Effects of equipment and technique on peak flow measurements.
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.
Bongers
Thomas
T
School of Clinical Sciences, University of Liverpool, Liverpool, UK. tbongers@liv.ac.uk
O'Driscoll
B Ronan
BR
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