Inhalation Sedation

Question 1

indications for IS

Answer 1

anxiety
needle phobia
gagging
traumatic procedure
medical conditions aggravated by stress
unaccompanied adults requiring sedation

Question 2

contraindications for IS

Answer 2

common cold
tonsillar / adenoidal enlargement
severe COPD
1st trimester of pregnancy
fear of ‘mask’ i.e. claustrophobia
pt with limited ability to understand

Question 3

flow control meter - O2

Answer 3

quantiflex oxygen flow meter
measures flow rates up to 10L/min
reading taken from equator of ball
accuracy +/- 5%

Question 4

flow control meter - N2O

Answer 4

blue and measures flow rates up to 10L/min
read from centre of ball
accuracy +/- 5%
air entrainment valve opens to allow room air into circuit if gases fail
oxygen flush button flushes O2 35L/min - for emergency use only

Question 5

reservoir bag

Answer 5

2-3L rubber/silicone bag
smaller for children
should visibly move with each inspiration & expiration
must not collapse

Question 6

gas delivery hoses

Answer 6

2.5cm diameter
1 delivers fresh gas from machine
1 delivers waste gas to scavenging system
non return valve in expiratory limb prevents rebreathing expired gases
single use
12-16 breaths / min

Question 7

scavenging system

Answer 7

active scavenging of waste gases through small negative pressure
changing surgery air reduces N2O levels; 15 changes of room air per hr
watch for pt mouth breathing
check mask seal for contamination
use of rubber dam decreases likelihood of mouth breathing

Question 8

tank usage in IS

Answer 8

work from front to back
front tank used 1st
back tank always full - not essential for N2O but is essential for O2
always have full unopened tank of O2 at back of machine

Question 9

adv of IS

Answer 9

rapid onset 2-3mins
rapid peak action 3-5mins
depth altered either way
flexible duration
rapid recovery
no inj for sedation
few side effects to pt
drug not metabolised
some analgesia
no amnesia

Question 10

disadv of IS

Answer 10

equipment expensive
gases expensive
space occupying equipment
not potent
requires ability to breathe through nose
chronic exposure risk
staff addiction
difficult to accurately determine actual dose

Question 11

signs of adequate sedation

Answer 11

pt relaxed
awake
reduced blink rate
laryngeal reflexes unaffected
vital signs unaffected
gag reflux obtunded
mouth open on request
verbal contact maintained
decrease in reaction to painful stimuli / spontaneous movements

Question 12

symptoms of adequate sedation

Answer 12

mental & physical relaxation
lessened awareness of pain
paraesthesia
lethargy
euphoria
detachment
warmth
unawareness of passage of time
dreaming

Question 13

signs & symptoms of over sedation

Answer 13

mouth closing repeatedly
spontaneous mouth breathing
nausea / vomiting
irrational & sluggish responses
decreased cooperation
incoherent speech
uncontrolled laughter/tears
pt no longer enjoying effects
LOC

Question 14

pre op instructions before IS

Answer 14

light meal before
routine meds as normal
children accompanied by competent adult
adults accompanied at 1st appt but then may attend alone
do not drink alcohol on day of
wear sensible clothing
arrange care of children during & after appt
plan to remain in clinic for up to 30mins after tx

Question 15

IS technique

Answer 15

set up machine
select nasal hood (record size in notes)
connect to hoses
set dial to 100% O2
pt in chair & reinforce explanations of procedure
set flow to 5-6L/min
position hood on pt nose
encourage nasal breathing
check reservoir bag movements
once pt comfortable proceed
ask pt to signal when they begin to feel different
reduce O2 by 10%
wait for 1min then repeat
after O2 reaches 80% reduce by 5%/min
stop titration when pt ready for tx

Question 16

how to check reservoir bag movements

Answer 16

small movements = check seal & look for mouth breathing +/- decrease flow
movement too great = increase flow rate

Question 17

during IS

Answer 17

monitor pt
if over sedated increase O2 in 5-10% increments until satisfactory sedation
if under sedated decrease O2 in 5% increments until satisfactory

Question 18

when stopping IS

Answer 18

gradually increase O2 by 10-20%/min until 100% or can turn to 100% straight away
administer 100% O2 for 2-3 mins to prevent diffusion hypoxia (can occur with administration of inadequate amounts of O2 during or immediately after N2O anaesthesia but this is theoretical risk)
remove hood & turn gas flow off
return pt upright slowly, praise & reassure