Acute respiratory distress syndrome, commonly called ARDS, is a sudden failure of the respiratory system that occurs when fluid builds up in the tiny, elastic air sacs in your lungs. in a short time, breathing becomes difficult, depriving your organs of the oxygen they need to function.
ARDS usually 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 original disease or trauma.
ARDS is fatal in 25 to 40 percent of the people who develop it. Some people who survive ARDS recover completely, though they may not regain full lung function for a year or more.
Symptoms
The signs and symptoms of ARDS can vary in intensity, depending on its cause and severity. They include:
* Severe shortness of breath
* Labored and unusually rapid breathing
* low blood pressure
* Confusion and extreme tiredness
* Cough or fever, in some cases
When to see a doctor
ARDS usually follows a major illness or injury, and most people who are affected are already hospitalized. Still, if you develop any serious breathing problem, see your doctor or get emergency care right away. Several disorders that require immediate treatment, including heart problems, have signs and symptoms similar to those of ARDS. in the case of ARDS, the need for medical treatment is urgent.
Causes
The mechanical cause of ARDS is fluid leaked from the smallest blood vessels in the lungs into the tiny air sacs where blood is oxygenated. Normally, a protective membrane keeps this fluid in the vessels. Severe illness or injury, however, can cause inflammation that undermines the membrane's integrity, leading to the fluid leakage of ARDS.
A number of conditions can injure your lungs and lead to inflammation, including:
* Severe viral or bacterial pneumonia
* Infection spreading through your bloodstream (sepsis)
* Heart failure with fluid in your lungs
* Multiple or massive blood transfusions
* A serious head or chest injury
* fractures of long bones, such as the femur, which can release fat particles that are carried through your bloodstream to your lungs (fat embolism)
* Prolonged use — from several days to a week — of large volumes of supplemental oxygen
* Accidental inhalation of vomit or chemicals, such as ammonia or chlorine
* Smoke inhalation
* Near drowning
* an adverse reaction to cancer drugs or other medications
* Drug overdose, most commonly with heroin
* Inflammation of your pancreas (pancreatitis)
* Shock from any cause
If possible, it's important to find the cause behind ARDS, because it can determine treatment and can predict your chances for survival. in some cases, though, the cause of ARDS is never found.
Risk factors
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)
* Have chronic liver disease (cirrhosis)
* Use a breathing machine (mechanical ventilator)
* Have had certain types of surgery recently
* are a heavy drinker
* are a current or former smoker
Complications
ARDS is extremely serious, but thanks to improved treatments, more people are surviving it. However, many survivors end up with potentially serious — and sometimes lasting — complications, including:
* Pulmonary fibrosis. Scarring and thickening of the tissue between the air sacs (interstitium) 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.
* Collapsed lung (pneumothorax). usually, a breathing machine called a ventilator is used in the treatment of ARDS to increase oxygen in the body and force fluid out of the lungs. However, the ventilator can cause its own problems. The pressure and air volume of the ventilator can force gas to go through a small hole in the very outside of the lung and out into the pleural space in your chest, causing your lung to collapse. if this happens, your doctor will insert a tube between your ribs into the pleural space to remove the excess air, allowing your lung to reinflate.
* Bacterial infections. sometimes, the ventilator is attached directly to a tube inserted in your trachea to assist breathing. but this can also make you more susceptible to bacterial infections like pneumonia, which can further injure your lungs. Infections can also occur in other parts of your body, including in your bloodstream, urinary tract and spinal fluid. Some of these infections may be difficult to control if the bacteria have become resistant to commonly used antibiotics. The problem may be compounded even further if ARDS was initially caused by a bacterial infection.
* Abnormal lung function. 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. if you have other lung diseases, such as emphysema, you're especially likely to have a difficult time recovering from ARDS. even people who do well usually have shortness of breath and fatigue and may even need supplemental oxygen in the first months after they leave the hospital.
* Muscle wasting and weakness. if you need to use a ventilator for longer than a week, it can begin weakening your muscles because of nutritional deficiency. many people recovering from ARDS require physical therapy, both in the hospital and once they're at home, to restore strength and stamina. The extent to which you'll regain full functioning depends on many factors, including weight loss, the length of time you were sedated, the length of time on the ventilator, and the amount of damage to your lungs and other organs.
* Memory, cognitive and emotional problems. 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. most ARDS survivors also report going through a period of depression, which for some people is quite severe. if you are a friend or family member of someone who has had ARDS, be alert to symptoms of depression and urge him or her to seek professional help as soon as possible.
Tests and diagnosis
Tests to confirm ARDS may include:
* Chest X-ray
* Arterial blood gas analysis
* Computerized tomography (CT) scan
* Blood tests to determine infection
* Heart tests to rule out heart problems that can cause fluid to build up in your lungs
Treatments and drugs
The first goal in treating ARDS is to get oxygen flowing to your lungs and organs until the fluid is cleared out of the lungs and they can function more normally. Treating the underlying condition then becomes equally important.
Oxygen
To get more oxygen into your bloodstream, your doctor will likely use supplemental oxygen and mechanical ventilation.
* Supplemental oxygen (noninvasive positive pressure ventilation). for milder symptoms or as a temporary measure, oxygen may be delivered through a mask that fits tightly over your nose or your nose and mouth.
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Mechanical ventilation, or breathing machine (positive pressure mechanical ventilator). most people with ARDS also will need assisted breathing. A positive pressure mechanical ventilator pushes air into your lungs, forcing the fluid out of your air sacs. Air flows from a bedside ventilator into your windpipe (trachea) through a tube placed in your nose or mouth. if you need help breathing for more than several days, it's likely that the breathing tube will be inserted directly into your trachea through an incision in your neck (called a tracheotomy).
you remain on a ventilator until you can breathe on your own. for some people, this may be a matter of days. for others it may take weeks or even months. The longer you remain on a ventilator, the greater the chances of serious complications, including pneumonia and further lung damage. The first week of treatment is critical. People who are weaned from the ventilator within a week have the best chance of a complete recovery.
Fluids
Managing fluids carefully is crucial. in the past, doctors gave people with ARDS large amounts of fluids through an IV to keep oxygen flowing to other parts of the body. now, doctors know that too much fluid can increase the fluid buildup in the lungs. However, depriving your body of fluids can put a strain on your heart and other organs that depend on adequate volumes of blood and oxygen to function properly. Your doctor will likely closely monitor the amount of fluids you receive so that you get just the right balance to regain lung function but protect your other organs.
Medication
People with ARDS are also given medication to prevent and treat infections, as well as relieve pain and discomfort. all people on mechanical ventilation are given comfort sedation. sometimes it is necessary to paralyze the skeletal muscles to relax them and prevent them from "fighting" the respirator. you may also be given an anticoagulant to prevent blood clots (deep venous thrombosis) and pulmonary embolism.
In the past, corticosteroids — meant to reduce lung inflammation — were a routine part of managing ARDS. Several studies, however, have found that corticosteroid treatment has no effect on survival rates among people with ARDS.
Coping and support
Recovery from ARDS can be a long road, and you'll need plenty of support. Although everyone's recovery is different, being aware of common physical and mental difficulties encountered by others with the disorder can help. consider these tips:
* Ask for help. particularly after you're released from the hospital, be sure you have help with everyday tasks until you know what you can manage on your own.
* Attend pulmonary rehabilitation. many medical centers now offer pulmonary rehabilitation programs, which incorporate exercise training, education and counseling to help you learn how to return to your normal activities and achieve your ideal weight.
* Join a support group. There are support groups for people with chronic lung problems. Discover what's available in your community and consider joining others with similar experiences.
* Seek professional help. if you have symptoms of depression, such as hopelessness and loss of interest in your usual activities, tell your doctor or contact a mental health professional. Depression is common in people who have had ARDS, and treatment can help.
* Quit smoking. if you smoke, seek help to quit, and avoid secondhand smoke whenever possible.
* Get vaccinated. To prevent future complications, be sure to get the yearly influenza shot, as well as the pneumonia vaccine every five years.