1 - Sedation and GA in Paediatric Dentistry Flashcards
Sedation is used to reduce fear, anxiety and distress and to maximise procedural success - what pharmacological techniques can we use in dentistry to achieve this? (5)
- Nitrous oxide sedation
- Oral sedation
- IV sedation
- General anaesthetic
- …combination
What are the different stages of sedation/anaesthesia?
Stages 1 to 4 with varying planes.
S1 P1/2 = relative analgesia
S1 P3 = total analgesia
S2 = excitement
S3 P1-4 = surgical anaesthesia
S4 = medullary depression, respiratory paralysis
How can you assess which sedation plane a patient is in?
there is no clear indication for each plane, every pt is different
need to monitor vitals, responses, behaviour and how they appear to assess
NO sedation. Type and plane.
conscious sedation
relative analgesia
Why is NO commonly used in paeds and at which concentration
safe and effective when administered properly
anxiolytic and mild analgesic
sub-anaesthetic doses of NO relieve anxiety w/o loss of consciousness where patient is relaxed but responsive
usually up to 50% NO (maintenance 20)
Describe stage 1 plane 1 NO sedation (8)
relative analgesia -> moderate sedation and analgesia
- increased pain threshold
- vitals intact: normal HR, BP, RR
- laryngeal and pharyngeal reflexes unaffected
- vasomotor: feeling of warmth
- feeling relaxed and less fearful
- paraesthesia: tingling sensation in fingers, toes, lips
- normal blinking
- conscious communication and co-operation
Describe stage 1 plane 2 NO sedation (8)
relative analgesia -> dissociation sedation and analgesia
- as s1p1 but further relaxation
- possibly reduced blink rate
- pharyngeal (gag) reflex REDUCED
- laryngeal reflex INTACT
- drift: floating, euphroci, detached feeling
- can maintain open mouth (dont use bite block so can assess this)
- mild flushing of face/extremities
- possible amnesia and telescoping of time (appt seems shorter)
Describe the transition beyond stage 1 plane 2 NO? Is it noticeable?
no longer RA
no, theres no gradual transition from one plane to next
(not done in clinic but important to monitor to avoid this level)
Describe stage 1 plane 3 (5)
total analgesia
- may not be able to maintain open mouth
- may be sleepy, sweaty and/or nauseous
- may not respond to verbal or painful stimuli
- reduced phayngeal and laryngeal (risk of accidental aspirations)
Describe stage 2. Do you want this? (7)
excitement or delerium
- undesirable sedation stage in dental surgery
- pt may exhibit excitement and or struggle
- pharyngeal and laryngeal reflexes significantly reduced
- BP and HR increased
- irregular RR
- pupils dilated
- possible loss of consciousness
(pt may be calm then chatty)
Describe stage 3
surgical anaesthesia i.e GIA
Describe stage 4
respiratory paralysis
respiratory arrest -> death
NO properties
- non-irritating, colourless, sweet smelling gas
- non-flammable
- blood-gas solubility coefficient low (0.47)
- metabolism - no biotransformation in body - excreted unchanged at similar rate to absorption (doesnt hang around system)
- solubility ratio 15-35x that of N, risk of pressure changes in patient w blocked ear -> pain and discomfort
Blood-gas solubility coefficient of NO. Meaning?
0.47 (low)
relatively insoluble in blood meaning quick onset/recovery (no hangover)
primary saturation of blood & brain within 3-5 mins
How does the solubility ratio of NO compare to that of N. What implication does this have.
15-35x more
N is displaced from blood as NO is taken up
can have signficant pressure/volume increase in closed air filled cavities where NO enters the space at about 35x speed N leaves the cavity
e.g. ear infection
Describe metabolism of NO
doesnt undergo biotransformation in the body therefore excreted unchanged via lungs (99%) and at similar rate to absorption
small amt through skin, sweat glands, urine, intestinal gas
CNS effect of NO
- likely acts directly on opioid receptors (indirect evidence that opioid blockers inhibit the effects of NO)
- acts on reticular activating system (RAS) - controlling emotions
- analgesia* (~20% NO similar to 10-15mg IV morphine)
- euphoria and depressant
- amnesia (telescoping of time)
- anxiolytic/sedative
*relative analgesia, need for LA depends on the procedure and individual pain threshold e.g. exfoliating wobbly tooth vs infected tooth
Cardiovascular effects of NO (heart -2 and vasculature -1)
Heart
- no clinically signficant difference at therapeutic dose (no direct effect)
- reducee HR in 1st stage of anaesthesia could be due to peripheral vasodilation or anxiolytic effect
Vasculature
- peripheral vasodilation - flushing of skin or sweating
Respiratory effect of NO (3)
- no direct effect
- non-irritating
- caution w emphysema/COPD
(since administering NO along with O, giving O might cause issues as they need CO)
GIT effect of NO
nausea during latter plane of 1st stage due to vertigo effect of NO
Effect of NO on reflexes
progressive reduction in reflexes with increasing conc
Effect of NO on haemopoetic system
transient bone marrow depression with long term exposure (>24h)