Inhalation Sedation

Question 1

What are possible indications for IS for adults and children?

Answer 1

• anxiety
  
  • mild to moderate
  • not good for severe anxiety
• needle phobia
• gagging
  
  • uncontrollable gag reflex
• traumatic procedures
  
  • extractions
  • small surgical procedures
• medical conditions
  
  • aggravated by stress
    
    • asthma
• unaccompanied adult
  
  • no escort required
    
    • IV not suitable

Question 2

What are possible contraindications for IS in adults and children?

Answer 2

• common cold
  
  • reduced breathing through nose
• tonsillar/adenoidal enlargement
  
  • obstruction
  • natural mouth breathers
• COPD
  
  • severe
  • not enough air able to pass
• pregnancy
  
  • first trimester
  • NO2 contraindicated
    
    • no evidence of toxicity
• claustrophobia
  
  • nasal mask and tubes can trigger
• limited understanding
  
  • small children
    
    • > 7 years old
  • additional support needs

Question 3

What equipment is required for IS sedation?

Answer 3

• gas cylinders
• pressure reducing valves
• flow control meter
• reservoir bag
• gas delivery hoses
• nasal hood
• waste gas scavenge system

Question 4

What machine is widely used for IS and what colours are the gas cylinders

Answer 4

• quantified machine
  
  • black cylinder = oxygen
  • blue cylinder = nitrous oxide

Question 5

What is the function of a flow control meter in IS?

Answer 5

• measures flow rates of gases
  
  • reading from equator of ball
    
    • accuracy +/- 5%
• mixture control dial
  
  • changes percentage of gases
• flow control knob
  
  • changes how many litres delivered
• air entrainment valve
  
  • in case of gas failure
  • valve opens and allows room air in
• oxygen flush button
  
  • flushes 35l/min oxygen
  • for emergency use only
    
    • fill reservoir bag

Question 6

What is the minimum oxygen percentage that can be delivered for IS

Answer 6

30%

Question 7

What is the function of a reservoir bag in IS?

Answer 7

• 2-3 litre bag
  
  • rubber or silicon
  • smaller size available for children
• moves visibly on inspiration and expiration
  
  • helps to monitor respiration
  • 12-16 breaths per minute
    
    • anxiety can cause hyperventilating
• must not collapse

Question 8

What are the functions of gas delivery hoses in IS?

Answer 8

• 2.5cm diameter, corrugates hoses
  
  • universal joints
• one hose delivers fresh gas
  
  • from machine
• one hose delivers waste gas
  
  • to scavenging system
    
    • prevents sendation of others
• non-return valve in expiratory limb
  
  • prevents rebreathing
• single use breath circuits
  
  • tubing and masks

Question 9

What is the function of the nasal mask/hood in IS?

Answer 9

• forms a seal around patients nose
  
  • various sizes
    
    • find best fit for patient
• two connections to breathing circuit

Question 10

What is the importance of a scavenging system in IS?

Answer 10

• active scavenging of waste gases
  
  • small negative pressure
  • sucks gases away

Question 11

What can be done alongside a scavenging system in IS to ensure safety?

Answer 11

• 15 changes of room air per hour
  
  • reduces nitrous oxide levels
• watch for mouth breathing
  
  • check mask seal
  • reduces contamination
• use rubber dam
  
  • reduces likelihood of mouth breathing

Question 12

What safety features are present for IS?

Answer 12

• pin index system
  
  • prevents wrong cylinder attachment
• diameter index system
  
  • prevents pipe cross connection
• minimum oxygen delivery
  
  • 30%
• oxygen fail safe
  
  • operates at <40psi oxygen pressure
• air entrainment valve
  
  • in case of gas failure
  • allows room air into circuit
• oxygen flush button
  
  • for emergencies
• oxygen monitor
  
  • how much is being received
• reservoir bag
  
  • emulates lungs
  • monitor for correct breathing
• colour coded cylinders
  
  • blue = nitrous oxide
  • black = oxygen
• scavenging system
  
  • removes expired gases
• oxygen and NO2 pressure dials
  
  • know how much is remaining
  • always have a second, full tank
• pressure reducing valves
• one way expiratory valve
• quick fit connection
  
  • positive pressure oxygen delivery

Question 13

What is the onset period of IS and when does it reach peak action?

Answer 13

• onset
  
  • 2-3 minutes
• peak action
  
  • 3-5 minutes

Question 14

What are the advantages of IS?

Answer 14

• rapid onset and peak action
• depth altered either way
  
  • sedation easily turned up or down
• flexible duration
  
  • long or short procedures
• rapid recovery
  
  • drug not present in the body
• no cannulation
  
  • injection still required if LA needed
• few side effects
  
  • pins and needles
    
    • fingers and toes
  • oral dysaethesia
    
    • tingling
    • numbness
    • usually tongue and lips
• soem analgesia
  
  • better for ischaemic than inflammatory
• no amnesia
  
  • good for future
  • may manage treatment without sedation

Question 15

What are the disadvantages of IS?

Answer 15

• expensive equipment
• expensive gases
• space occupying equipment
  
  • gas cylinders stored specifically
• not potent
  
  • only for mild anxiety
• requires nose breathing
• chronic exposure risk
  
  • safety measures in place
• staff addiction
  
  • regulations in place
• difficult to determine actual dose
  
  • +/- 5% from dials
    
    • leakage
    • crying
    • speaking

Question 16

What are signs of adequate IS?

Answer 16

• patient relaxed and comfortable
• patient awake and able to interact
• 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 maintined
• mental and physical relaxation
• lessened awareness of pain
• paraesthesia - lips, toes, fingers, tongue
• lethargy
• euphoria
• detached ‘floating’ feeling
• warmth
• altered awareness of passage of time
• dreaming
• small but controllable fit of giggles

Question 17

What are signs and symptoms of over sedation?

Answer 17

• mouth closing repeatedly
• spontaneous moth breathing
• nausea/vomiting depending on eating
• irrational and sluggish response
• decreased cooperation
• incoherent speech
• uncontrolled laughter and tears
• patient no longer enjoying the effects
• banging feeling in head
• loss of consciousness

Question 18

What pre-operative instructions should be given for IS?

Answer 18

• have a light meal before appointment
  
  • do not attend on an empty stomach
• take routine medicines as usual
• children accompanied
  
  • competent adult
    
    • +18 years old
• adults accompanied first appointment
  
  • can attend alone afterwards
• do not drink alcohol on day of appointment
• wear sensible clothing
  
  • remove any thick jumpers or jackets
• arrange care of children
  
  • during and after appointment
• plan to stay in clinic after treatment
  
  • 30 minutes after treatment

Question 19

What technique is used for IS?

Answer 19

• set up machine
• select nasal hood
  
  • record size
• connect to hoses
• set mixture dial to 100% oxygen
• settle patient in dental chair
• reinforce explanations of procedure
• set flow to 5-6l per minute
• position hood on patients nose
• encourage nasal breathing
• check reservoir bag movements
  
  • small movements
    
    • check seal
    • look for mouth breathing
    • decrease flow
  • large movements
    
    • increase flow rate
• allow patient 100% oxygen for 1 minute
  
  • comfortable with hood
  • patient to indicate feeling different
• reduce oxygen by 10%
  
  • wait 1 minute then repeat
• when oxygen reaches 80%
  
  • reduce by 5% per minute
• stop titration when patient ready for treatment
• constant reassurance
  
  • hypnotic suggestion
  • calm, gently voice
• monitor signs and symptoms
  
  • nurse should monitor
  • maintain adequate sedation
  • adjust oxygen levels as required

Question 20

Describe the process of terminating sedation at the end of treatment?

Answer 20

• increase oxygen
  
  • gradually by 10-20% per minute
  • straight to 100%
• administer 100% oxygen for 2-3 minutes
  
  • prevents diffusion hypoxia
• remove hood and turn gas flow off
• return patient to upright slowly
  
  • give praise and reassurance

Question 21

What is diffusion hypoxia?

Answer 21

• occurs if inadequate oxygen delivered after IS
• Fink effect
  • diffusion anoxia/diffusion hypoxia
  • influences partial pressure of oxygen
    
    • in alveolus
  • theoretical risk
    
    • equipment delivers enough oxygen

Question 22

What is the success rate for IS and what can influence this?

Answer 22

• between 50-90% success
• success depends on patient selection
  
  • assessment is vital
• greater success in ortho extractions
  
  • highly motivated patients
  • just need some help
• reduced success in pain cases

Question 23

What must be happen after completion of treatment under IS

Answer 23

• adult patients can leave unaccompanied
• child patients must be accompanied
• ask the patient how the procedure went
  
  • how do they feel?
• reassure patients if feeling shivery
  
  • very common
  • passes quickly