A metered-dose inhaler (MDI) is a handheld device that delivers medication to the lungs, typically consisting of a pressurized canister fitted into a mouthpiece. Patients use MDIs for respiratory conditions like asthma and chronic obstructive pulmonary disease (COPD). While effective, using an MDI often requires precise coordination between pressing the canister and inhaling. A spacer, also known as a holding chamber or valved holding chamber, functions as an accessory to improve MDI medication delivery.
Understanding the Function
A spacer creates a chamber between the metered-dose inhaler and the patient’s mouth. When the inhaler is actuated, medication sprays into this chamber, held as a fine mist for a few seconds. This temporary holding allows aerosol particles to slow down and become smaller, reducing their velocity upon inhalation. Instead of directly inhaling a fast-moving spray, the patient breathes in the medication slowly and deeply from the spacer.
This mechanism addresses the common challenge of coordinating MDI activation with inhalation. Without a spacer, medication can impact the back of the throat or be exhaled prematurely if not timed precisely. By providing a reservoir, a spacer allows the patient to inhale at their own pace, ensuring more medicine reaches the lungs rather than settling in the mouth or throat. The slowed velocity and dispersal within the chamber also help prevent medication loss to the air.
Advantages of Use
Using a spacer with a metered-dose inhaler offers several benefits. It enhances medication delivery directly to the lungs, where it is most effective. Without a spacer, a substantial portion of medication may deposit in the mouth and throat, with less reaching the airways. Spacers significantly improve lung deposition, ensuring more of the prescribed dose reaches the small airways.
Another benefit is a reduction in potential systemic side effects. When medication settles in the mouth and throat, it can lead to localized issues such as oral thrush or hoarseness, particularly with corticosteroid inhalers. By minimizing medication in the oral cavity, spacers help mitigate these adverse effects. Spacers also make MDIs easier to use for individuals who struggle with coordination, such as young children, older adults, or those with physical limitations. This ease of use can lead to better adherence to treatment plans.
Types and Components
Spacers generally consist of a tube-shaped chamber with openings at both ends. One end features an adapter for the metered-dose inhaler, while the other serves as the mouthpiece. The standard spacer is a simple open tube that extends the distance between the inhaler and the mouth.
More advanced versions include valved holding chambers (VHCs), which incorporate a one-way valve. This valve allows medication to enter the chamber but prevents it from escaping until the patient inhales, ensuring the dose remains contained. Some VHCs also include a whistle that indicates if the patient is inhaling too quickly. For infants, young children, or individuals unable to use a mouthpiece, some spacers are designed with a soft, adjustable facemask that creates a secure seal over the nose and mouth for medication delivery.
Proper Usage and Care
To use a spacer with an MDI, first remove the caps from both the inhaler and spacer, then shake the MDI vigorously for a few seconds. Insert the MDI’s mouthpiece firmly into the designated opening on the spacer. Next, exhale fully, away from the spacer, to empty the lungs. Place the spacer’s mouthpiece into the mouth, sealing the lips tightly, or ensure the facemask forms a good seal over the nose and mouth.
Press down on the MDI canister once to release a puff of medication into the spacer. Immediately breathe in slowly and deeply through the mouthpiece for 3 to 5 seconds. If a whistling sound is heard, slow down the inhalation. After inhaling, hold your breath for 5 to 10 seconds to allow the medication to settle deeply into the lungs, then exhale normally. If more than one puff is prescribed, wait about one minute before repeating the steps, shaking the MDI again before each subsequent puff. After use, if the medication is a corticosteroid, rinsing the mouth with water and spitting it out can help prevent oral thrush.
Cleaning the spacer is important for effectiveness and hygiene. Spacers should be cleaned at least once a week, or more frequently if recommended by a healthcare provider. To clean, separate components if applicable, and wash them in warm water with a mild liquid dishwashing detergent. After washing, rinse the parts thoroughly with clean water, then allow them to air dry completely on a clean surface without wiping. Wiping can create static electricity on the inside of the spacer, which may cause medication to stick to the walls, reducing delivery. Consult the device’s guidelines for specific cleaning instructions.