Advantages and disadvantages of a spacer/valved holding chamber (VHC)

 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)
 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.