Metered-Dose Inhalers (MDIs) are handheld devices that deliver aerosolized medication directly to the lungs to treat respiratory conditions like asthma and COPD. Using an MDI effectively requires precise coordination—the user must simultaneously press the canister and begin a slow, deep inhalation. This “press and breathe” technique is difficult for many people to master, often leading to a significant portion of the medicine landing in the mouth or throat instead of the airways. A simple accessory device, called a spacer, is frequently recommended to overcome this coordination challenge and ensure the medication reaches its intended target.
Defining the Inhaler Spacer
An inhaler spacer is a tube-shaped accessory that attaches to the mouthpiece of a Metered-Dose Inhaler (MDI), creating a space between the inhaler and the user’s mouth. Constructed from plastic or metal, these devices temporarily hold the aerosolized medicine after the inhaler is activated. The spacer’s primary role is to simplify the delivery process, making it easier to inhale the full dose of medication.
A more advanced version is the Valved Holding Chamber (VHC). VHCs contain a one-way valve at the mouthpiece that traps the medicine inside the chamber after actuation. This valve prevents the medication from escaping and allows the user to take multiple, slow breaths to inhale the entire dose, rather than relying on a single, perfectly timed inhalation.
Spacers and VHCs are available with different interfaces. While a mouthpiece allows the user to seal their lips, a fitted face mask is often used for infants, young children, or adults who have difficulty creating a tight seal or coordinating their breathing.
Why Spacers Improve Medicine Delivery
Spacers improve the effectiveness of MDIs by addressing the physics of aerosol delivery. When an MDI is actuated directly into the mouth, the medication is released at a high velocity. This high speed causes a large percentage of the drug particles to impact the back of the throat and mouth, a phenomenon known as oropharyngeal deposition.
The tube of the spacer or VHC provides distance, which serves two main purposes. First, it significantly slows the speed of the aerosol particles, reducing the force with which they hit the throat. Second, the extra time and space allow the propellant that carries the medicine to evaporate.
This evaporation process leaves behind smaller, lighter drug particles. These smaller particles remain suspended in the chamber longer and are much more likely to be carried deep into the lower airways of the lungs. Maximizing this pulmonary deposition ensures the medicine acts directly on the inflamed tissue. Using a spacer increases the amount of medication that reaches the lungs and reduces the amount swallowed, minimizing the risk of local side effects like hoarseness and oral thrush, especially with inhaled corticosteroid medications.
Step-by-Step Guide for Proper Use
To maximize medication delivery, using a spacer correctly requires adherence to a specific sequence.
Preparation
The MDI canister must be shaken thoroughly for a few seconds to ensure the medicine is properly mixed. After removing the caps, the inhaler is firmly inserted into the rubber ring at the end of the spacer.
Inhalation Technique
The user should exhale fully to empty the lungs before placing the spacer’s mouthpiece between the teeth and sealing the lips tightly around it. Next, the inhaler is actuated, releasing a single puff of medication into the chamber. Immediately after actuation, a slow, deep breath should be taken through the mouth, lasting approximately three to five seconds.
After the slow inhalation, the breath should be held for up to ten seconds, if possible, to allow the drug particles time to settle deep within the lungs. Breathing too quickly will often cause the valve in a VHC to whistle, serving as an audible reminder to slow the inhalation flow.
For patients using a face mask, the mask should be held firmly over the nose and mouth to create a seal. The patient should then take five to six slow breaths after the inhaler is actuated into the chamber.
Essential Care and Maintenance
Regular care is necessary to maintain the spacer’s effectiveness and prevent the growth of microorganisms. Medication residue can build up inside the chamber, potentially reducing the device’s ability to deliver a full dose. Spacers should be cleaned regularly, typically once a week or monthly, depending on the manufacturer’s instructions.
To clean the device, disassemble it and soak all parts in warm water mixed with a mild liquid dishwashing detergent. The parts must not be rinsed with water after soaking. A thin film of detergent residue helps prevent the buildup of static electricity, which otherwise causes medicine particles to stick to the chamber walls.
The spacer parts must be allowed to air dry completely in a vertical position without being wiped, as wiping generates static. Spacers, especially VHCs, should be checked periodically for any cracks or damage and replaced, typically every twelve months. This replacement schedule ensures the valves and chamber material remain in optimal condition for effective drug delivery.