A Metered Dose Inhaler (MDI) is a pressurized handheld device that delivers a precise, aerosolized burst of medication to the lungs. Using an MDI alone requires coordinating the canister’s activation with a simultaneous, slow inhalation, a maneuver difficult for most adults and nearly impossible for young children. A spacer, or Valved Holding Chamber (VHC), resolves this coordination problem by creating a reservoir between the inhaler and the child’s face. The VHC slows the high-velocity aerosol spray, allowing medication particles to become smaller, which significantly increases the amount of drug reaching the lower airways. The combination of the MDI and the VHC is the standard method for effective inhaled medication delivery in pediatric patients.
Preparing the Inhaler and Spacer
Before every use, inspect the equipment to ensure safe and effective delivery. Remove the cap from the MDI and check the spacer for foreign objects or debris that could be inhaled. Check the expiration date on the medication canister to confirm its potency.
A new MDI canister must be “primed” before its first use to ensure the propellant and medication are properly mixed and the metering valve is functioning. Priming involves shaking the canister and releasing a set number of test sprays into the air, typically four sprays, away from the child’s face. This priming step must be repeated if the inhaler has been unused for a manufacturer-specified period (often seven days or more). Once primed, shake the MDI canister for a few seconds immediately before inserting it securely into the back port of the spacer.
The Step-by-Step Guide to Administration
Ensure the child is calm and positioned upright (sitting or standing), which aids in lung expansion. After shaking the MDI and connecting it to the spacer, gently place the mask interface over the child’s nose and mouth. A tight seal must be maintained against the face, as any gaps allow the medication mist to escape and reduce the dose delivered.
Once the seal is established, press the MDI canister once to release a single puff of medication into the holding chamber. The child should then be allowed to breathe normally, known as tidal breathing, for a minimum of five to six full breaths while the mask remains securely in place.
Administer only one puff into the spacer at a time, even if the prescription calls for multiple doses. If a second puff is required, the caregiver must wait between one and three minutes before repeating the entire sequence, starting with shaking the inhaler again. This waiting period allows the first dose to begin opening the airways, potentially improving the depth of penetration for the subsequent dose.
Cleaning and Replacing the Device
Routine maintenance of the Valved Holding Chamber prevents the buildup of static electricity and medication residue. The spacer should be cleaned regularly (typically once a week) to maintain effectiveness. To clean the VHC, disassemble all parts, including the mask and the backpiece where the MDI is inserted.
Soak the disassembled components in a bowl of lukewarm water mixed with a mild, liquid dishwashing detergent for about fifteen minutes. The detergent counteracts the static charge that causes medication particles to stick to the plastic walls. After soaking, rinse the parts with clean water and shake off excess moisture. Let the pieces air dry completely in a vertical position without wiping them, as towels or heat can damage the plastic and reintroduce static charge.
The MDI canister should be replaced when the integrated dose counter reaches zero, even if it can still produce a spray. The spacer has a limited lifespan; replacement is often recommended after six to twelve months. Watch for visible signs of wear, such as cracks or a cloudy interior, which indicate the device needs replacement.
Troubleshooting and Confirming Effective Dosage
To ensure the child receives the full dose, monitor the spacer’s internal components during use. Most VHCs are equipped with a one-way valve that should visibly flutter or move with each breath, confirming the medication mist is being inhaled. If the child uses a mouthpiece instead of a mask, a whistling sound upon inhalation indicates the breath is too quick.
A fast inhalation causes the medication particles to impact and deposit high in the throat, limiting the amount reaching the lungs. If the child is resisting or crying during the procedure, the breathing pattern becomes erratic and shallow, which significantly reduces drug delivery. In such cases, the caregiver should pause and attempt to calm the child before proceeding with the dose. Maintaining a consistently tight mask seal is important, as any visible mist escaping around the edges confirms a substantial loss of the medication dose.