Measuring peak expiratory flow in general practice: comparison of mini Wright peak flow meter and turbine spirometer.
OBJECTIVE
To compare measurements of the peak expiratory flow rate taken by the mini Wright peak flow meter and the turbine spirometer.


METHODS
Pragmatic study with randomised order of use of recording instruments. Phase 1 compared a peak expiratory flow type expiration recorded by the mini Wright peak flow meter with an expiration to forced vital capacity recorded by the turbine spirometer. Phase 2 compared peak expiratory flow type expirations recorded by both meters. Reproducibility was assessed separately.


METHODS
Routine surgeries at Aldermoor Health Centre, Southampton.


METHODS
212 Patients aged 4 to 78 presenting with asthma or obstructive airways disease. Each patient contributed only once to each phase (105 in phase 1, 107 in phase 2), but some entered both phases on separate occasions. Reproducibility was tested on a further 31 patients.


METHODS
95% Limits of agreement between measurements on the two meters.


RESULTS
208 (98%) Of the readings taken by the mini Wright meter were higher than the corresponding readings taken by the turbine spirometer, but the 95% limits of agreement (mean difference (2 SD] were wide (1 to 173 l/min). Differences due to errors in reproducibility were not sufficient to predict this level of disagreement. Analysis by age, sex, order of use, and the type of expiration did not detect any significant differences.


CONCLUSIONS
The two methods of measuring peak expiratory flow rate were not comparable. The mini Wright meter is likely to remain the preferred instrument in general practice.
Jones
K P
KP
Faculty of Medicine, University of Southampton, Hampshire.
Mullee
M A
MA
D000293:Adolescent; D000328:Adult; D000368:Aged; D015982:Bias; D002648:Child; D002675:Child, Preschool; D016001:Confidence Intervals; D005194:Family Practice; D005260:Female; D005540:Forced Expiratory Flow Rates / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010366:Peak Expiratory Flow Rate / Q000502:physiology*; D011446:Prospective Studies; D015203:Reproducibility of Results; D012212:Rheology; D013147:Spirometry / Q000295:instrumentation*