Pulmonary function

ARDS causes diffuse alveolar damage, surfactant inactivation, and fluid accumulation, which stiffens the pulmonary tissue and decreases lung compliance. Distractors suggesting compliance increases or stays normal are incorrect because these pathological changes make the lungs much harder to inflate, requiring higher pressures to achieve the same tidal volume.

An FEV1/FVC ratio below 70% in adults indicates airway obstruction because it reflects a disproportionate reduction in expiratory flow compared to total lung volume. In contrast, restrictive lung diseases typically present with a normal or even elevated ratio because both FEV1 and FVC decrease proportionally.

An FEV1/FVC ratio below 70% in adults indicates airway obstruction because it reflects a disproportionate reduction in expiratory flow compared to total lung volume. A diagram for this topic isn't available yet — the worked example below walks the same reasoning step by step.

• !Distractors suggesting compliance increases or stays normal are incorrect because these pathological changes make the lungs much harder to inflate, requiring higher pressures to achieve the same tidal volume.

Answer each from memory — you'll see instantly whether you're right and why.

Run a focused 10-question mini-mock on Pulmonary function and see it stick.