Spirometer

• A spirometer is a device used to measure lung volume. A person using a spirometer breathes in and out of the airtight chamber, thus causing it to move up and down, leaving a trace on a graph which can then be interpreted
• Vital capacity – the maximum volume of air that can be inhaled or exhaled in a single breath. Varies depending on gender, age, size as well as height
• Tidal volume – the volume of air we breathe in and out at each breath at rest
• Breathing rate – the number of breaths per minute, can be calculated from the spirometer trace by counting the number of peaks or troughs in a minute
• The volume of air which is always present in the lungs is known as the residual volume. The tidal volume can be exceeded, in cases such as during exercise where the inspiratory reserve volume is reached in an attempt to increase amount of air breathed in
• Similarly, the expiratory reserve volume is the additional volume of air that can be exhaled on top of the tidal volume.