inhalation sedation

Question 1

Give 4 indications for IS

Answer 1

Any from:
- anxiety
- needle phobia
- gagging
- traumatic procedures
- medical conditions aggravated by stress
- unaccompanied adults requiring sedation

Question 2

Give 4 contra-indications for IS

Answer 2

Any from:
- common cold
- tonsillar/adenoidal enlargement
- severe COPD
- first trimester of pregnancy
- fear of mask/claustrophobia
- patients with limited ability to understand

Question 3

What equipment is needed for IS?

Answer 3

Gas cylinders
Pressure reducing valves
Flow control meter
Reservoir bag
Gas delivery hoses
Nasal hood
Waste gas scavenging system

Question 4

What makes up the flow control meter?

Answer 4

Quantified O2 flow meter - measures flow rates up to 10L/min
Nitrous oxide flow meter - blue and measures flow rates up to 10L/min
Air entrainment valve - if gases fail, valve opens allowing room air into circuit
Oxygen flush button - emergency use, flushes O2 at 35L/min

Question 5

Describe the reservoir bag

Answer 5

2 or 3 L bag - rubber or silicone
Bag should move visibly with each inspiration and expiration
Helps to monitor respiration
Must not collapse

Question 6

What are the gas delivery hoses?

Answer 6

2.5cm diameter, corrugated
One hose delivers fresh gases from the machine
One hose delivers waste gas to scavenging system
Non-return valve prevents rebreathing expired gases

Question 7

Describe the nasal mask/hood

Answer 7

Comes in various sizes
Should form a seal around the patients nose
Has two connections to the breathing circuit

Question 8

What is the scavenging system?

Answer 8

Active removal of waste gases
Has a small negative pressure

Question 9

Name 4 safety features of the IS set-up?

Answer 9

Any from:
- air entrainment valve
- oxygen flush button
- oxygen monitor
- reservoir bag
- colour coding
- scavenging system

Question 10

Give 4 advantages of IS

Answer 10

Any from:
- rapid onset (2-3 minutes)
- rapid peak action (3-5 minutes)
- depth altered either way
- flexible duration
- rapid recovery
- no injection (LA still possible required)
- few side effects to patient
- drug not metabolised
- some analgesia
- no amnesia

Question 11

Give 4 disadvantages of IS

Answer 11

Any from:
- expensive equipment
- gases expensive
- space occupying equipment
- not potent
- required ability to breathe through nose
- possible chronic exposure risk
- staff addiction
- difficult to accurately determine actual dose

Question 12

Give 5 signs of adequate IS sedation

Answer 12

Any from:
- patient relaxed/comfortable
- patient awake
- reduced blink rate
- laryngeal reflexes unaffected
- vital signs unaffected
- gag reflex obtunded
- mouth open on request
- decreased reaction to painful stimuli
- decrease in spontaneous movements
- verbal contact maintained

Question 13

Give 5 symptoms of adequate IS sedation

Answer 13

Any from:
- mental and physical relaxation
- lessened awareness of pain
- paraesthesia - lips, fingers, toes, legs, tongue
- lethargy
- euphoria
- detachment ‘floating feeling’
- warmth
- altered awarneness of passage of time
- dreaming
- small, controllable ‘fit of giggles’

Question 14

Give 5 signs and symptoms of oversedation

Answer 14

Any from:
- mouth closing repeatedly
- spontaneous mouth breathing
- nausea/vomiting
- irrational and sluggish responses
- decreased cooperation
- incoherent speech
- uncontrolled laughter, tears
- patient no longer enjoying the effects
- loss of consciousness

Question 15

What are the post-op instructions for IS?

Answer 15

Have a light meal before
Take routine meds as usual
Children accompanied by a competent adult
Adults accompanied at their first sedation appointment, afterwards they may attend alone
Do not drink alcohol on the day of the appointment
Wear sensible clothing
Arrange care of children during and after appointment
Plan to remain in clinic for up to 30 minutes after treatment

Question 16

How is the equipment set up for IS?

Answer 16

1. Set up the machine
2. Select nasal hood
3. Connect to hoses
4. Set mixture dial to 100% oxygen
5. Settle patient in dental chair
6. Reinforce explanations of procedure
7. Set flow to 5-6 litres per minute
8. Position hood on the patient’s nose
9. Encourage nasal breathing
10. Check reservoir bag movements

Question 17

How is nitrous oxide administered?

Answer 17

1. Ask patient to signal when they begin to feel different
2. Reduce oxygen by 10%
3. Wait 1 minute and repeat
4. After oxygen reaches 80% reduce by 5% per minute
5. Stop titration when patient is ready for treatment

Question 18

How should oxygen be adjusted during IS?

Answer 18

If under-sedated, decrease oxygen in 5% increments until satisfactory sedation
If over-sedated, increase oxygen in 5-10% increments until satisfactory sedation

Question 19

How should you take the patient off IS sedation?

Answer 19

1. Gradually increase oxygen by 10-20% per minute until 100%
2. Administer 100% oxygen for 2-3 minutes to prevent diffusion hypoxia
3. Remove hood and turn gas flow off
4. Return patient to upright slowly, give praise and reassurance

Question 20

Why is diffusion hypoxia a risk of IS?

Answer 20

Due to the inadequate amounts of oxygen during or immediately after nitrous oxide administration
It influences the partial pressure of oxygen within the alveolus

Question 21

Why is diffusion hypoxia only a theoretical risk of IS?

Answer 21

The equipment always delivers enough oxygen to the patient

Question 22

What is the success rate of IS?

Answer 22

Between 50-90%

Question 23

What happens on completion of IS treatment?

Answer 23

Adult patients may leave unaccompanied at dentists discretion
Child patients (<16) must be accompanied by a competent adult
Prior to discharge, ask how patient felt procedure went and listen to them
Patient may feel shivery after IS, reassure patient that this is common and will quickly pass