title: Method to produce American Thoracic Society flow-time waveforms using a mechanical pump.
abstract: The American Thoracic Society (ATS) recently adopted a new set of 26 standard flow-time waveforms for use in testing both diagnostic and monitoring devices. Some of these waveforms have a higher frequency content than present in the ATS-24 standard volume-time waveforms, which, when produced by a mechanical pump, may result in a pump flow output that is less than the desired flow due to gas compression losses within the pump. To investigate the effects of gas compression, a mechanical pump was used to generate the necessary flows to test mini-Wright and Assess peak expiratory flow (PEF) meters. Flow output from the pump was measured by two different independent methods, a pneumotachometer and a method based on piston displacement and pressure measured within the pump. Measuring output flow based on piston displacement and pressure has been validated using a pneumotachometer and mini-Wright PEF meter, and found to accurately measure pump output. This method introduces less resistance (lower back-pressure) and dead space volume than using a pneumotachometer in series with the meter under test. Pump output flow was found to be lower than the desired flow both with the mini-Wright and Assess meters (for waveform No. 26, PEFs 7.1 and 10.9% lower, respectively). To compensate for losses due to gas compression, we have developed a method of deriving new input waveforms, which, when used to drive a commercially available mechanical pump, accurately and reliably produces the 26 ATS flow-time waveforms, even those with the fastest rise-times.
authors.affiliation: National Institute for Occupational Safety and Health, Division of Respiratory Disease Studies, Morgantown, West Virginia 26505-2888, USA.
authors.forename: J L
authors.initials: JL
authors.lastname: Hankinson
authors.forename: J S
authors.initials: JS
authors.lastname: Reynolds
authors.forename: M K
authors.initials: MK
authors.lastname: Das
authors.forename: J O
authors.initials: JO
authors.lastname: Viola
mesh_terms: D005069:Evaluation Studies as Topic; D006801:Humans; D010366:Peak Expiratory Flow Rate; D012815:Signal Processing, Computer-Assisted; D013147:Spirometry / Q000295:instrumentation* / Q000592:standards