title: Effects of equipment and technique on peak flow measurements.
abstract: BACKGROUND
  Different lung function equipment and different respiratory manoeuvres may produce different Peak Expiratory Flow (PEF) results. Although the PEF is the most common lung function test, there have been few studies of these effects and no previous study has evaluated both factors in a single group of patients.
  
  
  METHODS
  We studied 36 subjects (PEF range 80-570 l/min). All patients recorded PEF measurements using a short rapid expiration following maximal inspiration (PEF technique) or a forced maximal expiration to residual volume (FVC technique). Measurements were made using a Wright's peak flow meter, a turbine spirometer and a Fleisch pneumotachograph spirometer.
  
  
  RESULTS
  The mean PEF was 8.7% higher when the PEF technique was used (compared with FVC technique, p < 0.0001). The mean PEF recorded with the turbine spirometer was 5.5% lower than the Wright meter reading. The Fleisch spirometer result was 19.5% lower than the Wright reading. However, adjustment of the Wrights measurements from the traditional Wright's scale to the new EU Peak Flow scale produced results that were only 7.2% higher than the Fleisch pneumotachograph measurements.
  
  
  CONCLUSIONS
  Peak flow measurements are affected by the instruction given and by the device and Peak Flow scale used. Patient management decisions should not be based on PEF measurement made on different instruments.
authors.affiliation: School of Clinical Sciences, University of Liverpool, Liverpool, UK. tbongers@liv.ac.uk
authors.forename: Thomas
authors.initials: T
authors.lastname: Bongers
authors.forename: B Ronan
authors.initials: BR
authors.lastname: O'Driscoll
mesh_terms: D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010366:Peak Expiratory Flow Rate; D012129:Respiratory Function Tests / Q000295:instrumentation* / Q000379:methods* / Q000592:standards; D015656:Respiratory Mechanics; D013147:Spirometry / Q000295:instrumentation / Q000592:standards; D014797:Vital Capacity