Advantages |
Slows down the aerosol cloud as it emerges from the pMDI |
Reduces impact of hand–breath (activation–inhalation) coordination problems |
Longer propellant evaporation time reduces particle size (increases respirable fine-particle fraction) and improves lung deposition |
Filters out larger aerosol particles |
Reduces oropharyngeal impaction/deposition and local side-effects (inhaled corticosteroids) |
Reduces fraction of swallowed drug, gastrointestinal absorption, systemic bioavailability and thus extrapulmonary unwanted effects (β-adrenergic agonists) |
VHCs can be used with tidal breathing, administered by a care giver |
For the very young (using a face mask) and any patient where coordination is a challenge |
During acute exacerbations (replacing nebulisers) |
Disadvantages |
Require regular cleaning |
Large-volume spacer/VHC devices are more bulky and less portable |
Electrostatic charge may reduce the respirable aerosol fraction |
More expensive (but may save medication) |
pMDI: pressurised, metered-dose inhaler.