Comparative Analytical Study of Intravenous Bolus Dose of Mephentermine and Phenylephrine for Hemodynamic Stability During Elective Cesarean Section Under Spinal Anesthesia at KIST Medical College and Teaching Hospital

Spinal anesthesia is the most common administered neuraxial anesthetic technique for patient undergoing cesarean section due to its rapid and reliable onset and remains preferred choice for cesarean deliveries. The advantage of spinal anesthesia includes no airway manipulation, profound analgesia and anesthesia, minimal maternal and fetal drug exposure stable hemodynamic parameters (based on level of anesthesia), decrease intraoperative blood loss and provide postoperative pain control. Hemodynamics changes is due to sympathetic block which causes reduction in venous return which further reduces the cardiac output and blood pressure by activation of Bezold Jarisch reflex In addition, the vasodilatory effect due to prostaglandins, progesterone relaxin and nitric oxide during pregnancy and loss of intrinsic sympathetic vascular tone further exaggerated fall of blood pressure with prevalence of 50-90% despite of fluid preload and uterine displacement Various preventive measures like fluid preload , left lateral tilt , left uterine displacement and along with vasopressors such as mephentermine , phenylephrine have been tried to prevent hypotension Phenylephrine is currently recommended as 1st line of vasopressor which acts as alpha 1 agonist with negligible beta action increasing blood pressure due to vasoconstriction whereas it causes dose dependent bradycardia and decrease cardiac output Mephentermine non catecholamine nondirectly acts on both adrenergic alpha and beta receptors and indirectly by releasing norepinephrine and epinephrine that increases blood pressure and augments cardiac output whereas tachyphylaxis may occur rapidly.

This study would help to compare the effectiveness of phenylephrine and mephentermine for maintenance of hemodynamic parameters in patient undergoing cesarean section under spinal anesthesia.

Inclusion criteria

• Patient undergoing elective cesarean section under spinal anesthesia
• Age between 18-48 years
• ASA class II ( all pregnant are categorized as ASA II)

Exclusion criteria

• Patient refusal
• Contraindication to spinal anesthesia like coagulation disorder , localized infection , sepsis, raised intracranial pressure etc
• Patchy spinal block , failed spinal block converting to GA
• Hypersensitivity to any drugs
• High Risk Pregnancy ( preeclampsia, eclampsia, preterm, Gestational Diabetes , etc )