Inspiratory reserve volume

Inspiratory Reserve Volume (IRV) is a component of the total lung capacity that refers to the additional volume of air that can be forcibly inhaled after the inspiration of a normal tidal volume breath. It is a measure used in pulmonology to assess lung function and is an important aspect of respiratory physiology.

Definition

Inspiratory Reserve Volume is the maximal amount of additional air that can be drawn into the lungs by determined effort after normal inspiration. This volume is not the same in all individuals and can be influenced by a variety of factors, including age, sex, body composition, and overall health status.

Measurement

The Inspiratory Reserve Volume is typically measured using spirometry, a common pulmonary function test. During this test, the individual takes a normal breath in, then inhales as much additional air as possible. The volume of this additional air is the Inspiratory Reserve Volume.

Clinical Significance

The Inspiratory Reserve Volume can be used to help diagnose and monitor respiratory conditions such as chronic obstructive pulmonary disease (COPD), asthma, and pulmonary fibrosis. A decreased IRV may indicate restrictive lung disease, while an increased IRV may be indicative of obstructive lung disease.

Related Concepts

Inspiratory Reserve Volume is one of several volumes that can be measured as part of lung function testing. Other related concepts include:

• Tidal Volume (TV): The amount of air inhaled or exhaled during normal breathing.
• Expiratory Reserve Volume (ERV): The maximum volume of air that can be forcibly exhaled after the expiration of a normal tidal volume breath.
• Residual Volume (RV): The volume of air remaining in the lungs after a maximal exhalation.
• Vital Capacity (VC): The total amount of air that can be exhaled after maximal inhalation. VC = TV + IRV + ERV.

See Also

• Spirometry
• Pulmonary function testing
• Lung volumes
• Respiratory system