Bronchiolitis Obliterans

Bronchiolitis obliterans (Image sourced from Bristol Biomed Image Archive with permission)

• Severe irreversible injury of the bronchioles, can be a sequelae to chronic bronchiolitis or bronchitis
• Bronchioles are ill equipped to remove airway inflammatory exudate and debris (see 'functional anatomy')
• The fibrin-rich exudate is infiltrated by fibroblasts -> fibroblasts synthesise collagen in the exudate -> results in polyp formation inside the lumen -> permanent obstruction of the bronchiolar lumen.
• Can occur within 7-10 days of the inception of the bronchial inflammation
• Hypertrophy of mural smooth muscle of medium to small-sized pulmonary arteries
• Results in pulmonary hypertension - cor pulmonale - potential cause for right-sided heart failure