Anaesthetic Drugs Flashcards
what are the three components of general anaesthesia
hypnosis
analgesia
paralysis
what two methods can be used for induction of a GA
IV: propofol
Gas: sevoflurane / desflurane
what can propofol cause
hypotension due to vasodilation
what agent can be used in initiation of GA in patients who are hypotensive pre-op? e.g. from major trauma
ketamine
what channels does ketamine block
NMDA receptors (glutamate receptors)
what analgesics are commonly used in GA?
IV morphine
IV fentanyl
what drugs are used for paralysis in GA?
depolarising agents : e.g. suxamethonium
non-depolarising agents: rocuronium / atracurium
what type of drug is suxamethonium? how does it work?
depolarising muscle relaxant
- inhibits acetylcholine action at neuromuscular junction
side effects of suxamethonium
hyperkalaemia
malignant hyperthermia
suxamethonium apnoea
what is suxamethonium apnoea
rare abnormality in production of plasma cholinesterase’s
- increased duration of action suxamethonium
- respiratory arrest
what is malignant hyperthermia
caused by excessive release of calcium from sarcoplasmic reticulum of skeletal muscles
- rigidity + hyperpyrexia
- autosomal dominant
- Tx: dantrolene (prevents calcium release)
benefits of total intravenous anaesthesia (TIVA) over gas for maintenance of GA
TIVA = Less post op N +V, quicker waking up, more eco-friendly
what is lidocaine
short acting amide local anaesthetic
what is bupivacaine
long acting local anaesthetic
what channels do lidocaine / bupivacaine block
sodium channels
what is ELMA cream
topical lidocaine cream
what is Ametop
topical tetracaine gel
what drugs are in an epidural/spinal anaesthetic
local: lidocaine / bupivacaine
analgesic: opiod / fentanyl
why might adrenaline also be used with local anaesthetics
prolonged duration of action
limits systemic absorption – higher doses can be used
what steroid is used as an anti-emetic
dexamethasone
what is ondansetron
anti-emetic - 5HT3 receptor antagonist
common anti-emetics
ondansetron
dexamethasone
cyclizine
prochlorperazine
side effects of an epidural
dural headache
epidural haematoma
hypotension
what is metaraminol
alpha adrenergic agonist
- causes vasoconstriction – increased venous return – increased BP
- used to treat hypotension during surgery
why is cardiac output + BP reduced after an epidural/spinal anaesthetic
sympathetic blockage
- vasodilation by blocking alpha 1 receptors
using opioids in an epidural anaesthetic can cause what side effect?
itch
what is contained in the epidural space
adipose tissue
venous plexus
spinal nerve roots
