ARDS

ARDS

Definition  :

Acute respiratory distress syndrome (ARDS) occurs when fluid builds up in the tiny, elastic air sacs (alveoli) in your lungs. More fluid in your lungs means less oxygen can reach 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 original disease or trauma.

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.

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

When to see a doctor
ARDS usually follows a major illness or injury, and most people who are affected are already hospitalized.

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.
The most common underlying causes of ARDS include:

• Sepsis. The most common cause of ARDS is sepsis, a serious and widespread infection of the bloodstream.
• Inhalation of harmful substances. Breathing high concentrations of smoke or chemical fumes can result in ARDS, as can inhaling (aspirating) vomit.
• Severe pneumonia. Severe cases of pneumonia usually affect all five lobes of the lungs.
• Head or chest injury. Accidents, such as falls or car crashes, can directly damage the lungs or the portion of the brain that controls breathing.

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 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). 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. 

• 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 of your lungs (pulmonary embolism) — where it blocks blood flow.

• 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.

• 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. Even people who do well usually have shortness of breath and fatigue and may need supplemental oxygen at home for a few months.

• 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 is treatable.

Treatments and drugs:

The first goal in treating ARDS is to improve the levels of oxygen in your blood. Without oxygen, your organs can't function properly.
Oxygen
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.

Fluids
Carefully managing the amount 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.
Medication
People with ARDS usually are given medication to:

• Prevent and treat infections
• Relieve pain and discomfort
• Prevent clots in the legs and lungs
• Minimize gastric reflux