Acute Respiratory Distress Syndrome - Signs and Symptoms

Signs and Symptoms

People usually present with shortness of breath, tachypnea leading to hypoxia and providing less oxygen to the brain, occasionally causing confusion.

ARDS mostly occurs about 72 hours after the trigger, such as an injury (trauma, burns, aspiration, massive blood transfusion, drug/alcohol abuse) or an acute illness (infectious pneumonia, sepsis, acute pancreatitis).

ARDS is characterized by:

• Acute onset
• Bilateral infiltrates on chest radiograph sparing costophrenic angles
• Pulmonary artery wedge pressure < 18 mmHg (obtained by pulmonary artery catheterization), if this information is available; if unavailable, then lack of clinical evidence of left ventricular failure suffices
• if PaO₂:FiO₂ < 300 mmHg (40 kPa) acute lung injury (ALI) is considered to be present
• if PaO₂:FiO₂ < 200 mmHg (26.7 kPa) acute respiratory distress syndrome (ARDS) is considered to be present

The PaO₂:FiO₂ ratios above refer to the gradient between the inspired oxygen level and the oxygen that is present in the blood. The lower the ratio, the less inspired oxygen is getting into the blood, and so the worse the patient's condition — so ARDS represents a more severe progression of disease from ALI by these diagnostic criteria.

To summarize and simplify, ARDS is an acute (rapid onset) syndrome (collection of symptoms) that affects the lungs widely and results in a severe oxygenation defect, but is not due to heart failure.