What do the terms "pink puffer" and "blue bloater" mean?

Chronic lung disease: Those terms are sometimes used for patients with COPD or emphysema. They are usually signs of low oxygen state.

Older Terms: These are older terms- the pink puffer classically described a patient with emphysema (thin, pink means oxygenated). The blue bloated means a patient with chronic bronchitis (poorly oxygenated- blue and overweight). We now know there is a lot of overlap between these two types of patients.

COPD types: Classically, COPD is separated into patients who predominantly have either chronic bronchitis (blue bloater because they're frequently cyanotic and overweight) or emphysema ( pink and thin or underweight). Most patients are mixtures of both with 75% or more patients having chronic bronchitis.