Lung Volume and Chronic Lung Disease

Question :

Pulmonary function tests (PFTs) are important tools for evaluating patients who have symptoms of lung disease or at risk factor for lung disease, such as occupational hazards or smoking. Spirometry and lung volumes may be two PFTs that you have heard of. They help to diagnose obstructive or restrictive lung disease, monitor disease progression, and check whether treatments are effective.

Understanding the different volumes and capacities associated with lung function will help you to better understand PFTs, respiratory disease and treatment for your patients.

Lung volumes include tidal volume (TV), inspiratory reserve volume (IRV), expiratory reserve volume (ERV), and residual volume (RV).

The various lung capacities include inspiratory capacity (IC), vital capacity (VC), functional residual capacity (FRC), and total lung capacity (TLC).

Answer :

Lung Volume and Chronic Lung Disease

There are different lung volumes such as tidal volume, inspiratory reserve volume, expiratory reserve volume, and residual volume. 

Tidal volume: this is one of the lung volumes that represent the normal air volume which displaced between normal inhalation as well as exhalation without applying extra effort. The tidal volume in a young and healthy adult is 500 mL per inspiration (Carteaux et al., 2016). 

Inspiratory reserve volume: it can be defined as the additional volume of air that is inhaled after a normal inspiration. It represents the extra amount of air inhaled above the tidal volume by putting extra effort or forceful breath-in. In a human being, inspiratory reserve volume is between 2000 to 3000 ml. 

Expiratory reserve volume: it is opposite to inspiratory reserve volume that represents the extra volume of air exhaled above a normal breath during a forceful breath-out. It is the extra volume of air that is expired by the extra effort from the lungs (Hallett & Ashurst, 2019). In the male, the average volume of expiratory reserve volume is 1100 ml while it is 800 ml in the female.

Chronic lung disease and vital capacity 

Asthma is a chronic lung disease that significantly affects the vital capacity of lungs. Asthma is an obstructive lung disease because it narrows airways and narrowing airways makes it tough to get enough air out of the lungs. It affects the vital capacity of the lungs and it decreases slightly. However, it also may be normal. 

References 

Carteaux, G., Millán-Guilarte, T., De Prost, N., Razazi, K., Abid, S., Thille, A. W., ... & Mekontso Dessap, A. (2016). Failure of noninvasive ventilation for de novo acute hypoxemic respiratory failure: role of tidal volume. Critical care medicine, 44(2), 282-290.

Hallett, S., & Ashurst, J. V. (2019). Physiology, Tidal Volume. In StatPearls [Internet]. StatPearls Publishing.