title: Accuracy of portable devices in measuring peak cough flow.
abstract: Peak cough flow (PCF) measurements can be used as indicators of cough effectiveness. Portable peak flow meters and spirometers have been used to measure PCF, but little is known about their accuracy compared to pneumotachograph systems. The aim of this study was to compare the accuracy of four portable devices (Mini-Wright and Assess peak flow meters, SpiroUSB and Microlab spirometers) in measuring PCF with a calibrated laboratory based pneumotachograph system. Twenty healthy volunteers (mean (SD) age 45 (16) years) coughed through a pneumotachograph connected in series with each portable device in turn, and the differences in PCF readings were analysed. In addition, mechanically generated flow waves of constant peak flow were delivered through each device both independently and when connected in series with the pneumotachograph. Agreement between PCF readings obtained with the pneumotachograph and the portable devices was poor. Peak flow readings were on average lower by approximately 50 L min(-1) when measured using the portable devices; 95% limits of agreement spanned approximately 150 L min(-1). The findings highlight the potential for inaccuracy when using portable devices for the measurement of PCF. Depending on the measurement instrument used, absolute values of PCF reported in the literature may not be directly comparable.
authors.affiliation: Stroke Research Team, Department of Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, PO Box 41, Denmark Hill, London, SE5 8AF, UK.
authors.forename: Stefan Tino
authors.initials: ST
authors.lastname: Kulnik
authors.forename: Victoria
authors.initials: V
authors.lastname: MacBean
authors.forename: Surinder Singh
authors.initials: SS
authors.lastname: Birring
authors.forename: John
authors.initials: J
authors.lastname: Moxham
authors.forename: Gerrard Francis
authors.initials: GF
authors.lastname: Rafferty
authors.forename: Lalit
authors.initials: L
authors.lastname: Kalra
mesh_terms: D003371:Cough / Q000503:physiopathology*; D005260:Female; D045268:Flowmeters / Q000592:standards*; D005540:Forced Expiratory Flow Rates / Q000502:physiology; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D008875:Middle Aged; D010366:Peak Expiratory Flow Rate / Q000502:physiology*; D013147:Spirometry / Q000295:instrumentation