Typical questions on the boards address the following: common features of uncommon diseases, uncommon features of common diseases, disease associations, and knowledge of established treatments.

Questions on the board examinations are less likely to address straightforward associations, such as common complications of commonly used medications and common medical manifestations of common illnesses.

Measuring pulmonary function tests can help the astute clinician identify the physiologic signature of the pulmonary illness in order to categorize it as restrictive or obstructive and, in so doing, narrow down a specific etiology.

In addition to the normal flow-volume loop, three characteristic deviations from the normal flow-volume loop suggest various forms of upper airway obstruction.

The identifying criterion for restrictive lung disease is decreased total lung capacity.

Calculation of the alveolar-arterial oxygen gradient is very useful for approaching the differential diagnosis of hypoxemia. Six mechanisms of hypoxemia should be remembered: anatomic shunt, mismatch, diffusion impairment, hypoventilation, inhaling a decreased inspired oxygen fraction (hypoxic hypoxemia) or breathing at altitude (hypobaric hypoxemia), and diffusion-perfusion impairment (e.g., as seen in the hepatopulmonary syndrome).