What is the recommended dosing for vasopressin (antidiuretic hormone) in patients with septic shock or cardiac arrest?

Vasopressin Dosing in Septic Shock and Cardiac Arrest

Septic Shock Dosing

For septic shock, initiate vasopressin at 0.01 units/minute and titrate up by 0.005 units/minute every 10-15 minutes to a maximum of 0.03 units/minute, adding it only as a second-line agent to norepinephrine—never as monotherapy. 1, 2

Initial Administration Protocol

• Start vasopressin at 0.01 units/minute when norepinephrine alone fails to maintain MAP ≥65 mmHg despite adequate fluid resuscitation (minimum 30 mL/kg crystalloid in first 3 hours) 1, 3
• Titrate upward by 0.005 units/minute increments at 10-15 minute intervals until target blood pressure is achieved 1
• The standard maintenance dose is 0.03 units/minute—this is the dose recommended by guidelines and should not be exceeded for routine use 2, 3

Maximum Dosing Limits

• Do not exceed 0.03-0.04 units/minute for standard septic shock management 3
• Doses above 0.07 units/minute have limited safety data and should be reserved only for salvage therapy when all other vasopressors have failed 1, 3
• Adverse reactions increase significantly with higher doses 1

Critical Administration Requirements

• Vasopressin must be diluted in normal saline (0.9% sodium chloride) or 5% dextrose in water prior to intravenous use 1
• Discard unused diluted solution after 18 hours at room temperature or 24 hours under refrigeration 1
• Requires central venous access for administration 3
• Place an arterial catheter for continuous blood pressure monitoring as soon as practical 2, 3

Post-Cardiotomy Shock Dosing

For post-cardiotomy shock, start vasopressin at 0.03 units/minute (higher than septic shock) and titrate up to a maximum of 0.1 units/minute. 1

• Initial dose: 0.03 units/minute 1
• Titrate by 0.005 units/minute every 10-15 minutes 1
• Maximum dose: 0.1 units/minute (higher ceiling than septic shock) 1

Cardiac Arrest Dosing

For cardiac arrest during cardiopulmonary resuscitation, administer a single 40 IU intravenous bolus as an alternative to epinephrine 1 mg in patients refractory to electrical countershock. 4

• Dose: 40 IU intravenous bolus (not an infusion) 4
• Use in ventricular fibrillation, pulseless electrical activity, or asystole 4
• Vasopressin showed superior outcomes compared to epinephrine specifically in asystolic cardiac arrest 4
• Vasopressin followed by epinephrine resulted in significantly higher survival rates to hospital admission and discharge 4

Weaning Protocol

After target blood pressure has been maintained for 8 hours without catecholamines, taper vasopressin by 0.005 units/minute every hour as tolerated. 1

• Wait until MAP target maintained for 8 hours without catecholamine support before initiating taper 1
• Reduce by 0.005 units/minute decrements every hour 1
• Consider discontinuing vasopressin last (not second-to-last) among vasopressors to reduce risk of rebound hypotension 5

Critical Pitfalls to Avoid

• Never use vasopressin as the sole initial vasopressor—it must always be added to norepinephrine, not used as monotherapy 2, 3, 6
• Do not titrate vasopressin like other vasopressors—use a fixed dose of 0.03 units/minute and adjust norepinephrine instead to achieve MAP targets 3, 6
• Avoid doses above 0.03-0.04 units/minute for routine septic shock—higher doses offer minimal benefit and increase adverse effects 3, 5
• Monitor for digital ischemia, mesenteric ischemia, and skin necrosis—vasopressin can cause severe peripheral vasoconstriction 1, 6
• Do not use for renal protection—there is no evidence supporting renal benefit from vasopressin 5

When to Add Vasopressin

Add vasopressin when norepinephrine requirements exceed 0.25-0.50 mcg/kg/min (or approximately 0.2 mcg/kg/min in practice) and hypotension persists despite adequate fluid resuscitation. 3, 7

• The goal is "decatecholaminization"—reducing norepinephrine dose to minimize catecholamine-related adverse effects (tachyarrhythmias, immunosuppression, cardiotoxicity) 7
• Adding vasopressin allows you to either raise MAP to target OR decrease norepinephrine dosage while maintaining hemodynamic stability 2, 3

Alternative Escalation if Vasopressin Insufficient

• If MAP targets still not achieved with norepinephrine plus vasopressin 0.03 units/minute, add epinephrine (0.05-2 mcg/kg/min) rather than increasing vasopressin dose 3
• For persistent hypoperfusion despite adequate vasopressor support, add dobutamine (up to 20 mcg/kg/min) rather than escalating vasopressors further 2, 3