Acute respiratory distress syndrome (ARDS) occurs when fluid builds up in the tiny, elastic air sacs (alveoli) in your lungs. The fluid keeps your lungs from filling with enough air, which means less oxygen reaches your bloodstream. This deprives your organs of the oxygen they need to function.
ARDS typically occurs in people who are already critically ill or who have significant injuries. Severe shortness of breath the main symptom of ARDS usually develops within a few hours to a few days after the precipitating injury or infection.
Fulminant pulmonary interstitial and alveolar edema, which usually develops within a few days after the initiating trauma, thought to result from an alveolar injury that has led to increased capillary permeability.
Many people who develop ARDS don’t survive. The risk of death increases with age and severity of illness. Of the people who do survive ARDS, some recover completely while others experience lasting damage to their lungs.
The acute respiratory distress syndrome (ARDS) is a medical emergency. It may occur in people who already have lung disease or in those with previously normal lungs. This syndrome used to be called the adult respiratory distress syndrome, although it can occur in children. The less severe form of this syndrome is called acute lung injury (ALI).
what are the Causes of Acute Respiratory Distress Syndrome
- Aspiration (inhalation) of food into the lung
- Coronary bypass surgery
- Chest injury (pulmonary contusion)
- Inflammation of the pancreas (pancreatitis)
- Inhalation of large amounts of smoke
- Inhalation of other toxic gas
- Injury to the lungs from inhaling high concentrations of oxygen
- Major trauma
- Near drowning
- Overdose of certain drugs, such as heroin, methadone, propoxyphene, or aspirin
- Prolonged or severely low blood pressure (shock)
- Pulmonary embolism
- Severe, widespread infection (sepsis)
- Stroke or seizure
- Transfusions of more than about 15 units of blood in a short period of time
What are the Risk Factors for Acute respiratory distress syndrome (ARDS)
People at risk for ARDS have a condition or illness that can directly or indirectly injure their lungs.
Most people who develop ARDS are already hospitalized for another condition, and many are critically ill. You’re especially at risk if you have a widespread infection in your bloodstream (sepsis).
People who have a history of chronic alcoholism are at higher risk of developing ARDS. They’re also more likely to die of ARDS.
Direct Lung Injury
Conditions that can directly injure the lungs include:
- Pneumonia. This is an infection of the lungs.
- Breathing in harmful fumes or smoke.
- Inhaling vomited stomach contents from the mouth.
- Using a ventilator. This is a machine that helps people breathe; rarely, it can injure the
- Nearly drowning.
Indirect Lung Injury
Conditions that can indirectly injure the lungs include:
- Sepsis. This is a condition in which bacteria infect the bloodstream.
- Severe bleeding caused by an injury to the body or having many blood transfusions.
- An injury to the chest or head, such as a severe blow.
- Pancreatitis. This is a condition in which the pancreas becomes irritated or infected. The pancreas is a gland that releases enzymes and hormones.
- Fat embolism. This is a condition in which fat blocks an artery. A physical injury, like a broken bone, can lead to a fat embolism.
- Drug reaction.
What are the Complications of Acute respiratory distress syndrome (ARDS)
If you have ARDS, you can develop other medical problems while in the hospital. The most common problems are:
- Blood clots. Lying still in the hospital while you’re on a ventilator can increase your risk of developing blood clots, particularly in the deep veins in your legs. If a clot forms in your leg, a portion of it can break off and travel to one or both of your lungs (pulmonary embolism) — where it blocks blood flow.
- Collapsed lung (pneumothorax). In most ARDS cases, a breathing machine called a ventilator is used to increase oxygen in the body and force fluid out of the lungs. However, the pressure and air volume of the ventilator can force gas to go through a small hole in the very outside of a lung and cause that lung to collapse.
- Infections. Because the ventilator is attached directly to a tube inserted in your windpipe, this makes it much easier for germs to infect and further injure your lungs.
- Scarring (pulmonary fibrosis). Scarring and thickening of the tissue between the air sacs can occur within a few weeks of the onset of ARDS. This stiffens your lungs, making it even more difficult for oxygen to flow from the air sacs into your bloodstream.
Thanks to improved treatments, more people are surviving ARDS. However, many survivors end up with potentially serious and sometimes lasting effects:
- Breathing problems. Many people with ARDS recover most of their lung function within several months to two years, but others may have breathing problems for the rest of their lives. Even people who do well usually have shortness of breath and fatigue and may need supplemental oxygen at home for a few months.
- Depression. Most ARDS survivors also report going through a period of depression, which is treatable.
- Problems with memory and thinking clearly. Sedatives and low levels of oxygen in the blood can lead to memory loss and cognitive problems after ARDS. In some cases, the effects may lessen over time, but in others, the damage may be permanent.
- Tiredness and muscle weakness. Being in the hospital and on a ventilator can cause your muscles to weaken. You also may feel very tired following treatment.
How to Diagnose Acute respiratory distress syndrome (ARDS)
Your doctor will diagnose ARDS based on your medical history, a physical exam, and test results.
Analysis of a blood sample taken from an artery indicates low levels of oxygen in the blood, and chest x-rays show fluid in spaces that should be filled with air. Further tests may be needed to ensure that heart failure is not the cause of the problem
ARDS may cause abnormal breathing sounds, such as crackling. Your doctor will listen to your lungs with a stethoscope to hear these sounds.
He or she also will listen to your heart and look for signs of extra fluid in other parts of your body. Extra fluid may mean you have heart or kidney problems.
Your doctor will look for a bluish color on your skin and lips. A bluish color means your blood has a low level of oxygen. This is a possible sign of ARDS.
Because the signs and symptoms of ARDS are similar to those of certain heart problems, your doctor may recommend heart tests such as:
- Electrocardiogram. This painless test tracks the electrical activity in your heart. It involves attaching several wired sensors to your body.
- Echocardiogram. A sonogram of the heart, this test can reveal problems with the structures and the function of your heart.
- Chest X-ray. A chest X-ray can reveal which parts of your lungs and how much of the lungs have fluid in them and whether your heart is enlarged.
- Computerized tomography (CT). A CT scan combines X-ray images taken from many different directions into cross-sectional views of internal organs. CT scans can provide detailed information about the structures within the heart and lungs.
You may have ARDS or another condition that causes similar symptoms. To find out, your doctor may recommend one or more of the following tests.
The first tests are done are:
- An arterial blood gas test. This blood test measures the oxygen level in your blood using a sample of blood taken from an artery. A low blood oxygen level might be a sign of ARDS.
- Chest x-ray. This test creates pictures of the structures in your chest, such as your heart, lungs, and blood vessels. A chest x-ray can show whether you have extra fluid in your lungs.
- Blood tests, such as a complete blood count, blood chemistries, and blood cultures. These tests help find the cause of ARDS, such as an infection.
A sputum culture. This test is used to study the spit you’ve coughed up from your lungs. A sputum culture can help find the cause of an infection.
Other tests used to diagnose ARDS include:
- Chest computed tomography (to-MOG-rah-fee) scan, or chest CT scan. This test uses a computer to create detailed pictures of your lungs. A chest CT scan may show lung problems, such as fluid in the lungs, signs of pneumonia, or a tumor.
- Heart tests that look for signs of heart failure. Heart failure is a condition in which the heart can’t pump enough blood to meet the body’s needs. This condition can cause fluid to build up in your lungs.
How to Treat Acute respiratory distress syndrome (ARDS)
The first goal in treating ARDS is to improve the levels of oxygen in your blood. Without oxygen, your organs can’t function properly.
To get more oxygen into your bloodstream, your doctor will likely use:
- Supplemental oxygen. For milder symptoms or as a temporary measure, oxygen may be delivered through a mask that fits tightly over your nose and mouth.
- Mechanical ventilation. Most people with ARDS will need the help of a machine to breathe. A mechanical ventilator pushes air into your lungs and forces some of the fluid out of the air sacs.
Carefully managing the number of intravenous fluids is crucial. Too much fluid can increase fluid buildup in the lungs. Too little fluid can put a strain on your heart and other organs and lead to shock.
People with ARDS usually are given medication to:
- Prevent and treat infections
- Relieve pain and discomfort
- Prevent blood clots in the legs and lungs
- Minimize gastric reflux
People with ARDS are treated in an intensive care unit. Successful treatment usually depends on treating the underlying disorder (for example, pneumonia). Oxygen therapy, which is vital to correcting low oxygen levels, also is given.
If oxygen delivered by a face mask or nasal prongs does not correct the low blood oxygen levels, or if very high doses of inhaled oxygen are required, mechanical ventilation must be used. Usually, a ventilator delivers oxygen-rich air under pressure using a tube inserted through the mouth into the windpipe (trachea). For people who have ARDS, the ventilator pressure is delivered during the inhaled breath and at a lower pressure during exhalation (called positive end-expiratory pressure), which helps keep the alveoli open at the end of exhalation.
Oxygen Therapy for Acute respiratory distress syndrome (ARDS)
One of the main goals of treating ARDS is to provide oxygen to your lungs and other organs (such as your brain and kidneys). Your organs need oxygen to work properly.
Oxygen usually is given through nasal prongs or a mask that fits over your mouth and nose. However, if your oxygen level doesn’t rise or it’s still hard for you to breathe, your doctor will give you oxygen through a breathing tube. He or she will insert the flexible tube through your mouth or nose and into your windpipe.
Before inserting the tube, your doctor will squirt or spray a liquid medicine into your throat (and possibly your nose) to make it numb. Your doctor also will give you medicine through an intravenous (IV) line in your bloodstream to make you sleepy and relaxed.
The breathing tube will be connected to a machine that supports breathing (a ventilator). The ventilator will fill your lungs with oxygen-rich air.
Your doctor will adjust the ventilator as needed to help your lungs get the right amount of oxygen. This also will help prevent injury to your lungs from the pressure of the ventilator.
You’ll use the breathing tube and ventilator until you can breathe on your own. If you need a ventilator for more than a few days, your doctor may do a tracheotomy.
This procedure involves making a small cut in your neck to create an opening to the windpipe. The opening is called a tracheostomy. Your doctor will place the breathing tube directly into the windpipe. The tube is then connected to the ventilator.
For more information, go to the Health Topics Oxygen Therapy article.
Supportive Care for Acute respiratory distress syndrome (ARDS)
Supportive care refers to treatments that help relieve symptoms, prevent complications, or improve quality of life. Supportive approaches used to treat ARDS include:
- Medicines to help you relax, relieve discomfort, and treat pain.
- Ongoing monitoring of heart and lung function (including blood pressure and gas exchange).
- Nutritional support. People who have ARDS often suffer from malnutrition. Thus, extra nutrition may be given through a feeding tube.
- Treatment for infections. People who have ARDS are at higher risk for infections, such as pneumonia. Being on a ventilator also increases the risk of infections. Doctors use antibiotics to treat pneumonia and other infections.
- Prevention of blood clots. Lying down for long periods can cause blood clots to form in the deep veins of your body. These clots can travel to your lungs and block blood flow (a condition called pulmonary embolism). Blood-thinning medicines and other treatments, such as compression stocking (stockings that create gentle pressure up the leg), are used to prevent blood clots.
- Prevention of intestinal bleeding. People who receive long-term support from a ventilator are at increased risk of bleeding in the intestines. Medicines can reduce this risk.
- Fluids. You may be given fluids to improve blood flow through your body and to provide nutrition. Your doctor will make sure you get the right amount of fluids. Fluids usually are given through an IV line inserted into one of your blood vessels.