Heparin IV Drip Rate Calculator
How to Calculate Heparin Infusion Rates
Heparin is a critical anticoagulant medication that requires precise dosing to ensure patient safety and therapeutic efficacy. In clinical settings, heparin is most commonly delivered via a continuous intravenous (IV) infusion. The infusion rate is typically measured in mL/hr, while the dose is ordered in Units/hr or Units/kg/hr.
The Mathematical Formula
To determine the infusion rate, you must first calculate the concentration of the medication in the IV bag and then determine the total units required per hour.
- Concentration: Total Units in Bag / Total Volume in Bag = Units per mL
- Total Hourly Dose: Dose Rate (Units/kg/hr) × Patient Weight (kg) = Units per hour
- Infusion Rate: Total Hourly Dose / Concentration = mL per hour
A patient weighing 80 kg is ordered heparin at 18 Units/kg/hr. The pharmacy provides a bag containing 25,000 Units of Heparin in 250 mL of D5W.
1. Concentration = 25,000 Units / 250 mL = 100 Units/mL.
2. Hourly Dose = 18 Units/kg/hr × 80 kg = 1,440 Units/hr.
3. Rate = 1,440 Units/hr / 100 Units/mL = 14.4 mL/hr.
Standard Heparin Concentrations
While concentrations can vary, the most common "standard" concentration used in many hospitals is 25,000 Units in 250 mL (100 Units/mL) or 25,000 Units in 500 mL (50 Units/mL). Always verify the concentration on the physical IV bag before starting an infusion.
Safety Considerations
Heparin is considered a high-alert medication. Errors in calculation can lead to significant bleeding or therapeutic failure (clotting). Most healthcare facilities require a "double-check" where two registered nurses independently calculate the rate and verify the pump settings against the order and the patient's weight.