Anaesthetic Assessment for Dental Patients

• What are the variables when choosing what anaesthetic to administer?

  availability - equipment, cost

  
  

  practical - duration, is there infection, ease of access

  
  

  safe - operator skill + experience

  
  

  acceptable - anxiety, medical history, compliance

  
  

  affordable
• what are the main anaesthetics

  local

  IV sedation

  GA
• what is chosen most of the time in practice

  LA
• what are the advantages of LA

  low risk

  lowest cost

  patient full cooperation
• what are the disadvantages of LA

  pressure/movement felt - e.g the drilling feeling

  
  

  may not work

  
  

  conscious awareness /anxiety still

  
  

  medical contraindications
• what is IVS

  direct into bloodstream

  
  

  benzodiazepine - anti-anxiety and muscle relaxants such as midazolam- (short action and duration) and diazepam (longer procedures )

  
  

  propofol- hypnotic, potent, rapid, GA if high enough dose

  
  

  opioid- fentanyl, morphine, with benzodiazepines for extra pain relief

  
  

  ketamine

  
  

  dexmedetomidine - selective alpha 2 adrenergic agonist , no respiratory depression
• what are the advantages of IVS

  reduces anxiety/awareness

  low risk

  less cost than GA

  primary/secondary care availability
• what is inhalation sedation

  It involves the passage of gases to the cardiovascular system via the lungs.

  
  

  nitrous oxide
• what are the disadvantages of IVS

  some awareness remains

  needle phobia

  less patient co-operation

  specialist equipment/training
• what are the advantages of inhalation sedation

  good for children

  analgesia

  avoid needles
• what are disadvantages to inhalation sedation

  awareness remains

  need to be able to breath through nose

  claustrophobia

  face mask obstructs access

  special equipment/training
• what is general anaesthetic

  reversible unconsciousness and loss of total sensation

  
  

  IV or inhalation

  
  

  IV= propofol, thiopental, etomidate, ketamine

  
  

  inhalation= sevoflurane, desflurane, isoflurane

  
  

  neuromuscular blockers= rocu/vecuronium, atracurium

  
  

  opioids = fentanyl, remifentanil, morphine
• what are the advantages of GA

  no muscular activity so good access

  no memory

  no patient interference

  can create acute infection and bad anxiety patients
• what are the disadvantages of GA

  need secondary care

  no patient co-operation

  expensive

  mortality 1:400,000, morbidity
• what are the indications for a patient needing GA

  - LA failed many times

  - sedation not effective

  - surgery over 40 mins

  - unpleasant surgery

  - can't be still, Parkinsons

  - anxiety/phobia is extreme
• why would LA not work

  inflammation increases pH of tissue, decrease LA effectiveness

  
  

  inflammation effect ability to penetrate nerve fibres

  
  

  anatomic variations

  
  

  patient factors- drug metabolism, altered sensitivity, tolerance if drug user

  
  

  drug interactions

  
  

  
  

  EHLERS-DANLOS SYNDROME
• Ehlers-Danlos Syndrome

  group of inherited disorders affecting connective tissue - increase joint mobility, stretchy skin and fragile skin

  
  

  tissue is different and LA is absorbed differently

  
  

  they respond best to articaine, bupivacaine, mepivacaine

  
• What must a patient do before undergoing GA

  fasting to reduce regurgitation and aspiration into lungs

  
  

  6 hours no solid food

  
  

  2 hours only clear liquid, no carbonated/particulated
• what is the ASA GA risk assessment

  ASA 1 - heathy patient

  
  

  ASA 2- mild systemic disease, smoker , pregnancy, obesity, controlled diabetes/HT etc

  
  

  ASA 3 - severe systemic disease ,non incapacitating, diabetes + hypertension uncontrolled, MI, CVA, COPD etc
• who is not suitable for GA for DAY surgery

  ASA 4 - unstable systemic disease

  
  

  limited mouth opening

  
  

  no home support

  
  

  BMI +40

  
  

  surgery over 2 hours
• what are the risks associated with sedation and obesity

  hard to access airways

  
  

  difficulty ventilating/intubating

  
  

  DVT risk higher

  
  

  hard to cannulate
• what is the risk associated with pregnancy


  GA contraindicated

  
  

  risk to foetal development

  
  

  risk to others as uterus pressure, chest/abdominal veins

  
  

  IVS also contraindicated
• if LA is used on pregnant women , when should this be done

  ideally in 2/3rd trimester
• what are the risks associated with COPD

  irreversible airflow limitation with progressive lung disease means GA/IVS risks

  
  

  ask the patient about previous history with GA, if their disease is managed well etc
• what is the risk of GA and diabetes

  loss of glucose control

  
  

  hypoglycemic emergency

  
  

  medical comorbidity

  
  

  diabetes = obesity