What is the primary function of a vented needle?

The primary function of a vented needle is to vent powders during reconstitution. When reconstituting powdered medications, particularly in a vial, a vented needle allows air to enter the vial as the liquid is drawn in. This process prevents a vacuum from forming inside the vial, which could hinder the flow of the liquid and make it difficult to draw the correct volume. By facilitating airflow, a vented needle ensures that the reconstitution process is efficient and effective, allowing for the proper mixing of the powdered medication with the liquid.

Other choices address different functions. Storing sterile medications typically involves using appropriate containers rather than a needle. Airflow in hoods is managed by the design of the hood itself, not by a vented needle. While extracting liquid from ampules could be done with a regular needle, it does not specifically require a vented needle, as ampules are typically designed to allow liquid to flow freely for extraction.