- Section 1 ICU organization and management
- Section 2 Pharmacotherapeutics
- Section 3 Resuscitation
- Section 4 The respiratory system
- Part 4.1 Physiology
- Part 4.2 Respiratory monitoring
- Part 4.3 Upper airway obstruction
- Part 4.4 Airway access
- Part 4.5 Acute respiratory failure
- Part 4.6 Ventilatory support
- Part 4.7 Weaning ventilatory support
- Part 4.8 Extracorporeal support
- Part 4.9 Aspiration and inhalation
- Part 4.10 Acute respiratory distress syndrome
- Part 4.11 Airflow limitation
- Part 4.12 Respiratory acidosis and alkalosis
- Part 4.13 Pneumonia
- Part 4.14 Atelectasis and sputum retention
- Part 4.15 Pleural cavity problems
- Part 4.16 Haemoptysis
- Section 5 The cardiovascular system
- Section 6 The gastrointestinal system
- Section 7 Nutrition
- Section 8 The renal system
- Section 9 The neurological system
- Section 10 The metabolic and endocrine systems
- Section 11 The haematological system
- Section 12 The skin and connective tissue
- Section 13 Infection
- Section 14 Inflammation
- Section 15 Poisoning
- Section 16 Trauma
- Section 17 Physical disorders
- Section 18 Pain and sedation
- Section 19 General surgical and obstetric intensive care
- Section 20 Specialized intensive care
- Section 21 Recovery from critical illness
- Section 22 End-of-life care
(p. 319) The respiratory system
The lungs contain 200–300 million alveoli that are reached via 23 generations of airways. The volume in the lungs after an ordinary expiration is called functional residual capacity (FRC) and is approximately 3–4 L. The lung is elastic and force (pressure) is needed to expand it and to overcome the resistance to gas flow in the airways. This pressure can be measured as pleural minus alveolar pressure. The inspired volume goes mainly to dependent, lower lung regions, but with increasing age and in obstructive lung disease airways may close in dependent lung regions during expiration, impeding oxygenation of the blood. With lowered functional residual capacity,airways may be continuously closed with subsequent gas adsorbtion from the closed off alveoli. Perfusion of the lung goes also mainly to dependent regions, but there is in addition, possibly more important, a non-gravitational inhomogeneity. A ventilation-perfusion mismatch may ensue that impedes oxygenation and CO2 removal, but can to some extent be corrected for by hypoxic pulmonary vasoconstriction.
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- Section 1 ICU organization and management
- Section 2 Pharmacotherapeutics
- Section 3 Resuscitation
- Section 4 The respiratory system
- Part 4.1 Physiology
- Part 4.2 Respiratory monitoring
- Part 4.3 Upper airway obstruction
- Part 4.4 Airway access
- Part 4.5 Acute respiratory failure
- Part 4.6 Ventilatory support
- Part 4.7 Weaning ventilatory support
- Part 4.8 Extracorporeal support
- Part 4.9 Aspiration and inhalation
- Part 4.10 Acute respiratory distress syndrome
- Part 4.11 Airflow limitation
- Part 4.12 Respiratory acidosis and alkalosis
- Part 4.13 Pneumonia
- Part 4.14 Atelectasis and sputum retention
- Part 4.15 Pleural cavity problems
- Part 4.16 Haemoptysis
- Section 5 The cardiovascular system
- Section 6 The gastrointestinal system
- Section 7 Nutrition
- Section 8 The renal system
- Section 9 The neurological system
- Section 10 The metabolic and endocrine systems
- Section 11 The haematological system
- Section 12 The skin and connective tissue
- Section 13 Infection
- Section 14 Inflammation
- Section 15 Poisoning
- Section 16 Trauma
- Section 17 Physical disorders
- Section 18 Pain and sedation
- Section 19 General surgical and obstetric intensive care
- Section 20 Specialized intensive care
- Section 21 Recovery from critical illness
- Section 22 End-of-life care