title: Aerosol profile extracted from spacers as a determinant of actual dose.
abstract: OBJECTIVE
  We propose a novel method to evaluate the efficacy of a pressurized metered dose inhaler (pMDI) in combination with a spacer, by not only considering the total dose extractable from the spacer but also the dependence of dose on the volume available for aerosol inhalation.
  
  
  METHODS
  We studied volume-dependence of aerosol concentration during extraction from two commonly used plastic spacers (150 ml AerochamberPlus; 750 ml Volumatic) after a single puff of a 100 microg salbutamol pMDI (HFA-Ventolin), using laser photometric measurements.
  
  
  RESULTS
  After a delay of is in each spacer, the aerosol peak dose for AerochamberPlus was 2-fold that for Volumatic (p < 0.001), with the peak appearing well within the first 0.5 L even for the largest spacer. The opposite dose relationship is reached when considering total cumulative dose, which was 2-fold higher for Volumatic than for AerochamberPlus (p < 0.001); >95% of total cumulative dose was extracted well within 3 L for the largest spacer. The 2-fold cumulative dose relationship was confirmed by chemical assay on an absolute filter [AerochamberPlus: 21.4+/-3.2 (SD) microg; Volumatic: 43.8+/-9.1 (SD) microg].
  
  
  CONCLUSIONS
  Actual aerosol dose available to patients during inhalation via spacers can only be done on the basis of a quantification of aerosol peak dose and cumulative dose as a function of extracted volume.
authors.affiliation: Academic Hospital, Vrije Universiteit Brussel, 1090 Brussels, Belgium. sylvia.verbanck@az.vub.ac.be
authors.forename: Sylvia
authors.initials: S
authors.lastname: Verbanck
authors.forename: Chris
authors.initials: C
authors.lastname: Vervaet
authors.forename: Daniël
authors.initials: D
authors.lastname: Schuermans
authors.forename: Walter
authors.initials: W
authors.lastname: Vincken
mesh_terms: D000280:Administration, Inhalation; D000336:Aerosols / Q000008:administration & dosage*; D000420:Albuterol / Q000008:administration & dosage*; D036501:Metered Dose Inhalers / Q000592:standards*
chemical_list: D000336:Aerosols; D000420:Albuterol