7 - Inhalation sedation

Question 1

What are indications for IS?

Answer 1

• anxiety
• needle phobia
• gagging
• traumatic procedures
• medical conditions aggravated by stress
• unaccompanied adults who require sedation

Question 2

What are contraindications for IS?

Answer 2

• common cold
• tonsillar or adenoidal enlargement
• severe COPD
• first trimester of pregnancy
• claustrophobia associated with mask
• patients with limited understanding

Question 3

What equipment is involved in 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 is the lowest possible oxygen percentage on the flow control meter?

Answer 4

30%

Question 5

What is the flush button for?

Answer 5

• oxygen flush can be used in emergency
• can also be used to inflate the reservoir bag

Question 6

What is the air entrainment valve?

Answer 6

If the gases stop flowing from the cylinders, the valve will open and allow room air to flow to the nasal hood

Question 7

What is the reservoir bag?

Answer 7

• 2/3 litre bag (Smaller bag for children)
• visual of how the patient is breathing, should move visibly with every breath

Question 8

What are the gas delivery hoses?

Answer 8

• one for fresh gas from cylinder, other for scavenger system
• single use

Question 9

What is the scavenging system?

Answer 9

• active scavenging of waste gas using negative pressure
• prevents gases from escaping into room to affect operators
• surgery air should also change 15 times/hour

Question 10

What are signs of adequate IS?

Answer 10

• patient relaxed and comfortable, body can feel tingly
• patient awake
• reduced blink rate
• laryngeal reflexes are unaffected but gag relex reduced
• vital signs unaffected
• warmth, lethargy, time passes differently
• reduced reaction to stimuli
• verbal contact maintained

Question 11

What are signs of oversedation in IS?

Answer 11

• mouth closing repeatedly or spontaneous mouth breathing
• nausea or vomiting
• irrational or sluggish responses, incoherent speech
• decreased cooperation
• uncontrollable laughter (+/- tears)
• patient not enjoying effects
• LOC

Question 12

What are the pre-op instructions you should give to patients?

Answer 12

• have a light meal before
• take routine meds
• children must be accompanied by adult
• adults should be accompanied for first appointment, can attend alone subsequently
• no alcohol on the day
• sensible clothing
• plan to remain for 30 mins after appointment

Question 13

How do you decide the flow rate of oxygen?

Answer 13

• use the reservoir bag, usually around 5-6l/min
• if movements are small, decrease the flow
• if movements large, increase flow

Question 14

How do you control the titration of gas during IS?

Answer 14

• 100% oxygen for a couple of minutes until patient is comfortable with hood
• begin in 10% increments
• when at 80% oxygen, move to 5% increments
• when patient ready for treatment stop titration

Question 15

How should you talk to your patient during IS?

Answer 15

• constant reassurance
• hypnotic suggestion (you are feeling …)

Question 16

How do you manage an oversedated patient?

Answer 16

Increase oxygen by 5-10% increments until patient is comfortable

Question 17

How do you prevent diffusion hypoxia?

Answer 17

• gradually increase oxygen back by 10-20% per minute until 100%
• keep nasal hood in place with 100% oxygen for 2-3 minutes

Question 18

Define diffusion hypoxia.

Answer 18

• can occur during or immediately after sedation with nitrous oxide gas
• if there is not enough oxygen, the partial pressure changes within the alveolus
• a theoretical risk as the equipment always delivers enough oxygen