An inhaler is a medical device designed to deliver a specific dose of medication directly to the lungs, making it an effective treatment for respiratory conditions like asthma and Chronic Obstructive Pulmonary Disease (COPD). The term “metered-dose” signifies that the device releases a precisely measured amount of medication with each activation, typically as a liquid mist. For this localized delivery system to work, the user’s technique must be nearly flawless, as even minor errors can significantly reduce the amount of medicine that reaches the lower airways. Correct usage maximizes the medication’s therapeutic benefit while minimizing potential side effects.
The Standard Technique Using a Metered-Dose Inhaler
Before each use, the Metered-Dose Inhaler (MDI) must be prepared to ensure the medication is properly mixed and the dose is consistent. If the inhaler is new or has not been used for a period of time, it must be “primed” by spraying a specified number of puffs into the air, away from the face, following the device’s instructions. For regular use, vigorously shake the canister for about five seconds before removing the mouthpiece cap.
Proper positioning involves holding the inhaler upright with the mouthpiece at the bottom; the user should stand or sit up straight for a full breath. Next, breathe out slowly and completely, pushing as much air out of the lungs as possible to create space for the inhaled dose. Place the mouthpiece into the mouth, closing the lips tightly around it to create a seal, ensuring the tongue is clear of the opening.
The coordination of activation and inhalation is key; begin to breathe in slowly through the mouth, and at the same time, press down once on the canister to release the medication. The inhalation must be slow and deep, lasting approximately three to five seconds, ensuring the medicine travels into the lungs. After the full breath is taken, remove the inhaler and hold the breath for five to ten seconds, or as long as comfortably possible, allowing the aerosolized medication to settle in the airways.
If the prescribed dose requires a second puff, the user must wait 30 seconds to one minute before repeating the entire process, starting with shaking the inhaler again. For individuals using a corticosteroid inhaler, rinsing the mouth with water and spitting it out immediately after use is necessary to prevent localized side effects like oral thrush.
Enhancing Delivery The Role of Spacers and Holding Chambers
Spacers, also known as valved holding chambers, are plastic tubes that attach to the MDI mouthpiece and temporarily hold the medication mist. This chamber slows down the fast-moving aerosol particles, reducing the force with which the medicine enters the mouth. By slowing the medication, spacers reduce the amount of drug that deposits in the back of the throat, a common issue with direct MDI use.
Using a spacer simplifies the technique by eliminating the need for perfect hand-lung coordination. After attaching the MDI and shaking the combination, the user presses the canister to release a puff into the chamber. The user then breathes in slowly and deeply through the spacer’s mouthpiece; some spacers feature a whistle to indicate if the inhalation speed is too fast. This method is particularly beneficial for children or those with limited coordination, as it allows the user to take multiple slow breaths to inhale the dose from the chamber.
Ensuring Medication Effectiveness Maintenance and Tracking
Routine maintenance of the MDI is necessary to prevent medication residue buildup that can clog the device and interfere with proper dosing. To clean the MDI, remove the metal canister from the plastic actuator, or “boot,” and rinse only the plastic mouthpiece under warm running water. The canister should never be submerged in water or allowed to get wet.
After washing, shake off excess water and allow the plastic components to air-dry completely, ideally overnight, before reassembling the device. If the inhaler must be used before it is fully dry, it may need to be test-sprayed into the air a couple of times to clear any remaining water. Most MDIs should be cleaned at least once a week.
Tracking the remaining doses is important to ensure the medication is replaced before it runs out. Many modern MDIs have a built-in dose counter that clearly indicates the number of available puffs, and the inhaler should be replaced when the counter reaches zero. If the inhaler lacks a counter, the user must manually track the number of puffs taken each day and divide that into the total number of doses listed on the canister label. Floating the canister in water is an unreliable method and should not be used to determine the remaining medication supply.
Addressing Technique Errors Common Mistakes to Avoid
Many MDI users make at least one technique error, which limits the amount of drug reaching the lungs. One frequent mistake is failing to fully exhale before beginning the inhalation, which limits the lung capacity available to draw in the medication. Not shaking the inhaler before use is another common error that leads to an inconsistent dose, as the medication and propellant separate when the device is stored.
A lapse in coordination, where the user presses the canister too early or too late relative to the start of the inhalation, can reduce lung deposition by half. Inhaling too quickly causes the medication particles to impact the back of the throat and mouth instead of continuing down into the airways. The inhalation should be slow and steady, taking several seconds to fully draw in the mist.
Failing to hold the breath for the recommended five to ten seconds after inhalation is a common error that prevents the medicine from settling in the lung tissue. Another mistake is not forming a tight seal with the lips around the mouthpiece, which allows the released dose to escape into the air. To correct these issues, users should practice the sequence of exhalation, sealing, coordinated activation, slow inhalation, and breath-holding to ensure the full therapeutic effect.