In a patient with a barrel-shaped chest and pursed lip breathing, what is likely the underlying pathophysiology?

In a patient with a barrel-shaped chest and pursed lip breathing, the underlying pathophysiology is likely an increase in residual volume. This condition is often associated with chronic obstructive pulmonary disease (COPD), particularly emphysema, where the alveoli become damaged, causing air to be trapped in the lungs. As a result, the lungs are unable to fully exhale, leading to an increase in the amount of air that remains in the lungs after exhalation, which is categorized as residual volume.

The barrel-shaped chest reflects the overinflation of the lungs, while pursed lip breathing is a compensatory mechanism the patient employs to help control their breathing and improve airflow. This breathing technique prolongs the expiration phase, allowing for better elimination of trapped air, thereby helping to relieve the symptoms associated with overinflation. Thus, the increase in residual volume directly contributes to the characteristic physical findings and respiratory patterns observed in such patients.