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Being put to sleep
This is the most common form of anaesthetic people will encounter. The name
implies a state where your whole body is included in the unfeeling, uncaring state which is induced.
While most people think of it as sleep, it is much more than sleep. When you are
asleep your body is still just as active as when you are awake. All your body
reflexes are still at similar levels to when you are awake - for example if
someone was to cut you with a knife you'd wake up in pain and do something to
protect yourself from it. General anaesthesia on the other hand is a state of
induced coma. It changes the way the body responds to different senses. You
usually do not dream except just as you're being anaesthetised and when you are
rousing from your anaesthetic. Your bodies reflexes are very changed with only
primitive body functions still working. No actual rest like sleep is actually
achieved during a general anaesthetic so if you are sleepy prior to being
anaesthetised you are still sleepy afterwards no matter how long you have been
anaesthetised for. Despite this, I will still refer to it as "sleep" from here
on for simplicity.
Most forms of general anaesthesia involve some combination of intravenous drugs and anaesthetic gases. Although you
will be rendered asleep for this sort of anaesthetic this does not mean you wont
get some form of regional anaesthetic also. Most
commonly the drug that will put you off to sleep will be but into your
intravenous drip and then you will be kept asleep by anaesthetic gas during the
operation. Once you have been anaesthetised a breathing tube is normally placed
into your mouth which keeps you connected to the anaesthetic machine. This
anaesthetic machine gives you all the oxygen and anaesthetic gas you need and
may help your breathing as well. Further drugs are given by either the drip and
the gases as are required during the operation (simple examples are pain killers and antibiotics). Whether you have
full muscle strength for yourself or if this is weakened during the operation is
determined by the requirements of the operation and the anaesthetic - more often
you have full muscle strength. Waking up is the process of weaning you off the
gases and drugs, and giving you drugs to increase your muscle strength. When you
have reached a certain level of consciousness the breathing tube will be removed
and you will have an oxygen mask placed on your face and you will be moved to
the recovery room.
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Being made numb
Regional anaesthesia, as the name implies, is where
only a region or part of your body is given the unfeeling, uncaring state. As
well as this state, you can be given differing degrees of sedation to make you comfortable or even asleep if
appropriate. This can be accomplished in numerous ways.
Local Anaesthetic
The simplest form of regional anaesthesia most people understand is having an
operation under local anaesthetic. This is - like at the dentist - where local
anaesthetic drug is injected around the area where the operation is to occur and the
area to be operated on becomes numb. Then the operation can proceed without you
feeling any pain. Occasionally the sensation that someone is touching you is
still there but it is not painful. The local anaesthetic has a duration which
long outlasts the operation but the feeling usually returns within 1-4 hours
depending on the drug used. Other painkillers can then
be taken to prevent pain being felt in the area.previously operated on.
Nerve Block
A more involved form of regional anaesthesia is the nerve block. As the name
implies the nerves that give the feeling to the area being operated on are
`blocked' by local anaesthetic, preventing pain being felt. A common example of
this is the arm block. If you need an operation on your hand for example, an
arm block can be used for this. An arm block involves injecting local
anaesthetic at a discrete spot (usually in the armpit). An arm block usually
lasts between 2 and 16 hours depending on the drug used. There are numerous
other nerve blocks than can and are performed around the body to make different
areas numb. While these can be used alone for the operation you may be put to
sleep as well. They have the benefit of decreasing the amount of other drugs
given to you for the general anaesthetic thereby limiting the side effects you
may get from the general anaesthetic, and providing you with excellent pain
relief after the operation while it remains numb. Occasionally a small drip can
be inserted near the nerve to continually give local anaesthetic after the
operation to give better pain relief.
Spinal Anaesthetic
A spinal anaesthetic is a very specialised way of applying local anaesthetic to
make the lower half of the body numb. It is performed by placing a very fine
needle into your lower back - the `lumbar region' between the bones of the
spine, and injecting local anaesthetic drug into the fluid that surrounds your spinal
cord (which gives all your body it's feeling). The needle is not injected into
the nerves or the bones, and is usually only as painful as having blood taken.
Local anaesthetic then blocks the nerves in your spine and makes you go numb
from about the waist down. Along with this your legs feel very weak and often
you will be unable to move them during the operation. A spinal usually lasts
between 2 and 6 hours depending on the drugs used.
Epidural Anaesthetic
An epidural anaesthetic is similar to the spinal in many
ways. A needle is placed between the bones of your spine but it can be anywhere
from the top to the bottom of the spine. The needle is not injected into the
nerves or the bones, and is usually only as painful as having blood taken. Then
a very small drip is often placed in the epidural space and taped to your
back. Local anaesthetic can then be injected into this drip as often and as much
as is required. This local anaesthetic then numbs the nerves as they come out of
the spine. Because it can be put in a discrete position in your back, parts of
your body can be made numb selectively. A common example of this is the pain of labor and childbirth where the pain is
initially in the abdomen or back. A carefully placed epidural will allow this
area to be made pain free in a band from about the mid chest to the mid thighs.
By so doing it will allow your legs to still have most of the
strength. Also we can vary the strength of the epidural to make it just numb
enough to not feel labour pains or strong enough to allow surgery to be performed. A major advantage of
the epidural anaesthetic is that further local anaesthetic can be injected into
the epidural drip for days after the operation maintaining excellent pain relief
no matter how painful the operation might have been.
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Being made relaxed
There are some surgical procedures which are not painful but are unpleasant and
mildly uncomfortable. For these procedures it is unnecessary to perform a
general anaesthetic and so various degrees of sedation can be given to make them
less unpleasant. Furthermore, the drugs used for this sedation often make you
forget most of the procedure. Sedation can be used by itself for procedures such as
a gastroscopy where you swallow a special telescope that looks into your
stomach, or sedation can be used to supplement a regional anaesthetic, to make
the overrall experience not unpleasant.
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What are the advantages and disadvantages of each anaesthetic
technique?
A whole textbook of anaesthesia can be dedicated to this
question alone so I will summarise only the key issues of concern. Because the
safety of anaesthesia is so high it is difficult to prove that one
technique is safer than another. In terms of overall safety there are a small
number of operations and medical illnesses which are safer under regional
anaesthesia. However for the majority of operations the differences are more
subtle, with safety apparently being similar. There is no doubt that some people
prefer to be asleep and some people prefer to be awake. If someone was to have a
caesarean section to deliver their baby for
example, most people would want to be awake to see the baby born - it is
therefore lucky that this is one of the operations that is safer under regional
anaesthesia.
Under general anaesthesia you are more likely to wake up at
the end with some pain, nausea and drowsiness, but
it has the obvious advantage of one injection and the next thing you know you're
awake and it's over. With regional anaesthesia more procedures are performed on
you prior to the operation (further injections for example), and the part of
your body that is made numb remains numb for some time after the operation -
this is an advantage as well as a disadvantage. One of the disadvantages of
regional anaesthesia is that occasionally it does not make the area fully numb -
don't worry no one will operate on you without testing the area first. This can
usually be fixed with further local anaesthetic into the area or, if necessary,
by putting you off to sleep. There is also a small risk of doing damage to the
nerves that the regional block is working on. An arm block for example has a
small rate of leaving a numb patch or weak spot in your hand that most often
gets better within months but rarely can be permanent. Most people's fear of
epidurals is that of being paralysed. This is an extremely rare occurrence and
happens as rarely as dying under anaesthetic. In
terms of advantages, regional anaesthesia minimises the amount your breathing
and heart function is affected and this may have major benefits. It also
decreases the amount of `stress' your body has in response to the operation and
this too may be beneficial. Finally with regional anaesthesia you usually have
better pain relief, and less nausea and drowsiness after the operation.
A common practice is to combine regional and
general anaesthesia to capitalise on the advantages of both and decrease the
disadvantages of using one alone. Ultimately your anaesthetist will have a plan
for what they believe you are best served by and if there are options they will
discuss them with you.
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| Going off to sleep (Click for larger image) |
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