What is a primary reason for the increase in total lung capacity (TLC) observed in obstructive lung disease?

What is a primary reason for the increase in total lung capacity (TLC) observed in obstructive lung disease?

• A. Restricted airflow into the lungs
• B. Air trapping leading to an increased residual volume (RV)
• C. Increased lung compliance
• D. Decrease in total lung volume

Answer: (B)

In obstructive lung disease, the primary reason for the increase in total lung capacity (TLC) is air trapping, which leads to an increased residual volume (RV). In conditions such as asthma, chronic bronchitis, and emphysema, the air passages become obstructed, making it difficult for air to exit the lungs during expiration. This causes air to remain trapped in the lungs, which subsequently increases the residual volume— the air left in the lungs after a forced expiration. As the residual volume rises because of this trapped air, it contributes to an increase in total lung capacity. The combination of a larger residual volume with the normal lung volumes leads to an overall expansion of TLC. In persons with obstructive lung disease, this phenomenon is a critical component of their pulmonary function, as it emphasizes the struggle to expel air and the resultant changes in lung mechanics. While increased lung compliance can be a factor in some lung conditions, it does not specifically explain the increase in TLC in the context of obstructive lung diseases, where it is primarily due to air trapping. Additionally, restricted airflow and a decrease in total lung volume would not typically lead to an increase in TLC, which further underlines why air trapping due to increased RV is the correct focus

In obstructive lung disease, the primary reason for the increase in total lung capacity (TLC) is air trapping, which leads to an increased residual volume (RV). In conditions such as asthma, chronic bronchitis, and emphysema, the air passages become obstructed, making it difficult for air to exit the lungs during expiration. This causes air to remain trapped in the lungs, which subsequently increases the residual volume— the air left in the lungs after a forced expiration.

As the residual volume rises because of this trapped air, it contributes to an increase in total lung capacity. The combination of a larger residual volume with the normal lung volumes leads to an overall expansion of TLC. In persons with obstructive lung disease, this phenomenon is a critical component of their pulmonary function, as it emphasizes the struggle to expel air and the resultant changes in lung mechanics.

While increased lung compliance can be a factor in some lung conditions, it does not specifically explain the increase in TLC in the context of obstructive lung diseases, where it is primarily due to air trapping. Additionally, restricted airflow and a decrease in total lung volume would not typically lead to an increase in TLC, which further underlines why air trapping due to increased RV is the correct focus