A metered-dose inhaler (MDI) is a small, handheld device that delivers a precise amount of aerosolized medication directly to the lungs. The MDI consists of a pressurized canister containing the medicine and a propellant, which fits into a plastic actuator with a mouthpiece. This device is commonly used for managing conditions like asthma and chronic obstructive pulmonary disease (COPD). Correct technique is paramount because it dictates whether the medication reaches the narrow airways or settles prematurely in the mouth and throat. Proper usage maximizes therapeutic benefit and reduces side effects.
Preparing the Inhaler for Use
Before use, check the device’s remaining capacity. Many modern MDIs include a dose counter; if yours lacks one, manually track the doses used for timely replacement. The inhaler should be shaken vigorously for 5 to 10 seconds before every use to thoroughly mix the medicine and propellant. If the inhaler is brand new or has not been used for a period (typically a few days to two weeks), it must be “primed.” Priming involves spraying a test puff or two away from the face to ensure the valve is filled with the correct mixture.
Step-by-Step Guide to Taking a Dose
Begin by standing or sitting upright, then remove the cap and check the mouthpiece for debris. Exhale completely and gently, pushing out as much air as possible away from the inhaler. Position the inhaler with the mouthpiece between your teeth, sealing your lips tightly around it, while keeping your tongue out of the path.
As you start to breathe in slowly and steadily through your mouth, press down firmly on the canister once to release the dose. The inhalation should be slow and deep, lasting approximately three to five seconds, which helps the medicine particles travel into the small airways. Remove the inhaler and hold your breath for up to 10 seconds, or as long as is comfortable, allowing the medication to settle and be absorbed. If a second puff is required, wait for at least one minute before repeating the entire sequence of shaking, exhaling, inhaling, and holding your breath.
Modifying the Technique with a Spacer
A spacer, also known as a valved holding chamber, is a plastic tube that attaches to the MDI mouthpiece. Its function is to hold the aerosolized medicine temporarily after actuation. This eliminates the need for perfect coordination between pressing the canister and inhaling. The spacer also reduces the speed of the spray, allowing medicine droplets to become finer, improving delivery to the lungs and reducing throat deposition.
When using a spacer, the steps change after the device is shaken and attached. After exhaling fully, place the spacer mouthpiece in your mouth and create a tight seal. Press the canister once to release the medicine into the chamber, then immediately begin to breathe in slowly and deeply. If the spacer has a built-in whistle, slow your inhalation if you hear the sound, as this indicates you are breathing in too quickly.
Essential Care and Maintenance
Regular cleaning of the MDI is important to prevent medicine residue buildup that can clog the spray nozzle and affect dosing accuracy. The plastic casing and mouthpiece should be cleaned at least once a week. To clean the device, remove the metal canister from the plastic actuator and set it aside, as it must never be submerged in water. Rinse the plastic casing under warm running water for about 30 seconds through the top and 30 seconds through the mouthpiece end.
After rinsing, gently shake out excess water and allow the plastic parts to air-dry completely overnight. Do not use a towel or cloth to dry the parts, as this can leave lint or residue. Once fully dry, reinsert the metal canister and replace the cap for storage. The inhaler should be stored at room temperature, away from direct sunlight, extreme cold, or moist environments.