A nurse is preparing to administer ketorolac 0.4 mg/kg IM to an adolescent who weighs 96.8 Ib. The amount available is ketorolac 15 mg/mL. How many mL should the nurse administer? (Round the answer to the nearest tenth. Use a leading zero if it applies. Do not use a trailing zero.)
The Correct Answer and Explanation is:
To solve this problem, we will go step by step to determine how many milliliters of ketorolac the nurse should administer based on the given dosage and the adolescent’s weight.
Step 1: Convert the adolescent’s weight from pounds to kilograms.
Since the adolescent weighs 96.8 pounds (lb) and the conversion factor from pounds to kilograms is 1 kg = 2.2 lb, we divide the weight in pounds by 2.2 to convert to kilograms.
[
\text{Weight in kilograms} = \frac{96.8 \, \text{lb}}{2.2} = 44 \, \text{kg}
]
Step 2: Calculate the prescribed dosage in milligrams.
The prescribed dosage of ketorolac is 0.4 mg/kg. To determine the total dosage in milligrams, multiply the weight in kilograms by the dosage per kilogram.
[
\text{Dosage in mg} = 0.4 \, \text{mg/kg} \times 44 \, \text{kg} = 17.6 \, \text{mg}
]
Step 3: Determine the volume of medication to administer.
The medication available is ketorolac 15 mg/mL. This means that every 1 mL of the solution contains 15 mg of ketorolac. To determine how many milliliters to administer, divide the total prescribed dosage by the concentration of the solution (15 mg/mL).
[
\text{Volume in mL} = \frac{17.6 \, \text{mg}}{15 \, \text{mg/mL}} = 1.173 \, \text{mL}
]
Step 4: Round the answer to the nearest tenth.
When rounding 1.173 mL to the nearest tenth, the answer is 1.2 mL.
Final Answer:
The nurse should administer 1.2 mL of ketorolac.
Explanation:
The calculation follows a standard procedure used in medication dosage determination, particularly in pediatrics, where weight-based dosing is common. First, the adolescent’s weight was converted from pounds to kilograms to fit the 0.4 mg/kg dosage requirement. The total dose of 17.6 mg was calculated, and this was divided by the concentration of the ketorolac solution (15 mg/mL) to determine the volume to administer. Rounding to the nearest tenth ensures accuracy without excessive precision that is unnecessary for the clinical setting.