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If
you are faced with the possibility of needing
surgery in the future, chances are you will
need some type of anesthesia to go along with
it. There are many different types of
anesthesia.
Which one you will need depends on a variety
of factors such as the type of surgery you are
having and your state of health. Some surgical
procedures require only an injection of local
anesthesia into the incision area. Other procedures
cannot be performed unless you are completely
anesthetized -- unconscious and unaware of pain.
Your anesthesiologist will tell you which type
of anesthesia you need. |
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in this article, we will look at the many types of anesthesia so that you can understand what it is,
how it works, and how the anesthesiologist determines
which type of anesthesia to use for your particular
situation. By addressing this topic, we hope that
you will have a better understanding of what happens
to you while you're anesthetized and perhaps make
the process a little less mysterious.
D is divided into four basic categories:
， General anesthesia
， Regional anesthesia
， Local anesthesia
， sedation
Each type of anesthesia has an effect on a part of
the nervous system, which results in a depression
or numbing of nerve pathways. General anesthesia affects
the brain cells, which causes you to lose consciousness.
Regional anesthesia has an effect on a large bundle
of nerves to a particular area of the body, which
results in losing sensation to that area without affecting
your level of consciousness. Local anesthesia causes
you to lose sensation in a very specific area.
Some of the drugs that produce general anesthesia
in large doses can be used to produce sedation, or
"twilight sleep" in lower doses. Sedation
can be given in many ways. A common example of an
anesthetic gas that is used for sedation is nitrous
oxide or laughing gas.
If you are scheduled to have surgery, you may be told
not to eat anything for eight hours. It is very important
that you follow whatever instructions you are given
for not eating or drinking anything prior to surgery.
Why? Because when you are given anesthesia, you lose
the ability to protect your lungs from inhaling something
you're not supposed to inhale. When you are awake,
you can usually swallow saliva and food without choking
because part of the swallowing mechanism involves
a reflex that results in covering the opening into
the lungs. When you are anesthetized, you lose that
reflex. So, if you have any solids or liquids in your
stomach, they could come up into your mouth and be
inhaled into your lungs. The result could be very
serious lung damage.
General Anesthesia
General anesthetics produce an unconscious state.
In this state a person is:
， unaware of what is happening
， pain-free
， immobile
， free from any memory of the period of time during
which he or she is anesthetized
It is not completely clear exactly how general anesthetics
work at a cellular level, but it is speculated that
general anesthetics affect the spinal cord (resulting
in immobility), the brain-stem reticular activating
system (resulting in unconsciousness) and the cerebral
cortex (seen as changes in electrical activity on
an electroencephalogram).
Photo courtesy Department of Defense: Defense Visual
Information CenterLt. Brenda Shealy checks a piece
of anesthesia equipment in an operating room during
Operation Desert Shield.
General anesthesia can be administered as an inhaled
gas or as an injected liquid. There are several drugs
and gases that can be combined or used alone to produce
general anesthesia. The potency of a given anesthetic
is measured as minimum alveolar concentration (MAC).
This term describes the potency of anesthetic gases.
(Aveolar is the area in the lung where gases enter
and exit the bloodstream via the capillary system).
Technically, MAC is the alveolar partial pressure
of a gas at which 50 percent of humans will not move
to a painful stimulus (e.g. skin incision). Injected
liquid anesthetics have a "MAC equivalent"
which is the blood concentration of the liquid anesthetic
that provides the same effect. Using MAC as a guideline,
the amount of anesthetic given to a patient depends
on that particular patient's needs.
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