An evaluation of peak expiratory flow measured on the smart peak flow meter

Background: Serial peak expiratory flow (PEF) readings are important to identify occupational asthma. The smart PEF meter (sPEF) allows integration with smart phone technology and real time data transfer. The sPEF meter records an acoustic signal from a rotating vane and uses ambient light without access to the phone’s battery. Aim: To compare PEF taken using the sPEF with the MiniWright (MW) meter. Methods: 10 workers from the respiratory physiology department recorded PEF readings on both meters; 6 times daily for 5 days, 3 readings per session on each. The meter used for the first reading alternated between and within each session. The mean within session coefficient of variation (CoV) for each meter and operator was calculated. Results: 347 readings were recorded on the MW and 336 on the sPEF, averaging 39 sessions per worker. Figure 1 shows the comparison of the mean CoV for each meter and operator.The mean CoV for MW was 3.12 and for sPEF was 15.7. The number of sessions on the sPEF were slightly lower due to technical issues such as, the session timing out and insufficient ambient light. Conclusion: The sPEF is more consistent in some workers than others. Reasons might include PEF itself (very low/very high), the environment (lighting, background noise) or the actual phone used and its connection (directly into the acoustic jack or via a cable). We are doing further studies to investigate these factors.