Acute respiratory distress syndrome (ARDS) typically presents with dyspnoea and hypoxaemia, which progress to acute respiratory failure.
Common causes are pneumonia, sepsis, aspiration, and severe trauma.
Mortality is between 30% and 50%.
Low tidal volume, plateau-pressure-limited mechanical ventilation is the primary treatment that has been shown to reduce mortality. In severe ARDS, neuromuscular blockade and prone positioning may improve clinical outcomes.
Complications include pneumothorax, ventilator-associated pneumonia, multiple organ failure, and pulmonary fibrosis with prolonged respiratory failure.
This topic covers ARDS in patients over the age of 12 years.
Acute respiratory distress syndrome (ARDS) is a non-cardiogenic pulmonary oedema and diffuse lung inflammation syndrome that often complicates critical illness. The diagnosis of ARDS is based on fulfilling three criteria:
Acute onset (within 1 week)
Bilateral opacities on chest x-ray
PaO₂/FiO₂ (arterial to inspired oxygen) ratio of ≤300 on positive end-expiratory pressure or continuous positive airway pressure ≥5 cm H₂O.
If no risk factors for ARDS are present, then acute pulmonary oedema as a result of heart failure should be ruled out.
History and exam
Key diagnostic factors
- presence of risk factors
- low oxygen saturation
- acute respiratory failure
Other diagnostic factors
- critically ill patient
- increased respiratory rate
- pulmonary crepitations
- low lung compliance
- fever, cough, pleuritic chest pain
- frothy sputum
- severe trauma
- blood transfusions
- lung transplantation
- history of alcohol misuse
- burns and smoke inhalation
- e-cigarette and vaping product use
- drug overdose
- cigarette smoking
1st investigations to order
- chest x-ray
- arterial blood gases
- sputum culture
- blood culture
- urine culture
- amylase and lipase
Investigations to consider
- brain natriuretic peptide (BNP)
- pulmonary artery catheterisation
- bronchoalveolar lavage or endotracheal aspirate
- CT scan of the thorax
- viral testing
- open lung biopsy
- Coronavirus disease 2019 (COVID-19)
- Acute heart failure
- Bilateral pneumonia
- Guidelines on the management of acute respiratory distress syndrome
- Mechanical ventilation in adult patients with acute respiratory distress syndrome
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