Glaxo Australia Pty., Ltd.

Frederick A Ebeling

Charles K Waterson

A self-contained portable spirometer includes a housing and an air tube with an orifice. Within the housing there is a transducer and microprocessor-based circuitry for generating standard exhaled air performance measurements such as forced expiration volume and peak expiratory flow rate, commonly referred to as FEV.sub.1 and PFER. These measurements are displayed on a screen disposed on the housing. Since the air tube has a non-linear response, two amplifier stages with different amplification are coupled between the transducer and the microprocessor. The microprocessor monitors the flow rate through the tube and selects the signal from either one or the other amplification stage depending on the flow through the tube. The microprocessor also monitors the flow to determine when no air is blown through the tube. In this latter case, the computer shuts the power to the analog circuitry to conserve power.

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Tucson, AZ, United States of America

Frederick A Ebeling