A physician ordered magnesium sulfate 2 grams per hour for a maintenance dose. There are 40 grams of magnesium sulfate in 1 liter of lactated Ringers solution.
What is the rate per hour to administer the maintenance dose?
10 mL/hr
25 mL/hr
50 mL/hr
100 mL/hr
100 mL/hr
The Correct Answer is C
the correct rate to administer the maintenance dose is 50 mL/hr.
Step 1: Determine the concentration of magnesium sulfate in the solution.
- There are 40 grams of magnesium sulfate in 1 liter of solution.
- 1 liter = 1000 mL.
Step 2: Calculate the concentration in grams per mL.
- 40 grams ÷ 1000 mL = 0.04 grams per mL.
- Result: 0.04 grams per mL.
Step 3: Determine the required dose per hour.
- The physician ordered 2 grams per hour.
Step 4: Calculate the volume of solution needed to provide 2 grams of magnesium sulfate.
- Required dose (2 grams) ÷ concentration (0.04 grams per mL) = volume in mL.
- 2 grams ÷ 0.04 grams per mL = 50 mL.
- Result: 50 mL.
- The calculated rate is 50 mL/hr.
the correct rate to administer the maintenance dose is 50 mL/hr.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
The dose of the medicine per day is 1.8 mcg.
This answer is correct because it is based on a simple multiplication calculation. The nurse should follow these steps to calculate the dose of the medicine per day:
1) Divide 24 hours by the frequency of the dose to get the number of doses per day, as follows:
24 / 4 = 6
Therefore, the client will receive 6 doses of the medicine per day.
2) Multiply the number of doses per day by the amount of each dose to get the total dose per day, as follows:
6 x 0.3 mcg = 1.8 mcg
Therefore, the dose of the medicine per day is 1.8 mcg.
Correct Answer is D
Explanation
To find the amount of solution to draw for one dose, you need to calculate the following:
- The body surface area (BSA) of the client in square meters (m²) using the formula: BSA (m²) = √(Height (cm) x Weight (kg) / 3600)
- The dose of allopurinol in milligrams (mg) using the formula: Dose (mg) = BSA (m²) x Prescribed dose
(mg/m²)
- The volume of solution in milliliters (mL) using the formula: Volume (mL) = Dose (mg) / Concentration (mg/mL)
First, use the formula for BSA to find the client's body surface area in square meters:
BSA (m²) = √(Height (cm) x Weight (kg) / 3600)
Since the client's height is 148 cm and weight is 55 kg, plug in these values into the formula:
BSA (m²) = √(148 cm x 55 kg / 3600)
Simplify and solve for the BSA:
BSA (m²) = 1.41 m²
Next, use the formula for dose to find the amount of allopurinol in milligrams:
Dose (mg) = BSA (m²) x Prescribed dose (mg/m²)
Since the client's BSA is 1.41 m² and the prescribed dose is 115 mg/m², plug in these values into the formula:
Dose (mg) = 1.41 m² x 115 mg/m²
Simplify and solve for the dose:
Dose (mg) = 162.15 mg
Then, use the formula for volume to find the amount of solution in milliliters:
Volume (mL) = Dose (mg) / Concentration (mg/mL)
Since the dose is 162.15 mg and the concentration is 25 mg/mL, plug in these values into the formula:
Volume (mL) = 162.15 mg / 25 mg/mL
Simplify and solve for the volume:
Volume (mL) = 6.486 mL
Therefore, the nurse should draw **6.486 mL** of solution for one dose of allopurinol.

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