Anaesthetics Flashcards
How can anaesthetics be given?
Intravenous to induce anaesthesia
Inhaled gaseous to maintain it
All lipophilic
How do general anaesthetics work?
Produce a generalised but reversible cns depression
Mechanism of action of anaesthetics
Lipid perturbation-agents change the volume/fluidity of cns cell membranes
Protein modification-action on receptors at appropriate concentrations
Ligand gated ion channels
Halothane
Gaseous anaesthetic Risk of liver damage with repeated use Cardiac depression Potent Malignant hyprexia
Nitrous oxide
Gaseous anaesthetic
Low anaesthetic potency
Powerful analgeic
Causes foetal abnormalities
Sevoflurane
No respiratory irritation Rapid onset Adequately potent No hepatoxicity Little effect on heart
Cyclopropane
Explosive
No cardiovascular effects
Zenon
No cvr effects
Non explosive
Expensive
Gaseous
Thiopental
Intravenous Rapid onset, slow recovery Acts on gabaa Respiratory and cvr inhibition in overdose Inducing agent
Propofol
Rapid onset Rapid recovery Gabaa Resp and cvr inhibition Induction agent for deep sedation
Ketamine
Intravenous Slow onset Involuntary movements and hallucinations Inactiviated by metabolism Blocks nmda r Analgesia without loss of concious ess Does not inhibit cv or resp Used in children and military
Why do you not use just one anasthetic at a time?
Using a mixture of agents, its possible to get the desired degree of unconciousness, analgesia and muscle relaxant without having to give doses leading to potential dangerous side effects.
What are the 4 analgesics good to use?
Induction propfol Maintain Sevoflurane unconcousness N2o analgesia Vecuronium muscle relaxation
How do local anaesthetics work?
Prevent ap formation by blocking volt gated na channels
Need to be lipid soluble to get inside neurones to na channels
Lidocain
Local anaesthetic Potent Low irritancy Adequate duration of action Low allergic potential
