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)
Effect of NO on skeletal muscle
no clinical effect
PNS effect of NO
sensory neuropathy with chronic abuse
Effect of NO on reproductive system. When should it be avoided in pregnancy?
passes readily across placenta
avoid in 1st trimester - no proper evidence tho (aim tx for early 2nd trim)
Indications of NO (4)
- cooperative child
- mild to moderate fear or anxiety
- sensitive gag reflex
- intolerance to long appts
Contraindications of NO (10) (highlight the absolutes)
- pre-cooperative child (<3yo) or intellectually disabled
- uncooperative child, severe behavioural problems (must build rapport first)
- extensive or very complex tx
- airway blockage - cold or obstructive passage
- conditions with trapped gas: ostitis media, bowel obstruction, brain injury/surgery,pneumothorax
- claustrophobia
- psychiatric disorders (unpredictable rxn)
- signficantly medically compromised child*(bleomycin chemotherapy** and **MTHFR deficiency)
- 1st trimester of pregnancy
- caution w patients at risk of NO induced bone marrow suppression
Which medical conditions should you avoid NO with? (8) Which 1 is a true contraindication.
- complex cardiac conditions
- Myaesthenia gravis
- Multiple sclerosis
- COPD e.g. chronic bronchitis or emphysema, a lowered blood O level is stimulus for breathing, high O levels in RA will elevate blood O level
- Bleomycin chemotherapy - breathing affected bc lungs fibrosed
- Immunosuppressed
- Severe Asthmatic
- MTHFR deficiency - rare metabolic condition
Which patients are at risk of N2O induced bone marrow suppression, neurotoxicity or increased homocysteine levels? (4)
- hx of B12 or folate deficiency
- nutritionally compromised patients, vegetarians, patients on H2 blockers or PPIs
- Concurrent underlying serious illness, severe infection of extensive tissue damage
- Metabolic diseases associated with homocysteine metabolism (MTHFR deficiency, methionine synthesase deficiency, homocystinuria, methylmalonic acidemia)
3 safety features of NO equipment
- minimum 3L/min O flow, minimum 10L/min NO flow (or 30% O)
- capacity for administration of 100% oxygen (oxygen flush)
- automatic air intake in event of oxygen/NO supply failure
What are some equipment features requires by guidelines? (5)
- 3 safety features (minimum O, oxygen flush, automatic air intake during supply failure*)
- one way valve to prevent re-breathing
- reservoir bag
- scavenging system of expired gases
- Australian standards, checked and serviced routinely
*if gas runs out, automatically switches off?
What are the requirements when administering NO? (6)
- additional current training and credentials
- advanced life support skills
- adminstering person present at all times
- chaperone
- informed consent and post-op
- record details
What details should you record when administering NO?
Conc, how long, HR and O sat at baseline
Use of pulse oximeter during NO (2)
- Check vitals - HR and oxygen saturation
- audible and visual alarm system
Technique for administering NO
- nasal mask fit according to pt size
- flow rate
- starting with 100%
Technique for administering NO (7)
- nasal mask fit with good seal according to pt size
- flow rate 6L/min
- starting with 100% oxygen
- reservoir bag partially inflated but not fully (so you can see it go up and down as pt breathes)
- titrate (check response, titrate..)
- constant monitoring
- rubber dam, HVE
What is diffusion hypoxia?
N2O diffuses out of blood into the alveoli rapidly, this dilutes the available O in lungs → administer O for 3-5mins after you stop
its not a significant problem in N2O sedation in dentistry
(kids might push the O mask away but its fine)
Even though NO is safe, when are complications most likely to occur? (3)
- over-sedation
- lack of monitoring
- interaction w other medications → CNS depressants/sedatives (e.g. valium)
What are the adverse reactions of N2O? (6) Which is most and least common?
- nausea and vomiting (most common - w high conc
- dizziness, light-headedness
- hypoxia - caused by failure of O supply, medical condition or airway obstruction
- oversedation resulting in: respiratory depression, loss of consciousness
- volume/pressure on trapped gas filled cavities e.g. ostitis media
- bone marrow depression from chronic use (>24h)
nausea vomiting most common, oversedation very possible, hypoxia uncommon
What are the occupational hazards of N2O? (5)
Prolonged exposure to low levels of NO can have chronic health effects on HCWs due to interference with vitamin B12 synthesis causing haematopoietic and myeloneuropathic disturbances:
Haematological disorders: impaired RBC production and development of pernicious anaemia
Neurological disorders/toxicity: rare but can be rapid and irreversible - can have paraesthesia, ataxia (gait), diminished propioception
More evidence needed* but reported tetarogenicity (impact on DNA synthesis) causing reduced fertility and spontaneous abortions
*only in animal studies
Advantages and disadvantages of NO
Advantages
- non-invasive
- mild analgesic
- anxiolytic/sedative
- minimal impact on reflexes and vitals at RA concentrations
- depth of sedation easily titrated
- rapid onset (2-3min) and complete recovery (5min)
Advantages and disadvantages of NO
- non-invasive
- mild analgesic
- anxiolytic/sedative
- minimal impact on reflexes and vitals at RA concentrations
- depth of sedation easily titrated
- rapid onset (2-3min) and complete recovery (5min)
- cooperation w mask
- interference of mask w procedure (esp incisor trauma)
- continuous administration and monitoring needed (AND dentistry)
- occupational hazard due to potential exposure
- may still need non-pharmacological behaviour mgt/psychological reassurance
- cost
What is oral and iv sedation in terms of depth of sedation?
- form of conscious sedation
- minimally depressed level of consciousness meaning:
- pt retains ability to independently and continously maintain an airway
- can respond appropriately to physical stimulation and verbal command
Indications and Contraindications of Oral sedation. (3,3)
- anxious
- cooperation required for long procedures
- when parenteral routes undesirable/not possible
- unable to take oral medications
- medical issues and interactions
- precaution w children under 6 (unable to communicate feeling)
Indications and contraindications of IV sedation.
- anxious
- invasive procedures of SHORT duration
- inability to tolerate IV access
- medical issues and interactions
- precaution w children under 6
What oral and iv sedatives are used? (5 types, examples)
Benzodiazepines - oral Midazolam most common, Diazepam(Valium)
Antihistamines -Promethazine(Phernergan), Hydroxyzine
Opioids - Meperidine (Demerol) weak
Ketamine
Barbiturates
What is the paradoxical effect of sedation?
child may become sedated OR become hyper
Main difference with NO and oral/IV sedation?
DOES have prolonged effects
What is needed to ensure clinical safety of oral/iv sedation? (6)
- administration by qualified trained person
- constant monitoring
- advanced life support skills and resuscitation equipment
- recovery bay similar to hospital setting
- chaperone always present
- paediatric - more critical assessment and precaution - age, development, anatomy, physiology, dosage
Definition of General Anaesthesia
induced state of unconsciousness
accompanied by partial or complete loss of protective reflexes - including inability to independently maintain airway and respond purposefully to physical stimulation/verbal command
Objectives of GA (5)
- provide safe, efficient and effective/definitive dental care
- eliminate anxiety
- eliminate pain response
- reduced untoward movement and reaction to dental tx
- aid in tx of mentally, phsyically or medically compromised patient
Objectives of GA (5)
- provide safe, efficient and effective/definitive dental care
- eliminate anxiety
- eliminate pain response
- reduced untoward movement and reaction to dental tx
- aid in tx of mentally, phsyically or medically compromised patient
Indications and contraindications of GA (7,2)
- very anxious
- moderately-extremely uncooperative
- lack of cooperation due to emotional immaturity, mental or physical disability
- not responsive to other behaviour management
- extensive, surgical tx
- when prompt treatment of acute condition needed e.g. dental abscess threatening airway patency or dental trauma
- may not be able to achieve ideal treatment outcomes in chair
- medical issues where risk outweights benefit
- pt manageable w other forms of behaviour management
What is the risk of GA in paeds?
extremely safe but there is an inherent risk
What are requirements for GA in paeds? (4)
- make sure there is only one GA (piggyback other tx)
- comprehensive workup - including radiographs
- comprehensive treatment planning
- defintive treament
