How Does a Ventilator Work?
Ventilators blow air-or air with increased amounts
of oxygen-into the airways and then the lungs.
The airways are pipes that carry oxygen-rich air to
your lungs and carbon dioxide, a waste gas, out of your lungs. The airways
include your:
- Nose and linked air passages, called nasal
cavities
- Mouth
- Larynx (LAR-ingks), or voice box
- Trachea (TRA-ke-ah), or windpipe
- Tubes called bronchial tubes or bronchi, and
their branches
For more information on the airways, see the
Diseases and Conditions Index article on
How
the Lungs Work.
The Breathing Tubes
A ventilator blows air into your airways through a
breathing tube. One end of the tube is inserted into your windpipe and the
other end is attached to the ventilator.
The breathing tube serves as an airway by letting
air and oxygen from the ventilator into the lungs. The process of placing the
tube into your windpipe is called intubation.
Usually, the breathing tube is put into your
windpipe through your nose or mouth. The tube is then moved down into your
throat. A tube placed like this is called an endotracheal (en-do-TRA-ke-al)
tube.
In an emergency, you're given medicine to make you
sleepy and ease the pain of the breathing tube being put in your windpipe. If
it's not an emergency, the procedure is done in an operating room using
anesthesia. That is, you're given medicines that temporarily put you to sleep
and cause a loss of feeling.
An endotracheal tube is held in place by tape or
with an endotracheal tube holder. This often is a strap that fits around the
head.
Sometimes the breathing tube is put into the
windpipe through a hole in the front of the neck. A surgeon makes the hole
using a procedure called tracheotomy (TRA-ke-O-to-me). The tube put into the
hole is sometimes called a "trach" tube.
A tracheotomy is done in an operating room.
You’ll be under anesthesia, so you won’t be awake or feel any pain.
Specially made ties, or bands, that go around the neck hold the trach tube in
place.
Both types of breathing tubes pass through your
vocal cords. Thus, while a breathing tube is in your throat, it affects your
ability to talk.
Endotracheal tubes are mainly used for people who
are on ventilators for shorter periods. The advantage of this tube is that it
can be placed in an airway without surgery.
Trach tubes are used for people who need ventilators
for longer periods. For people who are awake, this tube is more comfortable
than the endotracheal tube. Under certain conditions, a person who has a trach
tube may be able to talk.
The Ventilator
A ventilator uses pressure to blow air or a mixture
of other gases (like oxygen and air) into the lungs. This pressure is known as
positive pressure. You usually breathe out the air, but sometimes the
ventilator does this for you.
A ventilator can be set to “breathe” a
set number of times a minute. Sometimes it’s set so that you can trigger
the machine to blow air into your lungs. But, if you fail to trigger it within
a certain amount of time, the machine automatically blows air to keep you
breathing.
Rarely, a ventilator called a chest shell is used.
This type of ventilator works like an iron lung—an early ventilator used
by many polio patients in the last century. However, the chest shell
isn’t as bulky and confining as the iron lung.
The chest shell fits snugly to the outside of your
chest. A machine creates a vacuum between the shell and the chest wall. This
causes your chest to expand, and air is sucked into your lungs. No breathing
tube is used with a chest shell.
When the vacuum is released, your chest falls back
into place and the air in your lungs comes out. This cycle of vacuum and
release is set at a normal breathing rate. |