Question 32 of 46

That response is correct.

The vasoconstrictor lowered the pH of the solution in the cartridge down to 3.3 - 4.0, thus making it more acidic and more likely to create a burning sensation upon injection.

When a vasoconstrictor is present in an anesthetic solution, the preservative sodium bisulfite is frequently used to prevent the biodegration of the vasoconstrictor by oxygen. If oxygen is present in the cartridge, the sodium bisulfite will react with it before it can destroy the vasoconstrictor. This creates sodium bisulfate that has an even lower pH and will cause the burning sensation.

To avoid this from occurring, use only fresh cartridges - avoid using older cartridges when using a vasoconstrictor.