ARDS (cont.)
How the Lungs Work
To understand acute respiratory distress syndrome (ARDS), it is helpful to
understand how your lungs work.
Normal Lung Function
A slice of normal lung looks like a pink sponge—filled with tiny bubbles or
holes. Around each bubble is a fine network of tiny blood vessels. These
bubbles, which are surrounded by blood vessels, give the lungs a large surface
to exchange oxygen (into the blood where it is carried throughout the body) and
carbon dioxide (out of the blood). This process is called gas exchange. Healthy
lungs do this very well.
Here's how normal breathing works:
- You breathe in air through your nose and mouth. The air travels down
through your windpipe (trachea)
through large and small tubes in your lungs
called bronchial (BRON-kee-ul) tubes. The larger tubes are bronchi (BRONK-eye),
and the smaller tubes are bronchioles (BRON-kee-oles). Sometimes, we use the
word "airways" to refer to the various tubes or passages that air uses to
travel from the nose and mouth into the lungs. The airways in your lungs look
something like an upside-down tree with many branches.
- At the ends of the small bronchial tubes, there are groups of tiny
bubbles called air sacs or alveoli. The bubbles have very thin walls, and
small blood vessels called capillaries are next to them. Oxygen passes from
the air sacs into the blood in these small blood vessels. At the same time,
carbon dioxide passes from the blood into the air sacs.
Effects of ARDS
In ARDS, the tiny blood vessels leak too much fluid into
the lungs. This results from toxins (poisons) that the body produces in response
to the underlying illness or injury. The lungs become like a wet sponge, heavy
and stiffer than normal. They no longer provide the effective surface for gas
exchange, and the level of oxygen in the blood falls. If ARDS is severe and goes
on for some time, scar tissue called fibrosis may form in the lungs. The
scarring also makes it harder for gas exchange to occur.
People who develop ARDS need extra oxygen and may need a breathing machine to
breathe for them while their lungs try to heal. If they survive, ARDS patients
may have a full recovery. Recovery can take weeks or months. Some ARDS survivors
take a year or longer to recover, and some never completely recover from having
ARDS.
Other Names for ARDS
- Adult respiratory distress syndrome
There is a similar condition in infants called Infant
Respiratory Distress Syndrome (also called IRDS, RDS, and hyaline membrane disease). It mainly
affects premature infants whose lungs are not well developed when they are born.
Next: What are other names for ARDS? »
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