general anaesthesia for dental treatment in children Flashcards
what is the definition of general anaesthesia
- any technique using equipment or drugs which produces a loss of consciousness in specific situation associated with medical or surgical interventions
- loss of consciousness or abolition of protective reflexes
what percentage of hospital elective procedures with GA are for dental extractions
- around 25%
how to anaesthesia agents produce anaesthesia
- by depressing specific areas of the brain
how do inhaled GA work
- enter through the lungs, distribute to tissues by the circulation
- reach specific sites in the central nervous system by crossing the blood brain barrier
- magnitude of CNS depression is proportional to partial pressure as they reach CNS
how to intravenous GA work
- given straight into circulation
- distributed through body and reach specific sites in CNS by crossing blood brain barrier
what is the anatomy to be aware of in a child
- large head, short neck
- narrow nasal passages
- high anterior larynx
- larynx narrowest at cricoid cartilage
- large floppy epiglottis
what causes CROOP in children
- large floppy epiglottis
what is respiratory physiology to be aware of in children for GA
- low functional residual capacity (FRC)
- closing volume is greater than FRC up to 5, leading to increased perfusion/ventilation mismatch
- horizontal rids, weak intercostal muscles leading to relatively fixed tidal volume (can’t increase)
- oxygen consumption is high (6ml/kg/min)
what is the normal oxygen consumption in adults
- 3ml/kg/min
what are some temperature regulation things to be aware of in children for GA
- high surface area to body weight
- large head surface area and heat loss
- require higher temperature for a therm-neutral environment
- immature response to hypothermia (poor shivering and vasoconstriction
- brown fat metabolism which increase oxygen consumption
what does brown fat metabolism do
- uses a lot more oxygen which is why children’s oxygen consumption is so much higher than adults
- adults don’t have brown fat metabolism
what is some nervous system things to be aware of in children for GA
- increased incidence of periodic breathing and apnoea’s (irregular breathing)
- ventilatory response to CO2 is more readily depressed by opiates (sensitive to muscle relaxants)
- immature neuromuscular junction leads to increased sensitivity to muscle relaxants
what are some common drugs for GA
- inhaled agents = nitrous oxide, sevoflurane, halothane, isoflurane, desflurane
- intravenous agents = propofol
how decides on what drugs are sued for GA
the anaesthetist
what does the drug choice depend on
- length of procedure
- patient preferences
- medical history
- previous GA experience
- anaesthetist’s recommendations
- equipment
- staff and other resources
what are the types of airway used in GA
- LMA = laryngeal mask airway (most common)
- nasal endotracheal intubation = tube not in mouth so better for access
- oral endotracheal intubation =