CPTP 3.24 General anaesthetics Flashcards
What adjunct medications can be given over and above GA
What are their purposes?
think of intubation purposes/ protecting lungs, analgesia, preventing bradycardia
-Benzodiazepines (not routinely given)
(for anxiolysis and amnesia)
-H2 antagonists
(prevent secretion of gastric acid which may be breathed into lungs)
-Antimuscarinics e.g. atropine
(prevent bradycardia)
-Neuromuscular blocker e.g. suxamethonium
(facilitate intubation)
- Analgesic e.g. fentanyl
- Anti-emetic
Name excitatory/inhibitory receptors
What do anaesthetics do to excitatory/inhibitory receptors at ligand gated ion channels
Excitatory:
NMDA, 5HT, nicotinic Ach
Inhibitory:
GABA, glycine
GA
- Inhibits excitatory receptors
- Potentiates inhibitory receptors
4 stages of general anaesthesia
Which stage is maintained with GA
- Analgesia
- Excitement (delirium)
- Surgical anaesthesia (unconciousness, decreased eye movement, regular respiration)
- Medullary depression
Stage 3 is maintained with GA
Main side effects of general anaesthesia
Respiratory arrest, cardiac depression, no eye movement
Nitrous oxide
- mode of administration
- speed of induction/recovery
- clinical use
Inhaled
Fast induction/recovery
Clinical use:
combined with other agents as low potency
Note: doesn’t induce unconsciousness on its own (if pt is becoming unconscious it’s cos they’re on 100% NO & becoming oxygen starved)
Sevoflurane
- mode of administration
- speed of induction/recovery
- clinical use
Inhaled
Fast induction/recovery
Clinical use:
Day surgery
Isoflurane
- mode of administration
- speed of induction/recovery
- clinical use
Inhaled
Medium induction/recovery
Clinical use:
Surgery (not used for induction due to pungent odour)
Halothane
- mode of administration
- speed of induction/recovery
- clinical use
Inhaled
Medium induction/recovery
Ether
- mode of administration
- speed of induction/recovery
- clinical use
Inhaled
Slow induction/recovery
Halothane
- mode of administration
- speed of induction/recovery
- clinical use
Inhaled
Medium induction/recovery
Clinical use:
Rare nowadays due to potential for accumulation of toxic metabolites
Ether
- mode of administration
- speed of induction/recovery
- clinical use
Inhaled
Slow induction/recovery
Clinical use:
Rare nowadays due to flammability + slow onset
Thiopental sodium
- mode of administration
- speed of induction/recovery
- clinical use
Intravenous
Fast induction/recovery (onset in 30s)
Clinical use:
Given in 1 off bolus injection.
If given as infusion, will buildup in fat stores (patient may never wake up)
Propofol
- mode of administration
- speed of induction/recovery
- clinical use
Intravenous
Fast induction/recovery
Clinical use:
Induction + maintenance (total IV anaesthesia)
Ketamine
- mode of administration
- speed of induction/recovery
- clinical use
Intravenous
Slow induction/recovery
Clinical use:
dissociative anaesthesia
