Which statement best describes when air is injected into a vial before drawing medication?

Which statement best describes when air is injected into a vial before drawing medication?

• A. To lubricate the needle
• B. To prevent the vacuum as medication is drawn
• C. To mix the contents
• D. To sterilize the vial

Answer: (B)

Injecting a small amount of air into a vial before drawing medication is about equalizing pressure. When you remove liquid from a sealed vial, the remaining contents can create a slight vacuum that makes it harder to withdraw the rest of the dose or causes inconsistent flow. By introducing air into the vial, you equalize the pressure with the surrounding atmosphere, allowing the medication to be drawn smoothly and to the correct volume. This step doesn’t serve to lubricate the needle, mix the contents, or sterilize the vial. (And remember to expel any excess air from the syringe before administration, especially if giving intravenously.)

Injecting a small amount of air into a vial before drawing medication is about equalizing pressure. When you remove liquid from a sealed vial, the remaining contents can create a slight vacuum that makes it harder to withdraw the rest of the dose or causes inconsistent flow. By introducing air into the vial, you equalize the pressure with the surrounding atmosphere, allowing the medication to be drawn smoothly and to the correct volume. This step doesn’t serve to lubricate the needle, mix the contents, or sterilize the vial. (And remember to expel any excess air from the syringe before administration, especially if giving intravenously.)