A nurse is to administer naloxone 0.4 mg IV bolus to a client with opioid-induced respiratory depression. If the naloxone injection available is 0.2 mg/mL, how many mL should the nurse give?

To determine the correct volume in mL to administer for naloxone, it is essential to first understand the concentration of the naloxone available and the dosage required. The injection available has a concentration of 0.2 mg/mL, and the nurse needs to deliver a total dose of 0.4 mg.

To find the volume to administer, the formula used is:

Volume (mL) = Dose (mg) / Concentration (mg/mL).

Substituting the values into the formula:

Volume (mL) = 0.4 mg / 0.2 mg/mL = 2 mL.

This calculation shows that to achieve the required dose of 0.4 mg of naloxone, the nurse must administer 2 mL of the solution that has a concentration of 0.2 mg/mL. This is why the choice of 2 mL is the correct answer to the question.