What characterizes patients known as "pink puffers" in relation to emphysema?

Patients who are referred to as "pink puffers" in the context of emphysema are primarily characterized by a relatively mild hypoxemia coupled with a barrel-shaped chest. This designation is commonly associated with individuals who exhibit classic symptoms of emphysema, including difficulty in expiration due to the destruction of alveolar walls, leading to air trapping and hyperinflation of the lungs.

The term "pink puffer" implies that these patients tend to have less severe hypoxemia compared to "blue bloaters," who have more pronounced cyanosis and hypoxemia. Due to their efficient breathing techniques, often involving pursed-lip breathing, those classified as "pink puffers" maintain better oxygenation and have a healthier appearance (often with a pinkish skin tone) relative to their respiratory distress. The barrel-shaped chest results from chronic overinflation of the lungs, a hallmark of emphysema.

This combination of moderate hypoxemia and structural changes in the chest due to lung hyperinflation distinctly characterizes "pink puffers." They tend to be more active and are less likely to present with significant edema, which differentiates them from other patients with respiratory conditions.