Effect of Ageing on the Respiratory System

Question 1

Mechanics of Breathing - Chest Wall Changes (3)

Answer 1

• Rounding of the thorax -> Barrel chest
• Calcification of costal cartilage (↓ Tx compliance)
• ↓ space between spinal vertebrae and ↑ spinal curvature
  Leading to ↓ chest ROM

Question 2

Mechanics of Breathing - Airways and Parenchyma (3)

Answer 2

• Progressive enlargement of respiratory bronchioles and alveolar ducts.
• Loss of functional aveolar surface area and surface tension.
• Negative effect on forced expiratory flow.

Question 3

Mechanics of Breathing - Muscles (1)

Answer 3

↓ respiratory muscle strength and endurance.

Question 4

Mechanics of Breathing - Lung Volume Changes (3)

Answer 4

• ↓ inspiratory reserve volume (IRV), expiratory reserve volume (ERV) and vital capacity (VC).
• ↑ residual volume (RV) and functional residual capacity (FRC).
• Total lung capacity (TLC) remains about the same.

Question 5

Airway Function and Structure (7)

Answer 5

• ↑ airway reactivity
• ↓ ciliary number and activity
• Diminished airway reflexes (coughing) -> weak resp. muscles
• Allergies activated easily, threshold ↓
• ↑ risk of bronchospasm, requires lesser stimulus
• Clearance of secretion is impaired - cilia not working well, cough impaired.
• ↑ propensity towards pharyngeal collapse -> reduced patency of upper airway due to adipose tissue infiltration.

Question 6

Respiratory Muscle Changes (3)

Answer 6

↓ total muscle mass
↓ muscle strength
↓ proportion of fast-twitch fibers

Question 7

Respiratory Muscle Change Effect (7)

Answer 7

↓ Maximum inspiratory pressure (MIP)
↓ FEV1
RR higher than 15 (8-12 norm)
↓ Maximum minute ventilation
Fatigue develops more rapidly
↓ Exercise capacity
↓ diaphragmatic excursion

Question 8

Structural Changes of the Lung (3) and Effect (2)

Answer 8

Degeneration of elastic fibers.
Alveolar dilation.
Reduction in supporting tissue around small airways.
- ↑ dead space ventilation
- Premature small airway closure -> ↑ risk of gas trapping.

Question 9

Lung Function Changes

Answer 9

Lung function decreases.
↓ FEV1 and FVC due to loss of alveoli, dilated airspaces and ↓ respiratory muscle function.

Question 10

Gas Exchange Changes (4)

Answer 10

• Declines at 0.5% per year.
• ↑ physiological dead space (no gas exchange) due to loss of alveoli walls -> loss of capillaries.
• Blood gas value changes have no correlation with ageing.
• ↑ collagen -> ↓ elasticity + airspace enlargement.

Question 11

Changes in Control of Breathing (4)

Answer 11

• Increased respiratory frequency
• ↓ efferent neural output of respiratory muscles.
• Significantly diminished response to hypoxia and hypercapnia.
• ↓ response for vocal chord closure -> increased risk of aspiration.

Question 12

Immunological Changes (5)

Answer 12

• ↑ antibody content, ↓ alveolar macrophages
• ↑ susceptibility to bronchospasms
• ↑ susceptibility to infections
• Slower recovery from infection
• Progressive decline in immune function and inflammageing through effects of primary and secondary lymphoid and lung tissue.

Question 13

Clinical Implications (4)

Answer 13

• ↓ maximal breathing capacity, VC and max O2 uptake
• ↓ mucociliary clearance and cellular and humoral lung defence mechanisms.
• ↑ risk for respiratory infections
• Acute and chronic respiratory conditions can have severe consequences due to hypoxemia and hypercapnia.

Question 14

Exercise Performance Changes (2)

Answer 14

VO2max declines with age -> needs O2 uptake to produce energy and proper lung ventilation. In ageing: ↓ alveoli -> ↓ capillaries to take O2 blood to the heart -> ↓ O2 reaching muscles.
- Mitochondrial dysfunction -> ↓ energy production.