An electronic peak flow meter with optional coded display.

A portable electronic spirometer giving peak expiratory flow rate has been developed and used successfully in studies of asthma. A turbine flow transducer produces a pulsed output whose frequency is proportional to flow. The output was coded to keep the results 'blind' to the patient. The code is suitable for use on other electronic instruments employing a similar display. It has been successfully used to investigate patients' perception of their asthma.