The Drip Rate Formula
Drops per minute equals the volume to be infused times the drop factor, divided by the time in minutes. A macrodrip set typically delivers 10 or 15 gtts/mL, while a microdrip set delivers 60 gtts/mL. Always confirm the drop factor on the packaging.
Worked Example
To infuse 1,000 mL over 4 hours with a 10 gtts/mL set, multiply 1,000 by 10 to get 10,000, then divide by 240 minutes. The answer is about 42 gtts per minute. With a microdrip set, the drops per minute in mL/hr equals the mL/hr rate.
Medication Infusions
For a dopamine drip, first calculate the dose in mcg/min or mcg/kg/min, convert to mg if needed, then divide by the concentration. Take your time and estimate to see if the answer is plausible. Verify with your partner before starting any infusion.