Acute respiratory distress syndrome (ARDS) is the sudden failure of the respiratory system, leading to build-up of fluid in the air sacs. This fluid prevents oxygen from passing into the bloodstream in the lungs. As a result, the patient will have difficulty getting enough oxygen into his circulation and this may be associated with failure of the other organs eg liver and kidneys.
The fluid build-up also makes the lungs heavy and stiff, and decreases the lungs’ ability to expand. The level of oxygen in the blood may become dangerously low, requiring the use of an artificial ventilator.
Patient with ARDS due to severe pneumonia
- Inhaling vomit or upper airway secretions into the lungs (aspiration)
- Septic shock resulting from bacteria invading the bloodstream
- Near drowning
- Inhalation of toxic chemicals
- Pancreatitis (inflammation of the pancreas)
- Massive blood transfusions
- Difficult or rapid breathing
- Low blood pressure and multi-organ failure
Symptoms usually develop within 24 to 48 hours of the injury or illness.
Tests commonly used in patients with suspected ARDS include:
- Arterial blood gas
- Blood tests, including complete blood count and blood chemistries
- Chest x ray
- Sputum cultures
- Tests for possible infections
Typically, patients with ARDS need to be managed in the hospital intensive care unit (ICU). The goal of treatment is to provide breathing support and treat the cause of ARDS. This involves the use of an artificial ventilator to force oxygen into the lungs via a tube (endotracheal or tracheostomy tube). As the process is uncomfortable, patients will usually need to be sedated with medication. Concurrently, treatment must be targeted towards the etiology of the ARDS, eg antibiotics for bacterial pneumonia or anti-virals for influenza. Patients who are in the ICU also need to be under regular physiotherapy and nutrition support, which may involve artificial feeding via a nasogastric tube. Treatment continues until the patient is well enough to breathe on his own.
Patients with ARDS are very sick and have a significant mortality rate. Much of this depends on the underlying disease that triggered the ARDS.