The metered-dose inhaler (MDI) is a pressurized canister of medicine that releases a medicated mist. Your child inhales the mist into the airways of his lungs. Inhaled asthma medicines contain a gas that helps the medicine get into your lungs. Chlorofluorocarbon (CFC) depletes the ozone layer in our atmosphere. It has been replaced by hydrofluoroalkane (HFA). The medicine in HFA inhalers is the same as the medicine in CFC inhalers. It's the gas used to push the medicine out of the inhaler that is changing. The HFA inhaler looks just like a CFC inhaler, but is a little different. The spray comes out with less force, is warmer, and has a slightly different taste. It is not felt as much in the throat when inhaled, but you still get the right amount of medicine.

The MDI can be used alone, but it is highly recommended that your child use a spacer or valved holding device attached to the MDI.

Several different types of medicines are available as MDIs, including:

• bronchodilators (ProAir HFA, Proventil HFA, Ventolin HFA, or Maxair)
• inhaled steroids (Flovent, Pulmicort, Qvar)
• combination of long-acting bronchodilator and inhaled steroid ( ADVAIR HFA, Symbicort)
• cromolyn (Intal)
• ipratropium bromide (Atrovent).

When a child is using more than one type of MDI, he will usually use the bronchodilator first.

There are several ways to use an MDI. If your child is not using a spacer or valved holding device, the technique most often recommended is as follows:

1. Shake the MDI vigorously.
2. If the MDI has not been used before or if the MDI has not been used for a while, you must then "prime" the MDI. Do this by spraying several sprays of the medicine into the air. Each time you use the MDI, the next dose is drawn into a chamber inside the MDI. If the MDI has not been used or sits for a long time without being used, some of the medicine leaks out of the holding area. This means you will not get the full dose of medicine the next time it is used. Priming the MDI makes sure that you get the full dose of the medicine.
3. Hold the MDI upright so the mouthpiece is at the bottom.
4. The best way to use the MDI is to hold the mouthpiece 1-and-1/2 to 2 inches in front of an open mouth (about 2 to 3 finger widths). This method helps keep medicine from ending up in your child's mouth, which may cause increased side effects. It also helps medicine to reach your child's lungs rather than the back of his throat. If the open mouth technique is too difficult, you may also place the MDI mouthpiece directly into your child's mouth and have your child close his lips snugly around it. Talk with your provider or pharmacist about this.
5. Have your child breathe out normally.
6. Press the MDI down once so it releases a spray of medicine into the mouth while your child breathes in slowly. (One spray is often called a puff.)
7. Have your child continue breathing in as slowly and deeply as possible.
8. Have your child hold his breath for 10 seconds or as long as is comfortable (this gives the medicine time to reach the airways).
9. Have your child breathe out slowly.
10. After your child takes a few normal breaths, repeat steps 1 through 8 for another inhalation (puff) if required. Take the number of puffs prescribed by your healthcare provider.
11. If your child is taking a inhaled steroid medicine, have him rinse his mouth and spit out the water after the last dose is taken.