Inhalation sedation 1 Flashcards
Why do we need sedation
Dental anxiety
What is dental anxiety associated with
- Poor oral health
- Poor attendance
- Poor compliance with prevention
can GA be carried out in practice
no it used to be however now it must be carried out in an environment with critical care facilitates eg hospital
What does dental anxiety look like
- Irregular attenence
- Disruptive behaviour
- Low elf esteem
- Expecting the worst
- Increased heart and breathing rate
- Perspiration
- Dryness of mouth
- Muscle tension
- feeling dizzy, sick or butterflies in tummy
Define conscious sedation
A technique in which the use of a drug or drugs produces a state of depression of the central nervous system enabling treatment to be carried out but during which verbal contact is maintained throughout
What must the drug and techniques used to carry out sedation ensure
Should carry a margin of safety wide enough to render loss of consciousness unlikely
What are the properties of an ideal sedative agent
- Wide margin of safer
- No adverse side effects
- Reversible
- Easy to administer and titrate
- Rapid onset and recovery
- Anxiolytic
- Analgesic
- Easily accepted by patient
- Inexpensive
- Minimum integration with other drugs or systems
Define Anxiolytic
Reduces anxiety
In the UK name the main inhalation sedation agent we use
Nitrous oxide
Who discovered nitrous oxide
Joseph Priestley In 1772
Who first reported the analgesic properties of nitrous oxide
Humphrey Davey in 1799
When was nitrous oxide first used clinically
in 1844 by Horace wells
Describe nitrous oxide
Colourless gas at room temperature that is reported to have a slightly sweet odour
it is 1.5x the density of room air
How is nitrous oxide stored
Stored as liquid in blue cylinders at 750 psi
List some of the properties of nitrous oxide
- Non flammable
- Non irritant to mucosa
- Relatively insoluble in blood
What are the clinical effects of nitrous oxide
- Rapid onset of effects
- Depression of the CNS
- Relaxation
- Paraesthesia
- Sedation
- Analgesia
- Euphoria
- Mild depression of the respiratory system
- Mild effects on the cardiovascular system
What can high doses of nitrous oxide cause
Nausea and heachahes
Talk through the action of nitrous oxide
- Inhaled through nose
- Raises partial pressure of nitrous oxide in lungs
- Nitrous oxide is forces into bloodstream across alveolar membrane
- Nitrous oxide is carried to the brain
- Gas exchanges within the brain producing effect
How is the analgesic effect of nitrous oxide achieved in the brain
Due to integration with opioid receptors in the mid brain
How is the anxiolytic effect of nitrous oxide achieved in the brain
Due to interaction with GABA receptors
What can happen rarely in inhalation sedation cases
Diffusion hypoxia
What causes diffusion hypoxia
Rapid elimination of nitrous oxide from the blood
What happens in diffusion hypoxia
Large volumes of nitrous oxide enter the lungs
This can displace oxygen from the alveoli causing diffusion hypoxia
How can diffusion hypoxia be avoided
By giving 100% oxygen for more than 3mins
Name an acute adverse effect of nitrous oxide
Hypoxia leading to nausea or dizziness
Who can be affected by chronic adverse effects of nitrous oxide
- Staff from repeated exposure
- Substance abuse
What causes chronic adverse effects of nitrous oxide
Oxidation of vitamin B12 which reduces methionine synthetase
What effects can chronic effects of nitrous oxide have
- Haematological eg pernicious anaemia
- Neurological
- Malignancy
- Reproductive eg spontaneoud abortion
- Liver and kidney
How do we limit adverse effects on staff
- Exposure limit of 100ppm for time weighted average 8 hour period
- Active scavenging 45l per min
- Good technique using minimal effective dose
- Risk assessment for pregnant staff
What is scavenging in terms of nitrous oxide inhalation
Actively removing excess nitrous oxide
What are the indication of inhalation sedation
- Mild to moderate dental anxiety
- Traumatic procedures
- Gag reflex
- Medically compromised patients
- Prior to IV sedation for cannulation
What are the contra indications for inhalation sedation
- Upper respiratory tract infections
- Chronic respiratory disease
- Pregnancy
- Blocked nose
- Pre co operative children
- Ocular surgery
- If PT is taking methotrexate and bleomycin
Which two medications are a contraindication fr inhalation sedation
methotrexate and bleomycin
What are the advantages of inhalation sedation with nitrous oxide
- Simple non invasive
- Rapid onset and recovery
- Can regulate depth of sedation
- Minimal effect on cardio respiratory system
- Minimal interaction with other drugs
- Easily reversed with 100% oxygen
What are the advantages of inhalation sedation with nitrous oxide
- Nasal mask is not always accepted
- Nasal hood can interfere with treatment especially central incisors
- Some degree of patient compliance is required
- Need continuous nitrous oxide delivery
- Cost of equipment
- Nitrous oxide pollution
