2. INTRODUCTION
In the practice of medicine , especially surgery ,
and dentistry, anesthesia is an induced,
temporary state with one or more of the
following characteristics: analgesia, paralysis
, amnesia , and unconsciousness.
An anesthetic is an agent that causes
anaesthesia. A patient under the effects of
anesthesia is anesthetized.
An anesthesiologist (US) or anaesthetist (UK) is
a physician who performs anesthesia.
3. HISTORY OF ANESTHESIA
The first documented general anesthetic was
performed by Crawford W. Long in 1842.
Unfortunately for Long, he did not publish his
successes with ether for general anesthesia until 1849.
The first public demonstration of general anesthesia
was in 1846 by a Boston dentist named William T.G.
Morton at the Massachusetts General Hospital. Dr.
Morton gave an ether anesthetic for the removal of a
neck tumor by surgeon John Collins Warren (the first
editor of the New England Journal of Medicine and
dean of Harvard Medical School).
4. MEDICAL USES
hypnosis
Analgesia
muscle relaxation
Different types of anesthesia effect the endpoints differently.
Regional anesthesia, for instance effects analgesia, benzodiazepine-
type sedatives favor amnesia and general anesthetics can effect all of
the endpoints. The goal of anesthesia is to achieve the endpoints
required for the given surgical procedure with the least risk to the
patient.
5. GENERAL ANESTHESIA AND
EQUIPMENT
Has three main goals: lack of movement (paralysis), unconsciousness,
and blunting of the stress response.
The most common approach to reach the endpoints of general
anesthesia is through the use of inhaled general anesthetics.
It has vaporizers, ventilators, an anesthetic breathing circuit, waste
gas scavenging system and pressure gauges.
The purpose of the anesthetic machine is to provide anesthetic gas at
a constant pressure, oxygen for breathing and to remove carbon
dioxide or other waste anesthetic gases.
6. SEDATION
Sedation
creates hypnotic, sedative, anxiolytic, amnesic, anticonvulsant, and
centrally produced muscle-relaxing properties. From the perspective
of the person giving the sedation, the patient will appear sleepy,
relaxed and forgetful, allowing unpleasant procedures to be more
easily completed. Sedatives such as benzodiazepines are usually
given with pain relievers because they don't, by themselves, provide
significant pain relief.
Many drugs can produce a sedative effect
including benzodiazepines, propofol, thiopental, ketamine and
inhaled general anesthetics.
7. REGIONAL ANESTHESIA
When pain is blocked from a part
of the body using local
anesthetics, it is generally referred
to as regional anesthesia. There
are many types of regional
anesthesia either by injecting into
the tissue itself, a vein that feeds
the area or around a nerve trunk
that supplies sensation to the area.
The latter are called nerve blocks
8. RISKS AND COMPLICATIONS
Risks and complications as they relate to
anesthesia are classified as either morbidity (a
disease or disorder that results from
anesthesia) or mortality (death that results from
anesthesia). Attempting to quantify how
anesthesia contributes to morbidity and
mortality can be difficult because a person's
health prior to surgery and the complexity of
the surgical procedure can also contribute to
the risks.
9. RECOVERY
The immediate time after anesthesia is
called emergence. Emergence from general anesthesia
or sedation requires careful monitoring because there
is still a risk of complication. Nausea and vomiting are
reported at 9.8% but will vary with the type of
anesthetic and procedure. There is a need for airway
support in 6.8%, there can be urinary retention
and hypotension in 2.7%. Hypothermia, shivering and
confusion are also common in the immediate post-
operative period because of the lack of muscle
movement during the procedure.
