Overview
ICU drip calculations combine weight-based dosing, concentration math, and unit conversions into multi-step problems. It sounds intimidating — but every single one of these problems follows the same pattern.
Once you learn the universal drip formula and understand how to calculate concentration, you can figure out the pump rate for any drip in the ICU. Let's break it down together.
The Universal Drip Formula
mL/hr = (Dose in mcg/kg/min x Weight in kg x 60) / Concentration in mcg/mL
This single formula works for dopamine, dobutamine, norepinephrine, nitroglycerin, nitroprusside, milrinone, and most other mcg/kg/min drips. Memorize it.
Calculating Concentration
You need to know the concentration of your dopamine drip: 400 mg in 250 mL D5W.
Convert to matching units: 400 mg = 400,000 mcg Concentration = 400,000 mcg / 250 mL = 1,600 mcg/mL
1,600 mcg/mL. Always convert the drug amount to the same unit as the dose order before dividing.
Common ICU Drips Quick Reference
Dopamine: 400 mg/250 mL, start 2-5 mcg/kg/min, max 20 mcg/kg/min. Low dose (renal), medium dose (cardiac), high dose (vasopressor).
Dobutamine: 250 mg/250 mL, start 2.5 mcg/kg/min, max 20 mcg/kg/min. Inotrope — increases cardiac contractility.
Norepinephrine (Levophed): 4 mg/250 mL, start 0.1-0.5 mcg/kg/min, max 30 mcg/min. First-line vasopressor in septic shock.
Nitroglycerin: 50 mg/250 mL, start 5 mcg/min (not weight-based), max 200 mcg/min. Vasodilator for chest pain and heart failure.
Propofol: 10 mg/mL (premixed), start 5 mcg/kg/min. Titrate for sedation. Watch for propofol infusion syndrome with prolonged use.
Insulin: 100 units/100 mL NS (1 unit/mL), start per protocol. The 1:1 concentration means mL/hr = units/hr.
Titration Principles
Always titrate to a specific clinical goal — MAP > 65 for vasopressors, RASS score for sedation, blood glucose range for insulin. Document the current rate, dose, and clinical parameter every time you titrate. Know the maximum dose and alert the provider when you're approaching it. When weaning, reduce by the same increment you used to increase. Never abruptly stop a vasopressor — taper gradually.
Practice with NurseTally Calculators
Calculate any critical care drip rate accurately.