Spirometry is the biological process of recording the changes in the volume movements of air into and out of the lungs. Spirometer is an instrument which is used to measure the movement of air into and out of the lungs. It is used to access the pulmonary function of lungs like ventilation, inspiration and expiration of air. Using spirometer, the physiological condition can be assessed by measuring different respiratory volumes such as Tidal volume (TV), Inspiratory reserve volume (IRV), Expiratory reserve volume (ERV), etc.
The sphygmomanometer is used to check blood pressure. Barometer is used to measure air pressure.