onset, effective analgesia and reduced aspiration risk compared to general anaesthesia. This study aimed to compare phenylephrine and mephentermine in preventing oxytocin-induced hemodynamic changes during the caesarean section under spinal anaesthesia. Materials and methods: The study included 64 patients aged 18 to 40 years with American Society of Anesthesiologists (ASA) II physical status who were scheduled for elective lower segment caesarean section (LSCS) under spinal anaesthesia. Patients were randomly allocated into two groups (n=32 each). Group A received phenylephrine 75 mcg intravenous (IV) bolus and group B received mephentermine 6 mg IV bolus. Hemodynamic parameters were observed and recorded every minute for 5 minutes. Hemodynamic changes like heart rate, systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP) were observed and compared between the two groups. Results: Phenylephrine demonstrated superior efficacy in maintaining blood pressure, making it an excellent choice for preventing oxytocin-induced hypotension during caesarean section under spinal anaesthesia. Conversely, mephentermine was more effective in maintaining heart rate stability. Conclusion: Phenylephrine proved superior in stabilizing SBP, DBP and MAP. Mephentermine, on the other hand, showed better performance in maintaining heart rate stability.