A child weighs 39 lbs (about 17.7 kg). Using a conservative maximum dose of 4.4 mg/kg for 2% lidocaine with 1:100,000 epinephrine, what is the maximum number of standard 1.8 mL carpules that can be safely administered?

Step by step: 39 lb ÷ 2.2 = ~17.7 kg. Max dose = 17.7 kg × 4.4 mg/kg ≈ 78 mg. Each 1.8 mL carpule of 2% lidocaine contains 36 mg (2% = 20 mg/mL × 1.8 mL). 78 mg ÷ 36 mg/carpule ≈ 2.16 carpules — round DOWN for safety, giving a maximum of 2 full carpules. Always show your work on these calculation questions, and remember the absolute (not just per-kg) maximum dose ceiling also applies.