An Anti-Static Valved Holding Chamber (ASVHC) is a tube-shaped medical device used with a Metered Dose Inhaler (MDI) to improve medication delivery to the lungs. This accessory features a mouthpiece or mask at one end and a port for the MDI at the other. A one-way valve holds the medication until the user inhales, separating the steps of pressing the inhaler and breathing in. The anti-static coating prevents aerosol particles from clinging to the interior walls, ensuring a consistent dose. By slowing the MDI spray velocity, the ASVHC allows medication particles to break into smaller sizes, maximizing the amount reaching the lower airways and minimizing deposition in the mouth and throat.
Preparing the Chamber and Medication
Before using the ASVHC, inspect the device to ensure it is fully functional and safe. Check the chamber for damage, such as cracks or debris, and confirm that the one-way valves move freely. Prepare the Metered Dose Inhaler by removing the cap and shaking the canister vigorously for five to ten seconds to ensure the medication and propellant are well-mixed.
Next, insert the MDI securely into the backpiece of the holding chamber. Some ASVHCs, especially new ones, require “priming” to activate their anti-static properties. Priming involves actuating one to two test puffs of medication into the chamber and waiting a few seconds before administering the therapeutic dose. This initial step ensures the anti-static coating is fully effective, which helps prevent the medication from sticking to the chamber walls and improves the reliability of the dose.
Detailed Step-by-Step Usage Guide
First, exhale completely, gently breathing out away from the chamber and mouthpiece. Immediately place the mouthpiece into the mouth, forming a tight seal with the lips, or secure the mask snugly over the nose and mouth. Press the MDI canister down once to release a single dose of medication into the chamber.
Adult and Older Child Technique
The ideal technique for adults and older children is to take a single, slow, deep breath immediately after actuation, sustained for about three to five seconds. This slow inhalation prevents the device from whistling—a signal that the breath is too quick—and allows the aerosol to travel deeper into the lungs. After fully inhaling, remove the chamber and hold the breath for up to 10 seconds before exhaling normally. This maximizes the drug’s deposition within the airways.
Tidal Breathing Technique
For individuals who cannot take a single slow, deep breath, such as young children, a tidal breathing method is recommended. In this technique, the user takes four to six normal, steady breaths through the mouthpiece or mask after the MDI is actuated. The one-way valve ensures the medication remains in the chamber during exhalation, allowing the user to capture the full dose over multiple breaths. If the prescribed treatment requires more than one dose, wait 30 to 60 seconds after the first inhalation. Re-shake the MDI before repeating the entire sequence, ensuring only one puff is sprayed into the chamber per inhalation cycle.
Essential Cleaning and Maintenance
Regular cleaning is necessary to maintain the hygiene and effectiveness of the ASVHC, typically recommended at least once a week for daily users. Disassemble the chamber by separating the MDI adapter end and the mouthpiece or mask, following the manufacturer’s specific instructions. Avoid disassembling the valve components unless specifically instructed.
The proper cleaning method involves soaking the parts for about 15 minutes in lukewarm water mixed with a mild liquid dishwashing detergent. The detergent solution helps neutralize the electrostatic charge that can build up on the plastic, which would otherwise trap medication particles. After soaking, the parts should be gently agitated in the water, but avoid scrubbing or wiping the inside of the chamber, as this can damage the delicate anti-static coating.
Following the soak, all pieces should be thoroughly rinsed in clean water to remove the soap residue. The ASVHC must then be allowed to air dry completely in a vertical position without wiping the interior. Wiping can induce a static charge and negate the cleaning’s purpose. Replacement of the entire holding chamber is recommended every six to twelve months, or sooner if any part becomes cracked, warped, or if the internal valves begin to stick.