• Obstruction of airway

• Compression with fluid/blood/neoplasm/air in pleural space

• Loss of surfactant

• Complete obstruction of inflow results in eventual absorption of air; partial obstruction results in hyperinflation

• Compression results from increased intrathoracic pressure by accumulation of material generally in pleural spaces

• Acquired in adulthood

• Airway obstruction by foreign object or secretion

• Pleural effusions with congestive heart failure

• Reversible process

• Correct underlying problem

• Dark purple, airless (non-crepitant) tissue

• Hyperinflated regions are tan and pillowy

• Collapse of alveolar septae against each other

• May be difficult to separate from artifacts of
sectioning

• Cotran RS, Kumar V, Robbins SL: Robbins Pathologic Basis of Disease. 5th edition. Philadelphia, W.B. Saunders, 1994, pp. 675.

• Current literature from PubMed at National Library of Medicine