Vasopressin Dosing for Neonatal Hypotension

Clinical Context and Indications

Vasopressin is reserved for rescue therapy in neonates with refractory hypotension despite adequate fluid resuscitation, adequate cardiac output or SVC flow >40 mL/kg/min documented by echocardiography, central venous oxygen saturation (ScvO2) >70%, and persistent hypotension requiring high-dose catecholamines, as recommended by the American College of Critical Care Medicine 1
The American College of Critical Care Medicine specifically states that vasopressin, terlipressin, or angiotensin should only be considered "in the presence of adequate cardiac output, SVC flow, and/or ScvO2 monitoring" 1

For a 3.3 kg patient, the initial rate is 0.00066-0.00132 units/hour (0.66-1.32 milliunits/hour) 1
The alternative expression for the initial rate is 0.01-0.02 milliunits/kg/minute 1
The starting infusion rate is 0.3-0.7 mL/hour (using 1 unit/mL concentration) 1

Continuous arterial blood pressure monitoring (preferably invasive) is required before and during vasopressin infusion 1
ScvO2 monitoring >70% is required before and during vasopressin infusion 1
Urine output monitoring (target >1 mL/kg/hour) is required before and during vasopressin infusion 1

Vasopressin should be used alongside volume resuscitation with crystalloid as first-line, and packed red blood cells if hemoglobin <12 g/dL 1
First-line vasopressors, such as epinephrine 0.05-0.3 μg/kg/min or norepinephrine, should be used concurrently with vasopressin 1
Hydrocortisone should be used if adrenal insufficiency is suspected (basal cortisol <18 μg/dL) 1
Calcium normalization is required before vasopressin, with ionized calcium corrected 1

Inadequate cardiac output without echocardiographic confirmation is a contraindication for vasopressin 1
Severe right ventricular dysfunction or right-to-left shunting is a contraindication for vasopressin 1
Uncorrected hypovolemia is a contraindication for vasopressin 1
Starting vasopressin before adequate fluid resuscitation can worsen tissue perfusion despite improved blood pressure 1
Using vasopressin without cardiac output monitoring may mask inadequate cardiac output with falsely reassuring blood pressure 1
Decreased urine output may indicate excessive vasoconstriction 1

If hypotension persists despite vasopressin, re-evaluate for unrecognized morbidities, such as pericardial effusion, pneumothorax, ongoing blood loss, hypoadrenalism, hypothyroidism, inborn errors of metabolism, or critical congenital heart disease 1
Consider ECMO, with a current survival rate for neonatal sepsis of 80% 1
Add continuous renal replacement therapy (CRRT) if >10% fluid overloaded 1