Using a Metered Dose Inhaler
Drugs Go Directly to the Lungs
Metered dose inhalers (MDIs) are used to treat asthma or other lung diseases. The inhalers deliver medication directly to the lungs, where it can be absorbed quickly and completely at the site where it is needed. MDIs are designed to deliver an exact amount, or metered dose, to the lungs each time they are used. A metered dose inhaler can be used alone or it may be attached to a spacer device before inhaling. A patient must understand exactly how to use the metered dose inhaler correctly; incorrect use will mean that medication is wasted and that the patient will not be helped. Patients must understand that they have to follow the instructions carefully each time they use the inhaler so that the right amount of drug will reach the lungs.
A metered dose inhaler (MDI) is used to deliver asthma medicine directly to the lungs, where it is absorbed quickly and completely at the site where it is needed.
How to Use an MDI Correctly
Many drugs used to treat asthma and other lung diseases are delivered directly to the lungs by a device known as a metered dose inhaler (MDI). The drug reaches the lungs faster than with oral medications, and it does not have to be absorbed from the gastrointestinal tract as do drugs that are swallowed. A smaller amount of drug can be used when it is inhaled because it is not “wasted” by traveling into other parts of the body. In addition, many drug side effects can be avoided. Metered dose inhalers can be used by almost every asthmatic patient. In order for an inhaled drug to be effective, however, the patient must learn to use the MDI correctly.
Spacing devices: A spacing device attached to the inhaler can be helpful for children, who often have trouble coordinating the pressing of the inhaler with a breathing-in motion. A spacer is actually a holding chamber that is attached to an inhaler. When the inhaler is pushed, the medication first goes into the spacer, and then is inhaled into the mouth. The spacer helps to direct the medicine past the tongue and back of the throat directly to the trachea. It also helps the patient to avoid coughing when inhaling the medicine. Spacers are especially useful with a steroid inhaler. If inhaled steroids such as triamcinolone or beclomethasone are deposited in the mouth or back of the throat, thrush can develop. Thrush is a painful fungal infection, with creamy white sore patches in the mouth or tongue, sore throat and hoarseness. Infection can be prevented by the use of a spacer (which may come as part of the inhaler device), thoroughly rinsing the mouth with water after using the medication, and rinsing and drying the inhaler each day.
Proper use of MDIs: MDIs should be stored at room temperature, away from direct sun, and protected from freezing temperatures. The plastic inhaler pieces should be rinsed and dried each day according to the patient instruction sheet that accompanies the MDI. When it is empty, the canister should be disposed of properly. An MDI canister, like any other canister under pressure, should never be punctured or thrown into an incinerator or near an open flame since this may cause it to explode. Many metered dose inhalers come with a checklist that helps determine when the canister must be replaced. The canister should be replaced when all the doses have been used. If you are not sure whether the canister is empty, a simple test will tell if medicine still remains. Place the canister in a container of water. If it is full, it will sink and lay horizontally on the bottom of the container. If it is partially full, it will stand upright, floating on the water line. If it is empty, it will float horizontally on top of the water. MDIs also have an expiration date, after which they should not be used at all because the potency of the medication has been lost. Common mistakes patients make with the use of metered dose inhalers are forgetting to shake the canister before inhaling; pressing down on the canister, then waiting before inhaling the medicine; not holding their breath for the correct time after inhaling; taking the wrong number of inhalations; and pressing on the canister more than once in a row. If you have questions about how to use a metered dose inhaler or a spacer device properly, be sure to review the steps with your pharmacist.
