Acute Respiratory Distress Syndrome (ARDS) Definition

Acute Respiratory Distress Syndrome (ARDS) is a complex of symptoms, formerly called adult respiratory distress syndrome, in which respiratory distress and respiratory failure develop accompanying severe illness or trauma. ARDS involves the whole of both lungs, as the lungs become inflamed and fill with fluid. ARDS may develop as a consequence of injury that directly affects the lungs (notably blunt trauma to the chest, near drowning, pneumonia, and smoke inhalation) or when the injury or illness affects other parts or systems of the body.

Systemic infection (sepsis), drug overdose, and blood transfusion may also result in ARDS. ARDS can affect people of any age and is life-threatening. Because people who develop ARDS are already very ill, ARDS has a high death rate (about 40 percent). The syndrome may cause complete respiratory failure or lead to total system failure, either of which presents significant challenge for recovery.

Symptoms and Diagnostic Path

People who develop ARDS have generally sustained severe trauma or infection and most are already in the hospital when their symptoms begin. Early symptoms of ARDS include restlessness, tachypnea (rapid, shallow breathing), and hypoxia (reduced oxygen to the body’s tissues). ARDS progresses rapidly to full involvement of the lungs. Chest X-rays show the filling of the lungs with inflammation and fluid (called diffuse infiltration). Arterial blood gases show the decreased percentage of oxygen in the blood. Doctors often perform tests on sputum and fluid from the lungs to identify any pathogens, notably bacteria, that may be present.

Treatment Options and Outlook

Immediate oxygen supplementation is essential. Many people require mechanical ventilation with positive end expiratory pressure (PEEP) to increase the amount of oxygen entering the lungs. Doctors generally administer sedation while the person is on mechanical ventilation, to provide comfort and to prevent the natural tendency to fight the intervention. Treatment primarily is supportive, including close monitoring of cardiovascular and renal (kidney) functions. Because infection, either in the lungs or elsewhere in the body, is often present, many people may also receive intravenous (IV) antibiotic medications.

The outlook for full recovery depends on numerous factors including the person’s age, general health status, and the ability to reverse the circumstances responsible for the initial development of ARDS. Even medical intervention that begins early in the course of ARDS cannot predict the success of treatment. About 60 percent of people survive the ARDS episode, though the severity of illness can require extensive recuperation.

Risk Factors and Preventive Measures

The primary risk factors for ARDS are sepsis (severe infection) and major trauma, either to the lungs or to the body in general. Though such infection or trauma alerts doctors to the grave risk for ARDS, there are no known measures that can head off the development of ARDS. Public health measures to minimize the risk factors (trauma and infection) are critical. Once ARDS occurs, however, aggressive medical intervention and support provide the best chance for survival.


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