General anaesthesia

• Principles of general anaesthesia:

  • induced a reversible loss of consciousness (and memory)
  • produced temporary blockade of gross response to stimulation
  • inhibits skeletal muscle contraction
  • inhibits protective reflexes e.g. cough
  • can be administered intravenously or via inhalation of gas
  • delivered in combination with neuromuscular blocking agents and analgesic agents
  • patient unable to maintain airway so requires intubation via ETT or laryngeal mask
• Cardiorespiratory Effects of general anaesthesia:

  • decreased lung volume (functional residual capacity - is at the lower part of compliance curve, so takes more pressure to move little amount of air)
  • reduced lung compliance
  • basal atelectasis
  • increase in airways resistance
  • diaphragmatic dysfunction
  • impaired Mucociliary transport
  • reduced cilia action
  • increased mucus viscosity
  • suppression cough reflex
  • reduced cardiac output
  • depression of central drive to breath