The Client Who Regularly Uses a Metered-Dose Inhaler Four Times

The client who regularly uses a metered-dose inhaler four times a day tells the nurse that it is difficult to tell when the canister is empty. What instruction should the nurse give this client?

A) Place the canister in a bowl of water. If the canister floats, it is not empty.
B) You can tell that the canister is empty when you can no longer smell the medication when you activate the plunger.
C) When you feel like you are no longer getting maximum effect from the medication, your canister is empty.
D) When you get a new canister, divide the number of puffs that is listed on the label by four. That will tell you how many days the canister will last.