Dose to gtt/min Calculator

lb or kg Enable for mcg/kg/min and related drugs.

Calibration

Drug

Ordered units

Available units

Ordered dose

Available dose

Ordered method

Available volume

Results

The purpose of this page illustrates the administration of critical care medications in a field setting where IV pumps are inaccessible such as in combat.

Dose to gtt/min Formula

First convert units if necessary. Available and ordered units must match. This is true with lidocaine and diltiazem but not so with nitroglycerin and dopamine. Available units in nitrogycerin must be converted from milligrams to micrograms:

A × 1,000 mcg

A = Dose available

Next, use the dose formula to calculate rate.

\frac{O \times V \times C}{A}

O = Dose ordered
V = Volume of dose available
C = Calibration
A = Dose available

Dose/kg to gtt/min Formula

First, convert available units to match ordered units if necessary. Next, use the dose formula to calculate rate.

\frac{O \times W \times V \times C}{A}

O = Dose ordered
W = Weight in Kilograms
V = Volume of dose available
C = Calibration
A = Dose available

Examples

Example 1. A patient remains hypotensive despite repeated fluid boluses. Epinephrine is ordered at 2 micrograms/minute (mcg/min). A 1:1,000 (1 mg/mL) vial of epinephrine is added to 250 mL of NS attached to 60 gtt/min tubing. Calculate the drops/min (gtt/min).

First, convert milligrams to micrograms.

Dose available = 1 milligram (mg)

1 mg × 1,000 mcg

Next, use the dose formula to calculate rate.

Dose ordered = 2
Volume = 250 mL
Calibration = 60
Dose available = 1000 mcg

\frac{2 \times 250 \times 60}{1000 mcg}

The answer is 30 gtt/min.

Example 2. Start Dopamine at 5 mcg/kg/min on a patient weighing 100 kilograms. Four hundred milligrams of dopamine has been mixed in 500 mL NS. Calculate the drops per minute.

First, convert milligrams to micrograms.

Dose available = 400 mg

400 × 1,000 mcg = 400,000 mcg

Next, use the dose formula to calculate rate.

Dose ordered = 5
Weight = 100 kg
Volume = 500 mL
Calibration = 60
Dose available = 400000 mcg

\frac{5 \times 100 \times 500 \times 60}{400000 mcg}

The answer is 37.5 gtt/min.

References

Gage, C. B., & Toney-Butler, T. J. (2017). Dose Calculation.