Question

Magnesium sulfate 30 grams is mixed in 500 mL LR. Order: infuse a maintenance dose of magnesium sulfate at 2.7grams/hour. How many mL/hr will the IV run? (Round the tenths if necessary)

a. 50
b. 100
c. 150
d. 200

Answer 1

To determine the IV rate for a 2.7 grams/hour dose of magnesium sulfate, divide the total volume of solution by the amount of solute to find the volume per gram, then multiply by the hourly dose. The calculation yields 45 mL/hour, which when rounded to the tenths, is 50 mL/hr.

Step-by-step explanation:

To calculate the rate at which the intravenous (IV) will run to administer magnesium sulfate at 2.7 grams per hour, we need to determine how many milliliters of the solution corresponds to the 2.7 grams of magnesium sulfate. We have a solution where 30 grams of magnesium sulfate is mixed in 500 mL of LR (Lactated Ringer's solution). This means that for every gram of magnesium sulfate, there are ⅓ mL of LR (÷ 30 grams = 16.67 mL/gram). Therefore, to infuse 2.7 grams per hour, the calculation is:

1. Calculate the volume per gram: 500 mL ÷ 30 grams = 16.67 mL/gram.
2. Multiply the volume per gram by the hourly dose: 16.67 mL/gram × 2.7 grams/hour = 45 mL/hour.

After performing these calculations, we find that the IV rate to administer 2.7 grams of magnesium sulfate per hour is 45 mL/hour, which rounded to the tenths is 50 mL/hr, corresponding to option (a).