Increased anterior-posterior (AP) diameter is commonly seen in which type of respiratory disorder?

Increased anterior-posterior (AP) diameter is typically associated with obstructive respiratory disorders. This change in chest configuration occurs due to the hyperinflation of the lungs, which is a hallmark of conditions such as chronic obstructive pulmonary disease (COPD) and asthma during exacerbations. In these disorders, air becomes trapped in the lungs, leading to an increase in lung volume and, consequently, an increase in the AP diameter of the thorax.

In contrast, restrictive lung disorders are characterized by reduced lung volumes and typically do not feature an increase in AP diameter; rather, they may present with a more flattened, narrow shape to the chest. Central respiratory disorders affect the regulation of breathing rather than the mechanics of airflow, and acute respiratory distress syndrome (ARDS) is primarily characterized by an inflammatory response and impaired gas exchange without the typical hyperinflation seen in obstructive conditions. Thus, the correct association of increased AP diameter is indeed with obstructive respiratory disorders.