In obstructive lung disorders, what is commonly true about the total lung capacity (TLC)?

In obstructive lung disorders, what is commonly true about the total lung capacity (TLC)?

• A. TLC is decreased
• B. TLC remains unchanged
• C. TLC is increased due to elevated RV
• D. TLC is only affected during exercise

Answer: (C)

In obstructive lung disorders, total lung capacity (TLC) is commonly increased due to an elevated residual volume (RV). This increase occurs because individuals with obstructive lung diseases, such as asthma or chronic obstructive pulmonary disease (COPD), often have difficulty expelling air from the lungs due to narrowed airways. As a result, air becomes trapped, leading to an increase in RV, which in turn contributes to an overall rise in TLC. In such conditions, while the functional residual capacity (FRC) and RV are elevated, TLC encompasses the total volume of air the lungs can hold, including both the air that can be forcefully exhaled (vital capacity) and the air that remains in the lungs after maximal exhalation. The combination of increased RV and unchanged or slightly decreased vital capacity results in an overall increase in TLC. Understanding these changes in lung volumes is crucial for assessing and managing patients with obstructive lung diseases, as they provide insights into the severity of airway obstruction and its functional implications on respiratory mechanics.

In obstructive lung disorders, total lung capacity (TLC) is commonly increased due to an elevated residual volume (RV). This increase occurs because individuals with obstructive lung diseases, such as asthma or chronic obstructive pulmonary disease (COPD), often have difficulty expelling air from the lungs due to narrowed airways. As a result, air becomes trapped, leading to an increase in RV, which in turn contributes to an overall rise in TLC.

In such conditions, while the functional residual capacity (FRC) and RV are elevated, TLC encompasses the total volume of air the lungs can hold, including both the air that can be forcefully exhaled (vital capacity) and the air that remains in the lungs after maximal exhalation. The combination of increased RV and unchanged or slightly decreased vital capacity results in an overall increase in TLC.

Understanding these changes in lung volumes is crucial for assessing and managing patients with obstructive lung diseases, as they provide insights into the severity of airway obstruction and its functional implications on respiratory mechanics.