10 - anaesthesia Flashcards

1
Q

what are components of the reticular activating system?

A
  • midbrain reticular formation
  • mesencephalic nucleus (in midbrain)
  • thalamic intralaminar nucleus
  • dorsal hypothalamus
  • tegmentum
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2
Q

anterior vs posterior part of reticular activating system

A

anterior — mood and behaviour
posterior — sleep awake cycle

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3
Q

the RAS receives sensory information and sends the sensory information to the cerebral cortex throguh what?

A

specific relay nuclei in the thalamus, esp the intralaminar and reticular nuclei of the thalamus

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4
Q

where does the ascending reticular activating system project to?

A

intralaminar nuclei of the brainstem, whcih in turn projects diffusely to the cerebral cortex

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5
Q

what serves as the central pacemaker of the circadian timing sstem and regulates most circadian rhythms in the body?

A

suprachiasmatic nucleus (bilateral structure located in the anterior part of the hypothalamus)

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6
Q

what is the tegmentum?

A

a region of grey matter on either side of the cerebral aqueduct in the midbrain

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7
Q

what does the tegmentum consist of?

A

this anterior surface of the midbrain contains numerous structures including :

the reticular formation, the periaqueductal gray (PAG) matter, certain cranial nerve nuclei, sensory and motor nerve pathways (the corticospinal and spinothalamic tract), the red nucleus, the substantia nigra, and the ventral tegmental area (VTA)

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8
Q

what part of the midbrain contains the superior and inferior colliculus?

A

tectum

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9
Q

what are the phases of surgery and anaesthesia?

A
  • preparation
  • induction
  • maintenance
  • early recovery
  • delayed recovery
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10
Q

what is Bis?

A

bispectral analysis

  • measures electrical activity of brain
  • iv induction agent : Bis = 80/100
  • flattens out. want it to be 60-40 — wont wake up at this level (electrical activity depressed enough)
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11
Q

why is an overweight person harder to anaesthetise?

A

more lipid to absorb drug — more drug needed and takes longer to work

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12
Q

what are the different types of anaesthesia?

A
  • local — consciousness not impaired : topical, field, regional (spinal, epidural)
  • general — hypnosis is an essential feature
  • combined — general anaesthesia is combined with some regional technique
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13
Q

what are key components of general anaesthesia?

A
  • hypnosis
  • analgesia
  • muscle relaxation
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14
Q

what are used for hypnosis?

A

iv agents — propofol, barbiturates (thiopentone), benzodiazepines

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15
Q

what are used for analgesia?

A

opiates (synthetic or natural) and non-opiates

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16
Q

what are the 2 types of muscle relaxants?

A

depolarising and non-depolarising

17
Q

more soluble inhalational anaesthetic agents have a ______

A

higher coefficient

18
Q

agents with a lower coefficient have a ___ onset and _____ emergence

19
Q

more lipid soluble = ____ onset

20
Q

N2O potency?

21
Q

rank the anaesthetic inhalational agents in terms of potency

A

halothane > isoflurane > sevoflurane > desflruane > N2O

22
Q

characteristics of propofol

A
  • rapidly acting
  • high potency
  • rapid elimination
  • usually propofol and remifentanyl
  • total intravenous anaesthesia (TIVA) (not as easy as inhalation, have to be careful where cannula is put)
23
Q

what are some potential advantages of TIVA?

A

reduced incidence of post-operative nausea and vomiting, reduced atmospheric pollution, more predictable and rapid recovery, greater haemodynamic stability, preservation of hypoxic pulmonary vasoconstriction, reduction in intracerebral pressure and reduced risk of organ toxicity

24
Q

where does the thalamus project to (descending inhibition) in pain pathway?

A

periaqueductal grey matter

25
what part of the midbrain is involved in the supraspinal modulation of pain?
periaqueductal grey matter
26
name 3 natural opiates
morphine dihydropyridine-morphine codeine
27
name an opiate analogue
tramadol
28
name 4 synthetic or semisynethic opiates
pethidine fentanyl alfentanyl remifentanyl used more byt more addictive. less SE and renal excretion
29
analgesia and respiratory depression and vasodilation are mediated by what opiod receptors?
mu receptors u1 = analgesia u2 = resp depression u3 = vasodilation
30
side effects of opioids
dependence, miosis (excessive pupil constriction), constipation, nausea, vomiting, confusion, dysphoria
31
where do muscle relaxers work?
motor end plate
32
what is suxamethonium?
- 2 ACh molecules bound together - depolarising agent — Na+ influx, K+ efflux, Ca release - prolonging action
33
adverse effects of suxamethonium
- muscle pain - hyperkalaemia - malignant hyperthermia - anaphylaxis - suxamethonium apnoea - increase intra ocular and cranial pressure (due to twitches) - muscle twitches
34
what is suxamethonium apnoea?
genetic inability to break it down
35
adverse effects of non-depolarising blockers
- hypotension - histamine release - wheeze - tachycardia or bradycardia - anaphylaxis - incomplete reversal
36
describe components of long term recovery
- early mobilisation - physiotherapy : prevention of pulmonary complications - prevention of thrombo-embolic disorders (LMWH) - early enteral nutrition