What is the recommended dosage of vasopressin (antidiuretic hormone) for various clinical uses?

Vasopressin Dosing for Clinical Use

For septic shock, add vasopressin at 0.03 units/minute as a continuous infusion when norepinephrine alone fails to maintain a mean arterial pressure of 65 mmHg, and never exceed 0.04 units/minute except as salvage therapy when all other vasopressors have failed. 1, 2

Standard Dosing by Clinical Indication

Septic Shock (Primary Indication)

• Standard dose: 0.03 units/minute as a continuous IV infusion added to norepinephrine 1, 2, 3
• Dose range: 0.01-0.04 units/minute for titration purposes 2, 3
• Maximum dose: 0.04 units/minute for routine use; higher doses reserved only for salvage therapy 1, 2, 3
• Vasopressin must be added to norepinephrine, never used as sole initial vasopressor 1, 2, 3

Variceal Hemorrhage

• Dose: 0.2-0.4 units/minute as continuous IV infusion 3
• Maximum dose: 0.8 units/minute 3
• Must be administered with concurrent IV nitroglycerin to prevent cardiac ischemia 3

Post-Cardiotomy Shock

• Dose: 0.03 units/minute added to norepinephrine 2

Pediatric Vasodilatory Shock

• Initial dose: 0.0002-0.0005 units/kg/minute 4
• Maximum dose: 0.002 units/kg/minute (equivalent to ≤0.04 units/kg/minute in context) 2, 4
• Reserved as rescue therapy for catecholamine-resistant shock 4

Clinical Algorithm for Vasopressin Initiation

Step 1: Ensure Adequate Fluid Resuscitation

• Administer minimum 30 mL/kg crystalloid bolus before or concurrent with any vasopressor 1, 2
• Vasopressin should never be started without adequate volume resuscitation 2, 3

Step 2: Start First-Line Vasopressor

• Initiate norepinephrine as first-choice vasopressor targeting MAP ≥65 mmHg 1, 2
• Administer through central venous access with arterial catheter monitoring 1, 2

Step 3: Add Vasopressin at Specific Threshold

• Add vasopressin 0.03 units/minute when norepinephrine reaches 0.25 mcg/kg/minute and MAP remains <65 mmHg 2, 4
• Alternative indication: Add vasopressin to decrease norepinephrine dosage while maintaining MAP target 1, 2

Step 4: Escalation for Refractory Shock

• If MAP remains inadequate with norepinephrine plus vasopressin 0.03 units/minute, add epinephrine 0.1-0.5 mcg/kg/minute rather than increasing vasopressin dose 2, 4
• Vasopressin doses >0.04 units/minute reserved only for salvage therapy when all other agents have failed 1, 2, 3

Administration Requirements

Route and Monitoring

• Administer as continuous IV infusion, never as bolus 3, 5
• Central venous access preferred 2
• Continuous arterial blood pressure monitoring mandatory 1, 2
• Monitor for signs of ischemia: digital/peripheral ischemia, decreased urine output, rising lactate, cardiac ischemia 2, 3, 6

Preparation

• Standard adult concentration varies by institution 4
• Infusion must be continuous and stable 3

Critical Evidence and Nuances

The VASST trial (2008) demonstrated that vasopressin 0.01-0.03 units/minute added to norepinephrine showed no overall mortality difference compared to norepinephrine alone (35.4% vs 39.3%, P=0.26), but suggested potential benefit in less severe septic shock (26.5% vs 35.7%, P=0.05) 7. This equipoise supports the guideline recommendation to use vasopressin as adjunctive therapy rather than replacement for norepinephrine.

The dose of 0.03 units/minute represents a critical threshold: doses above 0.04 units/minute are associated with cardiac arrest, cardiac ischemia, digital ischemia, and splanchnic ischemia 3, 5, 6. A 2025 retrospective cohort found the 90th percentile cutoff for high-dose vasopressin was 3.6 units/hour (0.06 units/minute), well above guideline recommendations, with significantly worse survival in high-dose recipients 8.

Common Pitfalls to Avoid

• Never use vasopressin as monotherapy for initial vasopressor support in septic shock 1, 2, 3
• Never exceed 0.04 units/minute except as last-resort salvage therapy 1, 2, 3
• Never start vasopressin without adequate fluid resuscitation (minimum 30 mL/kg crystalloid) 1, 2, 3
• Never titrate vasopressin like other vasopressors—it should be used at fixed low dose (0.03 units/minute), not escalated 9, 5
• Do not use dopamine for renal protection when managing shock requiring vasopressin 1, 2
• Monitor closely for ischemic complications: skin lesions, intestinal ischemia, cardiac ischemia, digital ischemia 3, 6
• Do not use phenylephrine as first-line agent before adding vasopressin to norepinephrine 1, 2

Adverse Effects Requiring Monitoring

• Cardiac ischemia and potential cardiac arrest at doses >0.04 units/minute 3, 6
• Digital and peripheral ischemia 3, 6
• Intestinal/splanchnic ischemia 3, 6
• Skin necrosis and ischemic lesions 9, 6
• Decreased cardiac output (though MAP increases) 6