In North America, norepinephrine, ephedrine, and epinephrine have been recommended as first-choice vasopressors for the treatment of spinal hypotension during cesarean delivery. However, in international consensus guidelines, epinephrine was recommended for circulatory collapse only. Phenylephrine infusion is an important therapeutic strategy for preventing spinal-induced hypotension (SIH) in cesarean delivery, as it decreases the incidence of hypotension, nausea, and vomiting. However, high doses may reduce maternal heart rate and cardiac output in a dose-dependent manner.
Ephedrine, previously considered the first-choice drug, has both α and β receptor agonistic activity and causes norepinephrine release from sympathetic neurons. Its β1 effect increases heart rate and contractility, but may cause undesirable tachycardia. Tachyphylaxis can develop with repeated doses. Norepinephrine, the biosynthetic precursor of epinephrine, has both potent α and weak β agonist effects, tending to cause bradycardia.
Despite a lower incidence of hypotension with prophylactic norepinephrine, PSH still occurs in up to 30% of parturients undergoing cesarean section. The administration of a bolus dose of epinephrine prior to continuous infusion is an unusual practice in obstetric anesthesia, but has been reported to be safe in other contexts and in pregnant women when used for hemodynamic support.
Epinephrine has both potent α- and β-adrenoceptor agonist activity. Its β effects could offset reflex decreases in maternal HR and CO during spinal anesthesia for cesarean delivery. Although some studies compared epinephrine infusion with phenylephrine, it remains unclear whether adding an initial bolus of epinephrine before infusion offers superior maternal hemodynamic stability compared to infusion alone.
Age: 18 to 35 years.
American Society of Anesthesiologists (ASA) physical status II.
Undergoing Elective Lower Segment Cesarean Section under Spinal Anesthesia.
Uncontrolled cardiac morbidities as reduction of ejection fraction< 60%, History (within 3months) of myocardial infarction, cerebrovascular accident, transient ischemic attacks or coronary artery disease/stents
Poorly controlled Hypertensive disorders of pregnancy
Peripartum bleeding
Multiple pregnancies (e.g., twin gestations)
Parallel
Epinephrine (Adrenaline) bolus then infusion
DrugA bolus of 4 mcg epinephrine will be given just after spinal anaesthesia followed by 0.03 mcg/kg/min infusion which is equivalent to 1.8 mcg/kg/hr. Epinephrine dose of 3000 mcg will be diluting in 500 mL saline (6 mcg/mL), and the infusion rate will be set on 0.3 mL/kg/hr.
Epinephrine (Adrenaline) infusion
DrugPatients will receive the epinephrine infusion dose of 0.03 mcg/Kg/min (6) immediately without the bolus.
Incidence of post-spinal hypotension
defined as systolic blood pressure drop \>20% from baseline, measured from block onset until 5 minutes after delivery
Incidence of severe post-spinal hypotension
systolic blood pressure drop \>30% from baseline or systolic blood pressure\<80 mmHg
Number of hypotensive and severe hypotensive episodes per patient
Incidence of reactive hypertension (systolic blood pressure ≥ 120% of baseline)
Number of reactive hypertension episodes per patient
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