Senile emphysema

Definition and why the name is a misnomer. "Senile emphysema" (better called the ageing or senile lung) is the physiological enlargement of alveolar ducts and alveoli that occurs with normal ageing. Crucially, it occurs WITHOUT destruction of alveolar walls and without inflammation — the features that define true emphysema. It is therefore a normal age-related change, not a disease, and the term "emphysema" is strictly incorrect.

Mechanism. There is an alteration in the collagen and elastic fibre network of the lung, leading to dilated alveolar ducts and alveolar enlargement and a loss of elastic recoil. Loss of recoil reduces the tethering (radial traction) of small airways, so they close at higher lung volumes, producing premature airway closure, air trapping and hyperinflation. Alveolar surface area for gas exchange falls (roughly 4% per decade after 30).

Associated extrapulmonary changes. The chest wall stiffens: rib cage stiffening, degenerative spinal change with kyphosis, reduced thickness of parietal muscles and reduced respiratory muscle mass, giving decreased chest wall compliance, increased anteroposterior diameter and a flattened diaphragm with decreased curvature. The result is increased work of breathing, a higher respiratory rate with lower tidal volume, and reduced exercise tolerance.

Physiological consequences (very examinable).

Clinical relevance. The senile lung is asymptomatic at rest — there is no cough, sputum or wheeze — but there is reduced ventilatory reserve, so exercise tolerance falls and the older person decompensates rapidly during pneumonia, heart failure, surgery or anaesthesia. Physical signs may mimic emphysema (barrel chest, reduced expansion, hyper-resonance, quiet breath sounds), and this must not be mistaken for COPD.

Distinguishing senile lung from true emphysema (the crux of the answer).

GOLD 2023–2026 reports formally recognise the diagnostic problem posed by the ageing lung by introducing the categories of "Pre-COPD" (respiratory symptoms and/or structural or functional abnormality with normal spirometry) and "PRISm" — Preserved Ratio Impaired Spirometry (FEV /FVC ≥ 0.70 but FEV < 1 1 80% predicted), both of which carry increased risk of progression and mortality. GOLD also continues to caution that the fixed FEV /FVC ratio of 0.70 over-diagnoses airflow obstruction in older adults, and to recommend 1 confirming abnormality against age-appropriate reference equations — the modern, guideline-level restatement of exactly what "senile emphysema" describes.