GA Flashcards
What is GA
- Any technique using equipment or drugs which produces a loss of consciousness in specific situations associated with medical or surgical interventions
- Loss of consciousness or abolition of protective reflexes
How do anesthetic agents produce anaesthesia
by depressing specific areas in the brain
How do inhaled agents reach the CNS
• Inhaled agents enter through the lungs distributed to tissues by the circulation, reach specific sites in the CNS by crossing the blood brain barrier. The magnitude of CNS depression is proportional to partial pressure as they reach the CNS
How do IV agents reach the CNS
• IV agents are given straight into circulation, distributed through the body and reach specific sites in the CNS by crossing the blood brain barrier
Describe a child’s anatomy
○ Large head, short neck, large tongue
○ Narrow nasal passages
○ Are obligate nasal breathers at birth
○ High anterior larynx
○ Larynx narrowest at cricoid cartilage
Large floppy epiglottis
Describe a child’s respiratory physiology
○ low functional residual capacity
○ Closing volume is greater than functional residual capacity up to 5 years of age, leading to an increased ventilation/perfusion mismatch
○ Horizontal ribs, weak intercostals muscles leading to relatively fixed tidal volume
Oxygen consumption is high 6ml/kg/min compared to 3ml/kg/min in adults
Describe a child’s temperature regulation
○ High surface area to body weight ratio
○ Large head surface area and heat loss
○ Require a higher temperature for a thermoneutral environment
○ Immature responses to hypothermia (poor shivering and vasoconstriction)
Brown fat metabolism (adults have less brown fat) which increases oxygen consumption
Describe a child’s nervous system
○ Increased incidence of periodic breathing and apnoea’s (breathing isn’t as regular and they hold their breath more)
○ Ventilatory response to CO2 is more readily depressed by opiates
Immature neuromuscular junction leads to increased sensitivity to muscle relaxant
What are the common inhaled agents
- Inhaled agents: nitrous oxide, sevoflurane (agent of choice for induction), halothane, isoflurane, desflurane
What are the common IV agents
propofol (used for induction and in some situations for maintenance)
How does the anesthetist decide on what drugs they will use
○ Depends on § Length and type of procedure § Patient preferences for induction § Medical history § Previous GA experience § Anaesthetists recommendations § Equipment § Staff § Other resources
What are the types of airway for GA
laryngeal airway mask
nasal endotracheal intubation
oral endotracheal intubation
Which airway requires a throat pack
all do
What is a throat pack
a throat pack is gauze that you pack around the tube at the back of the mouth away from where you are working to catch saliva, material, blood etc to stop it going down the airway
What are the stages of anesthesia
○ Stage 1 is induction
○ Stage 2 is excitement
○ Stage 3 is surgical anaesthesia (what we want)
Stage 4 is respiratory paralysis (what we don’t want)
What do the GDC expect from dentists regarding GA
○ As a registered dental professional you could be held responsible for the actions of any member of your team who does not have to register with the GDC
○ Be competent in when, how and where to refer a patient for GA
Evaluate the risks and benefits of treatment under GA
What are indications for GA
- Child needs to be asleep for tx because they are too young, anxious, or too uncooperative to accept treatment any other way
- Dentist needs patient to be guaranteed to be completely still, operation is complex i.e the surgeon needs the child to be fully anaesthetised