What is the recommended initial dose of norepinephrine (vasopressor) for a patient in cardiogenic shock?

Norepinephrine Dosing for Cardiogenic Shock

Norepinephrine should be initiated at 0.2-1 mcg/kg/min when inotropic therapy and fluid resuscitation fail to restore systolic blood pressure >90 mmHg with persistent signs of inadequate organ perfusion, and should be used with extreme caution as a second-line agent only. 1

Algorithmic Approach to Vasopressor Use

Step 1: First-Line Therapy

• Initiate inotropes first (dobutamine 2.5-10 mcg/kg/min or dopamine), NOT vasopressors 2, 3
• Optimize volume status with fluid challenge (250 mL over 10 minutes if clinically indicated) 1
• Target systolic blood pressure >90 mmHg and mean arterial pressure ≥65 mmHg 2, 3

Step 2: When to Add Norepinephrine

Only add norepinephrine when:

• Inotropic therapy PLUS fluid challenge has failed to restore adequate blood pressure 1, 2
• Systolic blood pressure remains <90 mmHg 1
• Signs of inadequate organ perfusion persist (altered mental status, oliguria, elevated lactate, poor skin perfusion) 2, 3

Step 3: Norepinephrine Dosing

• Initial dose: 0.2-1 mcg/kg/min 1
• Titrate to maintain mean arterial pressure ≥65 mmHg 2, 3
• Administer through central line ideally to avoid tissue necrosis from extravasation 1, 3

Critical Pitfalls to Avoid

Never use vasopressors as first-line agents - this is explicitly contraindicated by European guidelines 1, 2. Cardiogenic shock is characterized by high systemic vascular resistance, and adding vasopressors prematurely increases afterload on an already failing heart, potentially worsening cardiac output and end-organ perfusion 1.

Discontinue as soon as possible - all vasopressors should be tapered rapidly once hemodynamic stability is achieved, as they increase myocardial oxygen demand and arrhythmia risk 2, 3.

Evidence Nuances

The evidence base reveals important considerations:

• Norepinephrine may increase short-term mortality: A 2022 retrospective study of 927 patients found norepinephrine use associated with 41% vs 30% 30-day mortality (OR 1.61, p=0.017), though this may reflect selection bias toward sicker patients 4

• Norepinephrine-dobutamine superior to epinephrine: A 2011 randomized trial demonstrated that norepinephrine-dobutamine combination resulted in lower heart rates, fewer arrhythmias, decreased lactate levels, and better splanchnic perfusion compared to epinephrine alone 5. This supports current guideline recommendations against epinephrine use 1

• Hemodynamic tolerance: A 2010 study showed that short-term norepinephrine up-titration (MAP 65→85 mmHg) was well-tolerated without worsening cardiac output in patients already on inotropes 6

Monitoring Requirements

Continuously assess:

• Blood pressure (arterial line preferred), heart rate, oxygen saturation 3
• Perfusion markers: urine output, serum lactate clearance, mental status, skin perfusion 2, 3
• Mixed or central venous oxygen saturation 2
• ECG for arrhythmias 3

Alternative Considerations

If norepinephrine requirements remain high:

• Add vasopressin up to 0.03 units/min to reduce norepinephrine dose 2
• Consider levosimendan if dobutamine fails to restore adequate perfusion 2
• Evaluate for mechanical circulatory support (IABP, ventricular assist devices) as vasopressors are only a bridge therapy 1, 2