STANDARD FLOW-TIME WAVE-FORMS FOR TESTING OF PEF METERS

The American Thoracic Society (ATS) has recommended the use of 24 volume-time waveforms for the testing of spirometers. Although these waveforms include values of peak expiratory flow (PEF), they were not originally intended to test PEF meters but, rather, volume parameters for spirometers. In addition, the practice of using ATS volume-time Waveform 24 with varying multiplying factors does not provide the range of flow-time waveform shapes (rise times) needed to evaluate PEF meters. Accordingly, we have developed a set of 26 flow-time waveforms specifically selected to evaluate PEF meters. PEF and other flow parameters (rise time and time to PEF) can be directly measured from these flow-time waveforms. When PEF determined directly from the flow-time curve was compared with PEF determined indirectly from a volume-time curve (ATS-recommended algorithm with an 80 ms time segment), as much as a 10.7% difference between the two methods was observed using a waveform with a fast rise time. In contrast, there was very little difference between the various methods of deriving PEF for waveforms with slower rise times. These 26 Row-time waveforms provide a means of defining PEF for the testing of software algorithms and the testing of PEF meters with computer-driven mechanical pumps.