Spirometry (spy-ROM-uh-tree) is a common office test used to assess how well your lungs work by measuring how much air you inhale, how much you exhale and how quickly you exhale. Spirometry is used to diagnose asthma, chronic obstructive pulmonary disease (COPD) and other conditions that affect breathing.

What Cannot be measured by a spirometer?

Functional Residual Capacity, Residual Volume, and Total Lung Capacity. These three volumes cannot be measured with a spirometer (a device that measures the volume of air being exhaled or inhaled) because there is no way of knowing the volume remaining in the lung after a maximal expiration (i.e., the RV).

What does a spirometer measure directly?

Spirometry measures the amount (volume) and/or speed (flow) of air that can be inhaled and exhaled. The most common measurements used are: Forced expiratory volume in one second (FEV1). This is the amount of air you can blow out within one second.