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What is General Anesthesia?
General anesthesia is a state of total unconsciousness that
is a result of the use of
general anesthetic drugs. Several drugs are given to the
patient that have different effects with the goal of
ensuring
unconsciousness,
amnesia and
analgesia.
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Effects of General Anesthesia
The
objectives of anesthesia include anesthesia (lack of
awareness of surrounding events), akinesia (keeping the
patient still to allow surgery to take place), muscle
relaxation (to enable access through muscles to bones and
body cavities) and autonomic control (to prevent dangerous
surges in hemodynamics).
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Candidates for General Anesthesia
General anesthesia is ideal for patients who need to undergo
more extensive procedures or procedures that are not
amenable to regional anesthesia.
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Your
Consultation
Before the surgery, the anesthetist will interview the
patient to determine the best combination and drugs and
dosages and the degree of how much monitoring is needed to
ensure a safe and effective procedure. The patient will fill
out a form where important information such as age, weight,
medical history, current medications, previous anesthetics
and fasting time are asked. The anesthetist will review this
information and will select the proper anesthetics based on
it.
The doctor will then assess the patient's airway, involving
inspection of the mouth opening and visualisation of the
soft tissues of the
pharynx. The doctor will also check the condition of
teeth and location of dental crowns and caps, as well as the
neck flexibility and head extension. And if an
endotracheal tube is indicated and airway management is
considered difficult, then alternative placement methods
like
fiberoptic intubation may be used.
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The General Anesthesia
Procedure
General anesthesia can either be induced by
intravenous (IV) injection or breathing a
volatile anesthetic through a facemask (inhalational
induction). The effect of anesthesia is faster with an IV
injection than with inhalation, taking about 10 to 20
seconds to induce total unconsciousness. With this, there is
an advantage of avoiding the excitatory phase of anesthesia,
which reduces complications related to induction of
anesthesia. The anesthetist may choose inhalational
induction when IV access is difficult to obtain, when
difficulty maintaining the airway is anticipated, or because
of patient preference. The IV induction agents that are
commonly used include
propofol,
sodium thiopental,
etomidate and
ketamine.
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Recovery
After the procedure, the patient will be given a management
plan for post-operative pain relief, which may be in the
form of
regional analgesia, oral or
parenteral medication. Oral pain relief medications are
ideal for minor surgical procedures. While moderate levels
of pain need the addition of mild
opiates such as
codeine. But major surgical procedures might require a
combination of modalities to confer adequate pain relief.
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Risks
The
major risks with general anesthesia include death,
myocardial infarction and stroke. Other less serious
complications are nausea or vomiting, sore throat, headache,
shivering, and delayed return to normal mental functioning.
General anesthesia can also cause malignant hyperthermia, a
rare, inherited muscular condition in which exposure to some
(but not all) general anesthetic agents results in acute and
potentially lethal temperature rise, hypercarbia, metabolic
acidosis, and hyperkalemia.
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Frequently Asked
Questions
Q:
What are the different types of anesthesia?
A:
Anesthesia can be categorized by the degree to which it
suppresses the patient’s consciousness and protective
reflexes. Greater amounts of anesthesia are required for
larger procedures. From least to most, the levels of
anesthesia include local, conscious sedation, regional and
general.
Q:
What are the advantages of general anesthesia?
A:
First
of all, general anesthesia makes no psychological demand of
the patient. It allows complete stillness for prolonged
periods of time and permits surgery to take place in widely
separated areas of the body at the same time. Also, it
facilitates complete control of the airway, breathing and
circulation. General anesthesia can be adapted easily to
procedures of unpredictable duration or extent and it
usually can be administered rapidly.
Q:
When and why is general anesthesia used?
A:
General anesthesia is recommended for more extensive
procedures or for procedures that are not amenable to
regional anesthesia. The anesthetics used are given
intravenously or by inhalation and the drugs circulate in
your bloodstream to all areas of your body, including your
brain. When you are under general anesthesia, all of your
protective reflexes, such as coughing, gagging and even
breathing are suppressed. Consequently, the use of a mask or
breathing tube is necessary while you are asleep during the
procedure.
Q: How
safe is general anesthesia?
A:
Nowadays, doctors have a better understanding of how
anesthesia affects the individual and can choose from many
anesthetic drugs depending on the needs of the patient. It
also helps that advances in monitoring equipment have
dramatically reduced anesthesia-related complications. Such
advances include a device that determines whether a
breathing tube placed in your windpipe is properly
positioned during general anesthesia. The device also
measures whether you are getting enough ventilation during
general anesthesia. There are other monitors that keep track
of your heart rate, circulation, blood pressure,
temperature, body fluid balance and other body functions.
Q: Is
it possible to die because of anesthesia?
A:
Death due to anesthesia is most commonly related to surgical
factors or pre-existing medical conditions which include
major
haemorrhage,
sepsis, and organ failure (eg. heart, lungs, kidneys,
liver). The common causes of death that are directly related
to anesthesia include aspiration of stomach contents,
suffocation (due to airway management), allergic reactions
to anesthesia (specifically and not limited to anti-nausea
agents) and other deadly genetic predispositions, human
error and equipment failure.
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