Peak flow meter test3/13/2024 ![]() We noticed that the peak flow measurement from the two devices differed by up to 20%. In our chest clinic, technicians record the FEV1/FVC of all patients using a Fleisch pneumotachograph-based spirometer and the Peak Flow is measured by the same technician using a Wright's Peak Flow Meter using "PEF technique". They concluded that this small difference was not clinically significant but they did not compare the measurement made on a Peak Flow meter. Wensley and colleagues found that the PEF of children was 3% higher when measured using a PEF technique compared with a FVC technique on a turbine spirometer. Although PEF measurements and FEV1/FVC measurements both require a rapid exhalation, the instructions given to the subject are different and it is possible that the two techniques are not interchangeable. The FVC measurement requires a blow that starts from maximal inspiration and proceeds to residual volume. For most subjects, a short but forceful blow will be sufficient to register the maximal expiratory flow ("PEF technique"). It is not necessary for the subject to continue exhaling to residual volume. ![]() Maximal expiratory flow lasts for only a fraction of a second and occurs very early in expiration. This requires the subject to exhale as quickly as possible into a recording device following maximum inspiration. The Wright Peak Flow Meter was developed to measure Peak Expiratory Flow. Furthermore, some spirometers use a traditional Wright scale to record PEF whilst others use a scale which corresponds more closely to the new European scale which is closer to the true PEF measured in laboratory studies. Previous studies have found that different spirometers and different Peak Flow Meters can record PEF differently with error rates of up to 26% in laboratory calibration tests. It is not known if these PEF measurements correspond to those made on Wright's or Mini-Wrights meters. It is customary for spirometers to print out Peak Expiratory Flow (PEF) measurements as well as measurements of Forced Expiratory Volume in one second (FEV1) and Forced Vital Capacity (FVC). Patient management decisions should not be based on PEF measurement made on different instruments. Peak flow measurements are affected by the instruction given and by the device and Peak Flow scale used. 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. The Fleisch spirometer result was 19.5% lower than the Wright reading. The mean PEF recorded with the turbine spirometer was 5.5% lower than the Wright meter reading. ![]() The mean PEF was 8.7% higher when the PEF technique was used (compared with FVC technique, p < 0.0001). Measurements were made using a Wright's peak flow meter, a turbine spirometer and a Fleisch pneumotachograph spirometer. 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). We studied 36 subjects (PEF range 80–570 l/min). 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. Different lung function equipment and different respiratory manoeuvres may produce different Peak Expiratory Flow (PEF) results. ![]()
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