A metered-dose inhaler (MDI) is a handheld device that delivers a precise, measured dose of medication directly to the lungs. The medication is suspended in a liquid propellant and released as a fine mist or aerosol spray when the canister is pressed. MDIs treat conditions like asthma and Chronic Obstructive Pulmonary Disease (COPD) by allowing the medicine to reach the small airways. Achieving the full therapeutic effect depends on mastering the correct inhalation technique. Without a synchronized method, a large portion of the medication may be deposited in the mouth and throat instead of the target tissues.
Step-by-Step Technique Without a Spacer
Check the dose counter to confirm an adequate number of doses remain. If the inhaler is new or has not been used for several weeks, it must first be primed with a few test sprays into the air. Remove the cap from the mouthpiece and shake the inhaler vigorously for about five seconds to thoroughly mix the medicine and propellant. Sit or stand upright to allow for maximum lung expansion.
Tilt your head back slightly and exhale completely, pushing all the air out of your lungs gently and away from the device. Place the mouthpiece into your mouth, positioning it above your tongue and sealing your lips tightly around it. Start to take a slow, deep breath in through your mouth, and simultaneously press down firmly on the canister once to release the dose.
Continue to inhale slowly and steadily for three to five seconds after actuating the puff, ensuring the aerosol travels deep into the lungs. Remove the inhaler from your mouth and hold your breath for five to ten seconds, or as long as you comfortably can. This breath-hold allows the medicine particles to settle within the airways for optimal absorption. If a second puff is prescribed, wait 30 to 60 seconds before shaking the inhaler and repeating the sequence.
Adapting the Technique Using a Spacer Device
A spacer is a tube-like attachment, often with a one-way valve, that connects to the MDI mouthpiece, creating a holding chamber for the aerosolized medication. This chamber significantly improves drug delivery by slowing the mist’s velocity, allowing the propellant to evaporate, and reducing the size of the drug particles. The use of a spacer is recommended because it eliminates the difficulty of coordinating the press-and-breathe action, which is a common point of failure.
To use this setup, shake the MDI and firmly insert it into the rubber ring opening at the end of the spacer. After exhaling fully, place the spacer’s mouthpiece in your mouth and create a tight seal with your lips. Press the inhaler canister once to release a single puff of medication into the chamber, where it is held by the spacer’s valve.
The medication can be inhaled from the spacer using one of two methods. You can take one slow, deep breath from the spacer and hold it for ten seconds before exhaling. Alternatively, breathe in and out normally through the mouthpiece for four to ten breaths. This simpler approach is often easier for individuals with limited lung capacity or poor coordination.
Proper Cleaning and Storage
Routine maintenance of the MDI prevents the buildup of medication residue that can clog the nozzle and lead to inaccurate dosing. At least once per week, clean the plastic casing of the inhaler. First, remove the metal canister, as it must never be exposed to water. Rinse the plastic case and cap thoroughly under warm running water for about 30 seconds to dissolve any powder or residue.
The plastic components should be left to air-dry completely, ideally overnight, before the metal canister is reinserted and the cap is replaced. Never use pins or sharp objects to clear the nozzle hole, as this can damage the device and alter the delivered dose. If a spacer is used, clean it weekly with warm, soapy water, rinse it, and allow it to air-dry without wiping. Wiping can create a static charge that attracts medicine particles.
For long-term function, the MDI should be stored at room temperature, as exposure to extreme heat or cold can affect the propellant and the medicine. The protective cap should remain on the mouthpiece when the device is not in use to prevent dust, debris, and lint from entering the delivery port. Storing the inhaler in a cool, dry place away from direct sunlight maintains drug stability.
Identifying and Correcting Common Errors
A high percentage of users make mistakes that reduce the amount of medicine reaching the lungs. The most frequent error is poor coordination between pressing the canister and initiating inhalation. This lack of synchronization means the aerosol hits the back of the throat and is swallowed instead of being carried into the lower airways. Another common error involves inhaling too quickly or too forcefully, which causes the drug particles to impact the back of the throat rather than following the airflow.
Failing to exhale fully before the puff or not holding the breath for five to ten seconds after inhalation significantly reduces the medicine’s effectiveness. For any MDI containing a corticosteroid, always rinse the mouth and gargle with water immediately after the final dose. This action prevents the localized side effect of oral candidiasis (thrush), which is caused by the deposition of the steroid drug on the tissues of the mouth and throat.