31. Basic mechanisms disturbing lung function – types of restrictive ventilatory disorders. Main pathogenetic mechanisms, causing restriction – inflammation, fibrosis, edema, reduction of lung parenchyma, pleural and rib-cage dysfunctionalities.

Restrictive ventilatory disorders

• Caused when there is a decrease in lung volume/volume deficiency of the lungs
• Lungs are described as too small or too rigid
• Minute ventilation = respiratory rate x tidal volume
• In restrictive disorders the respiratory rate increases as compensation
• However an increase in shallow breathing respiratory rate is not a good compensatory mechanism because with shallow breathing, there is a higher rate of anatomical dead space ventilation → no gas exchange occurs here
• With deeper breathing, the alveoli are more well ventilated

Classification

1. Clinical course - acute, chronic
2. Severity - mild, moderate, severe, very severe
3. Anatomical - intrapulmonary, extrapulmonary

Extrapulmonary

• Muscle weakness
• Myasthenia gravis (autoimmune) → ↑ Ab produced against receptors on muscles
• Spine irregularities/ thoracic cage abnormalities
• Kyphosis, scoliosis
• Bone problems
• Chest trauma
• Neuromuscular disorders
• Pleuritis
• Hydrothorax (water), hemothorax (blood), pneumothorax (air)
• Pain in the chest therefore unable to expand as it compresses the lungs
• Pneumothorax can be spontaneous or traumatic
• It occurs due to rupture of air filled bleb + insufficiency of connective tissue