Quantitative and qualitative breathing disorders. Basic pathogenetic mechanisms of lung diseases.
I. Quantitative breathing disorders
Disorders involving changes in the rate and depth of ventilation, affecting the overall amount of air moved.
Types
- 1 Hyperventilation
Increased alveolar ventilation, exceeding metabolic demand.
Etiology:
- Anxiety, panic attacks.
- Hypoxemia (high altitude, severe anemia).
- Metabolic acidosis (e.g., diabetic ketoacidosis —Kussmaul breathing).
Pathogenesis:
- Excess CO₂ elimination → hypocapnia → respiratory alkalosis.
Clinical features:
- Lightheadedness, tingling, muscle cramps.
- 2 Hypoventilation
Decreased alveolar ventilation, inadequate to meet metabolic demand.
Etiology:
- CNS depression (sedatives, trauma).
- Neuromuscular disorders (myasthenia gravis, Guillain- Barré).
- Severe obesity (Pickwickian syndrome).
Pathogenesis:
- CO₂ retention → hypercapnia → respiratory acidosis.
Clinical features:
- Headache, confusion, somnolence, eventual coma.
II. Qualitative breathing disorders
Disorders involving abnormal patterns or rhythm of breathing, not necessarily related to ventilation quantity.
- 1 Dyspnea
Subjective feeling of difficult or labored breathing.
Etiology:
- Lung disease (e.g., COPD, asthma).
- Heart failure.
- Anemia.
- 2 Orthopnea
Dyspnea in supine position (classic in left heart failure).
- 3 Paroxysmal nocturnal dyspnea
Sudden nighttime attacks of dyspnea; typically in heart failure.
- 4 Cheyne- Stokes breathing
Cyclic breathing pattern: gradual hyperpnea → hypopnea → apnea.
Etiology:
- Severe heart failure.
- CNS disorders.
- High altitude.
- 5 Biot’s breathing (ataxic breathing)
Irregular breathing with unpredictable apnea.
Etiology:
- Medullary brainstem damage (e.g., stroke, trauma).
- 6 Kussmaul breathing
Deep, labored breathing pattern.
Etiology:
- Severe metabolic acidosis (e.g., diabetic ketoacidosis).