When to consider adding vasopressin to noradrenaline (norepinephrine) in septic shock?

When to Add Vasopressin to Norepinephrine in Septic Shock

Vasopressin should be added to norepinephrine when target mean arterial pressure (MAP) of 65 mmHg cannot be achieved by norepinephrine alone, or to decrease norepinephrine dosage requirements. 1, 2

Initial Management of Septic Shock

1. First-line vasopressor therapy:

   • Norepinephrine is the first-choice vasopressor for septic shock (strong recommendation, moderate quality evidence) 1
   • Initial dose: 0.05-0.1 μg/kg/min IV infusion 2
   • Titrate by 0.05-0.1 μg/kg/min every 5-15 minutes based on blood pressure response 2
   • Target MAP: 65 mmHg 1, 2

2. Arterial line placement:

   • Place arterial catheter as soon as practical for continuous blood pressure monitoring 1, 2

When to Add Vasopressin

Specific Indications:

• When target MAP cannot be achieved with norepinephrine alone 1, 2
• To decrease high norepinephrine dosage requirements 1, 2
• Early addition (within 3 hours of starting norepinephrine) may lead to faster shock resolution and decreased ICU length of stay 3

Dosing of Vasopressin:

• Starting dose: 0.01 units/minute for septic shock 4
• Titrate up by 0.005 units/minute at 10-15 minute intervals 4
• Maximum recommended dose: 0.03 units/minute 1, 2
• Higher doses (0.03-0.04 units/minute) should be reserved for salvage therapy 1

Clinical Benefits of Adding Vasopressin

• Vasopressin acts on different receptors (V1) than norepinephrine (α-adrenergic), making it effective in patients with catecholamine receptor downregulation 2
• May reduce the need for renal replacement therapy compared to norepinephrine alone 5
• Early addition (within 3 hours) is associated with faster time to shock resolution (37.6 vs 60.7 hours) 3
• Particularly beneficial in less severe septic shock 6

Important Considerations

• Vasopressin should not be used as the single initial vasopressor for septic shock 1, 2
• Monitor for adverse effects: decreased cardiac output, bradycardia, tachyarrhythmias, hyponatremia, and tissue ischemia 2, 4
• After target blood pressure has been maintained for 8 hours without catecholamines, taper vasopressin by 0.005 units/minute every hour as tolerated 4
• Dilute vasopressin in normal saline or 5% dextrose prior to administration 4
• Discard unused diluted solution after 18 hours at room temperature or 24 hours under refrigeration 4

Alternative Vasopressors

• If norepinephrine is not available, vasopressin or epinephrine can be used as first-line agents 1
• Epinephrine can be added when an additional agent is needed to maintain adequate blood pressure 1
• Dopamine should only be used in highly selected patients with low risk of tachyarrhythmias or relative bradycardia 1, 2
• Phenylephrine is not recommended except in specific circumstances (e.g., norepinephrine-associated arrhythmias) 1

By following these evidence-based recommendations for adding vasopressin to norepinephrine therapy in septic shock, clinicians can optimize hemodynamic support while minimizing adverse effects and potentially improving outcomes.