A physician orders Garamycin (gentamicin) 4 mg/kg/dose IV piggyback every 12 hours for a newborn weighing 7 lb, 11.2 oz. After reconstitution, the dosage is 20 mg/10 mL.
How many milliliters should the nurse administer to the patient?
1.4 mL
14 mL
7 mL
0.7 mL
0.7 mL
The Correct Answer is C
To answer this question, the nurse needs to perform the following steps:
1) Convert the patient's weight from pounds and ounces to kilograms, using the conversion factor of 1 pound = 0.45359237 kilograms¹². To do this, first convert the ounces to a fraction of a pound by dividing by 16, then add this fraction to the pounds, and then multiply by the conversion factor. For example:
7 lb, 11.2 oz = 7 + (11.2 / 16) lb
= 7.7 lb
= 7.7 × 0.45359237 kg
= 3.492 kg
2) Calculate the dose of Garamycin in milligrams, using the prescribed dose of 4 mg/kg and the patient's weight in kilograms. To do this, simply multiply the dose per kilogram by the weight in kilograms. For example:
4 mg/kg × 3.492 kg = 13.968 mg
3) Calculate the volume of Garamycin in milliliters, using the reconstituted dosage of 20 mg/10 mL and the dose in milligrams. To do this, use a proportion to find the unknown volume that corresponds to the known dose. For example:
20 mg / 10 mL = 13.968 mg / x mL Cross-multiply and solve for x: 20x = 139.68
x = 6.984 mL
x =7 mL
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Related Questions
Correct Answer is C
Explanation
To find the milliliters per hour, you need to calculate the following:
- The patient's weight in kilograms
- The dose of Principen in milligrams
- The infusion rate in milliliters per hour using the formula: Infusion rate (mL/h) = (Total volume (mL) x Flow factor (gt/mL)) / Time (min) x 60 min/h
First, convert the patient's weight from pounds to kilograms by dividing by 2.2:
22 lb / 2.2 = 10 kg
Next, multiply the patient's weight by the dose of Principen per kilogram to get the total dose in milligrams:
10 kg x 25 mg/kg = 250 mg
Then, use the formula for infusion rate to find how many milliliters per hour the IV pump should deliver:
Infusion rate (mL/h) = (Total volume (mL) x Flow factor (gt/mL)) / Time (min) x 60 min/h
Since the medication is prepared in 50 mL of solution and the infusion time is 30 minutes, plug in these values into the formula:
Infusion rate (mL/h) = (50 mL x 1 gt/mL) / 30 min x 60 min/h
Simplify and solve for the infusion rate:
Infusion rate (mL/h) = 100 mL/h
Therefore, the nurse should administer **100 mL/h** to infuse Principen 250 mg over 30 minutes.

Correct Answer is B
Explanation
To find the rate in mL/hr, you need to use the formula for infusion rate:
Infusion rate (mL/h) = Total volume (mL) / Time (h)
Since the total volume is 500 mL and the time is 2 hours, plug in these values into the formula:
Infusion rate (mL/h) = 500 mL / 2 h
Simplify and solve for the infusion rate:
Infusion rate (mL/h) = 250 mL/h
Therefore, the nurse should set the IV pump to deliver **250 mL/h** to infuse LR 500 mL over 2 hours.
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