ANAESTHESIA Flashcards
name the 5 stages of surgery
preparation induction maintenance early recovery late recovery
name 3 ways in which a patient should be prepared for general anaesthesia…
physiological
psychological
pharmacological
if an induction agent has a low oswalds coefficient, what would you expect to be the speed of onset and duration of action?
low coefficient = low solubility
low solubility = increased availability of drug in CNS, adequate partial pressures reached quickly
= Short speed of onset and duration of action
if an induction agent has a high oswalds coefficient, what would you expect to be the speed of onset and duration of action?
high coefficient = very soluble
high solubility = not much drug around to develop adequate partial pressures in CNS
= slow speed of onset and duration of action
potency of an anaesthic agent is determined by what?
the rate at which it dissolves in fatty tissue
where does the descending inhibitory pain pathway start?
periaqueductal gray matter
what are the natural opiates (3)?
morphine
dihydro-morphine
codeine
name a synthetic morphine analogue
tramadol
name 4 synthetic opiates
remifentanil
alfentinal
fentinal
pethidine
activation of mu1 receptors causes what physiological response?
analgesia
activation of mu2 receptors causes what physiological response?
respiratory depression
activation of mu3 receptors causes what physiological response?
vasodilation
what drug is an opioid receptor antagonist?
naloxone
what are the side effects of non-depolarising NMJ blockers?
hypotension
histamine release
tachycardia/bradycardia
incomplete reversal
what are the side effects of depolarising NMJ blockers?
muscle pain
hyperkalaemia
malignant hyperthermia
sux apnoea
what is the breakdown of eye response in GCS?
WORTH 4 POINTS
opens spontaneously 4
opens to sound 3
opens to pain 2
doesn’t open 1
what is the breakdown of verbal response in GCS?
WORTH 5
communicates clearly 5 confused 4 inappropriate words 3 random sounds 2 no speech 1
what is the breakdown of motor response in GCS?
6 POINTS
obeys command 6 localises to pain 5 normal flexion to pain 4 abnormal flexion to pain 3 extension to pain 2 no movement 1
what 2 cranial nerves are most commonly injured in acute head trauma?
trochlear
olfactory
(oculomotor secondary damage via uncal herniation)
what are the criteria for a CT scan within 1 hour of admission with acute head trauma?
GCS less than 13 open/depressed fracture any sign of basal skull fracture seizures vomitting
what are the criteria for a CT scan within 8 hours of admission with acute head trauma?
amnesia
over 65
history of bleeding
what is battles sign?
post-aurciular bleeding indiciates basal skull fracture
what are racoon eyes?
bilateral peri-orbital haematoma
what is the most common cause of an extradural haematoma?
damage to middle meningeal artery that runs between periosteum and dura mater
what is the most common cause of subdural haematoma?
damage to bridging veins that run between dura and arachnoid mater
how can extradural and subdural haematoma be disinguished via MRI?
sub-dural haematoma follows contours of gyri/sulci
how do extra-dural haematomas usually present?
acute- pt mainly symptomatic (during tamponade of blood between dura and skull)
peri-acute - ICP raises enough so that dura is pulled away from the skull. haemorhage speads and pt deteriorates
how do sub-dural haemorhages usually present?
progressive deterioration following head injury, leakage of venous blood into dural sinuses
what is normal ICP?
15mmHg
how is cerebral perfusion pressure calculated?
mean arterial pressure - ICP
what is the consequence of ICP being higher than MAP?
decrease in cerebral blood flow
what is the kelly munroe doctrine?
CSF and intracerebral blood flow are constant.
an increase in ICP causes a reciprocal decrease in cerebral blood flow.
This manages the problem of having a skull with a fixed volume
there are two phases; compensating and decompensating
what are the two types of ischaemia?
cytotoxic - fluid in cytoplasmic due to loss of ion gradients across cells
vasogenic - delayed, due to breakdown of blood brain barrier
how would you treat raised ICP? (5 things)
mannitol/furosemide head position at 30 degrees avoid hypoxia mechanical hyperventilation hypothermia
how does mechanical hyperventilation help reduce ICP?
induces cerebral vasoconstriction, reducing blood flow to brain, hence volume reduces, and lowers ICP
what are the 4 stages of sleep?
stage 1
stage 2
slow wave
REM sleep
what is the role of melatonin in sleep?
Suprachiasmatic nucleus responds to light stimuli causing pineal gland to secrete melatonin, this occurs 2-3 hours before bedtime
what is the function of the tuberomamillary nucleus in sleep?
secretes histamine to promote wakefulness
what is the function of the venterolateral preoptic neurones in sleep?
promotes sleep
what are the 4 parts of the neuropsychological assessment?
perception - how sensory input is perceived
memory
language
intellectual abilities
