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Acute respiratory distress syndrome
Definition
Acute respiratory distress syndrome (ARDS) is a life-threatening lung condition that prevents enough oxygen from getting to the lungs and into the blood.
See also: Infant respiratory distress syndrome
Alternative Names
Noncardiogenic pulmonary edema; Increased-permeability pulmonary edema; Stiff lung; Shock lung; ARDS; Acute lung injury
Causes
ARDS can be caused by any major injury to the lung. Some common causes include:
- Breathing vomit into the lungs (aspiration)
- Inhaling chemicals
- Lung transplant
- Pneumonia
- Septic shock (infection throughout the body)
- Trauma
ARDS leads to a buildup of fluid in the air sacs. This fluid prevents enough oxygen from passing into the bloodstream.
The fluid buildup also makes the lungs heavy and stiff, and decreases the lungs' ability to expand. The level of oxygen in the blood can stay dangerously low, even if the person receives oxygen from a breathing machine (mechanical ventilator) through a breathing tube (endotracheal tube).
ARDS often occurs along with the failure of other organ systems, such as the liver or kidneys. Cigarette smoking and heavy alcohol use may be risk factors.
Symptoms
- Difficulty breathing
- Low blood pressure and organ failure
- Rapid breathing
- Shortness of breath
Symptoms usually develop within 24 to 48 hours of the injury or illness. Often, people with ARDS are so sick they cannot complain of symptoms.
Exams and Tests
Listening to the chest with a stethoscope (auscultation) reveals abnormal breath sounds, such as crackles, which may be signs of fluid in the lungs. Often the blood pressure is low. Cyanosis (blue skin, lips, and nails caused by lack of oxygen to the tissues) is often seen.
Tests used to diagnose ARDS include:
- Arterial blood gas
- Blood tests, including CBC and blood chemistries
- Bronchoscopy
- Chest x-ray
- Sputum cultures and analysis
- Tests for possible infections
An echocardiogram or Swan-Ganz catheterization may be needed to rule out congestive heart failure, which can look similar to ARDS on a chest x-ray.
Treatment
Typically people with ARDS need to be in an intensive care unit (ICU).
The goal of treatment is to provide breathing support and treat the cause of ARDS. This may involve medications to treat infections, reduce inflammation, and remove fluid from the lungs.
A breathing machine is used to deliver high doses of oxygen and continued pressure called PEEP (positive end-expiratory pressure) to the damaged lungs. Patients often need to be deeply sedated with medications when using this equipment. Some research suggests that giving medications to temporarily paralyze a person with ARDS will increase the chance of recovery.
Treatment continues until you are well enough to breathe on your own.
Support Groups
Many family members of people with ARDS are under extreme stress. Often they can relieve this stress by joining support groups where members share common experiences and problems.
See also: Lung disease - support group
Outlook (Prognosis)
About a third of people with ARDS die from the disease. Those who live usually get back most of their normal lung function, but many people have permanent (usually mild) lung damage.
Many people who survive ARDS have memory loss or other quality-of-life problems after they recover. This is due to brain damage that occurred when the lungs weren't working properly and the brain wasn't getting enough oxygen.
Possible Complications
- Failure of many organ systems
- Lung damage (such as a collapsed lung--also called pneumothorax) due to injury from the breathing machine needed to treat the disease
- Pulmonary fibrosis (scarring of the lung)
- Ventilator-associated pneumonia
When to Contact a Medical Professional
Usually, ARDS occurs during another illness, for which the patient is already in the hospital. Occasionally, a healthy person may develop severe pneumonia that gets worse and becomes ARDS. If you have trouble breathing, call your local emergency number (such as 911) or go to the emergency room.
References
Hudson LD, Slutsky AS. Acute respiratory failure. In: Goldman L, Schafer AI, eds. Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders; 2011:chap 104.Reviewed By: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; and Denis Hadjiliadis, MD, Assistant Professor of Medicine, Division of Pulmonary, Allergy and Critical Care, University of Pennsylvaniga, Philadelphia, Pa. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M. Health Solutions, Ebix, Inc.
