Acute respiratory distress syndrome

Abstract

Acute respiratory distress syndrome presents as hypoxia and bilateral pulmonary infiltrates on chest imaging in the absence of heart failure sufficient to account for this clinical state. Management is largely supportive, and is focused on protective mechanical ventilation and the avoidance of fluid overload. Patients with severe hypoxaemia can be managed with early short-term use of neuromuscular blockade, prone position ventilation, or extracorporeal membrane oxygenation. The use of inhaled nitric oxide is rarely indicated and both β₂ agonists and late corticosteroids should be avoided. Mortality remains at approximately 30%.

Figure 1

A normal alveolus (A), plus the sequential exudative (B), proliferative (C), and fibrotic (D) phases in the pathogenesis of acute respiratory distress syndrome

Figure 2

Clinical and research investigational modalities used in acute respiratory distress syndrome PEEP=positive end-expiratory pressure. PaO₂/FiO₂=ratio of partial pressure of arterial oxygen to fraction of inspired oxygen. SpO₂/FiO₂=ratio of peripheral arterial oxygen saturation to fraction of inspired oxygen. PiCCO=Pulse Contour Cardiac Output. TNF-α=tumour necrosis factor α. vWF= von Willebrand factor.

Figure 3

A normal chest radiograph (A), and a chest radiograph demonstrating bilateral alveolar infiltrates consistent with acute respiratory distress syndrome (B); chest CT showing bilateral pneumonitis and consolidation with air bronchograms consistent with acute respiratory distress syndrome (C); lung ultrasonogram illustrating smooth pleural line, absence of horizontal A lines, and presence of vertical B lines suggestive of acute respiratory distress syndrome (D); and PET demonstrating increased areas of metabolic activity, reflective of underlying inflammation (E–H) Figures E and F are reproduced from Bellani and colleagues, by permission of Wolters Kluwer Health.

Figure 4

Algorithm of a suggested evidence-based approach to the management of acute respiratory distress syndrome VTE=venous thromboembolism. PaO₂=partial pressure of arterial oxygen. FiO₂=fraction of inspired oxygen. ECMO=extracorporeal membrane oxygenation. Pplat=airway plateau pressure. PEEP=positive end-expiratory pressure.

Figure 5

Acute respiratory distress syndrome therapies in clinical use Pplat=airway plateau pressure. GM-CSF=granulocyte–macrophage colony-stimulating factor. PEEP=positive end-expiratory pressure. ECMO=extracorporeal membrane oxygenation. ECCO₂R=extracorporeal carbon dioxide removal. *Evidence supports use. †No supporting evidence base, or evidence of harm. ‡Undergoing active research.