Spirometer

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A spirometer is an apparatus 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 time. The Spirometer and attached flow head function together as a pneumotachometer, with an output signal proportional to airflow. It was invented by John Hutchinson in 1846.

The output produced by a spirometer is called a kymograph trace. 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.

[edit] See also

• Spirometry
• Respiratory system
• Lung volumes
• Cardiopulmonary physiotherapy