How many carpules of lidocaine 2% with 1:100k epi can a child weighing 42 lbs receive?

• A. 1 carpule
• B. 2 carpules
• C. 3 carpules
• D. 4 carpules

Answer: (B)

To determine the appropriate number of carpules of lidocaine 2% with 1:100,000 epinephrine that a child weighing 42 pounds can receive, it's important to consider the maximum safe dosage of lidocaine for pediatric patients.

The safe dosage of lidocaine can typically be calculated based on the child's weight. The general guideline for lidocaine is 5 mg/kg for a pediatric patient. Given that there are approximately 2.2 pounds in a kilogram, a child weighing 42 pounds is about 19 kg (42 lbs ÷ 2.2).

Next, applying the maximum dosage guideline:

5 mg/kg × 19 kg = 95 mg of lidocaine is the maximum recommended dose for this child.

A carpule of lidocaine 2% contains 36 mg of lidocaine (because 2% solution means 2 grams of lidocaine per 100 mL, and there are 1.8 mL in a standard carpule).

To find out how many carpules can be administered:

95 mg (maximum dose) ÷ 36 mg (per carpule) = approximately 2.64 carpules.

Rounding down to ensure safety, this leads to the conclusion that