What is a Spirometer?

A spirometer is a medical device used for measuring the volume of air inspired and expired by the lungs. It is a precision differential pressure transducer for the measurements of respiration flow rates. The spirometer records the amount of air and the rate of air that is breathed in and out over a specified period of time. There are numerous different types of spirometer such as a USB PC-based spirometer, a ultrasound based desktop spirometer, and a portable spirometer.

A Tank-type spirometer works on the same principle as the gas meter. A canister of soda is usually attached to absorb carbon dioxide and a kymograph trace is produced to record changes in total volume gas. From this, vital capacity, tidal volume, breathing rate and ventilation rate (=tidal volume x breathing rate) can be calculated. From the overall decline on the graph, the oxygen uptake can also be measured.

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