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NA 3 > NEURO QUIZLET > Flashcards

NEURO QUIZLET Flashcards

1
Q

What percentage of total body oxygen does the brain usually consume?

A

15-20% CO

15-20%

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2
Q

What is the normal CBF in mL/100g/min?

A

50ml/100g/min

50

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3
Q

What is the primary energy source for neuronal cells and how much is consumed per minute?

A

glucose; 5mg/100g/min

5mg/100g/min

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4
Q

True or false: most glucose in the brain is metabolized anaerobically?

A

False: aerobically

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5
Q

What is the normal CBF in mL/min?

A

750ml/min

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6
Q

What is the normal CBF in %CO?

A

15-20% CO

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7
Q

What is the CBF at which you will see EEG slowing, flattening, and irreversible damage?

A

Slowing: 20-25
Flat: 15-20
Damage: <10-15

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8
Q

What does transcranial doppler measure?

A

velocity; middle cerebral

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9
Q

What is the normal CBF velocity as measured on transcranial doppler?

A

55mm/sec

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10
Q

Which has a high velocity flow, the MCA or the internal carotid?

A

MCA (x3)

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11
Q

Does infrared spectroscopy reflect cerebral arterial or cerebral venous oxygen saturation?

A

venous

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12
Q

Which region of the brain receives more CBF, cortical or subcortical?

A

cortical

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13
Q

Name the 5 determinants of CBF

A
  1. CMRO2
  2. CPP
  3. Venous pressure
  4. PaC02
  5. Pa02
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14
Q

Is more CMRO2 used for electrical activity or cellular integrity?

A

electrical activity

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15
Q

At what CPP does the brain autoregulate between?

A

CPP 50-150

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16
Q

What happens below the lower limit of cerebral autoregulation?

A

Lower: vessels are maximally dilated - risk of hypoperfusion and ischemia

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17
Q

What happens above the upper limit of cerebral autoregulation?

A

High: vessels are maximally constricted - risk of cerebral edema and hemorrhage

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18
Q

At what temperature does CMRO2 decrease by 7% for every 1 degree drop in temperature?

A

7

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19
Q

At what temperature does EEG suppression occur?

A

18-20

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20
Q

What temperature destroys neurons?

A

42

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21
Q

What controls cerebral vascular resistance?

A

PaC02

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22
Q

What is the pH of CSF around arterioles?

A

7.32

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23
Q

At a PaCO2 of 40, CBF is

A

ml/100g brain tissue

For every 1 mm increase or decrease in PaCO2, CBF will increase/decrease mL/100g/min.

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24
Q

Maximal vasodilation occurs at a PaCO2 of

A

while maximal vasoconstriction occurs at a PaCO2 of

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25
Q

What do the following things do to CBF?

A

-Resp. Acidosis
-Resp. Alkalosis
-Met. Acidosis

Resp. Acidosis increases CBF
Resp. Alkalosis decreases CBF
Met. Acidosis does not affect CBF

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26
Q

Pa02 below

A

CBF causes cerebral vasodilation and increases
Pa02 > does not affect CBF

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27
Q

Normal ICP

A

5-15 mmHg

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28
Q

Average brain weight, blood volume, and CSF volume

A

weight: 1350g
Blood: 50mL
CSF: 75mL

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29
Q

True or false: the brain has a large 02 reserve

A

false

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30
Q

LOC in <

A

80-100; 25

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31
Q

_ seconds without O2, ATP stores are depleted in

A
  • minutes
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32
Q

Which is more harmful, hyper- or hypoglycemia?

A

hyper-

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33
Q

CPP formula and normal

A

MAP - ICP or CVP (whichever is greater)
Normal: 80-100 mmHg

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34
Q

At what CPP will you see slowing on EEG, flattening, and irreversible brain damage?

A

Slowing: <50
Flat: 25-40
Damage< <25

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35
Q

Cerebral autoregulation curve is shifted to the

A

right

in patients with HTN

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36
Q

What is the myogenic mechanism of autoregulation?

A

intrinsic response of smooth muscle cells in cerebral arterioles to changes in MAP

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37
Q

What is the metabolic mechanism of autoregulation?

A

Cerebral metabolic demands determine arterial tone - when demand exceeds CBF, release of metabolites causes vasodilation and increases CBF

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38
Q

Hypotonicity moves water

A

into the brain,
whereas hypertonicity moves water out of the brain.

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39
Q

When the resting CBF is low, the reduction of CBF from hypocapnia is

A

less effective

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40
Q

Why is the decreased CB from hypocapnia not sustained?

A

the pH of CS normalizes with 6-8 hours from dissociation of HCO3 from H2CO3

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41
Q

What effect will an abrupt increase in CO2 have on CBF?

A

Increased CBF and ICP

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42
Q

What effect will an abrupt decrease in CO2 have on CBF?

A

potential ischemia! Decreased CBF

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43
Q

What does hypoxia (Pa02 < 60mm Hg) do to CBF?

A

causes rapid increase

44
Q

What is the target Hct for idea CBF? What happens to CBF with increased blood viscosity?

A

30-33%; decreases

45
Q

What happens in “steals” and what conditions can precipitate this?

A

Vessels that supply ischemic areas of the brain lose their tone and become maximally dilated. This means that when cerebral vasodilation occurs, vessels that still have tone will vasodilate and “steal” perfusion from those ischemic areas.
-hypercapnia, hypoventilation, vasodilators

46
Q

What happens in “inverse steal”?

A

Hyperventilation is used to constrict cerebral vessels that supply healthy tissues, therefore that flow will redistribute to ischemic regions

47
Q

What is another name for “steal”?

A

Collateral flow

Example sentence: Collateral flow can help compensate for reduced blood flow in certain areas.

48
Q

What is the most important chemical regulator of CBF?

A

PaCO2

Example sentence: PaCO2 levels play a critical role in regulating cerebral blood flow.

49
Q

CMRO2 decreases by % for every 10 degree decrease in temperature.

A

6%

Example sentence: CMRO2 decreases by 6% for every 10-degree decrease in temperature.

50
Q

What are the 4 compensatory mechanisms of the intracranial vault?

A
  1. displacement of CSF from cranial to spinal compartment
  2. Increase in CSF absorption
  3. decrease in CS production
  4. decrease in total CBV

These mechanisms help maintain intracranial pressure within normal limits.

51
Q

Which IA (sevo/iso/des) increases CBF production?

A

Iso

Isoflurane increases cerebral blood flow production.

52
Q

Which IA (sevo/iso/des) decreases CMR?

A

Des

Desflurane decreases cerebral metabolic rate.

53
Q

Which IA (sevo/iso/des) increases CSF absorption? Decreases it?

A

Increases: Iso
Decreases: Des

Isoflurane increases CSF absorption while Desflurane decreases it.

54
Q

Which IA (sevo/iso/des) increases CBV the most?

A

Des

Desflurane increases cerebral blood volume the most.

55
Q

What effect do the lAs have on ICP?

A

Increase it

Inhaled anesthetics can increase intracranial pressure.

56
Q

What effect do all the lAs and N20 have on CBF?

A

Increase it

All inhaled anesthetics and nitrous oxide increase cerebral blood flow.

57
Q

In protective hypothermia, body temp is reduced to degrees for 24 hours

A

32-34 degrees

Example sentence: Patients undergoing neurosurgery may be placed in protective hypothermia with a reduced body temperature of 32-34 degrees for 24 hours.

58
Q

In incomplete ischemia, where should MAP be maintained? How long should surgery be delayed if possible

A

MAP should be maintained in the 70-80 torr range. Surgery should be delayed 6 weeks if possible

Example sentence: In cases of incomplete ischemia, it is crucial to maintain MAP within the 70-80 torr range and consider delaying surgery for 6 weeks.

59
Q

Effect on EEG: <1 MAC

A

Increases BOTH frequency and amplitude

Example sentence: Anesthetic agents at less than 1 MAC can lead to an increase in both frequency and amplitude on the EEG.

60
Q

Effect on EEG: Barbs, benzos and etomidate

A

Activation

Example sentence: Barbiturates, benzodiazepines, and etomidate have an activating effect on the EEG.

61
Q

Effect on EEG: opioids

A

Depression

Example sentence: Opioids are known to cause a depressive effect on the EEG.

62
Q

Effect on EEG: propofol

A

Depression

Example sentence: Propofol administration results in a depressive effect on the EEG.

63
Q

Effect on EEG: N20

A

Activation

Example sentence: Nitrous oxide (N20) has an activating effect on the EEG.

64
Q

Effect on EEG: Mild hypercapnia

A

Activation; depression

Example sentence: Mild hypercapnia can lead to a mixed effect on the EEG, with both activating and depressive components.

65
Q

Effect on EEG: hypocapnia or marked hypercapnia

A

Depression

Example sentence: Both hypocapnia and marked hypercapnia result in a depressive effect on the EEG.

66
Q

Effect on EEG: hypothermia

A

Activation

Example sentence: Hypothermia can cause an activating effect on the EEG.

67
Q

Effect on EEG: early hypoxia vs. late

A

Activation; depression

Example sentence: Early hypoxia may lead to EEG activation, while late hypoxia can cause depression.

68
Q

Which IA can produce an isoelectric EEG at high clinical doses (1-2 МАС)?

A

Propofol, Barbs, Etomidate

Example sentence: Propofol, barbiturates, and etomidate are capable of producing an isoelectric EEG at high clinical doses.

69
Q

Which As produce burst suppression but not electrical silence at high clinical doses

A

Des and Sevo

Example sentence: Desflurane and sevoflurane can induce burst suppression on the EEG without causing electrical silence at high clinical doses.

70
Q

How does N20 impact EEG?

A

Unusual activation consisting of rhythmic High-amplitude theta activity followed by very high-amp gamma and low-amp beta

Example sentence: Nitrous oxide (N20) can produce an unusual EEG activation pattern characterized by rhythmic high-amplitude theta activity followed by high-amplitude gamma and low-amplitude beta waves.

71
Q

What are the only agents capable of producing burst suppression AND electrical silence at high doses (3)?

A

Propofol, Barbs, Etomidate

Example sentence: Propofol, barbiturates, and etomidate are the only agents that can induce burst suppression and electrical silence on the EEG at high doses.

72
Q

How does Ketamine impact EEG?

A

Activation

Example sentence: Ketamine administration results in an activating effect on the EEG.

73
Q

What is Cushing’s triad and what causes it?

A

Hypertension, bradycardia, cheyne-stokes respirations r/t SNS outflow from brainstem compression

Example sentence: Cushing’s triad consists of hypertension, bradycardia, and cheyne-stokes respirations related to sympathetic nervous system outflow from compression of the brainstem.

74
Q

Define intracranial HTN

A

Sustained increase in ICP >15 mmHg

Example sentence: Intracranial hypertension is defined as a sustained increase in intracranial pressure (ICP) greater than 15 mmHg.

75
Q

What is intracranial compliance? What does it mean if ICP is increasing?

A

Compliance is the ability of the compartment to accommodate increased volume without major changes in pressure. Increased ICP = decreased compliance

Example sentence: Intracranial compliance refers to the ability of the intracranial compartment to adapt to increased volume without significant changes in pressure. An increase in ICP indicates decreased compliance.

76
Q

What is cushing’s response?

A

Periodic increases in MAP with reflex slowing of the HR lasting 1-15 minutes

Example sentence: Cushing’s response is characterized by periodic increases in mean arterial pressure (MAP) along with reflex slowing of the heart rate, typically lasting 1-15 minutes.

77
Q

Treatment of Intracranial HTN and cerebral edema

A

Corticosteroids

Example sentence: Corticosteroids are commonly used in the treatment of intracranial hypertension and cerebral edema.

78
Q

True or false: hyperventilation should be used universally

A

False

Example sentence: Hyperventilation should not be universally employed in all cases.

79
Q

Symptoms of VAE

A

Decrease in ETCO2 or SpO2 (before hemodynamic changes)

Example sentence: Symptoms of venous air embolism (VAE) may include a decrease in end-tidal carbon dioxide (ETCO2) or oxygen saturation (SpO2) before hemodynamic changes occur.

80
Q

VAE can cause acute-sided heart failure

A

Right

Example sentence: Venous air embolism (VAE) can lead to acute right-sided heart failure.

81
Q

Treatment of VAE in neurosurgery

A
  1. Notify surgeon, flood field
  2. 100% FiO2, no N20
  3. Aspirate 60mL from multi-orifice CVC
  4. IVF to increase CVP
  5. Valsalva 5-10 seconds
  6. Head down, left tilt position

Example sentence: In neurosurgery, the treatment of venous air embolism involves various steps such as notifying the surgeon, providing 100% oxygen, and performing specific maneuvers to address the condition.

82
Q

True or false: mayfield pins should be removed while patient is in sitting position

A

False

Example sentence: Mayfield pins should not be removed while the patient is in the sitting position.

83
Q

Which volatile agent produces the LEAST cerebral vasodilation?

A

Sevo

true

84
Q

True or false: volatile agents impair CO responsiveness of cerebral vasculature

A

false

hypocapnia

85
Q

What are the two VAs of choice in patients with decreased intracranial compliance?

A

Iso and Sevo

true

86
Q

What is the only type of vasodilating agent that has little or no effect on CBF and CBV?

A

Ganglionic blocker (i.e. Trimethaphan)

decrease

87
Q

What effect does Remifentanil have on CBF and CMR alone vs. as an adjunct?

A

Alone: increases CBF and CMR

Adjunct: no effect

decrease

88
Q

What effect does fentanyl have on CBF and CMR?

A

no effect

decrease

89
Q

What effect does Lidocain have on CBF/CMR?

A

decrease

decrease

90
Q

True or false: IV induction agents cause parallel decreases in CMR and CBF, but preserve flow-metabolism coupling, autoregulation, and CO2 responsiveness

A

true

true

91
Q

All vasodilators cause ___, but catecholamine agonists only effect CBF/CMR when __

A

Cerebral vasodilation; BBB is disrupted

they increase ICP and CBF and abolish autoregulation but decrease CMRO2 (uncoupling)

92
Q

Which 2 induction agents may elicit seizures

A

Ketamine and etomidate

true

93
Q

True or false: Benzoes have no effect on CBF/CMR

A

false, moderate reduction

They increase ICP and CBF and abolish autoregulation but decrease CMRO2 (uncoupling)

94
Q

CBV vs. CBF: primarily determines ICP

A

CBV

decrease

95
Q

Patients who’ve had an ischemic stroke can receive PA within hours of symptom onset

A

3

185/110

96
Q

Altered area of the brain is known as the

A

ischemic penumbra

Global/complete

97
Q

Hypothermia is beneficial for what type of ischemia?

A

32-34

4 / 9

98
Q

In protective hypothermia, body temp is reduced to degrees for 24 hours.

A

32-34

Example sentence: The patient was placed in protective hypothermia with a body temperature of 33 degrees for 24 hours.

99
Q

In incomplete ischemia, where should MAP be maintained? How long should surgery be delayed if possible

A

70-80 torr

Delay surgery 6 weeks

100
Q

Which IA can produce an isoelectric EEG at high clinical doses (1-2 MAC)?

A

Propofol

Activation

101
Q

What is Cushing’s triad and what causes it?

A

Hypertension, bradycardia, cheyne-stokes respirations r/t SNS outflow from brainstem compression

Activation; depression

102
Q

Define intracranial HTN

A

Sustained increase in ICP >15 mmHg

103
Q

What is intracranial compliance? What does it mean if ICP is increasing?

A

Compliance is the ability of the compartment to accommodate increased volume without major changes in pressure

Increased ICP = decreased compliance

104
Q

What is cushing’s response?

A

Periodic increases in MAP with reflex slowing of the HR lasting 1-15 minutes

105
Q

True or false: hyperventilation should be used universally

A

False

106
Q

VAE can cause acute-sided heart failure

A

right

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