Dopamine Infusion Rate Calculator
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Drug Concentration:
0 mcg/mL
Total Dose Required:
0 mcg/min
Infusion Pump Rate:
0 mL/hr
*Verify all calculations with a colleague or pharmacist before administration. This tool is for educational verification purposes only.
Understanding Dopamine Infusion Calculations
Dopamine is a catecholamine used in critical care settings to treat hypotension (low blood pressure), shock, and low cardiac output. Because dopamine is a high-alert medication, calculating the infusion rate accurately is vital for patient safety. This calculator helps medical professionals, nursing students, and critical care staff determine the correct pump settings based on the ordered dosage, patient weight, and IV bag concentration.
Standard Concentration: Commonly, dopamine is premixed as 400 mg in 250 mL D5W (1600 mcg/mL) or 800 mg in 250 mL D5W (3200 mcg/mL). Always verify the bag concentration before calculating.
The Infusion Rate Formula
To calculate the rate in milliliters per hour (mL/hr) for an infusion pump, you must integrate the patient's weight-based requirement with the concentration of the drug available. The calculation involves three steps:
- Determine the Total Dose per Minute: Multiply the patient's weight (kg) by the ordered dose (mcg/kg/min).
Example: 70 kg × 5 mcg/kg/min = 350 mcg/min. - Determine the Concentration: Convert the total milligrams in the bag to micrograms (x1000) and divide by the total volume (mL).
Example: (400 mg × 1000) ÷ 250 mL = 1600 mcg/mL. - Calculate the Hourly Rate: Multiply the total dose per minute by 60 (to get dose per hour), then divide by the concentration.
Example: (350 mcg/min × 60) ÷ 1600 mcg/mL = 13.1 mL/hr.
Dopamine Dosage Ranges and Effects
Dopamine exhibits dose-dependent pharmacokinetics, meaning its effect on the body changes based on the rate of infusion. While individual responses vary, the general clinical guidelines are:
- Low Dose (1-3 mcg/kg/min): Often referred to as "Renal Dose." It primarily stimulates dopaminergic receptors, potentially increasing renal blood flow and urine output, though clinical evidence for renal protection is debated.
- Moderate Dose (3-10 mcg/kg/min): Often referred to as "Cardiac Dose." It stimulates Beta-1 adrenergic receptors, increasing cardiac contractility (inotropism) and heart rate (chronotropism), thereby increasing cardiac output.
- High Dose (10-20 mcg/kg/min): Often referred to as "Vasopressor Dose." It stimulates Alpha-adrenergic receptors, causing systemic vasoconstriction and significantly increasing blood pressure and systemic vascular resistance (SVR).
Safety Precautions for IV Administration
When administering dopamine via continuous IV infusion, adhere to the following safety protocols:
- Central Line Preference: Dopamine is a vesicant. Extravasation can cause severe tissue necrosis. Administration via a central venous catheter is strongly preferred. If a peripheral line must be used, monitor the site frequently for signs of infiltration.
- Weaning: Never stop dopamine abruptly. It must be titrated down gradually to prevent acute hypotension.
- Volume Status: Hypovolemia should ideally be corrected with fluids before or concurrently with starting dopamine therapy to ensure effectiveness.
- Incompatibilities: Dopamine is sensitive to alkaline solutions. Do not mix with sodium bicarbonate in the same line.
Example Scenario
A patient weighing 80 kg is in septic shock. The physician orders Dopamine at 10 mcg/kg/min. The pharmacy sends a standard bag containing 400 mg of Dopamine in 250 mL of D5W.
Using the logic above:
- Concentration: 400 mg = 400,000 mcg. 400,000 / 250 = 1600 mcg/mL.
- Patient Requirement: 80 kg × 10 mcg/kg/min = 800 mcg/min.
- Pump Rate: (800 mcg/min × 60 min) / 1600 mcg/mL = 30 mL/hr.