Geriatrics: Pulmonary changes

Ventilatory responses to hypoxia, hypercapnia, and stress are reduced, while the depressant effects of both intravenous agents (benzodiazepines, opioids) and volatile anesthetics are more pronounced. Elastic recoil is lost and surfactant is reduced, leading to an increase in lung compliance. These, combined with a loss of alveolar surface area leads to increased anatomic dead space, decreased diffusing capacity, and increased closing capacity

Loss of height and calcification lead to diaphragmatic flattening and barrel chest, decreasing mechanical efficiency which is worsened by loss of muscle mass. Work of breathing is increased

Total lung capacity is unchanged. Closing capacity increases (increased ventilation-perfusion mismatch is the most important reason for increased A-a gradient with aging). Residual volume increases by 7% per decade. At 44 years of age, closing capacity and FRC equalize in the supine position, and at 66 years of age, in the upright position.

Pulmonary Changes in the Elderly

• Decreased ventilatory response to hypoxia, hypercapnia, and stress
• Increased response to opioids, benzodiazepines, volatile anesthetics
• Diminution of elastic recoil, less surfactant, increased lung compliance
• Decreased mechanical efficiency
• Increased closing capacity and increased V-Q mismatching