Noradrenaline Infusion Rate Calculator
Required Pump Setting
0.00 ml/hr
How to Calculate Noradrenaline Infusion Rates
Noradrenaline (Norepinephrine) is a potent vasopressor commonly used in intensive care units (ICU) and emergency settings to treat severe hypotension and shock. Accurate calculation of the infusion rate is critical for patient safety, as small errors in dosage can lead to significant hemodynamic instability.
Clinical Disclaimer: This calculator is for educational and verification purposes only. Always double-check calculations with your institution's protocols and smart pump drug libraries before administering medication.
The Calculation Formula
To determine the flow rate in milliliters per hour (ml/hr) for an infusion pump, you must integrate the patient's weight, the prescribed dose, and the concentration of the prepared solution. The calculation involves three main steps:
Step 1: Calculate Total Concentration
Concentration (mcg/ml) = (Drug Amount in mg × 1000) / Total Volume in ml
Concentration (mcg/ml) = (Drug Amount in mg × 1000) / Total Volume in ml
Step 2: Calculate Required Dose per Minute
Total Dose (mcg/min) = Patient Weight (kg) × Target Dose (mcg/kg/min)
Total Dose (mcg/min) = Patient Weight (kg) × Target Dose (mcg/kg/min)
Step 3: Calculate Infusion Rate
Rate (ml/hr) = (Total Dose (mcg/min) × 60) / Concentration (mcg/ml)
Rate (ml/hr) = (Total Dose (mcg/min) × 60) / Concentration (mcg/ml)
Understanding the Variables
- Patient Weight (kg): The actual or ideal body weight of the patient, depending on your hospital's protocol for vasoactive drugs.
- Target Dose (mcg/kg/min): The specific amount of drug ordered by the physician. Typical starting doses often range from 0.01 to 0.05 mcg/kg/min, titrated to mean arterial pressure (MAP).
- Drug Amount (mg): The total mass of Noradrenaline added to the infusion bag or syringe. Common preparations include 4mg, 8mg, or 16mg.
- Total Volume (ml): The final volume of the solution (diluent + drug). Common volumes are 50ml (syringe driver) or 250ml (infusion bag).
Common Preparation Examples
Standardizing concentrations helps reduce medication errors. Here are frequent preparations used in clinical practice:
- Single Strength (4mg in 50ml): Concentration = 80 mcg/ml.
- Double Strength (8mg in 50ml): Concentration = 160 mcg/ml. Used for patients requiring higher doses to minimize fluid intake.
- Quad Strength (16mg in 50ml): Concentration = 320 mcg/ml. Reserved for cases of profound shock where fluid restriction is paramount.
Clinical Tips for Titration
When managing a Noradrenaline infusion, the goal is usually to maintain a Mean Arterial Pressure (MAP) > 65 mmHg. Titration should be done in small increments (e.g., 0.02 – 0.05 mcg/kg/min) every few minutes until the target hemodynamic parameters are met. Always monitor peripheral perfusion and urine output as indicators of end-organ perfusion.