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What are General Anaesthesia and Deep Sedation?
General anesthesia (GA) is when you are totally unconscious. In this state, you can't feel any pain, even without local anesthesia.
You can't reliably breathe on your own, so for more complex procedures (such as fillings - these are actually more complex
than extractions under GA!) and procedures of longer duration you need to having a "breathing tube" inserted.
Deep sedation is a state of depressed consciousness, where you may lose the ability to breathe independently and you can't
respond to verbal commands. However, you can still feel noxious stimuli like pain, so local anesthesia is necessary.
In contrast, what is usually called "IV sedation" (or, in advertisements, "twilight sleep") in dentistry is conscious sedation.
Conscious sedation is a minimally depressed level of consciousness during which the patient is able to breathe independently
and/or respond purposely to verbal command (American Dental Association's Guidelines for the Use of Conscious Sedation). You
can read more about IV sedation here.
In the UK, deep sedation counts as GA (GA, as per UK definitions, means that the patient is not responsive to verbal commands,
reflexes such as breathing are suppressed, etc.). Therefore it is only used by consultant anaesthetists under strict hospital
conditions, so far as dentistry goes. Most dentists never use deep sedation, because if you're going to go that "risky" you
may as well go to GA, where full airway management is provided.
Why is General Anaesthesia not used very much for dental work?
General anaesthesia is a procedure which is never without risk (including the risk of death). As a result, the General Dental
Council in the UK recommends that "the decision to refer a patient for treatment under general anaesthesia should not
be taken lightly." "In assessing the needs of an individual patient, due regard should be given to all aspects of
behavioural management and anxiety control before deciding to treat or refer for treatment under general anaesthesia. General
anaesthesia for dental treatment should only be administered in a hospital setting with critical care facilities. All dentists
involved in arranging or providing treatment under general anaesthesia should discuss with the patient advice and treatment
options to avoid or reduce future episodes of general anaesthesia. A dentist who refers a patient for treatment or carries
out treatment on a patient under general anaesthesia without ensuring that the relevant conditions ... are met is liable to
a charge of serious professional misconduct." (excerpt from "Maintaining Standards", GDC, 1997)
Apart from the risk of serious complications (which, while very small, is still significantly higher than for conscious IV sedation),
general anesthesia has a few major disadvantages:
(1) Complications are more likely with GA compared with conscious sedation both during and after the procedure. GA depresses
the cardiovascular and respiratory systems. For some groups of medically compromised patients, it is contraindicated for elective
procedures.
(2) It's not recommended for routine dental work like fillings. The potential risk involved is too high to warrant the
use of GA. For things like fillings, a breathing tube must be inserted, because otherwise, little bits of tooth, other debris
or saliva could enter the airway and produce airway obstruction or cause illnesses like pneumonia.
(3) Laboratory tests, chest x-rays and ECG are often required before having GA, because of the greater risks involved.
(4) Very advanced training and an anesthesia team are required, and special equipment and facilities are needed. GA introduces
a number of technical problems for the operator (i. e. dentist), especially when a "breathing tube" is involved:
the tongue is brought forward more into the dentist's way by the airway tubing, the muscles are paralysed so the operator
is working against a dead weight all the time and there are postural problems because the patient can't be moved about much.
The operator can get very tired very quickly when doing a session. It's physically the most demanding kind of dentistry (usually
standing, hot lights, compromised patient position).
(5) You can't drink or eat for 6 hours before the procedure (otherwise, vomiting is possible and this would be extremely
dangerous during GA).
(6) It's expensive.
(7) GA does nothing to reduce dental anxiety. The next time you need any work, or even a routine check-up, you'll most
likely be as afraid as ever. This may not be applicable to all situations - as mentioned below, GA can be useful or even indicated
for certain situations.
As a means of anxiety management however, GA is next to useless. Anecdotal evidence suggests that people who have treatment
done under GA as a means of anxiety-control are less likely return for regular check-ups and cleanings which are necessary
to maintain dental health. Obviously, there may be exceptions.
Are there any circumstances under which general anesthesia should be used?
Exceptional circumstances include treatment for certain groups of special needs patients, procedures which would be very unpleasant
if you were conscious (such as very complex extractions of bony impacted wisdom teeth), certain other types of oral surgery,
and people with an extreme anxiety of dental procedures for whom conscious IV sedation isn't enough (although IV sedation
works fine for about 97% of people with a high anxiety of dental procedures).
If it's extractions that really terrify you, it may be possible to be put to sleep for the extractions and then have fillings
etc. done under conscious sedation with local anaesthetic. However, general anaesthesia is not widely on offer, and must be
carried out in a hospital, in the UK at least.
How is it administered?
GA is usually started off with an injection in the hand or arm. It can be supplemented by a face mask but if a face mask is
used you probably won't remember it.
If post-op pain is expected, the normal practice is to inject a long acting local anaesthetic during the GA, so that when
you wake up everything is nice and numb for a good few hours (say 6 hours?) afterwards, which should give you time to take
some painkillers and allow them to kick in. It's much better to premptively stop pain than it is to try to deal with it once
it has started.
"I need to have severely impacted wisdom teeth taken out, and the oral surgeon strongly recommends GA - but I'm scared
to death of being 'put to sleep' and not waking up!"
If GA has actually been recommended because the surgeon anticipates that the removal will be difficult, general anesthesia
will make things much easier for you. Provided that a qualified anaesthesist oversees the procedure, the risk of death is
very small. A study from 1982 entitled "Deaths asociated with dentistry" (British Dental Journal) put the mortality
rate at 1:338,536 for outpatient general anaesthesia.
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