Albuterol is a fast-acting medication, known as a bronchodilator, which is primarily used to relieve acute symptoms of asthma and other respiratory conditions. The drug is most commonly delivered using a Metered-Dose Inhaler (MDI), a handheld pressurized device that releases a specific dose of aerosolized medicine. A spacer, or valved holding chamber, is a device that attaches to the MDI, creating an expansion area for the medication before it is inhaled. The use of this simple attachment significantly improves the effectiveness of albuterol delivery.
The Challenge of Metered-Dose Inhaler Technique
Using an MDI alone limits the amount of medication reaching the lungs due to several difficulties. The primary challenge is the need for precise hand-breath coordination, requiring the user to time the canister press with the start of a slow, deep inhalation. This coordination is difficult for many patients, including children, the elderly, or those experiencing an acute respiratory flare-up. Technical errors in MDI use are common, affecting a large percentage of patients.
Another issue is the high velocity of the aerosol spray as it exits the MDI mouthpiece. This fast-moving plume causes drug particles to immediately crash into the back of the throat, known as oropharyngeal deposition. When medication deposits in the mouth and throat instead of the airways, it results in a lower therapeutic dose reaching the lungs. This deposition can also increase the risk of localized side effects.
How Spacers Maximize Medication Reaching the Lungs
The spacer chamber addresses the problems of MDI use by changing the physical dynamics of the aerosolized medication. By creating a physical distance between the MDI and the mouth, the spacer significantly slows down the high-velocity spray. This reduction in speed prevents the drug particles from immediately impacting and depositing in the upper airway, which is the primary cause of reduced lung delivery.
The extended holding time within the chamber allows the propellant to evaporate, effectively reducing the size of the drug particles. Particles larger than 5 micrometers deposit in the throat, while particles in the optimal range of 1 to 5 micrometers are needed to travel deep into the smaller airways. The spacer helps ensure a higher fraction of the dose falls within this respirable size range.
The primary benefit of a valved holding chamber is the elimination of the complex coordination requirement. Once the MDI is actuated, the medication is held in the chamber by a one-way valve, allowing the patient to inhale the dose at their own pace. This feature allows the user to take multiple, slow breaths to ensure the entire dose is inhaled, which is important for individuals who cannot take one long, sustained breath.
Practical Guidelines for Effective Spacer Use
To ensure the benefits of the spacer are fully realized, proper preparation and technique are necessary for each use. Before attaching the MDI to the spacer, the canister must be shaken well to mix the medication and propellant. If the spacer is new, it should be “primed” by actuating a few puffs into it before the first use to reduce the static charge on the plastic walls.
During administration, the patient must create a tight seal around the mouthpiece with their lips, or use a face mask for very young children. The patient should press the canister once and immediately begin a slow, deep inhalation lasting three to five seconds. After inhalation, the breath should be held for five to ten seconds before exhaling.
Regular maintenance is necessary to maintain the device’s efficiency. Spacers should be cleaned weekly by dismantling them and washing them in warm water with a mild dishwashing detergent.
It is important to let the parts air dry completely without wiping, as towel drying can create an electrostatic charge inside the chamber. This static charge can cause the medication to stick to the walls, reducing the dose available for inhalation. Most spacers should be replaced at least annually, or sooner if any part becomes cracked or damaged.