What is acute respiratory distress syndrome?

Date: Sep-26-2013acute respiratory distress syndrome?

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Main Category: Respiratory / Asthma

Article Date: 26 Sep 2013 - 19:00 PDT

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What is acute respiratory distress syndrome?


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Acute respiratory distress syndrome is a condition where the body is not receiving enough oxygen from the lungs. Often referred to by its initials, ARDS is a complication of an existing lung infection, injury or serious illness.

ARDS is also known as respiratory distress syndrome (RDS) or adult respiratory distress syndrome.

According to the National Heart, Lung and Blood Institute, most people with ARDS are in hospital when the symptoms appear.

However, ARDS can develop outside a hospital setting. The National Health Service, UK, says that "(ARDS) may develop quickly due to an infection such as pneumonia or after somebody has accidentally inhaled their vomit."

The British Lung Foundation says that during the Vietnam War, the term "lung shock" was used when soldiers developed ARDS after injuries.
What are the signs and symptoms of ARDS

A symptom is felt by the patient and described to others, such as dizziness. A sign is something other people can detect, such as a swelling or a rash.

The signs and symptoms of acute respiratory distress syndrome may include:

Shortness of breath (severe)
Shallow and rapid breathing
Confusion
Drowsiness
Fatigue
Light headedness
Hypotension (low blood pressure)

What causes Acute Respiratory Distress Syndrome?

When the alveoli fill with fluid, breathing is impaired and levels of oxygen in the blood fall

When we breath, air enters through our nose and mouth and into our airways, initially into the windpipe. The air continues through the alveolar ducts and into the alveoli, small grape-like bunches of tiny sacs in the lungs. The plural of alveolus is alveoli.

Capillaries (small blood vessels) run through the walls of the alveoli. Oxygen in the air sacs passes into the capillaries, thus entering the bloodstream and nourishing every part of the human body, including vital organs such as the brain, heart, liver, kidneys, etc.

In acute respiratory distress syndrome, injuries, infections or some other condition cause fluid to accumulate in the air sacs - fluid and proteins leak out from the capillaries into the alveoli, making the whole lung stiff. This prevents the lung from working properly, it cannot fill up with air in a normal way, neither can it get rid of carbon dioxide effectively.

All this, in combination, turns the usually straightforward task of breathing into a tiring and labored ordeal.

As oxygen levels in the bloodstream start to drop, vital organs do not receive their oxygen and risk becoming seriously damaged.

Many different types of illnesses, conditions and situations can trigger ARDS, including:

A lung chest/infection or pneumonia
Severe flu, including avian (bird) flu
Other infections
Complications of routine surgery
A blood transfusion
A clot in the lung
Accidentally inhaling chemicals
Accidentally inhaling your own vomit
Acute pancreatitis - the inflammation can spread
Giving birth
Inhaling smoke
Near drowning

Nobody knows why illnesses, situations or conditions that do not affect the lungs directly may cause acute respiratory distress syndrome. Experts suggest that the body may perhaps produce harmful substances that overwhelm the system.
Diagnosing ARDS

There is no specific test currently available that can diagnose ARDS. In order to find out what the underlying cause might be, the medical team must carry out a full assessment. They also need to rule out other conditions.

The doctor may order the following diagnostic tests:

A blood test - to determine blood oxygen levels and see whether there is an infection, and if so, what type.

A pulse oximetry test - to determine how much oxygen is passing through into the blood. A sensor is placed onto the fingertip or earlobe.

X-ray - to determine which parts of the lungs have fluid accumulation. Doctors may also want to find out whether the patient's heart is enlarged.

CT (computerized tomography) scan - an imaging method that uses tomography, the process of generating a 2-dimensional image of a section through a 3-dimensional object (tomogram). CT scans can provide doctors with very detailed information about the structures in the heart and lungs.

An echocardiogram - a test of the action of the heart using ultrasound.

An electrocardiogram - this test measures the electrical activity in the heart.

Some of the signs and symptoms associated with ARDS are similar to those found in several heart diseases, that is why some of the tests are for checking the heart.

Fluids from the lungs may be extracted and tested to determine whether there is an infection, and if so what type it is.
What is the treatment for ARDS?

The majority of patients with acute respiratory distress syndrome are placed in the ICU (intensive care unit) and put on a ventilator.

The medical team's number one priority is to raise their blood oxygen levels. The other priority is getting rid of the cause of ARDS.

Depending on the state of the patient, either an oxygen mask is used, or a tube is inserted down their throat into the lungs to supply oxygen.

Nutrients and fluids will be supplied through a tube that goes into the patient's nose and down to his or her stomach.

Antibiotics will be administered if the cause of the ARDS is an infection.

As there is no targeted treatment specifically for ARDS, the medical team will support the patient until the lungs improve on their own.
What is the outlook for ARDS?

In the past, more than half of all patients with ARDS did not survive. However, survival rates over the last fifteen years have improved considerably.

The American Lung Association wrote "Patients who develop ARDS due to sepsis (infection of the blood) usually do not do as well as patients whose ARDS is related to trauma or pulmonary infection." It added that today between 25% to 40% of ARDS cases are fatal; an improvement compared to 20 years ago when the mortality rate was between 50% and 70%.

According to the National Health Service, about one third of ARDS patients in the United Kingdom do not survive. The majority of deaths, though, are due to another problem in the illness or circumstance that caused the ARDS, and not the ARDS itself.

ARDS survivors face a significantly higher risk of complications, including muscle and nerve damage, which can lead to pain and weakness. Some patients develop PTSD (post-traumatic stress disorder) and depression.

Among survivors, the lungs tend to recover well after ARDS.

Written by Christian Nordqvist

Copyright: Medical News Today

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