Alternate Names: Stiff lung; Shock lung; Acute respiratory distress syndrome

Causes and Risks:

ARDS is a medical emergency. It is caused by any condition that results in widespread inflammation of the lung. This inflammation leads to buildup of inflammatory fluid in the air sacs, which inhibits the passage of oxygen from the air into the bloodstream.

The fluid buildup makes the lungs heavy and stiff, and the lungs’ ability to expand is severely decreased. Blood concentration of oxygen remains dangerously low in spite of high concentrations of supplemental oxygen, which is often delivered by a mechanical ventilator (breathing machine) through an endotracheal tube (breathing tube).

Most often, patients require care in an intensive care unit (ICU). Causes of ARDS include sepsis (widespread infection), extensive trauma, aspiration of vomited stomach contents, severe pneumonia, severe burns, drug overdose (examples include aspirin and heroin), near-drowning, pancreatitis, and, rarely, blood transfusion (especially large amounts).

Symptoms usually develop within 24 to 48 hours of the original injury or illness. ARDS often occurs along with the failure of other organ systems, such as the liver or the kidneys. Cigarette smoking may be a risk factor. The incidence of ARDS in about 14 out of 100,000 people per year.

Prevention:

No measures to prevent ARDS are presently known.

Symptoms:

• labored, rapid breathing
• anxiety, a sense of impending doom, or confusion
• low blood pressure or shock (low blood pressure accompanied by organ failure)
• often, persons affected by ARDS are so sick, they are unable to complain of symptoms

Signs and Tests:

Chest auscultation (examination with a stethoscope) reveals abnormal breath sounds, such as crackles or wheezes. Often the blood pressure is low. Cyanosis (blue skin, lips, and nails caused by lack of oxygen to the tissues) is frequently seen.

Tests used in the diagnosis of ARDS include:

• chest X-ray
• arterial blood gas
• CBC and blood chemistries
• Evaluation for possible infections
• Bronchoscopy

Treatment:

The objective of treatment is to provide enough support for the failing respiratory system (and other systems) and to treat the underlying cause.

Oxygen is used to treat hypoxia, often at high concentrations (100% oxygen concentration may be needed).

Intubation, passing a tube through the nose or the mouth into the trachea (airway), is often necessary, and breathing support is provided by a mechanical ventilator (breathing machine).

This treatment is continued until the patient is well enough to breathe on his own.
Medications may be indicated to treat infections, reduce inflammation, and eliminate fluid within the lungs.

Support Groups: Many family members of people with ARDS are under extreme stress. This can often be alleviated by joining support groups where members share common experiences and problems. See lung disease - support group.

Prognosis:

The death rate exceeds 40%. Although survivors usually recover normal lung function, a few individuals may suffer permanent lung damage, which can range from mild to severe. Many people who survive ARDS suffer memory loss or other problems with thinking after they recover.

Complications:

• multiple organ system failure

Usually, ARDS occurs in the setting of another illness, for which the patient is already in the hospital. Occasionally, a healthy person may develop severe pneumonia that may progress to ARDS. If breathing difficulty develops, call the local emergency number (such as 911) or go to the emergency room.