title: Challenging the two-minute tidal breathing challenge test.
abstract: BACKGROUND
  In the adenosine 5'-monophosphate (AMP) bronchial challenge test, AMP is usually administered according to dosing protocols for methacholine. We investigated whether the 2-min tidal breathing challenge test for methacholine is applicable to AMP. Parameters known to affect nebulizer output were studied. Our aim was to determine whether control of additional parameters is needed for currently standardized protocols.
  
  
  METHODS
  The study was performed with the Sidestream nebulizer from the APS Pro Aerosol Provocation System (CareFusion Respiratory). The effects of AMP concentration, jet pressure, and suction flow rate on nebulizer output rate and aerosol droplet size distribution were determined.
  
  
  RESULTS
  The volume median diameter for water increased from 5.10 μm to 8.49 μm when the jet pressure was reduced to obtain the prescribed output rate of 0.13 mL/min. The output rate was increased when a suction flow rate was used to remove the aerosol. Increasing the AMP concentration resulted in smaller droplets and a lower output rate when a suction flow was applied.
  
  
  CONCLUSIONS
  The effects of AMP concentration on nebulizer performance may result in changes in the administered dose and site of deposition of AMP at dose escalation. All of the investigated parameters influence nebulizer performance, hence the outcome of a bronchial challenge test. Therefore, these parameters should not only be specified in challenge testing, but be actively controlled as well.
authors.affiliation: Department of Pharmaceutical Technology and Biopharmacy, University of Groningen , 9713 AV Groningen, The Netherlands .
authors.forename: Anne J
authors.initials: AJ
authors.lastname: Lexmond
authors.forename: Paul
authors.initials: P
authors.lastname: Hagedoorn
authors.forename: Henderik W
authors.initials: HW
authors.lastname: Frijlink
authors.forename: Anne H
authors.initials: AH
authors.lastname: de Boer
mesh_terms: D000249:Adenosine Monophosphate / Q000008:administration & dosage* / Q000737:chemistry; D000280:Administration, Inhalation; D000336:Aerosols; D016535:Bronchial Hyperreactivity / Q000175:diagnosis / Q000503:physiopathology; D001985:Bronchial Provocation Tests / Q000379:methods*; D016084:Bronchoconstriction / Q000187:drug effects; D016085:Bronchoconstrictor Agents / Q000008:administration & dosage* / Q000737:chemistry; D004305:Dose-Response Relationship, Drug; D004867:Equipment Design; D006801:Humans; D016210:Methacholine Chloride / Q000008:administration & dosage; D009330:Nebulizers and Vaporizers; D010316:Particle Size; D011237:Predictive Value of Tests; D011312:Pressure; D013997:Time Factors
chemical_list: D000336:Aerosols; D016085:Bronchoconstrictor Agents; D016210:Methacholine Chloride; D000249:Adenosine Monophosphate