Acute respiratory distress syndrome (ARDS) is characterised by a profound deterioration in systemic oxygenation or ventilation, or both, despite supportive respiratory therapy. ARDS is an acute and progressive respiratory disease of a non-cardiac cause that is associated with progressively diffuse bilateral pulmonary infiltrates, reduced pulmonary compliance, and hypoxaemia. The main causes of ARDS include direct lung injury (e.g., pneumonia, gastric acid aspiration) or indirect lung injury (e.g., sepsis, pancreatitis, massive blood transfusion, non-thoracic trauma). Sepsis and pneumonia account for about 60% of cases. Between one third and one half of people with ARDS die from the disease, but mortality depends on the underlying cause. Some survivors have long-term respiratory or cognitive problems.
Methods and outcomes
We conducted a systematic review and aimed to answer the following clinical question: What are the effects of interventions in adults with acute respiratory distress syndrome? We searched: Medline, Embase, The Cochrane Library, and other important databases up to December 2009 (Clinical Evidence reviews are updated periodically, please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA).
We found 20 systematic reviews, RCTs, or observational studies that met our inclusion criteria.
In this systematic review we present information relating to the effectiveness and safety of the following interventions: corticosteroids, low tidal-volume mechanical ventilation, nitric oxide, prone position, and protective ventilation.
Acute respiratory distress syndrome (ARDS) is a syndrome of inflammation and increased permeability that is associated with clinical, radiological, and physiological abnormalities, which usually develops over 4 to 48 hours and persists for days or weeks. Pathologically, ARDS is associated with complex changes in the lungs, manifested by an early exudative phase and followed by proliferative and fibrotic phases.
The main causes of ARDS are infections, aspiration of gastric contents, and trauma.Between one third and one half of people with ARDS die, but mortality depends on the underlying cause. Some survivors have long-term respiratory or cognitive problems.The treatment of ARDS is supportive care, including optimised mechanical ventilation, nutritional support, manipulation of fluid balance, source control and treatment of sepsis, and prevention of intervening medical complications.
Low tidal-volume ventilation, at 6 mL/kg of predicted body weight, reduces mortality compared with high tidal-volume ventilation, but can lead to respiratory acidosis.
Positive end expiratory pressure (PEEP) that maintains PaO2 above 60 mmHg is considered effective in people with ARDS, but no difference in mortality has been found for high PEEP compared with lower PEEP strategies.
People with ARDS may remain hypoxic despite mechanical ventilation. Nursing in the prone position may improve oxygenation but it has not been shown to reduce mortality, and it can increase adverse effects such as pressure ulcers.
The prone position is contraindicated in people with spinal instability and should be used with caution in people with haemodynamic and cardiac instability, or in people who have had recent thoracic or abdominal surgery.
We found insufficient evidence to draw reliable conclusions on the effects of corticosteroids on mortality or reversal of ARDS.
Nitric oxide has not been shown to improve survival or duration of ventilation, or hospital stay, compared with placebo. It may modestly improve oxygenation in the short term but the improvement is not sustained.