Physiological Adaptation in COPD Exacerbation

A 65-year-old male patient with a history of chronic obstructive pulmonary disease (COPD) presents to the emergency department with increased shortness of breath and a productive cough with greenish sputum. Upon assessment, he exhibits tachypnea, use of accessory muscles for breathing, and decreased oxygen saturation levels. The healthcare team suspects acute exacerbation of his COPD, potentially due to a respiratory infection.

In this scenario, you must identify the primary physiological adaptation that occurs in the alveolar-capillary membrane during a COPD exacerbation, characterized by impaired gas exchange. Fill in the blank: "During this exacerbation, there is a(n) __________ in the permeability of the alveolar-capillary membrane, leading to increased diffusion distance and impaired oxygen uptake."