In the PICU, you'll run vasopressors constantly. The art is matching the drug to the problem, not just jamming everything up until the pressure normalizes. Different agents do different things, and using them wrong wastes time and damages tissue.
Dopamine (2–20 mcg/kg/min)
Dopamine is a precursor that hits different receptors depending on dose. The problem is you can't count on it: kids respond unpredictably, and you can't cleanly separate "renal dose" from everything else.
- 2–5 mcg/kg/min: Dopamine receptors supposedly dilate the kidney and mesentery. The theory was that renal-dose dopamine (low-dose) would protect kidneys. It doesn't, and it's no longer used that way.
- 5–10 mcg/kg/min: Beta effects kick in, more contractility, more heart rate, mild vasodilation overall.
- >10 mcg/kg/min: Alpha effects dominate, vasoconstriction, pressure up.
Because you never know which effect you'll get and it changes between kids, dopamine isn't popular anymore. It has a role when you need chronotropic support (a slow bradycardic kid needs the heart rate bump), but that's about it.
Use Dopamine Drip calculator.
Dobutamine (2–20 mcg/kg/min)
Pure inotropy with vasodilation. The heart squeezes harder, vessels relax. It's what you want when the problem is a weak heart (post-op cardiac patient, myocarditis) and blood pressure isn't catastrophically low.
The catch: that vasodilation can tank the pressure. So often you're running it with a vasopressor, which gets annoying. But in cardiogenic shock, this is your go-to.
Use Dobutamine Drip calculator.
Epinephrine (0.01–1+ mcg/kg/min)
Epi has beta and alpha in one bottle: inotropy and vasoconstriction together. The dose dependence is real but not clean-cut like dopamine. At low doses (0.01–0.1 mcg/kg/min) you get more beta (contractility, some vasodilation). Increase it and alpha takes over (potent vasoconstriction).
It's tempting to use epi because you get both effects without extra lines. In septic shock, especially early, that's useful. But high-dose epi jacks up the heart rate, burns oxygen, causes arrhythmias, and can actually worsen tissue perfusion despite good pressures. Prolonged runs cause lactic acidosis.
Use Epinephrine Drip calculator.
Norepinephrine (0.01–1+ mcg/kg/min)
This is mostly alpha (vasoconstriction) with intact beta (preserved contractility). You get the pressure up without destroying the heart rate, which is better than epi. More and more pediatric sepsis protocols are going here first, the data suggests it's as good as epi for septic shock, with less tachycardia.
For true vasodilatory shock (sepsis, anaphylaxis), this is now the preferred first-line vasopressor.
Use Norepinephrine Drip calculator.
Milrinone (0.25–0.75 mcg/kg/min)
Milrinone is a phosphodiesterase inhibitor, which means it doesn't work through the usual catecholamine receptors. You get inotropy and vasodilation, and it drops pulmonary vascular resistance. This is a significant benefit.
Perfect for post-op cardiac kids with a weak heart and stiff lungs. Also invaluable if the kid has pulmonary hypertension layered on top of heart failure.
Again, the vasodilation can drop systemic pressure, so pair it with a vasopressor if needed.
Use Milrinone Drip calculator.
The Vasoactive-Inotropic Score
VIS = Dopamine + Dobutamine + (100 × Epinephrine) + (100 × Norepinephrine) + (10 × Milrinone) + (10,000 × Vasopressin)
All catecholamine doses in mcg/kg/min, vasopressin in U/kg/min. This scores your total support load, weighting the potent vasopressors (epinephrine, norepinephrine) and vasopressin more heavily. Higher VIS = sicker, worse prognosis. It's useful for team communication, quality metrics, and research.
Use VIS Score calculator.
More importantly, trending it shows whether the kid is improving. VIS creeping up while you're optimizing the rest of the resuscitation means you're behind. Falling VIS, even if slowly, usually means recovery.
How to Combine Them
Septic shock with poor contractility: Start norepinephrine (the vasopressor), add low-dose dobutamine (inotropy) if the ejection fraction is bad.
Cardiogenic shock: Start dobutamine or milrinone (inotropy + vasodilation), add norepinephrine if the pressure tanks.
Post-op cardiac with pulmonary hypertension: Milrinone (drops both systemic and pulmonary resistance, improves contractility) plus vasopressor to hold pressure.
Practical Rules
Check in daily on whether the kid still needs all this. Wean it early if they're improving. The longer you run vasopressors, the higher the risk of arrhythmias, tachyphylaxis, and tissue ischemia.
Titrate to real endpoints: adequate BP for age, urine output >1 mL/kg/hr, lactate normalizing, perfusion improving. Don't chase supranormal pressures, that burns oxygen and doesn't improve outcomes.
All catecholamines and milrinone go through central lines. PIVs blow out from extravasation. Check lines obsessively.
Understand what each drug does. Match it to the physiology. Combine them thoughtfully. Wean them early. Titrate to physiology, not numbers.