What is Acute Respiratory Distress Syndrome?

Acute Respiratory Distress Syndrome

It is originally described in adults, acute respiratory distress syndrome (ARDS) occurs in children of all ages; hence, it change from "adult" to "acute" respiratory distress syndrome. The syndromes of acute lung injury (ALI) and ARDS usually do not manifest in the typical time frame for emergency department (ED) treatment. However, effective early recognition and treatment of bacteremia, shock, and respiratory failure may prevent the cascade of host responses that result in ARDS as well as comorbidities.

Recognizing that patients who have been resuscitated from circulatory failure may have a period of relative stability followed by deterioration secondary to ARDS or other components of the multiple organ failure syndrome (MOFS) is important. This recognition should allow informed decision making of the need for transport or ongoing critical care.

History

Histories at the time of initial presentation offer little with regards to diagnosis of ALI/ARDS except for alerting the clinician to risks for development of lung injury such as exposure to gaseous fumes or hydrocarbon ingestion and potential aspiration. The time to develop hypoxemia severe enough for ALI/ARDS criteria is also dependent on the time of onset of the triggering disease or injury. ALI/ARDS may further be masked by preexisting medical problems including reactive airway disease and bronchopulmonary dysplasia. Exacerbation of such underlying chronic lung diseases can lead to severe wheezing as the chief complaint.

• Establishing ALI/ARDS criteria is highly variable and is dependent of the onset of illness/insult.
• In most patients, ARDS developed within 72 hours after the onset of the associated acute disease and many (42%) within 24 hours.
• In those with infectious pneumonia, the onset is often gradual.

Get here detailed EBM curriculum

Causes

• ARDS is a clinical syndrome for which no specific marker exists. However, several have been identified to be associated with ARDS including tumor necrosis factor- (TNF-), interleukin- (IL-), interleukin 10 (IL-10), and more recently, soluble intercellular adhesion molecule 1 (sICAM-1). One of the most common diseases associated with ARDS is sepsis and/or septic shock. Other more common etiologies include infectious pneumonia, aspiration pneumonia, aspiration of gastric contents and other noxious substances (eg, hydrocarbons), inhalational injury (eg, thermal injury, noxious gases), and barotrauma/volutrauma secondary to mechanical ventilation.
• Failure of other organ systems commonly results in ARDS.
• Most near-drowning victims aspirate at least some water. Both fresh and saltwater aspiration results in pulmonary edema. If near-drowning occurs in stagnant or contaminated water, the risk of bacterial pneumonia is high. However, neither corticosteroids nor prophylactic antibiotics are beneficial.