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6 • Conscious Sedation in Dentistry
157
Preparation of the Drugs
All drugs to be used for sedation (including normal saline)
must be drawn up by the dentist administering the sedation. This task must not be delegated to a dental nurse.
As with all agents to be administered to patients (including local anaesthetics), agents must be checked to
ensure that they have not passed their expiry date and
that there are no signs of damage to the containers in
which they are supplied. Once drawn up, drugs must be
clearly labelled as there are many clear solutions, which
can easily be confused.
Preparation of the Patient
It is important to ensure that all the formalities have been
completed before the patient is sedated. This will include
checking that the patient has signed a consent form and
that their blood pressure has been recorded. It is also good
practice to ensure that the patient has visited the toilet before embarking on a procedure that will keep the patient in
the dental chair for about an hour or so. The patient’s
medical and dental histories should also be checked to ensure that nothing has happened since the previous appointment either to change the dental treatment plan or to
modify the choice of sedation technique.
Intravenous Cannulation
Cannulation is a prerequisite for carrying out intravenous
sedation. It is important to select a site that is accessible to
the dentist, acceptable to the patient, away from structures
that might be damaged in the process but where there are
adequately sized superficial veins present. The dorsum of
the hand is the usual choice in this situation. The process of
cannulation is shown in Fig. 6.3.
Once the cannula has been sited, its correct location is
confirmed using a dose of saline. The sedative agent can
then be administered. The usual choice is midazolam (5 mg
in 5-mL formulation). The dose should be titrated according
to the patient’s response. A small dose is administered,
allowed to have its effect and then a decision made as to
whether or not a sufficient dose has been administered. If
not, the cycle is repeated. The usually recommended
regimen is:
1. Slow bolus of 2 mg (2 mL).
2. Wait for 90 seconds.
3. Administration of 1-mg (1 mL) increments at 1-minute
intervals until the patient is adequately sedated.
Signs of Adequate Sedation
A depth of sedation that will allow the patient to have treatment is often referred to as the ‘endpoint’, implying that it
is discrete and apparent. This is not the case. There is a
plane of sedation within which the patient needs to be to
allow treatment to be undertaken. Different patients will
require to be at different levels within this plane of sedation;
indeed, the same patient may require to be at different levels
of sedation depending on the type of treatment proposed,
and how they are feeling in general.
The judgement of the correct depth of sedation largely
comes down to clinical experience. An adjunct to assessing
the adequacy of sedation is to ask the patient if they are
ready to have dental treatment. A slow, ponderous answer is
usually indicative of the correct level of sedation. Tests of
co-ordination, such as asking the patient to touch their nose
(and watching them miss), tend to embarrass patients and
have the added disadvantage of being of little clinical use.
In general, once an adequate level of sedation has been
achieved, the duration of the dental treatment should be
tailored to the duration of the sedation, and no further increments of sedative given.
The dosage of midazolam required to produce sedation
is extremely variable. Given that the ethos of sedation is
that the dose of sedative is judged according to the patient’s response, it is difficult to justify setting maximum
doses. However, well over 95% of patients will be adequately sedated on a dose of 10 mg of midazolam or less.
Doses in excess of this should only be given after careful
assessment and consideration.
Dental Treatment Under Intravenous Sedation
Patients recover from the effects of intravenous sedation while
they are being treated. Consequently, the longer the appointment progresses, the less sedated the patient will become. The
pattern of dental treatment must be tailored to suit. The most
invasive treatment (the administration of local anaesthetic
and use of rotary cutting instruments) should be confined to
the first 25 minutes of treatment. The remaining treatment
(placement of restorations) can take place during the next
20 minutes or so. It should, however, be emphasised that all
patients are different, and each patient should be treated for
the amount of time that they are happy to receive treatment.
Recovery From Intravenous Sedation
Patients recover much more slowly from intravenous sedation than from inhalational sedation. It is impossible to set
strict time limits on when patients should be discharged. It
is more important to assess the patient’s state of mind and
ability to leave the surgery premises. A useful test is to ask
the patient to walk across the room, turn and walk back. If
they can negotiate that test without undue loss of balance,
they are probably fit to be discharged. It is also worth checking that the patient is happy to leave, and that the escort is
happy to take them.
All patients receiving intravenous sedation must be
charged into the care of a responsible adult.
Complications of Intravenous Sedation
complications associated with intravenous cannulation.
All of the following responses are difficult to cope with, and
patients in these categories should be treated by those who
are experienced in using sedation.
Venospasm. This is a condition, probably anxiety related,
where the veins collapse at attempted cannulation. It is
difficult to prevent even for those skilled at cannulation.
Extravascular injection. This results from an incorrectly
sited cannula. The main thing is to prevent the extravas-
cular injection of any pharmacologically active agent by
testing that the cannula is correctly sited.
Intra-arterial injection. Injection of drugs into an artery
is a potentially serious event. Once again it should be
prevented by careful technique, particularly by checking
that any vessel that is selected as a potential cannulation
site does not pulsate.
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Master Dentistry
A
C
B
D
E F
G
Fig. 6.3 The cannulation sequence. (A) Site for venepuncture disinfected with alcohol-containing wipe. (B) Vein immobilised with skin traction from
operator’s left hand. (C) Cannula inserted into vein. (D) Correct position confirmed by seeing flashback of blood. (E) Cannula slid down needle to site
completely. (F) Vein occluded by assistant while needle removed. (G) Cap placed on end of cannula and wings secured with tape.
6 • Conscious Sedation in Dentistry
159
Haematoma formation. Haematomata form as a result of
blood leaking from a blood vessel into the subcutaneous
tissues. Formation may occur at cannulation, as a result
of multiple vein wall punctures or when the cannula is
removed as a result of insufficient pressure being applied
to the site.
Pain on cannulation. Venous cannulation is uncomfort-
able, but for most patients it can be overcome with the
use of distraction techniques.
problems associated with sedation.
Oversedation. The most likely sign of a patient being
oversedated is respiratory depression. In the majority of
patients, this can be managed by encouraging the patient
to breathe and by support until the overdose wears off. In
more severe cases, supplemental oxygen may be required;
should that fail, the sedation should be reversed with the
benzodiazepine antagonist.
Hyporesponse. The patient fails to sedate despite the use of
large doses of sedative.
Paradoxical reaction. The patient appears to have sedated
normally but reacts in an uncontrolled fashion when
treatment is attempted.
Hyper-response. The patient sedates very deeply on a very
small dose of sedative.
Sexual fantasy. It appears that some patients who are se-
dated feel that they have been sexually assaulted. Such
allegations are potentially distressing to the dentist, not
to mention legally difficult as they may result in imprisonment. Consequently, no member of the dental team
should be left alone with a sedated patient. Dentist and
dental nurse act as each other’s chaperone.
Reversal of Intravenous Sedation
The advent of flumazenil raised the possibility of being able
to reverse a patient’s sedation. This is, however, not recommended as a routine practice.
indications for reversal
n
Oversedation
n
Patients with a difficult journey home
n
Patients who will be difficult to manage either because of
a learning difficulty or who are much larger than their
escorts.
contraindications to reversal
n
Patients taking concurrent oral benzodiazepines (especially if used to control epilepsy)
n
Patients who have had a suspected allergic reaction to
the sedative.
Oral Sedation and Transmucosal Sedation
The administration of oral or transmucosal drugs is an attractive way of producing sedation. This is largely because
of the simplicity of the techniques as far as the dentist is
concerned and the acceptability for patients, particularly in
the United Kingdom, of orally administered drugs. These
are techniques that are gaining in popularity in the United
Kingdom. These techniques still represent the third choice
of sedation technique, as the drugs are given as bolus doses
rather than titrated. In general, these techniques are not
used when either intravenous or inhalation sedation can be
used. The most commonly used transmucosal sedation
technique is intranasal sedation.
Disadvantages
There are significant disadvantages to this type of sedation.
Prolonged latent period. Drugs taken orally will take a
long time to act. It will usually be at least 20–30 minutes until there is a significant degree of sedation. The
main problem is that patients who require sedation do
not enjoy being in the dental environment and waiting
for the sedation to act can be traumatic. The lag time
with intranasal sedation is significantly less, but often
up to 10–15 minutes.
Untitratable dose. The other techniques that are recom-
mended for sedation involve titrating the dose of sedative
drug to the patient’s response. The long latent period
involved with these techniques means that the dose has
to be given on an mg/kg dose up to a set maximum. The
only variation in dose that is possible is by judging
the effect at one appointment and changing it for future
appointments.
Unpredictable absorption. There are many factors that
affect the absorption of drugs from the gastrointestinal
tract. Elixirs and gelatin-filled capsules tend to be ab-
sorbed more rapidly than tablet formulations. Other fac-
tors include the amount, timing and constituents of any
food in the stomach. Consequently, it cannot be predicted
exactly when the drug that has been administered will
have its effect. This only affects oral sedation.
First-pass metabolism. All drugs that are administered
orally and are absorbed from the upper part of the gastro-
intestinal tract pass to the liver via the portal circulation.
A significant proportion of the dose is metabolised as it
passes through the liver prior to reaching the systemic
circulation (first-pass metabolism). As a result, a higher
dose must be used for oral drugs to achieve the desired
effect. This only affects oral sedation.
Technique for Oral Sedation
Midazolam is administered mixed in a drink. The dose
for children is 0.5 mg/kg body weight up to a maximum of
20 mg. The adult dose is 20 mg.
The onset of sedation is more rapid than with other benzodiazepines, with the patient being adequately sedated
20–30 minutes after administration. A suitably trained
member of the dental team must supervise the patient once
the sedative has been administered.
Once sedation is achieved, careful consideration should
be given to siting an intravenous cannula to give intravenous access as when intravenous sedation is undertaken.
The patient should be either sedated in the dental surgery
or, if this is not possible, moved to the surgery as soon as
sufficiently relaxed to allow this. Electromechanical monitoring should ideally be commenced before administration
of the sedative.
Discharge after sedation depends on the patient being
sufficiently recovered to walk unaided and being sufficiently
co-ordinated to be discharged into the care of a responsible
adult.
Monitoring of sedated patients is discussed later.
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Master Dentistry
Technique for Intranasal Sedation
A concentrated version of midazolam (normally 10 mg/mL)
is used. A dose of 0.3 mg/kg up to a maximum of 12 mg is
administered. The dose is squirted up one nostril. The drug
stings significantly, and thus it is advisable not to try to use
divided doses. The onset of sedation is more rapid than with
oral sedation, but significantly slower than intravenous or
inhalation sedation.
Once sedation is achieved, careful consideration should
be given to siting an intravenous cannula to give intravenous access as when intravenous sedation is undertaken.
The patient should be either sedated in the dental surgery
or, if this is not possible, moved to the surgery as soon as
sufficiently relaxed to allow this. Electromechanical monitoring should ideally be commenced before administration
of the sedative.
Discharge after sedation depends on the patient being
sufficiently recovered to walk unaided and being sufficiently
co-ordinated to be discharged into the care of a responsible
adult.
ADVANCED SEDATION TECHNIQUES
The advanced sedation techniques have a role to play in the
management of patients for whom the basic techniques are
unsuitable or ineffective. As the techniques are more complicated, additional training is required after competence in
the basic techniques has been gained. A brief summary of
the types of advanced techniques used in dentistry is given
here. For more details, readers should consult specialist
sedation textbooks.
Intravenous Sedation With Combinations of Drugs
There are a number of techniques for producing conscious
sedation using two or more drugs. Advantages cited for
their use are that the drugs acting synergistically produce a
better quality of sedation; however, the synergistic reactions also apply to the side-effects of the drugs. The most
commonly used combination is an opioid (usually fentanyl)
and midazolam.
Intravenous Sedation With Propofol
There are a number of techniques described using propofol
for intravenous sedation. All involve using a syringe pump
to deliver the solution to the patient. The techniques fall
into two groups.
In the first group, the sedationist controls the level of sedation by altering the rate of infusion. The second group of
techniques allows the patient to control the depth of sedation with the use of sophisticated technology. Currently,
these techniques are used predominantly in hospital settings
and are unsuitable for the operator–sedationist.
Inhalation Sedation Using Any Agent Other Than Nitrous Oxide/Oxygen Alone
Techniques using anaesthetic volatile agents such as
sevoflurane or isoflurane either alone or in combination
with nitrous oxide have been described. Currently there is
no dedicated inhalation sedation equipment available to
deliver this type of sedation. Thus, its use is restricted to a
few ‘specialist’ centres, and these techniques are thus
largely of academic interest only.
Combined (Non-Sequential) Routes, For Example:
Intravenous 1 Inhalation Agent (Except for the
Use of Nitrous Oxide/Oxygen During Cannulation)
When drugs are administered by different routes, they have
different pharmacokinetic properties. Thus, using multiple
routes makes the process of achieving a sedation endpoint
more difficult. The use of oral followed by intravenous sedation can be an effective method of managing profoundly
needle phobic patients. This technique has the drug or drugs
administered by the two routes exerting a clinical effect at
the same time and is pharmacokinetically more challenging
than either technique alone.
MONITORING OF SEDATED PATIENTS
All patients who are having any form of dental treatment
should be monitored by those who are providing that treatment. The importance of monitoring is greater when patients
have been sedated, as they are less aware of their surroundings,
and any changes that are occurring within their own bodies.
Clinical Monitoring
The cornerstone of all monitoring is the clinical observation of the patient.
Is the patient conscious? In this context, consciousness is
defined as the ability to respond to verbal command.
Does the patient look relaxed and comfortable? This
will show that they are tolerating treatment without undue distress. The patient’s facial expression and general
demeanour in the dental chair are good indications of
their level of comfort.
Skin colour. Any changes in skin colour should be noted, as
they may be indicative of an impending medical incident,
for example, a bluish tinge may result from hypoxia secondary to respiratory depression. Reddening, particularly
in an area where there has been contact with surgical
gloves or rubber dam, may indicate an allergy.
Pattern and depth of respiration. Given that respiratory
depression can occur with benzodiazepine sedation,
patients should have the rate and depth of breathing
monitored. Patients who are receiving inhalational sedation should also be monitored, as mouth-breathing is an
early sign of overdose.
Electromechanical Monitoring
The clinical monitoring is complemented by the use of
electromechanical devices.
Non-Invasive Blood Pressure Recording During Sedation
Adult patients should have their blood pressure recorded
both as part of the assessment process and immediately
prior to sedation. This allows the establishment of a baseline reading. Patients receiving sedation with nitrous oxide
or midazolam alone do no need to have their blood pressure
recorded regularly throughout the sedation period unless
there is a medical issue that makes this advisable. Such patients would normally be categorised as ASA III (American
Society of Anesthesiologists) or IV and thus tend to be seen
in specialist facilities, by an experienced sedationist.
6 • Conscious Sedation in Dentistry
100
161
Any patient receiving multiple agent sedation or drugs
by continuous infusion should have their blood pressure
recorded at 5-minute intervals.
All adult patients should have a recording of their blood
pressure taken immediately prior to discharge.
It is not normal to measure blood pressure for fit and well
children prior to sedation.
Pulse Oximetry
The use of a pulse oximeter, which will pick up falls in
arterial oxygen saturation before they are clinically evident, provides an early warning of respiratory depression. Falls of 4–5% must be corrected, and any fall below
90% saturation must be treated as potentially serious.
The reasons for this will become apparent when the oxygen–haemoglobin dissociation curve is studied (Fig. 6.4).
The oximeter should be attached to the patient and be
switched on prior to the administration of any sedative so
that the normal saturation can be noted. The pulse oximeter also displays a reading of the patient’s pulse. Changes
(particularly increases) may indicate distress or pain during treatment.
Pulse oximetry is not routinely used with inhalational
sedation, as high concentrations of oxygen are always administered (the minimum is 30%), but should be considered as mandatory for intravenous, oral and transmucosal
sedation.
Reservoir Bag on a Relative Analgesia Machine
In addition to the aforementioned, when inhalational sedation is used, observation of the movements of the reservoir
bag allow an assessment of the patient’s pattern of breathing. Increases in rate or depth may indicate anxiety, whereas
a decrease in the amount of movement of the bag while the
chest movements remain the same may indicate that the
patient is mouth-breathing.
As most sedation is carried out by an operator sedationist,
the main burden of monitoring tends to fall on the dental
nurse. The issue of training for the dental team is covered
later.
The Future
Capnography
Monitoring exhaled carbon dioxide is a significantly more
sensitive measure of respiratory depression than measuring oxygen saturation. It is not used routinely, as currently
the technology is expensive and for the conscious patient
produces a significant number of false alarms. Currently,
sidestream capnography (diverting a portion of expired air
through a sensor) is the recommended technique. It is sensitive to a patient’s breath holding or mouth-breathing. An
alternative technique is transcutaneous monitoring via
electrodes placed on the skin.
The Academy of Medical Royal Colleges report in 2013
described capnography as a ‘developmental standard’ and
the Intercollegiate Advisory Committee for Sedation in
Dentistry indicated that there is little evidence to justify its
use in ASA I or II patients. In the future, it is likely to become the ‘go to’ monitor of respirator function.
Bispectral Index Monitoring
The Bispectral Index (BIS) monitoring uses an electroencephalogram (EEG) to monitor brainwave activity and produce a numerical reading between 0 and 100. BIS scores of
90–100 equate to being fully conscious, 70–90 conscious
sedation and 40–60 general anaesthesia. Currently, this
monitor has been used largely for research, with applications
including using the BIS reading to provide feedback to control infusion pumps administering agents such as propofol.
6.4 Dental Treatment Planning
90
75
50
saturation (%)
2
O
25
0
Partial pressure O2 (kPa)
Fig. 6.4 The oxygen–haemoglobin dissociation curve; 90% saturation
is at the top of the steep portion of the curve. Further respiratory depression will result in rapid falls in saturation.
14121086420 16
LEARNING OBJECTIVES
You should:
• appreciate which procedures benefit from the use of se-
dation
• understand how to encourage patients to complete and
maintain treatment.
All dental procedures that might be carried out under local
anaesthesia can be performed under sedation and local
anaesthesia. Some procedures are more easily carried out
under one form of sedation than another (e.g. apicectomies
on upper incisors are difficult under inhalational sedation,
as the nosepiece tends to interfere with the operating field).
The main decision rests on what treatment is advisable to
carry out for patients. As in all other areas of dentistry,
these decisions depend much on the patient’s co-operation.
Patients requiring sedation often have very poor attendance records, largely because they are terrified of being
in the dental environment. Previous non-attendance
means that they have not been exposed to oral health
education, such as diet advice and oral hygiene instruction. In these patients, poor oral hygiene at first attendance should not be taken as an indication of lack of will
to co-operate.
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Master Dentistry
The ideal for dental treatment planning is to deal with
any periodontal problems, manage the routine conservative work and provide advanced conservation (fixed
prosthodontics and endodontics) with removable prosthodontics as the final stage. Berating an anxious patient on
the merits of good oral hygiene and forcing them to have
all hard and soft deposits removed from their teeth as a
first stage will result in the patient failing to return for
treatment. It is important to engage the patient in treatment first to show them that they can attend and cope
with receiving treatment.
The decision of what treatment to provide will then depend on the patient’s ability to cope with treatment under
sedation, as well as their response to the health education
message. It is inappropriate to promise patients advanced
treatment prior to the initial sedation appointment, as it
may well be that even with sedation, co-operation may be
limited.
Treatment such as molar endodontics, multiple crowns
and bridges and technique-sensitive procedures should be
reserved for only the very co-operative and compliant patients who are likely to maintain good oral health in the
future.
6.5 Medicolegal Aspects
LEARNING OBJECTIVES
You should:
• appreciate the obligations on the dental profession us-
ing sedation
• know the importance of compliance with current stan-
dards.
Sadly, all aspects of medical and dental practice are being
affected by the need to consider the possibility of legal action for negligence.
The current standards for practice are found in the Intercollegiate Advisory Committee for Sedation in Dentistry’s
2015 report. In Scotland, the Scottish Dental Clinical
Effectiveness Programme produced guidance, which was
updated in 2016. The principal recommendations are
broadly similar, and the gist of the requirements is reproduced as follows:
n
The definition of conscious sedation is as given at the
beginning of this chapter. Although it allows latitude in
the techniques that may be used for sedation, it does go
on to say that ‘No one technique is suitable for all patients. However, adopting the principle of minimum intervention, the simplest and safest technique that is
likely to be effective, based on robust patient assessment
and clinical need, should be used’.
n
Dentists are entitled to act as operator/sedationist, with
the proviso that they must have undertaken the relevant
postgraduate training.
n
If a dentist is to exercise this right, then the appropriate
assistance must be available. This may be from a suitably
trained dental nurse. Such a dental nurse should be registered with the General Dental Council and must have
undertaken the relevant postcertification course.
n
Courses providing training in sedation must be accredited by the Sedation Training Accreditation Committee
based at the Royal College of Surgeons in London unless
run by a university or postgraduate deanery.
n
Those providing conscious sedation must undertake 12
hours of sedation-related continuing professional development (CPD) in every 5-year period.
n
Sedation activity, including complication rates, must be
audited.
n
All centres providing conscious sedation for the delivery
of dental care should be inspected to determine that the
necessary standards are in place.
n
All patients who are to have sedation must be assessed to
ensure that the most appropriate management plan is
devised.
n
All patients having any treatment under sedation of
any sort must give consent in writing. This consent
should be informed; that is, that the dentist who is to
administer the sedation explains the procedure to the
patient and any alternative treatments that may be possible. This allows the patient to give their consent based
on knowledge of the treatment options.
n
Patients should be given age-appropriate written information regarding the sedative technique to be used including
pre- and postoperative instructions. These instructions
must include advice as to whether fasting is required prior
to sedation. This is not normally required for sedation for
dentistry, but the advice must be tailored to the individual
patient.
n
All patients should be carefully monitored during
sedation (Section 6.3).
n
Patients who are recovering from sedation must be
protected and monitored in adequate facilities. They
should only be discharged when the person administering the sedation is satisfied that they have recovered
sufficiently. Patients receiving intravenous or oral sedation must be discharged into the care of a responsible adult, as must children receiving inhalational sedation. Adults receiving inhalational sedation with
nitrous oxide and oxygen may be discharged alone at
the dentist’s discretion. This will largely depend on the
patient’s response to sedation and, therefore, can only
really be suggested once the dentist has assessed the
patient’s reaction to having dental treatment in this
manner.
n
All of those who practise dentistry must be capable of
dealing with a patient collapse. There are, however, no
additional requirements on those practising sedation in
terms of resuscitation skills from those required of all
dentists. All who provide dental treatment should practise their emergency skills regularly in simulated emergency situations.
n
Children and adolescents aged between 12 and 16 years
should only receive sedation with midazolam or nitrous
oxide unless treated in a specialist environment.
n
Children aged under 12 years should only receive
sedation with nitrous oxide unless treated in a specialist
environment.
Intercollegiate Advisory Committee for Sedation in Dentistry’s 2015 report was reviewed in 2019. The result of the
review was that the committee felt that there was no reason
to change the current standards.
6 • Conscious Sedation in Dentistry
163
It is each professional’s responsibility to ensure that they
are familiar with and comply with the required standards
of practice. Although any discussion of medicolegal issues
Self-Assessment: Questions
MULTIPLE CHOICE QUESTIONS
1. Assessment for sedation involves:
a. Dental examination
b. A trial attempt at dental treatment
c. Recording the patient’s blood pressure
d. Taking a full medical history
e. Obtaining verbal consent for treatment
2. Nitrous oxide is:
a. A colourless gas with a pungent odour
b. Is lighter than air
c. Is highly soluble in blood
d. Is a weak anaesthetic with a MAC50 value of about
110%
e. Can only be used to sedate children
3. Flumazenil:
a. Is recommended for routine use in order to hasten
recovery
b. Is not a benzodiazepine
c. Antagonises the action of all benzodiazepines
d. Is useful for managing allergic reactions to benzodi-
azepines
e. Has a shorter half-life than midazolam
4. The following are contraindications to intravenous
sedation:
a. Myasthenia gravis
b. Chronic bronchitis
c. Liver failure
d. Well-controlled angina
e. Mild learning difficulty
5. The pharmacodynamic properties of the benzodiazepine group of drugs include:
a. Anxiolysis
b. Analgesia
c. Antiemetic effect
d. Sedation
e. Anaesthesia
6. Nitrous oxide cylinders:
a. Contain gaseous nitrous oxide at high pressure
b. The pressure of the cylinder contents is directly pro-
portional to the volume of gas remaining
c. Are light blue with a white quartered top
d. Must be stored vertically
e. Can be connected to the same mounts as Entonox
cylinders
7. Nitrous oxide sedation:
a. Can only be used for children
b. Is the only technique that can be used in general
dental practices for children and adolescents aged
12–16 years
c. Produces sufficient analgesia for soft tissue surgery
d. Relies heavily on the operator’s ability to use sugges-
tion
e. Is useful in patients with gagging problems
tends to cause panic, it should be remembered that those
who practise ethically in accordance with guidelines have
little to fear.
8. Oral sedation:
a. Is less predictable than intravenous sedation
b. Drugs may be subject to first-pass metabolism
c. May be achieved with midazolam
d. Means that the patient can attend without an escort
e. Should be titrated against the patient’s response
9. An overdose of intravenous benzodiazepine:
a. Will most often present as respiratory depression
b. May result in loss of consciousness
c. May produce severe systemic effects including liver
damage
d. Always requires treatment with flumazenil
e. Will result in the dental treatment having to be
postponed until a future occasion
10. An overdose of nitrous oxide:
a. Can lead to the patient laughing uncontrollably
b. Reduces patient co-operation
c. Occurs at the start of treatment but is unlikely later
d. Can lead to vomiting
e. Results in the patient’s mouth becoming fixed in an
open position
11. Midazolam:
a. Is water soluble at all pH values
b. Is half as potent as diazepam
c. Has an elimination half-life of about 2 hours
d. Metabolism is reduced by erythromycin
e. Causes thrombophlebitis on injection
12. Scavenging must be used with relative analgesia
sedation because nitrous oxide:
a. Reacts with cobalt-containing enzymes
b. Reduces the sperm count of male dentists
c. Can cause vitamin B12 deficiency
d. Makes female staff less fertile
e. May increase incidence of cervical carcinoma in
female staff.
EXTENDED MATCHING ITEMS QUESTIONS
Theme: Assessment for sedation
For each of the descriptions of patients who might be referred for conscious sedation for dental treatment (a–e),
select from the list below (1–10) the most appropriate
option for their management (more than one may be
correct). Each option may be used once, more than once or
not at all:
1. Provide treatment at a general dental practice with
intravenous conscious sedation
2. Provide treatment at a general dental practice with
inhalation sedation
3. Provide treatment at a ‘Specialist Setting’ with intravenous conscious sedation
4. Provide treatment at a ‘Specialist Setting’ with inhalation sedation
5. Provide treatment under local anaesthesia in a general
dental practice
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Master Dentistry
6. Provide treatment under local anaesthesia in a ‘Specialist Setting’
7. Postpone treatment until the medical condition is
controlled
8. Provide treatment with oral sedation
9. Provide dental treatment under general anaesthesia
a. A 65-year-old man with hypertension and ischaemic
heart disease taking aspirin, atenolol and ramipril.
He has regular episodes of ischaemic chest after moderate exertion.
b. A 58-year-old woman with untreated hypothyroid-
ism who attends with multiple carious teeth requiring restoration but gives a history of a longstanding
dental anxiety.
c. An anxious 10-year-old requiring a lower first de-
ciduous molar extracted. There is a history of previous failure of inhalation sedation.
d. A 20-year-old student with a history of pericoronitis
who requires both lower wisdom teeth extracted but
has little experience of dental treatment.
e. A 45-year-old patient who requires impressions
taken to construct an acid-etch bridge but cannot
tolerate these as they make him feel sick.
f
e
g
a
d
b
c
CASE HISTORY QUESTION
Case history
A 14-year-old female is referred for the extraction of
four first premolars for orthodontic reasons. She is a pleasant but anxious child who attends a local boarding
school.
Medical history
The patient says she faints easily but has not been investigated. She has an allergy to elastoplast.
Dental history
Although a regular attender for as long as she can remember, the patient has previously only had one small filling
that did not require local analgesia.
Intraoral examination
The patient has good oral hygiene, with all teeth bar the
third molars fully erupted. There is crowding evident in
both arches.
1. What are the treatment options?
2. Which is the best option and why?
3. What is the major problem with providing treatment for
this girl?
Fig. 6.5 Equipment used in sedation. (Image courtesy of Cestradent
McKesson.)
SHORT NOTE QUESTIONS
Write short notes on:
1. the advantages of midazolam over propofol as an intravenous sedative
2. the disadvantages of oral sedation
3. the signs and symptoms of oversedation with nitrous
oxide
4. factors that could cause the arterial saturation reading
on a pulse oximeter to fall to 85% during sedation with
intravenous midazolam
5. the principal clinical effects of the benzodiazepine group
of drugs
6. factors observed during the clinical monitoring of a
sedated patient.
PICTURE QUESTIONS
Picture 1
1. What is the piece of equipment shown in Fig. 6.5?
2. What are the features labelled a–g?
Picture 2
1. What are the pieces of equipment in Fig. 6.6?
2. Given the choice, which would be used for dental sedation and why?
Fig. 6.6 Equipment for venous access.
6 • Conscious Sedation in Dentistry
165
VIVA QUESTIONS
1. How would you assess a patient who attends asking to
be referred for intravenous sedation?
Self-Assessment: Answers
MULTIPLE CHOICE ANSWERS
1. a. True. It is important to at least have a look in the
patient’s mouth to establish that there is a treatment need and give the patient an idea of the
amount of time required. If the patient is very anxious, then probing cavities and restoration margins
or doing a periodontal assessment will tend to distress the patient.
b. False. It is cruel and heartless to imply that patients
must be shown to be unable to tolerate treatment
before offering sedation.
c. True. The only exception to this rule is that fit chil-
dren who are to receive relative analgesia do not
normally have their blood pressure recorded. It may
also be that with some patients with moderate learning difficulties, there may be insufficient co-operation
for what is an uncomfortable procedure.
d. True. All patients undergoing any dental interven-
tion should have a full medical history recorded.
e. False. Written informed consent is required for all
treatment under any form of sedation.
2. a. False. Although colourless, nitrous oxide has a sweet
odour.
b. False. Nitrous oxide is about 1.5 times as dense as air.
c. False. Nitrous oxide is very insoluble in blood, a fact
in the rapid onset of and recovery from sedation.
d. True.
e. False. Nitrous oxide is suitable for just about all ages
of patients. It is vastly underused in adult patients.
3. a. False. It is currently recommended that flumazenil is
only used in an emergency.
b. False. Flumazenil is a benzodiazepine. In fact, it is
very closely related to midazolam in chemical structure.
c. True.
d. False. If a patient is allergic to any other benzodiaze-
pine, they will almost certainly be allergic to flumazenil. Giving it in this situation will make things worse,
not better.
e. True. The shorter half-life has been used as an argu-
ment against its routine use.
4. a. True. The muscle-relaxant properties of the benzodiazepines coupled with the poor transmission of motor impulses to muscles can lead to paralysis.
b. True. The altered respiratory drive associated with
chronic hypoxia in severe chronic bronchitis makes
patients extremely sensitive to the respiratory depressant effects of the sedative agents.
c. True. Midazolam is principally broken down in the
liver. There is, however, significant extrahepatic
breakdown. Consequently, liver failure will only be a
2. Describe how you would explain inhalational sedation
to a 10-year-old child who is referred for treatment.
problem when the function is sufficiently severe to
cause problems with breakdown of local anaesthetics and a failure of clotting.
d. False. If the angina is well controlled, sedation may
be used. It may also be of great value if the patient
normally has few problems but gives a history of
exacerbation of the problem during dental treatment.
e. False. Sedation may help such patients to cope with
treatment.
5. a. True.
b. False. Relief of anxiety may influence the patient’s
perception of stimuli or reaction to chronic pain,
but benzodiazepines have no analgesic properties.
c. False.
d. True.
e. True. Large enough doses of benzodiazepines, par-
ticularly if given rapidly intravenously, will produce
loss of consciousness.
6. a. False. The cylinders contain both gas and liquid
under pressure.
b. False. The pressure remains constant until all the
liquid has vaporised. This occurs when only oneeighth of the contents are left.
c. False. The cylinders are light blue. The white
quartered top denotes an Entonox cylinder.
d. True. This prevents liquid entering the gas outlet.
e. False. The pin index system is gas specific.
7. a. False. This technique is useful for a wide range of
patients. Adults can be managed extremely well
with inhalational sedation.
b. False. Patients of this age can also be sedated with
midazolam if it is assessed as the technique of
choice for the dental treatment required.
c. False. There is some analgesia, but insufficient for
surgical procedures.
d. True.
e. True.
8. a. True. The pattern of drug absorption is unpredictable and, therefore, the effects of the dose and the
time to onset of sedation are unpredictable.
b. True. The drug once absorbed from the gastrointes-
tinal tract passes via the portal circulation to the
liver. Here, a significant proportion is metabolised.
c. True.
d. False. The effects may persist longer than intrave-
nous agents. Temazepam has a significantly longer
half-life than midazolam.
e. False. The long latent period for the absorption of
oral drugs means that the dose has to be given on a
best guess basis.
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Master Dentistry
9. a. True.
b. True.
c. False. There are no toxic effects to systems. The ef-
fects are of respiratory depression and anaesthesia.
If the patient is supported until the drugs are eliminated, they will make an uneventful recovery.
d. False. Minor overdose can be managed by encour-
aging the patient to breathe and supporting them
until they recover to a normal level of sedation.
e. False. Once the patient has returned to a normal
level of sedation (if managed as in [d]), treatment
can be carried out.
10. a. True. Hence the name laughing gas.
b. True. It feels unpleasant to the patient, and they
often become disorientated.
c. False. Overdose often occurs later in treatment,
when the part of the procedure that the patient
dislikes most is past and their requirement for anxiolysis reduces.
d. True. This is a relatively late sign of overdose, and
one would hope that remedial action would be
taken before this stage was reached.
e. False. Spontaneous mouth closing is an early sign of
overdose. Mouth props should not be used with inhalation sedation, as they mask this important sign.
11. a. False. It is lipid soluble at physiological pH and can
cross the blood–brain barrier.
b. False. It is about two to five times as potent as diazepam.
c. True.
d. True.
e. False. This is one of midazolam’s great advantages
over diazepam.
12. a. True.
b. False.
c. True.
d. True.
e. True.
EXTENDED MATCHING ITEMS ANSWERS
a. 3, 4. If the patient is assessed as needing sedation, then
either 3 or 4 would be correct. In theory, the use of inhalation sedation has advantages, as it provides an increased amount of oxygen. Nitrous oxide also produces
some vasodilatation, which may also improve the blood
supply to the myocardium. Intravenous sedation can be
used, but care should be taken to avoid hypoxia. This
patient is ASA III, and therefore the treatment should be
provided in a ‘specialist’ environment (i.e. one where the
staff are used to providing sedation for medically compromised patients). If the patient can cope with treatment under local anaesthesia alone, then treatment
could be provided in the primary care setting.
b. 7. Patients with untreated hypothyroidism are unduly
sensitive to both local anaesthetics and central nervous
system depressant drugs. Once an appropriate level of
thyroxine replacement is started, then the patient can be
treated under the type of sedation that is assessed as being
the most appropriate. There would then be no contraindication to sedation in the primary care environment.
c. 3 or 2. If at assessment it is felt that inhalation sedation
will fail again, then intravenous sedation is a possible option. General anaesthesia can be considered, but at the age
of 10 years, the extraction will be relatively straightforward due to physiological root resorption. Thus GA is best
avoided if possible. This patient cannot be treated in the
primary care setting. If the patient is assessed, and it is felt
that there has been a significant change in the patient
since inhalation sedation failed, it could be considered.
d. 1, 3. Many patients cope with the surgical extraction of
wisdom teeth under local anaesthesia alone. There is,
however, little doubt that it is a stressful procedure. The
use of intravenous sedation is useful as the amnesia prevents the patient remembering the treatment. The choice
between 1 and 3 will depend on the clinician’s surgical
ability. The sedation could be carried out in primary care.
e. 2. Inhalation sedation is very good at controlling prob-
lems with gagging. Consideration should also be given to
altering the impression technique (e.g. using a lower
tray in the upper arch so that contact between the impression material and the palate is reduced).
CASE HISTORY ANSWER
1. The treatment options are:
n
local anaesthesia
n
inhalation sedation
n
intravenous sedation if child appears mature for her
years
n
oral sedation
n
general anaesthesia.
2. Inhalation sedation is the best option, although all are
potentially possible. Local anaesthesia alone is asking a
child with little experience of dental treatment to tolerate
a total of eight local anaesthetic injections (including two
palatal) and cope with four extractions. In an attempt to
avoid using gas, many dentists tried to persuade children
in this category to have treatment under local anaesthesia, and the result was an increase in the number of children referred to have three first premolars out under
general anaesthesia. Intravenous, oral and transmucosal
sedation are all possible. At the age of 14 years, the patient is still considered a child in legal terms, but there is a
wide range of variation in the maturity of individuals of
the same age. Oral or transmucosal sedation would only
be considered if it was felt that a greater level of sedation
than could be produced by inhalation sedation was required, but the patient could not tolerate intravenous
cannulation. General anaesthesia should be avoided if at
all possible. Its use for a minor cosmetic procedure cannot
be justified, particularly in the light of recent publicity.
3. The major problem in this case is medicolegal, not clinical. Obtaining consent for treatment for this patient is a
problem, as the parents presumably live a long way from
the school. The head teacher will have the power to act
as guardian and give medical consent in an emergency
situation, but this would not be the case for orthodontic
treatment. The parents must at least be spoken to on the
telephone and be sent a consent form to sign if they cannot be seen face to face.
PICTURE ANSWERS
Picture 1
1. This is the head of a MAC1 Inhalation Sedation
Machine.