What feature does a valve holding chamber provide in a pMDI system?

What feature does a valve holding chamber provide in a pMDI system?

• A. It includes a one-way valve that allows aerosol to be drawn from the chamber during inhalation only.
• B. It heats the propellant for better deposition.
• C. It filters particles before inhalation.
• D. It stores the dose for later use.

Answer: (A)

The key idea is that a valve holding chamber uses a one-way valve to control the flow of aerosol. When the inhaler is actuated, aerosol fills the chamber, and the valve prevents it from flowing back out. On the next inhalation, the valve opens and the patient draws aerosol from the chamber. This coordination allows easier breathing with the dose, improves delivery to the lungs, and reduces loss of drug when exhaling. Heating the propellant, filtering particles, or simply storing the dose without the valve don’t describe this feature.

The key idea is that a valve holding chamber uses a one-way valve to control the flow of aerosol. When the inhaler is actuated, aerosol fills the chamber, and the valve prevents it from flowing back out. On the next inhalation, the valve opens and the patient draws aerosol from the chamber. This coordination allows easier breathing with the dose, improves delivery to the lungs, and reduces loss of drug when exhaling. Heating the propellant, filtering particles, or simply storing the dose without the valve don’t describe this feature.