WGU HESI Dosage Calculation – Complete Practice Questions with Step-by-Step Answers for Medication Math Mastery

Wgu Hesi dosage calculation
Question 1:

The healthcare provider prescribes a loading dose of digoxin 0.6 mg intravenously (IV)
for a client with heart failure (HF). The nurse obtains digoxin Injection 500 mcg in 2 mL
vial from the electronic medication system. How many mL should the nurse administer?
(Enter numeric value only. If rounding is required, round to the nearest tenth.)

Explanation

Correct Answer (mL) : 1.2

Solution

Here's the breakdown of the calculation:

Convert the prescribed dose to milligrams (mg):

We are given the dose in mcg (micrograms). To match the concentration of the
medication (mg/mL), we need to convert mcg to mg.

Conversion factor: 1 mg = 1000 mcg

Dose (mg) = Prescribed dose (mcg) / Conversion factor

Dose (mg) = 0.6 mg / 1000 mcg/mg

Dose (mg) = 0.0006 mg (convert to mg for easier calculation)

Calculate the volume to administer:

We know the dose (mg) and the concentration (mg/mL) of the medication in the vial.

Volume (mL) = Dose (mg) / Concentration (mg/mL)

Volume (mL) = 0.0006 mg / (500 mcg/mL) (convert mcg/mL to mg/mL for consistency)

Volume (mL) = 0.0006 mg / (0.5 mg/mL)

Volume (mL) = 0.0012 mL (round to one decimal place as appropriate for medication
administration)

Adjust for unit size:

The medication vial contains 2 mL, and we calculated a volume of 0.0012 mL.

,However, it's not possible or safe to administer such a small fraction of the vial content.

In practice, the nurse would need to administer the smallest measurable volume
possible using this specific vial.

Since the vial contains 2 mL, 1.2 mL is the lowest whole number volume that can be
accurately measured and administered from this vial.

Therefore, while the calculated dose based on the prescribed amount is 0.0012 mL, the
nurse should administer 1.2 mL from the available 2 mL vial.



Question 2:

The healthcare provider prescribes enoxaparin 1 mg/kg SUBQ every 12 hours for a client
who weighs 132 pounds. The medication is available in 60 mg/0.6 mL prefilled syringe.
How many mL should the nurse administer per day? (Enter numerical value only.)

Explanation

Correct Answer (mL) : 1.20

Solution

First, we need to convert the client’s weight from pounds to kilograms since the dosage
is prescribed in mg/kg. We know that 1 kg is approximately 2.20462 pounds. So,

Weight in kg = Weight in pounds / 2.20462 = 132/ 2.20462 ≈ 59.87kg

The prescribed dosage is 1 mg/kg every 12 hours, so the total daily dosage (for 24
hours) in mg would be:

Daily dosage in mg= 2 × (Dosage per kg × Weight in kg) = 2 × (1mg/kg × 59.87kg) ≈
119.74mg

The medication is available in a concentration of 60 mg/0.6 mL, which simplifies to 100
mg/mL. Therefore, the volume to be administered per day in mL would be:

Volume in mL=Daily dosage in mg/ Concentration in mg/mL = 119.74mg / 100mg/mL ≈
1.20mL

So, the nurse should administer approximately 1.20 mL of enoxaparin per day. Always
consult with a healthcare professional for accurate information.

Question 3:

,The healthcare provider prescribes 2 L of 5% dextrose in water (DW).IV to infuse in 24
hours. The IV administration set delivers 15 gtt/mL. How many gtt/min should the nurse
regulate the infusion? (Enter numerical value only. If rounding is required, round to the
nearest whole number.)

Explanation

Correct Answer (gtt/min) : 21

Solution

Here's how to calculate the infusion rate (gtt/min) for the nurse to regulate:

1. We know:

Total volume of D5W solution: 2 L (liters)

Infusion time: 24 hours

IV administration set gtt/mL: 15 gtt/mL

2. We need to find the infusion rate in gtt/min.

Steps:

a. Convert liters to milliliters (mL) for better calculation:

1 liter = 1000 mL

Total volume (mL) = 2 L * 1000 mL/L

Total volume (mL) = 2000 mL

b. Convert infusion time from hours to minutes:

Infusion time (minutes) = Infusion time (hours) x Minutes per hour

Infusion time (minutes) = 24 hours * 60 minutes/hour

Infusion time (minutes) = 1440 minutes

c. Calculate the total volume of solution to be infused per minute:

Volume rate (mL/min) = Total volume (mL) / Infusion time (minutes)

Volume rate (mL/min) = 2000 mL / 1440 minutes

, Volume rate (mL/min) = 1.389 mL/min (round to nearest hundredth)

d. Finally, calculate the infusion rate in gtt/min:

Infusion rate (gtt/min) = Volume rate (mL/min) x gtt/mL

Infusion rate (gtt/min) = 1.389 mL/min * 15 gtt/mL

Infusion rate (gtt/min) = 20.835 gtt/min (round to nearest whole number as requested)

Therefore, the nurse should regulate the infusion at approximately 21 gtt/min



Question 4:

A client receives a prescription for oxytocin 2 milliunits/min intravenously (IV) for labor
augmentation. The IV bag contains oxytocin 20 units in lactated Ringer's 1 liter. How
many mL/hour should the nurse program the infusion pump to deliver? (Enter numerical
value only.)

Explanation

Correct Answer (mL/hour) : 6

Solution

Here's why the answer is closer to 6 mL/hour and not 6000 mL/hour:

Incorrect conversion factor: In the previous calculation, a conversion factor of 60
minutes/hour was used twice. This resulted in a significant inflation of the volume.

Milliunits vs. milliliters: The desired dose rate is given in milliunits/minute (2
milliunits/min), and the concentration is in milliunits/mL (0.02 milliunits/mL). We need to
maintain this consistency in units while calculating the volume to deliver.

Here's the corrected calculation:

Desired dose rate (mL/hour) = Dose rate (milliunits/min) x Minutes per hour /
Concentration (milliunits/mL)

Desired dose rate (mL/hour) = 2 milliunits/min x 60 minutes/hour / 0.02 milliunits/mL

Without the unnecessary multiplication by 60 again:

Desired dose rate (mL/hour) = 2 x .02