Welcome back to our drug calculation series. In the primary two parts, we reviewed two common calculation methods – universal formula and dimensional evaluation (DA). In Part 3, we used DA to calculate continuous intravenous (IV) drips, starting with units per hour (u/h). In this blog, we are going to now use the DA method to calculate continuous IV drips in micrograms per minute (mcg/min). Don’t forget that each nurse ought to be comfortable using basic metric conversions. You’ll discover a useful conversion chart in our Nursing Pocket Chart: Common Calculations.

Intravenous drops: Convert ml/hour to mcg/min

You receive a shift report that your patient is receiving a nitroglycerin drip to regulate his blood pressure. You check the pump, which operates at a capability of 6 ml/hour. The label on the bottle states 50 mg in 500 ml of 0.9% sodium chloride solution. How many mcg/min does the patient receive?

Step 1: What label is required? Nitroglycerin is run by continuous drip at a dose of mcg/min. This is placed on the left side of the equation.

Step 2: Then we’d like to convert the concentration from mg/ml to mcg/ml to get the identical label within the meter. There are 50 mg in 500 ml. Convert mg to mcg by multiplying by 1000.
The concentration is there.

Step 3: Place the identical label within the numerator on the fitting side of the equation, then alternate the labels within the numerator and denominator in order that the labels cancel out.

Step 4: Multiply the numerators, multiply the denominators, after which divide the numerator by the denominator.

Intravenous drops: Convert mcg/min to mL/hour

Now let’s reverse the issue and convert mcg/min to search out the pump rate ml/h.
The provider places an order for a nitroglycerin drip at a dose of 10 mcg/minute. The pharmacy provides an infusion bag with nitroglycerin, and the label on the bottle states that it accommodates 50 mg in 500 ml of 0.9% sodium chloride solution. What speed should the IV pump be set to?

Step 1: What label is required? You wish to set your IV pump to ml/hour. This is placed on the left side of the equation.

Steps 2: Next, we’d like to convert the concentration from mg/ml to mcg/mL. There are 50 mg in 500 ml. Convert mg to mcg by multiplying by 1000.
The concentration is there.

Step 3: Place the identical label within the numerator on the fitting side of the equation. Reverse the concentration in order that ml is within the numerator and 100 mcg is within the denominator. Then alternate the labels within the numerator and denominator in order that the labels cancel out.

Step 4: Multiply the numerators, multiply the denominators, after which divide the numerator by the denominator.

Remember the following pointers:

• Check in case your answer makes clinical sense.
• Check your work rigorously.
• Ask a colleague or pharmacist to envision your work.
• Knowledge of general therapeutic doses of commonly used drugs

I hope this review was helpful. Next month, we are going to review continuous intravenous infusion of weight-based medications (µg/kg/min) using dimensional evaluation. Be sure to envision back!

Cookson, K. L. (2013). Dimensional evaluation: Calculate doses the straightforward way. , (6), 57-62.
Koharchik, L. S., and Hardy, E. C. (2013). Easy as 1, 2, 3! Dose calculations. , (1), 25 – 29.
Wilson, K. M. (2013). A fast guide for the nurse to calculate IV medication dosage. (2), 1 – 2.