Safe Sedation (Short)

8/9/2019 Safe Sedation (Short)

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Safe sedation

Dr M F Haque

CDOS, Oral Surgery

Institute of Dentistry, QMUL

[email protected]


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Overview

What is sedation?

Oral sedation

Inhalational sedation

Intravenous sedation

Midazolam and Flumazenil

Practicalities

Hot tips


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Sedation

Conscious sedation

Deep sedation Anaesthesia


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Conscious Sedation

Is just one facet of anxiety management for

dental patients

All patients must have their level of anxietyassessed and appropriate measures put in

place to help

Conscious sedation is a useful method ofanxiety management for anxious patients who

are unable to respond to non-pharmacological

technique


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Conscious sedation

A technique in which the use of a drug or drugs

produces a state of depression of the centralnervous system enabling treatment to be carried

out,

but during which verbal contact with the patient

is maintained throughout the period of sedation.

(General Dental Council)


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Conscious sedation

The drugs and techniques used to provide

conscious sedation for dental treatment should

carry a margin of safety wide enough to render

loss of consciousness unlikely

The ability to maintain a patient airway is the

important distinguishing feature

Under no circumstances be interpreted as light

general naesthesia


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Why go for sedation?

Nervousness, and fear:

Normal physiological / psychological responses

resulting from anticipation of what is about to

happen particularly if this is unknown

Anxiety:

- an emotion similar to fear but without any

objective evidence of danger

- involves physiological, behavioural and

psychological reactions by the individual

- it often synonymous with stress


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Continued-

Stress:

- The physiological and behavioural response

resulting from a lack ofharmony between an

individual and their environment- usually caused by stressors i.e. a stimuli

which cause stress

Phobia: An extreme instanse of anxiety which creates a

pattern of total avoidance behaviour


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Standard techniques

Intravenous sedation with Midazolam alone

Inhalantional sedation using Entnox (=Nitrous

oxide and Oxygen)

Oral/transmucosal Benzodiazepine


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Alternative Techniques

Any form of conscious sedation under 12 year

olds other than Entonox

Benzodiazepines plus any other intravenousagent (Opioid, Propofol, Ketamine)

Propofol either alone or in combination

Inhalational sedation using any agent other than

Nitrous Oxide

Combined routes of administration


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Types of sedation

Oral sedation

Oral Benzodiazepines

Inhalational sedation Nitrous Oxide

Anaesthetic agents (Sevoflurane)

Intravenous sedation Intravenous Benzodiazepines

Opioids

Anaesthetic agents


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Oral sedation

Oral or intranasal sedation should only be used

when it is not possible to use a titrateable

technique

Does not allow accurate titration against the

patients response

Risk of under- or over sedation with fixed dose


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Oral sedation II

Absorption and excretion unpredictable

Benzodiazepines

- Temazepam

- Lorazepam

- Diazepam


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Nitrous Oxide

Relative analgesia

- Mixture of nitrous oxide and oxygen

- Quantiflex machine

- Minimum 30% O2

Laughing gas

Colourless gas

Sweet and pleasant

Smelling

Scavenging

Effects on staff


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Nitrous oxide

Non-irritant

Rapidly absorbed

Low solubility in blood

Very quick recovery

Excreted by lungs

No central respiratory depression


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Health and safety guidelines

Occupational exposure to nitrous oxide should

not exceed 100 ppm over 8 hour period

Maximum of 2.5 hours per day in the sedation

environment to remain within the occupational

exposure limit


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Sevoflurane

Volatile anaesthetic agent

Flurinated ether

Scavenging

Causes CVS and respiratory depression

Apnoea common


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Intravenous sedation

Benzodiazepines

-Midazolam

- (Diazepam)

NMDA receptor antagonists

- Ketamine

Opioids

- Fentanyl

- Remifentanil Anaesthetic agents

- Propofol


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Advantages of intravenous sedation

Given remote from operating site

Administered as a single titrated dose

Titrateable to desired effect

Rapid onset (arm to brain time)

Mouth breathing not relevant


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Disadvantages of intravenous

sedation

Overdose may lead to profound respiratory

depression or even apnoea

Depression of laryngeal reflexes


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Opioids

Fentanyl

Synthetic primary Q-

opioid agonist 2 ml ampoules with

50 micrograms/ml

25 micrograms

Remifentani

Synthetic pure Q-

opioid agonist Ultrafast acting

Needs infusion

Serious potential

complications


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Ketamine

NMDA-receptor antagonist

Anaesthetic induction drug

Class C drug in UK

Good analgesic properties at sub-anaestheticdose

Slow recovery

High incidence of extraneous muscle

movements

Hallucinations


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Propofol

Diprivan (shortened version ofDI-isoPRopyl IV

Anaesthetic)

Anaesthetic induction agent

Pain on injection

Monitored Anaesthesia Care Sedation

Usually as infusion


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Midazolam profile

Selective impairment of memory

Minimal depression of ventilation or

cardiovascular system Specific site of action

Relative safety if taken in overdose

Low abuse and physical dependence potential

Specific antagonist available


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Midazolam: pharmacokinetics II

Onset of action: 2 minutes

Distribution half life: 6-15 minutes

Elimination half life: 1.5-6.4 hours

Metabolized in liver y cytochrome P450-3A4

Active metabolites

Interactions with grapefruit juice, Erythromicin,

Verapamil: higher plasma concentrations


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Midazolam: mechanism of action

Benzodiazepine receptors on the alpha subunits

of the GABA-A receptor

Enhance chloride gating function ofGABA

Hyperpolarization of cell membranes

GABA receptors almost exclusively in CNS

(cerebral cortex)


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Midozolam: body effects

Dose related decreases in cerebral blood flow

Respiratory depression and apnoea

Minimal cardiovascular changes (can lower

blood pressure)

Suppression ofhypothalamic-pituitary adrenal

axis

Paradoxical effects!


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Reported Adverse Effects

Hiccups 3.9%

Nausea 2.8%

Vomiting 2.6% Coughing 1.3%

Over-sedation 1.6%

Headache 1.5%

Drowsiness 1.2%

Local effects at the IV site:

Tenderness 5.6%

Pain during injection 5% Redness 2.6%

Induration

Phlebitis 0.4%


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Midozolam: contraindications

Hypersensitivity

Acute narrow angle glaucoma

Hypotension

Shock

Alcohol abuse

Head injury

Pregnancy Foetal malformations?

Withdrawal, hypotonia, apnoea, cyanosis in

newborn


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Midozolam: effects

1. Sedation

2. Anxiolysis

3. Hypnosis

4. Muscle relaxation

5. Anterograde amnesia

6. Anti-epileptic


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Signs of sedation

Relaxation

Delayed response

Slurred speech

Verrils signs- Ptosis

No hyperventilation

Lowered heart rate

Best signs:

Slurred speech and regular breathing


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Midazolam: overdose

Death

Coma

Impaired motor function

- Impaired reflexes

- Impaired coordination

- Impaired balance

Hypotension Mental confusion

Somnolence


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Flumazenil

Specific benzodiazepine antagonist

High affinity for receptor

Minimal agonist activity

Reverse effects within 2 minutes

Half life shorter than that of midazolam

May require repeated doses


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Flumazenil Preparations

Flumazenil (non-proprietary)

100 micrograms/ml, 5ml 14.49

Anexate

100 micrograms/ml, 5ml 14.49


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Flumazenil Doses

200 micrograms over 15 seconds, then 100

micrograms at 60 second intervals

Usual dose range 300-600 micrograms

Maximal dose 1mg


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Practicalities

Draw up midazolam to have 1 mg/ml: 1 ampoule

of midozolam diluted into 10 ml syringe

Have Flumazenil checked and ready

Know exactly where all your emergency

equipment is


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Patients


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Patients >60 years or concomitant

disease Danger ofhypoventilation, apnoea and airway

obstruction

Peak effect may take longer Smaller increments and slower rate of injection

No more than 1.5 mg over 2 minutes

Increments of 1 mg

Take time to evaluate response

Total dose 3.5 mg usually enough


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Hot tips

Never give more than 2 mg in one go

Total dose should not exceed 5 mg

Keep verbal contact with your patient

Know when to bail out

Take your time: sedation cannot be rushed

Remember: Sedation not Analgesia

Safe Sedation (Short)

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