How many cartridges of 1:200,000 epinephrine dilution could a patient safely receive based on the cardiac dose?

The correct answer reflects the safety threshold regarding the maximum dose of epinephrine that a patient with normal cardiac health can receive. The cardiac dose of epinephrine is typically established at about 0.2 mg for healthy adults.

In a solution of 1:200,000 epinephrine, there is 0.005 mg of epinephrine in each milliliter of solution. A cartridge of local anesthetic generally contains 1.8 mL, which would mean each cartridge has approximately 0.009 mg of epinephrine (0.005 mg/mL * 1.8 mL).

To determine how many cartridges can be safely used without exceeding the maximum cardiac dose of 0.2 mg, you would divide 0.2 mg by the amount of epinephrine per cartridge:

0.2 mg (max dose) ÷ 0.009 mg (epinephrine per cartridge) = approximately 22.22 cartridges.

However, this is the theoretical maximum for someone without cardiovascular issues. When considering practical application and for various safety guidelines in clinical practice, the limit is often kept lower. Therefore, 4.4 cartridges allows a margin of safety that is commonly accepted in dentistry, which