What are the uses of vasopressin?

Vasopressin Clinical Uses

Vasopressin is FDA-approved to increase blood pressure in adults with vasodilatory shock who remain hypotensive despite fluids and catecholamines, and is used as a second-line vasopressor in septic shock, hemorrhagic shock, and specific afterload-dependent cardiac conditions. 1

Primary Indications

Vasodilatory Shock (FDA-Approved)

• Vasopressin is indicated for adults with vasodilatory shock remaining hypotensive after adequate fluid resuscitation and catecholamine therapy. 1
• The mechanism involves V1-receptor activation causing vasoconstriction independent of catecholamine receptors, which is particularly valuable when alpha-adrenergic receptors are down-regulated in shock states. 2, 3

Septic Shock (Second-Line Agent)

• In distributive shock, norepinephrine is the first-line vasopressor, with vasopressin (up to 0.03 units/min) added as second-line therapy to reduce norepinephrine requirements. 2
• Vasopressin deficiency occurs in septic shock, with endogenous levels paradoxically decreasing to normal range within 24-48 hours despite ongoing hypotension. 2
• The VASST trial showed no mortality difference when adding vasopressin to norepinephrine in the overall population, though subgroup analysis suggested benefit in patients requiring ≥15 µg/min norepinephrine. 2
• Vasopressin should not be used as monotherapy and must always be combined with norepinephrine. 2, 4

Hemorrhagic/Traumatic Shock

• Vasopressin can be transiently used in hemorrhagic shock with life-threatening hypotension, in conjunction with rapid hemorrhage control, as it may improve blood pressure without increasing blood loss. 2

Cardiogenic Shock (Specific Situations)

• In afterload-dependent cardiac conditions (aortic stenosis, mitral stenosis), vasopressin is advised as it provides vasoconstriction without increasing heart rate. 2
• Vasopressin should not be used without cardiac output monitoring in cardiogenic shock due to potential cardiac depression. 2

Dosing Parameters

Standard Dosing

• Post-cardiotomy shock: 0.03 to 0.1 units/minute 1
• Septic shock: 0.01 to 0.07 units/minute 1
• Maximum recommended dose: 0.04 units/minute except as salvage therapy 2, 4
• Doses exceeding 0.04 units/min are associated with cardiac, digital, and splanchnic ischemia and should be reserved for refractory situations. 2

Variceal Bleeding

• Vasopressin (or its analog terlipressin) can be considered for bleeding anorectal varices to reduce splanchnic blood flow and portal pressure, though evidence is extrapolated from esophageal variceal studies. 2
• Terlipressin is preferred over vasopressin due to longer half-life and fewer adverse effects related to systemic vasoconstriction. 2

Critical Safety Considerations

Major Adverse Effects

• Decreased cardiac output and bradycardia 1
• Tachyarrhythmias (though less than norepinephrine) 2
• Ischemic complications: coronary, mesenteric, skin, and digital ischemia 1
• Hyponatremia and reversible diabetes insipidus 1
• Risk of cardiac arrest at doses >0.04 units/min 5

Contraindications

• Known allergy to 8-L-arginine vasopressin or chlorobutanol 1
• Should not be used as monotherapy without concurrent catecholamine support 2, 4

Weaning Strategy

When discontinuing vasopressors, wean norepinephrine first by gradually decreasing the dose while maintaining vasopressin at a fixed dose, then discontinue norepinephrine completely once reaching approximately 0.2 μg/kg/min with stable blood pressure, before beginning vasopressin taper. 4

Comparative Effectiveness

• Meta-analysis of 7 trials (n=963) comparing norepinephrine with vasopressin showed no mortality benefit (RR 1.12,95% CI 0.96-1.30), though vasopressin was associated with fewer supraventricular arrhythmias. 2
• Vasopressin provides a norepinephrine-sparing effect, potentially reducing complications from high-dose catecholamines. 6
• At low plasma concentrations, vasopressin paradoxically causes vasodilation in coronary, cerebral, and pulmonary circulations while causing systemic vasoconstriction. 3