Spirometry

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Spirometry is a common test for lung function. It is used to diagnose asthma, COPD, pulmonary fibrosis and other lung diseases. It can also be a helpful tool to monitor disease progression, and evaluate effectiveness of a treatment plan. A tube-like device, called a spirometer, is used to capture and record air volumes and breathing speed.

A spirometry test typically reports 4 respiratory volumes:

- Tidal volume, TV - the amount of air inhaled or exhaled during normal, quiet breathing, without effort.

- Inspiratory reserve volume, IRV - the amount of air that can be inhaled with maximum effort, after a quiet inhalation.

- Expiratory reserve volume, ERV - the amount of air that can be exhaled with maximum effort, after a quiet exhalation.

- Residual volume, RV – the amount of air remaining in the lungs after a maximum exhalation.

These volumes are used to calculate other parameters, called respiratory capacities:

- Inspiratory capacity, IC – the maximum amount of air that can be inhaled after a quiet exhalation.

- Functional residual capacity, FRC, - the amount of air remaining in the lungs after a quiet exhalation.

- Total lung capacity, TLC


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