A patient weighing 120 lbs can receive a maximum of how many cartridges of 2% lidocaine 1:100,000?

To determine the maximum number of cartridges of 2% lidocaine with a 1:100,000 epinephrine concentration that a patient can safely receive, we first need to calculate the patient's maximum dose based on their weight.

Lidocaine has a maximum safe dose of approximately 5 mg/kg for an adult. To convert the patient's weight from pounds to kilograms, we divide by 2.2:

120 lbs ÷ 2.2 = approximately 54.5 kg.

Next, we multiply the patient's weight in kilograms by the maximum dose per kilogram:

54.5 kg × 5 mg/kg = 272.5 mg.

Each cartridge of 2% lidocaine contains 36 mg of lidocaine (since 2% equates to 20 mg/mL in a 1.8 mL cartridge, leading to 2 mg/mL × 18 mL).

To find out how many cartridges can be administered without exceeding the maximum total dose, we divide the total allowable lidocaine dose by the amount of lidocaine in each cartridge:

272.5 mg ÷ 36 mg/cartridge = approximately 7.6 cartridges.

However, we must consider the presence of epinephrine in the lid