Neuro Pharmacology Flashcards

1
Q

Describe the affects of inhaled anesthetics on CMRO2, CBF and ICP

A

decrease CMRO2
increase CBF and increase ICP

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2
Q

What VA does not follow typically affects on CMRO, CBF and ICP?

A

nitrous oxide

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3
Q

Describe the affects of IV anesthetics on CMRO2, CBF and ICP

A

Decrease CMRO2
Decrease CBF
Decrease ICP

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4
Q

Describe the affects of local anesthetics on CMRO2, CBF and ICP

A

decrease CMRO2
Decrease in CBF
Decrease in ICP

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5
Q

Describe the affects of ketamine on CMRO2, CBF and ICP

A

+/- CMRO2
increase CBF
increase ICP

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6
Q

Describe the affects of opioids on CMRO2, CBF and ICP

A

+/- CMRO2
+/- CBF
+/- ICP

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7
Q

The effects of vasoactive drugs on cerebral physiology are dependent on

A

basal BP (+/- 20% of patients baseline)
Magnitude of drug induced change in BP
status of autoregulation
status of the BBB

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8
Q

How much more soluble is nitrous oxide more soluble in the blood then nitrogen?

A

34x

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9
Q

What are the physiological affects of nitrous oxide?

A

increase in CBF
Increase in CBV
Increase in ICP
(more dramatic if sole agent)
Unsure of CMRO2 affects

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10
Q

What are the affects of N2O influenced by?

A

other agents and changes in CO2 tension

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11
Q

How much does an ICP increase with an intracranial tumor with 66% N20?

A

increased from an avg ICP of 13mmHg to 40mmHg

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12
Q

Alpha 1 agonist affect on CBF and CMRO

A

no effect
possible decrease in CBF

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13
Q

Alpha 2 agonist affect on CMF and CMRO

A

decreased CBF and CMRO

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14
Q

Beta agonist affect on CMF and CMRO

A

increase CBF and CMRO

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15
Q

Beta agonist (with BBB open) affect on CMF and CMRO

A

BIG increase in CBF and CMRO

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16
Q

Dopamine affect on CMF and CMRO

A

Increase in CBF
no effect on CMRO

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17
Q

High doses of dopamine affect on CMF and CMRO

A

decrease in CBF
no affect on CMRO?

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18
Q

Fenoldopam affect on CMF and CMRO

A

decrease in CBF
no effect on CMRO

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19
Q

Norepinephrine affect on CMF and CMRO

A

decrease no affect on CBF
increase, no affect on CMRO

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20
Q

Norepinephrine (open BBB) affect on CMF and CMRO

A

increase CMRO and CBF

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21
Q

Epinephrine affect on CMF and CMRO

A

increase in CBF an CMRO

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22
Q

Epinephrine (open BBB) affect on CMF and CMRO

A

increase in CBF and CMRO

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23
Q

Describe the affect of a bolus of an alpha 1 agonist

A

may transiently (2-5minutes) change CBF & cerebral SaO2

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24
Q

Describe the affect of a continuous gtt of an alpha 1 agonist

A

little effect CBF & cerebral SaO2

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25
Q

Describe the overall affect of alpha 1 agonist on the brain

A

maintenance of CPP with these vasopressors
does not have an adverse affe

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26
Q

Alpha2 agonist cause

A

decrease in CBF (25-30%)
results from reduced CMRO2 leading to reduced CBF

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27
Q

Where are alpha 2 agonists found and what do they modulate?

A

found in brain and periphery
modulate sympathetic outflow

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28
Q

Where are alpha 1 receptors found?

A

post-synaptic alpha receptors on vascular smooth muscle
determine arteriolar resistance and venous capacitance (BP)

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29
Q

Alpha 1 agonist

A

phenylepherine
norepinephrine

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30
Q

Alpha 2 agonist

A

clonidine
precedex

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31
Q

Beta agonist examples

A

epinephrine

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32
Q

what do small doses of beta agonist cause?

A

little effect on CBF

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33
Q

What do large doses of beta agonists and physical stress cause?

A

increase in CMRO2 and CBF

34
Q

What happens to MAP with epinephrine 0.05mcg/kg/min? [larger doeses]

A

increase in MAP
may increase CMRO2 and CBF up to 20%
Beta 1 receptor mediated effects
response exaggerated with BBB defect

35
Q

Beta blockers affect on CBF and CMRO2

A

little to no effect

36
Q

Ace inhibitors and ARBS affect on CBF and CMRO2

A

little to no effect on CBF and CMRO2
autoregulation is maintained

37
Q

What drugs are preferred for control of emergence hypertension after intracranial procedures?

A

labetalol and esmolol

38
Q

Describe the use of barbiturates in neuro-anesthesia

A

dependent reduction in CBF and CMR until isoelectric EEG
(maximum reduction in CBF adn CMR of nearly 50%[flat EEG])

39
Q

What are barbiturates highly effective at?

A

lowering ICP

40
Q

Describe the robin hood effect seen with barbiturates?

A

Reverse steal phenomenon
CBF distributed from normal to ischemic areas in the brain

41
Q

What is decreased more then CBF in barbiturate administration?

A

CMR decreases more than CBF
metabolic supply exceeds metabolic demand

42
Q

What are barbiturates also helpful for?

A

anticonvulsants

43
Q

Benzodiazepines cause

A

a dose-dependent reduction in CMR and CBF

44
Q

Benzodiazepines cause a greater reduction in CMR and CBF then what other class of drugs?

A

narcotics

45
Q

Compared to barbiturates, propofol or etomidate, benzos have

A

less reduction

46
Q

What is the reduction of CBF with benzodiazepines?

A

moderate reduction
12-34% with 0.15mg/kg

47
Q

What is the benzo of choice and why?

A

midazolam b/c of its short neuro half life

48
Q

What can benzodiazepines prolong?

A

emergence
consider need for post-operative neuro exam

49
Q

What do benzodiazepines depress?

A

RAS
reticular activating system

50
Q

Propofol causes a dose-dependent reduction in

A

CBF and CMR

51
Q

What are two positive properties of propofol?

A

anticonvulsant
short elimination 1/2 life

52
Q

What is the most common induction agent for neuroanesthesia?

A

propofol

53
Q

What are characteristics of etomidate?

A

decreases CMR, CBF and ICP

54
Q

What are side effects of etomidate?

A

myoclonus on induction
not associated with seizure activity on the EEG

55
Q

What can small doses of etomidate activate?

A

seizure foci in patients with epilepsy

56
Q

What is the only IV anesthetic that dilates cerebral vasculature and increases CBF?

A

ketamine
increases (50-60%)

57
Q

What drug does not increase ICP in neurologically impaired patients under controlled ventilation with concomitant administeration of propofol or a benzo?

A

ketamine

58
Q

Why has ketamine been limited in neuroanesthesia in the past?

A

dissociative mechanism and stormy emergence

59
Q

What are advantages to ketamine use?

A

stable hemodynamics in trauma (head injury, hypovolemia, multisystem trauma)

60
Q

What does property does ketamine not effect?

A

CMR, but may vary regionally

61
Q

What affect does ketamine have on a BIS?

A

does not lower
may increase BIS

62
Q

Why is there re-newed interest in ketamine?

A

may be neuroprotective as NMDA antagonist

63
Q

How do NMDA antagonist help protect the brain?

A

may be protective against neuronal cell death

64
Q

How does an NMDA antagonist work?

A

functionally dissociates the thalamus from limbic cortex

65
Q

what is the role of the thalamus?

A

relays sensory impulses from the reticular activating system to the cerebral cortex

66
Q

what is the limbic cortex?

A

involved with the awareness of sensation

67
Q

Describe the effect of opioids on neuro-physiology

A

minimal affects of CBF, CMR, ICP (unless increase in PaCO2)

68
Q

What opioid is traditionally avoided?

A

morphine d/t poor lipid solubility, slow onset and long duration of sedative effect

69
Q

What do most anesthetics do to CNS?

A

decrease electrical activity

70
Q

What complicates the effects of anesthetics?

A

other drugs, surgical stimulation, intracranial compliance, BP and PaCO2

71
Q

IN general, anesthetic drugs

A

suppress CMR with the exception of ketamine and nitrous oxide

72
Q

What does energy substrates depend on to get to the brain?

A

cerebral blood flow

73
Q

what an influence the outcome in the setting of ischemia?

A

alternates in CBF

74
Q

What can be controlled and is central to management of ICP?

A

CBF

75
Q

What is usually parallel to the CBF?

A

Cerebral blood volume

76
Q

Cerebral blood volume is a critical variable for

A

ICP

77
Q

What is CBV?

A

~ 5ml/100g of brain (70ml)

78
Q

When does CBF not parallel CBV?

A

cerebral ischemia
Normal BP

79
Q

What happens to CBF and CBV during cerebral ischemia?

A

CBV increases but CBF decreases

80
Q

MAP=

A

CBF but cerebral vasoconstriction limits in CBV