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Author Zak, M.; Madsen, J.; Berg, E.; Bulow, J.; Bisgaard, H. url  openurl
  Title A mathematical model of aerosol holding chambers Type Journal Article
  Year (down) 1999 Publication Journal of Aerosol Medicine Abbreviated Journal J Aerosol Med  
  Volume 12 Issue 3 Pages 187-196  
  Keywords Aerosols/administration & dosage; Anti-Inflammatory Agents/*administration & dosage/pharmacokinetics; Budesonide/*administration & dosage/pharmacokinetics; Equipment Design; Equipment Safety; Humans; Lung/drug effects; *Models, Theoretical; *Nebulizers and Vaporizers; Pressure; Reproducibility of Results  
  Abstract A mathematical model of aerosol delivery from holding chambers (spacers) was developed incorporating tidal volume (VT), chamber volume (Vch), apparatus dead space (VD), effect of valve insufficiency and other leaks, loss of aerosol by immediate impact on the chamber wall, and fallout of aerosol in the chamber with time. Four different spacers were connected via filters to a mechanical lung model, and aerosol delivery during “breathing” was determined from drug recovery from the filters. The formula correctly predicted the delivery of budesonide aerosol from the AeroChamber (Trudell Medical, London, Ontario, Canada), NebuChamber (Astra, Sodirtalje, Sweden) and Nebuhaler (Astra) adapted for babies. The dose of fluticasone proportionate delivered by the Babyhaler (Glaxco Wellcome, Oxbridge, Middlesex, UK) was 80% of that predicted, probably because of incomplete priming of this spacer. Of the above-mentioned factors, initial loss of aerosol by impact on the chamber wall is most important for the efficiency of a spacer. With a VT of 195 mL, the AeroChamber and Babyhaler were emptied in two breaths, the NebuChamber in four breaths, and the Nebuhaler in six breaths. Insufficiencies of the expiratory valves were demonstrated by comparison of pressure flow curves during “inspiratory” flow with and without occluded expiratory openings. Insufficient inspiratory valves were demonstrated by comparison of “expiratory” pressure flow curves with and without occluded inspiratory openings. With children breathing through the spacers, mask pressure variations were generally on the same order as that seen with the mechanical respiratory, supporting the clinical relevance of the in vitro findings.  
  Address Department of Pediatrics, Rigshospitalet, Copenhagen, Denmark  
  Corporate Author Thesis  
  Impact Factor 01,610 First Author Zak, M. Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Senior Author Bisgaard, H.  
  ISSN 0894-2684 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:10623335 Approved no  
  Call Number Serial 213  
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