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Friday, August 11, 2017

Acute Respiratory Distress Syndrome


Acute Respiratory Distress Syndrome





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
Other symptoms can occur, depending on the event that caused the ARDS. For example, if pneumonia is causing the ARDS, symptoms may also include chest pain and fever.



Causes

ARDS can occur when a major injury or extreme inflammation somewhere in the body damages the small blood vessels, including those in the lungs. As a result, the lungs are unable to fill with air and can't move enough oxygen into the bloodstream.

The lung damage can be direct or indirect. Conditions that can directly injure the lungs and possibly lead to ARDS include:

· Breathing in smoke or poisonous chemicals
· Breathing in stomach contents while throwing up (aspiration)
· Near drowning
· Pneumonia
· Severe acute respiratory syndrome (SARS), a lung infection

Conditions that can indirectly injure the lungs and possibly lead to ARDS include:
· Bacterial blood infection (sepsis)
· Drug overdose
· Having many blood transfusions
· Heart-lung bypass
· Infection or irritation of the pancreas (pancreatitis)
· Severe bleeding from a traumatic injury (such as a car accident)
· Severe hit to the chest or head

· The conditions that have most commonly been linked to ARDS include sepsis, traumatic injury, and lung infections such as pneumonia. However, it's important to note that not everyone who has these conditions develops ARDS. Doctors are not sure why some people develop ARDS and others do not.

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.


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).

· People who have a history of chronic alcoholism are at higher risk of developing ARDS. They're also more likely to die of ARDS.

Complication

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.

Test and Diagnosis

There's no specific test to identify ARDS. A diagnosis is reached by ruling out other diseases and conditions — for example, certain heart problems — that can produce similar symptoms.

Imaging

· Chest X-ray. A chest X-ray can reveal which parts of your 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.

Lab Test: To determine there is any infection in blood. Also check sputum for culture if bacteria or fungi are present in a sample of mucus that you coughed up from your lungs

Heart tests
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.

Treatment 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

The Outlook of Patients with ARDS

The survival rate for people with ARDS has improved in recent years, although doctors aren't sure why. Some people who get ARDS make a full recovery, but others have lasting lung damage and long-term breathing problems.

The following factors have been associated with a poor prognosis:

· Active cancer
· Advanced age
· Bacteria blood infection (sepsis)
· Being African-American
· Long-term alcohol abuse
· Long-term liver disease
· HIV infection
· Multiple organ failure
· Organ transplant

The survival rate for people with ARDS has improved in recent years, although doctors aren't sure why. Some people who get ARDS make a full recovery, but others have lasting lung damage and long-term breathing problems.

The following factors have been associated with a poor prognosis:

· Active cancer
· Advanced age
· Bacteria blood infection (sepsis)
· Being African-American
· Long-term alcohol abuse
· Long-term liver disease
· HIV infection
· Multiple organ failure
· Organ transplant

It can take many months or even years to recover from ARDS. Some people are very tired and weak after being on a breathing machine, and still have some shortness of breath after going home from the hospital. Pulmonary rehabilitation is an important part of recovery. Such therapy teaches patients how to exercise their lungs and become active again. Support groups and counseling can also be helpful.

Life style and Home Remedies

If you're recovering from ARDS, the following suggestions can help protect your lungs:

· Quit smoking. If you smoke, seek help to quit, and avoid secondhand smoke whenever possible.

· Quit alcohol. Alcohol can relax the portion of your upper airway that keeps foreign material from entering your lungs.

· Get vaccinated. The yearly flu (influenza) shot, as well as the pneumonia vaccine every five years, can reduce your risk of lung infections.
 

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