What is injected into the cricothyroid membrane during a percutaneous transtracheal wash?

The correct answer is 0.5-1 ml of lidocaine, which is injected into the cricothyroid membrane during a percutaneous transtracheal wash to provide local anesthesia. Administering lidocaine in this area helps minimize discomfort and facilitates the procedure, allowing for easier access to the trachea for washing and sampling of respiratory secretions.

Using lidocaine is critical in ensuring that the patient remains calm and still during the procedure, as well as reducing any potential anxiety associated with invasive techniques. The specified volume helps create a localized effect, making the area numb without flooding it, which could complicate the procedure or lead to additional complications.

Other options, such as adrenaline or saline, do not serve the same purpose in this context. Adrenaline, while it can be used in medical procedures to reduce bleeding, is not appropriate for local anesthesia in this scenario. Saline may be used in other medical contexts, such as to flush out or hydrate tissues, but it does not provide the necessary anesthetic effect for this type of procedure.