## First-Line Vasopressor in Septic Shock **Key Point:** Noradrenaline is the first-line vasopressor agent in septic shock, as recommended by the Surviving Sepsis Campaign guidelines. ### Mechanism and Rationale Noradrenaline (norepinephrine) is a combined α1 and β1 adrenergic agonist that: - Restores systemic vascular resistance (α1 effect) - Maintains cardiac output through modest β1 inotropic support - Preserves renal and splanchnic perfusion better than pure α-agonists - Targets mean arterial pressure (MAP) ≥65 mmHg in septic shock **High-Yield:** Noradrenaline is preferred over dopamine because dopamine carries a higher risk of tachyarrhythmias and is associated with worse outcomes in septic shock when used as first-line therapy. ### Vasopressor Selection in Shock | Vasopressor | α1 | β1 | β2 | Renal Flow | First-Line Use | | --- | --- | --- | --- | --- | --- | | **Noradrenaline** | +++ | ++ | 0 | Preserved | **Septic shock** | | Dopamine | ++ | +++ | + | Dose-dependent | Cardiogenic shock (if low CO) | | Phenylephrine | ++++ | 0 | 0 | ↓ | Only if noradrenaline unavailable | | Vasopressin | V1 receptor | 0 | 0 | ↓ | Adjunct only | **Clinical Pearl:** In this case, the patient has septic shock (infection + hypotension despite fluid resuscitation + lactate elevation). Noradrenaline should be initiated targeting MAP ≥65 mmHg, with concurrent source control (antibiotics, possible drainage) and ongoing lactate monitoring. ### Dosing - **Noradrenaline:** Start 0.01–0.05 mcg/kg/min IV, titrate to MAP target - Administer via central line (preferred) or high-flow peripheral access - Reassess after 6 hours; add dobutamine if cardiac output remains low **Warning:** Avoid dopamine as monotherapy in septic shock due to increased arrhythmia risk and inferior mortality outcomes compared to noradrenaline.
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