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| General Dentistry » Sedation - IV and Relative Anaesthesia [Gas] (N2O) |
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How do I know if it's for me?
If you exhibit any of the following characteristics, "Sedation
Dentistry" may help you:
- Fear Stress and Anxiety about going to the Dentist
- People who desire a beautiful and natural smile and have fear
and anxiety associated with dentistry
- Fear of needles
- You are hard to get numb
- Dental Phobia
- A history of bad dental experiences
- Painful or sensitive teeth
- Afraid to go to the Dentist
- You are troubled with a bad gag reflex
- Difficulty controlling movement from conditions such as Cerebral
Palsy or Parkinson's disease
- You need complex treatment requiring long dental appointments
- People who have limited time to complete their required treatment
and want to accomplish a lot in a single appointment. Treatment
requiring multiple visits can often be accomplished in a single
visit.
What is nitrous oxide?
Nitrous oxide is a popular anaesthetic agent used by dentists.
Its safety has been well-established; it is effective, and the
anaesthetic effect wears off quickly so there is no extended
recovery time. It can be used for both children and adults.
Nitrous oxide has a very calming, comforting effect, even though
the patient remains in control. Some dental experts have called
it the "ideal anaesthetic" because it takes effect
quickly (in less than 5 minutes) and because there is a very
rapid recovery time (about 5 to 10 minutes). Nitrous oxide is
mixed with oxygen so that you will have an ample supply of oxygen
at the same time. |
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In addition to the sedative effect of nitrous oxide, it helps
control discomfort associated with some procedures. The level of
sedation can be easily adjusted for the best possible effect for
each individual patient.
The effects of nitrous oxide
Nitrous oxide kills pain and it induces a pleasurable feeling.
After 5 minutes or so of breathing in the gas, you should feel a
euphoric feeling spread throughout your body. It really kind of
feels like a 'happy drunk' feeling. Some people find that there
are auditory or visual effects as well. You will feel a bit light
headed and often people get 'the giggles' (hence the name laughing
gas!). As an interesting aside, nitrous oxide was one of the drugs
of choice for young people in the late1700s and early 1800s, when
"laughing gas demonstrations" were a popular source of
entertainment and enjoyment!
Depending on the concentration and length of administration of laughing
gas, four levels of sedation can be experienced (after an initial
feeling of light-headedness):
- a tingling sensation, especially in the arms and legs, or a
feeling of vibration, quickly followed by
- warm sensations, and
- a feeling of well-being, euphoria and/or floating ("drift").
During heavier sedation, hearing may dissolve into a constant,
electronic-like throbbing.
- At a deeper level of sedation again, sleepiness, difficulty
to keep one's eyes open or speak ("dream") can occur.
During relative anaesthesia, you should be maintained within the
first three stages. If you've had bad experiences with laughing
gas in the past, it is highly likely that these were due to improper
administration and too high a concentration of N2O.
It's been observed that N2O depresses almost all forms of sensation
- especially hearing, touch and pain, and that it seems to disinhibit
some emotional centres in the brain. The ability to concentrate
or perform intelligent acts is only minimally affected, as is memory.
How is it administered?
The equipment used for delivering "happy gas"
is quite simple. It consists of a supply of compressed gases
and an apparatus which delivers the gases to the patient. By
turning some knobs and flipping on/off switches, the administrator
can produce the desired mix of N2O-O2 in the desired quantities.
Flowmeters and pressure gauges allow the administrator to keep
an eye on the flow of gases.
The desired N2O-O2 mix is fed through a tube to which a nasal
hood or cannula is attached. This hood is put over your nose.
All you have to do now is breathe normally through your nose
- bingo! |
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The white inner mask (sticking out) comes in vanilla, strawberry
and mint |
In modern machines there is a sort of "double mask"
where the outside mask is connected to a vacuum machine to suck
away the waste gas - you wouldn't want your dentist to get a
face full of N2O... The white inside mask, which is placed over
your nose, comes in lots of yummy scents - vanilla, strawberry,
and mint!
The twin tubes running to the mask are for "gas in"
and "gas out". The "gas out" line is attached
to the vacuum machine, while the "gas in" line is
attached to the RA (short for relative analgesia) machine. The
inner mask is attached to the "line in", you breathe
out through a one-way valve in the inner mask, and the exhaust
gas is collected inside the outer grey mask (pictured to your
right) and sucked into the vacuum machine. |
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The grey "outer mask" ensures that your dentist doesn't
leave work with a headache |
What are the advantages?
- Happy gas works very rapidly - it reaches the brain within 20
seconds, and relaxation and pain-killing properties develop after
2 or 3 minutes.
- The depth of sedation can be altered from moment to moment,
allowing the person who administers the gas to increase or decrease
the depth of sedation. Other sedation techniques don't allow for
this. For example, with IV sedation, it's easy to deepen the level
of sedation, but difficult to lessen it. Whereas with gas, the
effects are almost instant.
- Other sedation techniques have a fixed duration of action (because
the effects of pills or intravenous drugs last for a specific
time span), whereas gas can be given for the exact time span it's
needed for. It can also be switched off when not needed and then
switched on again (though to avoid a roller-coaster effect, you
shouldn't do this too abruptly).
- There's no "hangover" effect - the gas is eliminated
from the body within 3 to 5 minutes after the gas supply is stopped.
- With nitrous oxide, it's easy to give incremental doses until
the desired action is obtained (this is called "titration").
So the administrator has virtually absolute control over the action
of the drug, preventing the possibility of accidental overdoses.
While giving incremental doses is possible with IV sedation, it's
not possible with oral sedation (as a result, oral sedation can
be a bit of a hit-and-miss affair).
- Unlike IV sedation, no injection is required. In cases of very
severe needle phobia, getting laughing gas first can help you
feel relaxed enough to allow the needle required for IV sedation
to be inserted in your arm or hand. The very deep state of sedation
achievable through IV sedation may then allow you to accept local
anaesthetic.
- Inhalation sedation is very safe. It has very few side effects
and the drugs used have no ill effects on the heart, lungs, liver,
kidneys, or brain.
- For certain procedures, especially those involving soft tissues
(e. g. deep cleaning), inhalation sedation may be used instead
of local anaesthesia. N2O acts as a painkiller; however, its pain-relieving
effects vary a lot from person to person and can't be relied upon.
So if you're determined to give the needle a miss, you and your
dentist will have to try and see what happens...
- Inhalation sedation has been found to be very effective in eliminating
or at least minimizing severe gagging.
When should I not use it?
There aren't any major contraindications to RA, except for emphysema
and some exotic chest problems. It hasn't been proven to be safe
during the first trimester of pregnancy, so you can't use it then.
Because you have to breathe it in through your nose, it's not suitable
for people who have a cold or some other condition which prevents
them from breathing through their nose. M.S. is another contraindication.
You can't be allergic to N2O. It's also safe to use if you suffer
from epilepsy, liver disease, heart disease, diabetes, or cerebrovascular
disease. It is also used quite successfully in many people with
respiratory disease - but it depends on the exact nature of the
disease, so check with your dentist!
Pre- and Post-sedation instructions
The patient should be given both verbal and written instructions,
including the instructions that:
- regular medicines must be taken at the usual times.
- a light meal may be taken 4 hours before the procedure under
conscious sedation.
- clear fluids or water may be taken in moderation up to 4 hours
before sedation
- he/she must bring a responsible person to escort him/her home
and to care for him/her for the rest of the day.
What is IV?
When a drug, usually of the anti-anxiety variety, is administered
into the blood system during dental treatment, this is referred
to as Intravenous Conscious Sedation (aka "IV sedation").
How is IV sedation administered?
"Intravenous" means that the drug is put
into a vein. An extremely thin needle is put into a vein close
to the surface of the skin in either the arm or the back of
your hand. This needle is wrapped up with a soft plastic tube.
The needle makes the entry into the vein, then is slid out leaving
the soft plastic tube in place. The drugs are put in through
that tube (which is correctly referred to as an "indwelling
catheter", but more commonly known by the tradename of
Venflon). The tube stays in place throughout the procedure. |
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A Venflon |
Throughout the procedure, your pulse and oxygen levels are measured
using a "pulse oximeter". This gadget clips onto a finger
or an earlobe and measures pulse and oxygen saturation. It gives
a useful early warning sign if you're getting dangerously low on
oxygen, although if your dentist and the nurses are paying attention
they should see it before the machine does). The warning signs
are unresponsiveness and slow breathing. Blood pressure before and
after the procedure should be checked with a blood pressure measuring
machine (a tongue-twister called "sphygmomanometer", which
for obvious reasons is referred to as "sphyg").
What does it feel like? Will I be asleep?
A lot of dental offices use terms such as "sleep dentistry"
or "twilight sleep" when talking about IV sedation. This
is confusing, because it suggests that IV sedation involves being
put to sleep. In reality, you remain conscious during IV sedation.
You will also be able to understand and respond to requests from
your dentist.
However, you may not remember much about what went on because of
two factors: firstly, in most people, IV sedation induces a state
of deep relaxation and a feeling of not being bothered by what's
going on. Secondly, the drugs used for IV sedation can produce either
partial or full memory loss (amnesia) for the period of time when
the drug first kicks in until it wears off. As a result, time will
appear to pass very quickly and you will not recall much, or perhaps
even nothing at all, of what happened. So it may, indeed, appear
as if you were "asleep" during the procedure.
Is it still necessary to be numbed with local anaesthetic?
Will my dentist numb my gums before or after I'm sedated?
The drugs which are usually used for IV sedation are not
painkillers (although some pain-killing drugs are occasionally added,
see below for a more detailed discussion), but anti-anxiety drugs.
While they relax you and make you forget what happens, you will
still need to be numbed. You will not remember having the anaesthetic.
Is it safe? Are there any contraindications?
IV sedation is EXTREMELY safe when carried out under the
supervision of a specially-trained dentist. Purely statistically
speaking, it's even safer than local anaesthetic on its own!
However, contraindications include pregnancy, known allergy to Diazepam,
alcohol intoxication, CNS depression, and some instances of glaucoma.
Cautions include psychosis, impaired lung or kidney or liver function,
and advanced age. Heart disease is generally not a contraindication.
What are the main advantages of IV sedation?
- IV sedation tends to be the method of choice if you don't want
to be aware of the procedure - you "don't want to know".
The alternative in the US is oral sedation using Halcion, but
oral sedation is not as reliably effective as IV sedation.
- The onset of action is very rapid, and drug dosage and level
of sedation can be tailored to meet the individual's needs. This
is a huge advantage compared to oral sedation, where the effects
can be very unreliable. IV sedation, on the other hand, is both
highly effective and higly reliable.
- The maximum level of sedation which can be reached with IV is
deeper than with oral or inhalation sedation.
- Amnesia result for the procedure.
- The gag reflex is hugely diminished - people receiving IV sedation
rarely experience difficulty with gagging. However, if minimizing
a severe gag reflex is the main objective, inhalation sedation
is usually tried first. Only if that fails to diminish the gag
reflex should IV sedation be used for this purpose.
- Can be ideal for those with a phobia of dental injections.
- Unlike General Anaesthesia or Deep Sedation, conscious IV sedation
doesn't really introduce any compromises per se in terms of carrying
out the actual procedures, because people are conscious and they
can cooperate with instructions, and there is no airway tube involved.
Are there any disadvantages?
- A very small needle has to be put in the arm or hand ("venipuncture").
- It is possible to experience complications at the site where the needle entered, for example hematoma (a localized swelling filled with blood)
- You need transport home..
After IV Sedation:
- Have your escort take you home and rest for the remainder of
the day.
- Have an adult stay with you until you're fully alert.
- Don't perform any strenuous or hazardous activities and don't
drive a motor vehicle for the rest of the day.
- Don't eat a heavy meal immediately. If you're hungry, eat something
light, e. g. liquids and toast.
- If you experience nausea, lie down for a while or drink a glass
of coke.
- Don't drink alcohol or take medications for the rest of the
day unless you've contacted your dentist first.
- Take medications as directed by your dentist.
- If you have any unusual problems, call your dentist.
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