Inhalers

What is a metered dose inhaler (MDI)?

Inhaled respiratory medications are often taken by using a device called a metered dose inhaler, or MDI. The MDI is a pressurized canister of medicine in a plastic holder with a mouthpiece. When sprayed, it gives a reliable, consistent dose of medication.

There are two methods for using an MDI. In many cases, the preferred method is with a device called a valved holding chamber (Figure 1). These devices attach to the MDI and hold the "spray" of medication. They make it easier to use the MDI and help get the medication into the lungs better. An MDI can also be used without a chamber (Figure 2). These methods are described below. Your healthcare professional will decide which method is most appropriate for you.

Priming: Priming (spraying one or more puffs into the air before use) assures that the inhaler is ready to use and will dispense the correct amount of medication. Priming varies between devices, so it is important to read the patient instructions that come with your medication.

Figure 1

Using an MDI with a valved holding chamber (Figure 1)

1. Remove the cap from the MDI and chamber. Shake well.
2. Insert the MDI into the open end of the chamber (opposite the mouthpiece).
3. Place the mouthpiece of the chamber between your teeth and seal your lips tightly around it.
4. Breathe out completely.
5. Press the canister once.
6. Breathe in slowly and completely through your mouth. If you hear a "horn-like" sound, you are breathing too quickly and need to slow down.
7. Hold your breath for 10 seconds (count to 10 slowly) to allow the medication to reach the airways of the lung.
8. Repeat the above steps for each puff ordered by your doctor. Wait about 1 minute in between puffs.
9. Replace the cap on your MDI when finished.
10. If you are using a corticosteroid MDI, rinse your mouth and gargle using water or mouthwash after each use. You should always use a chamber with a steroid MDI.

Figure 2

Using an MDI without a chamber (Figure 2)

1. Remove the cap from the MDI and shake well.
2. Breathe out all the way.
3. Place the mouthpiece of the inhaler between your teeth and seal your lips tightly around it.
4. As you start to breathe in slowly, press down on the canister one time.
5. Keep breathing in as slowly and deeply as you can. (It should take about 5 seconds for you to completely breathe in.)
6. Hold your breath for 10 seconds (count to 10 slowly) to allow the medication to reach the airways of the lung.
7. Repeat the above steps for each puff ordered by your doctor. Wait about 1 minute between puffs.
8. Replace the cap on the MDI when finished.
9. If you are using a corticosteroid MDI, you should use a valved holding chamber as described above.

Caring for your MDI and chamber

For most MDIs, remove the canister and rinse the plastic holder with warm running water once a week to prevent the holes from getting clogged. Shake well and let air dry. There are some medications in which the inhaler cannot be removed from the holder. These usually need to be cleaned by wiping the mouthpiece with a cloth or cleaning with a dry cotton swab. Refer to the patient instructions that come with your inhaler.

Clean the chamber about once a week. Remove the soft ring at the end of the chamber. Soak the spacer in warm water with a mild detergent. Carefully clean and, rinse, and shake off excess water. Do not hand dry. Allow to completely air dry. Do not store the chamber in a plastic bag.

Checking your MDI

It is important that you know how much medication is left in your inhaler. The number of puffs contained in your MDI is printed on the side of the canister. After you have used that number of puffs, you must discard your inhaler even if it continues to spray. Keep track of how many puffs you have used. You also must include priming puffs in this total.

If you use an MDI every day for control of symptoms, you can determine how long it will last by dividing the total number of puffs in the MDI by the total puffs you use every day. For example: 2 puffs x 2 times per day = 4 total puffs per day. At 120 puffs, the MDI will last 30 days.

If you use an inhaler only when you need to, you must keep track of how many times you spray the inhaler. Some of the newer MDIs have counting devices built in.

If your MDI does not have a dose counter, you can obtain a device that attaches to the MDI and counts down the number of puffs each time you press the inhaler. Ask your healthcare professional for more information about these devices, as well as how to best keep track of your medicine without an add-on device (if you prefer).