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perf tech 3 > 6. Neuro Response- Exam 2 > Flashcards

6. Neuro Response- Exam 2 Flashcards

1
Q

how many cardiac surgical procedures are carried out worldwide

A

1.4 million

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2
Q

overt stokes occur in what % of patients

A

1-5%

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3
Q

Neurologic dysfunction may be present in what % of pts.

A

25-80%

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4
Q

Annual cost for treating these pts. exceeds how much per year

A

$2 billion/ yr

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5
Q

Neurologic Deficits Include what 6 things

A 
Psychomotor speed
Attention
Concentration
New Learning Ability
Short term memory
Pediatrics: Seizures, Movement disorders, developmental delays
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6
Q

Transient Ischemic Attack (TIA)=

A

Localized event
Rapid onset and recovery (minutes to hours)
Severity depends on collateral flow

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7
Q

Reversible Ischemic Neurologic Deficit (RIND)=

A

Similar to TIA but lasts longer (24-72hrs)

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8
Q

Lacunar Brain Infarct (stroke)=

A

Specific focal deficit from cerebral artery occlusion.
Much more severe, often doesn’t resolve
Hemiparesis/aphasia/sensory

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9
Q

Global Ischemia=

A

Results from long periods of hypoperfusion or massive embolic load
Poor recovery. >50% are brain dead and never wake

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10
Q

do symptoms of different classifications of strokes often overlap and share causative mechanism

A

yep

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11
Q

Many cardiac pts have ______ risk factors for stroke and cognitive impairment. Without added risk of ____ and ____

A

pre-existing

cardiac surgery and bypass

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12
Q

____ patients experience ___ serious neurologic morbidity than age, and health matched controls undergoing non-cardiac surgery

A

Cardiac

more

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13
Q

name 6 Risk Factors

A
  1. Advanced Age (65+)
  2. Atherosclerosis (increases w/ age)
  3. History of previous neurologic incident (previous TIA)
  4. Intracardiac operation (valves-hearts open to air)
  5. Hypertension and Diabetes (most all patients)
  6. Carotid Stenosis (impairs BF to the head)
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14
Q

Age of <45 years old = what % incidence of stroke

A

~ 0.2% incidence of stroke

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15
Q

Age of <60 years old = what % incidence of stroke

A

1% incidence of stroke

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16
Q

Age of 60-70 years old = what % incidence of stroke

A

3.0% incidence of stroke

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17
Q

Age of >75 years old = what % incidence of stroke

A

8.0% incidence of stroke

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18
Q

__% of pts with stroke show multiple infarcts, with an average of _ zones

A

75%

6

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19
Q

Hartman et al, (1996)
•__% stoke in pts with normal aorta
•__% stroke rate with large intraluminal plaques

A

5%

45%

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20
Q

Embolic events are related to what 3 things

A

Aortic Plaques [not in our control]
Platelet-fibrin and leukocyte aggregates [in our control]
Bubbles from CPB circuit [in our control]

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21
Q

in the one study- why did embolic events at 100 minutes jump up so high

A

happened during short filling of the heart- they were probably not venting

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22
Q

in the second study- at what time during CPB did the % of embolic load jump up considerably

A

cross clamp release

release of partial occlusion clamps

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23
Q

what % of cardiac patients have a history of TIA/Stroke

A

13%

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24
Q

cardiac patients with a history of TIA/Stroke are how many times at greater risk of new deficit or exacerbation of previous deficit

A

3x

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25
Q

what are some examples of Intracardiac operation? what do they increase the risk of?

A

Valves, ASD/VSD, Myxomas, etc.

Increased risk of air emboli

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26
Q

Intracardiac operations have a risk (____%) is ___ higher than CABG alone

A

5-13%

2X

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27
Q

what % of cardiac surgical patients have HTN

A

55%

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28
Q

what % of cardiac surgical patients have diabetes

A

25%

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29
Q

the risk factors of HTN and DM may be due to changes in cerebral autoregulation- such as what 3 things

A

Narrows arteries penetrating the brain
Decrease in collateral blood flow
Decrease ischemic tolerance

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30
Q

__% of cardiac surgery patients have greater than __% carotid stenosis.

A

15%

50%

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31
Q

Brenner et al.
•__% stroke rate in asymptomatic patients with carotid disease
•__% stroke rate in patients with no carotid disease

A
  1. 2%

1. 3%

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32
Q

Faggioli et al.
•__% stroke rate with >75% Carotid Stenosis
•__ of __ pts with >75% Carotid Stenosis before carotid endarterectomy had strokes

A

14%

0 of 19

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33
Q

Mechanism is unclear [Carotid Stenosis], whether embolic or ↓Q, but >50% of strokes occur when?

A

in immediate postoperative period

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34
Q

how many studies prove higher CPB / MAP is beneficial

A

None

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35
Q

name 9 other risk factors for neurologic injury

A 
PVD
Alcohol abuse
IABP- balloon or preexisting condition??
MI
Prolonged hypotension
Arrhythmias
CHF
Gender
Decreased Cardiac Output
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36
Q

Cerebral Metabolic Requirement of Oxygen (CMRO2)=

A

CMRO2 ~40-50mL of O2/min

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37
Q

Cerebral Metabolic Requirement of Oxygen (CMRO2) indexed=

A

Indexed at 3.0-3.5 mL of O2/100g/min

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38
Q

Cerebral Blood Flow (CBF)=

A

CBF~ 750mL/min

39
Q

Cerebral Blood Flow (CBF) indexed=

A

Indexed at 50-60mL/100g/min (about 15% CO)

40
Q

Average brain weighs about?

A

1400g

41
Q

CBF:CMRO2 is typically?

A

10-15

42
Q

CBF is influenced by what 4 things

A

CMRO2, PaCO2, Hct, MAP

–All may increase or decrease cerebral blood flow

43
Q

Without bypass: Cerebral delivery of oxygen (CDO2) normally does what

A

exceeds the oxygen demand

44
Q

Without bypass: When delivery decreases, CMRO2 does what

A

is maintained by increasing oxygen extraction

–Further decrease in delivery will result in ischemia

45
Q

Autoregulation tries to maintain a constant CBF over what range of pressures

A

wide range of pressures

46
Q

Due to changes in CMRO2 between an awake patient and an anesthetized patient at hypothermic temperatures, different CBF’s are maintained over?

A

variable MAP’s

47
Q

Awake patients-Maintain autoregulation from?

A

50-150mmHg

48
Q

Anesthetized patients at moderate hypothermia may have preserved autoregulation down to CPP of?

A

28mmHg

49
Q

Anesthetized patients at Deeper Hypothermia may have preserved autoregulation down to CPP of?

A

down to 20mmHg

50
Q

While intrinsic autoregulation strives to maintain a CBF:CMRO2 coupling, there are other factors that play major roles- such as what 4 things

A
  1. Temperature
  2. Carbon Dioxide
  3. Oxygen Tension
  4. Mean Arterial Pressure
51
Q

what is the Primary determinant of CBF

A

temperature

52
Q

flow-metabolism “coupling”: Brain regulates flow in response to it’s ___ demand

A

O2

53
Q

flow-metabolism “coupling”: is maintained in _____ state

A

autoregulatory

54
Q

flow-metabolism “coupling”: When there is an increase or decrease in CMRO2, ____ is adjusted accordingly

A

CBF

55
Q

At profound levels of hypothermia (<22°C), what happens to flow-metabolism coupling

A

“coupling” disappears

CBF can become in excess of CMRO2

56
Q

Alpha Stat: pCO2 is a large player in determining CBF. what is the relationship btwn pCO2 and CBF

A

↑CBF as ↑pCO2 and vice versa

–Effects are regardless of Temperature, MAP, Hct, pO2

57
Q

pH-stat acid-base management= Maintain temperature CORRECTED pH= 7.40 and pCO2 = 40mmHg
By continually adding what?

A

CO2

–causes dilation so you increase flow and lose coupling

58
Q

Alpha-stat acid-base management= Maintain an UNcorrected value of pH = 7.40 and pCO2 = 40mmHg
Keeping the total __ constant

A

CO2

59
Q

what type of acid/base management is good for pediatric cases

A

ph management

- they do not have acquired diseases yet so they can use the increased flow without the extra chance of emboli

60
Q

why is ph management not that good for adults

A

Adult patients lose cerebral autoregulation where CBF becomes dependent on CPP
–causes dilation so you increase flow which increases chance for emboli

61
Q

Normal cerebral tissue pO2 =

A

35-40mmHg

62
Q

a pO2 < 30mmHg indicates what

A

Immediate reduction in cerebral vascular resistance

Yielding an increase in CBF

63
Q

Hyperoxia causes what

A

an increase cerebral vascular resistance.

64
Q

Rogers et al,

–showed a __% reduction in CBF when PaO2 was increased from ___ to ___ mmHg (all other parameters constant)

A

15%

125 to 300mmHg

65
Q

With alpha-stat:

  • -CBF is relatively constant over varying ___
  • -At mild hypothermia or normothermia, the safety margin for CDO2 vs. CMRO2 starts to narrow at MAP’s ____
A

MAP

< 50mmHg

66
Q

With pH-stat

  • -CBF is dependent on __
  • -High pressures can yield _____
  • -Low pressures can yield ______
A

MAP
excessive flow
hypoperfusion

67
Q

is CPB responsible for cognitive injury

A

Nope

68
Q

Attenuation of Neurological Injury via Surgical Management can be done what 6 ways

A
  • Attention to Aorta
  • Minimize aortic manipulations
  • Flood chest cavity with CO2
  • Use care during de/cannulation
  • Utilize TEE to ensure de-airing prior to XC removal
  • Pre-op carotid studies in older patients and those with a history of TIA/ Stroke/ Carotid Dz
69
Q

describe attention to the aorta for attenuation of neurological injury

A

Use the epiaortic ultrasound (versus “feel”) for cannulation, cross clamp, and proximal anastamosis sites
–Devices to deflect / trap emboli

70
Q

Attenuation of Neurological Injury via Anesthesia Management can be done what 3 ways

A
  • Pharmacologic agents that reduce CMRO2
  • Ensure air removed from IV’s and arterial lines
  • Apply manual compression on carotid arteries with XC removal
71
Q

name 2 Pharmacologic agents that reduce CMRO2

A

Thiopental

Propofol

72
Q

Attenuation of Neurological Injury via Perfusion Management can be done what 6 ways

A
  • Use of arterial line & cardiotomy filter
  • Ensure proper de-airing of circuit (CO2 flush)
  • Maintain adequate anticoagulation
  • Monitor warming/cooling gradients
  • Communicate with surgeon and understand surgical sequence of events
  • Alpha-stat acid-base management
73
Q

why is a slow rewarm is better

A

Better cognitive performance 6 weeks post op

37.5C is the max- Avoid Hyperthermia

74
Q

additional attenuation of Neurological Injury include:

Check arterial line post CPB prior to?

A

transfusion of volume

-ask if all clamps are off at the field and is the cannula is clear

75
Q

additional attenuation of Neurological Injury include:

Avoid hyperglycemia because..

A

(potential for ↑CMRO2)

May aggravate neurologic ischemic injury

76
Q

additional attenuation of Neurological Injury include:

Discuss venous drainage problems- If SVC is congested then ___ is diminished

A

CPP

77
Q

Near Infrared Spectroscopy=

A

Noninvasive transcutaneous assessment of regional brain oxygenation

78
Q

Near Infrared Spectroscopy is sensitive too what?

A

temperature, pCO2, Hct, CPB flow

79
Q

Near Infrared Spectroscopy hgb sat does NOT indicate what?

A

tissue utilization

80
Q

Transcranial Doppler=

A

Measures blood velocity in middle cerebral artery

–Correlation to blood flow

81
Q

Transcranial Doppler is sensitive too what?

A

Temperature, MAP, pump flow, pCO2, Hct

82
Q

Transcranial Doppler reliable velocity requires what?

A

a constant vessel diameter

  • Not always true on bypass
  • Better trending device
83
Q

Transcranial Doppler for peds=

A

much more useful – easier to obtain temporal window

84
Q

Transcranial Doppler for adults=

A

better at emboli detection than indicator of CBF

85
Q

with Antegrade Cerebral Perfusion, you put the patient in what position

A

Trendelenburg position

86
Q

describe the flow for Antegrade Cerebral Perfusion

A

Flow up the axillary artery to the innominate artery, to the head via the right common carotid artery. Thru the Circle of Willis and down the jugular veins to the SVC/ Atrium.
–Can also do via direct cannulation of the head vessels

87
Q

with Antegrade Cerebral Perfusion, what line do you have to leave open to drain the heart

A

venous line

88
Q

Antegrade Cerebral Perfusion flow=

A

10ml/kg/min

89
Q

describe the flow for Retrograde Cerebral Perfusion

A

Flow up the SVC through the Circle of Willis and down the carotid arteries

90
Q

what was the 1st method used to treat massive air embolus

A

Retrograde Cerebral Perfusion

91
Q

Retrograde Cerebral Perfusion may be useful for what surgeries

A

deair for aortic surgeries

92
Q

Retrograde Cerebral Perfusion flow

A

<500ml/min

93
Q

Retrograde Cerebral Perfusion SVC pressure=

A

<25mmHg

perf tech 3 (15 decks)

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