Which disorder is described by loss of lung elasticity with trapping of air, leading to a barrel-shaped chest and dyspnea?

• A. Emphysema
• B. Pneumonia
• C. Bronchitis
• D. Pulmonary fibrosis

Answer: (A)

Loss of lung elasticity with air trapping leads to hyperinflation of the lungs, which makes the chest adopt a barrel shape and causes dyspnea due to the increased work of breathing and decreased expiratory flow. Emphysema, a form of COPD, is defined by destruction of the alveolar walls and loss of elastic recoil, producing prominent air trapping and hyperinflation. This contrasts with pneumonia, which is an infectious consolidation of the lungs; bronchitis, which involves airway inflammation with cough and sometimes sputum but not the marked hyperinflation; and pulmonary fibrosis, which is a restrictive process with stiff lungs and reduced lung volumes rather than air trapping.