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Congenital Defects (exam 1) > Topic 3: Ped perfusion, Bld gases, hypothermia > Flashcards

Topic 3: Ped perfusion, Bld gases, hypothermia Flashcards

1
Q

Major differences exist between adult and pediatric cardiopulmonary bypass, stemming from: (3)

A

Anatomic differences
Metabolic differences
Physiologic differences

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2
Q

How are Myocytes and myofibrils different in peds than adults?

A

increased in size

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3
Q

The number of mitochondria increases as what in peds?

A

the oxygen requirements of the heart rises

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4
Q

The amount of sarcoplasmic reticulum and its ability to sequester what increase in early development?

A

Ca+ similarly increase in early development

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5
Q

Activity of Na+/K+ adenosine triphosphatase (ATPase) does what with maturation?

A

increases with maturation, and affects the Na-Ca+ exchange

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6
Q

what preceding factors affect the way in which the immature heart handles Ca (monitor Ca closely)?

A
  • Myocytes & Mitochondria Increase in size & #
  • The amount of SR and ability to sequester Ca increase
  • Na+, K+ and Ca++ movement have increased activity
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7
Q

Ca++ handling in immature myocardium ↑’s concentration of what post ischemia/reperfusion?

A

intracellular Ca++ concentrations

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8
Q

Activates energy-consuming processes –> __________–> lack of energy sources for cardiac function

A

decreased levels of adenosine triphosphatase (ATPase)

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9
Q

Activates energy-consuming processes –> decreased levels of adenosine triphosphatase (ATPase) –> _______

A

lack of energy sources for cardiac function

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10
Q

Abnormal and uncontrolled activation of these enzymes leads to cellular damage after CPB

A

Na, Ca, K, ATPase

Contributes to dysfunction observed after CPB

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11
Q

Increased myocardial oxygen demands

associated with what?

A

a switch from anaerobic metabolism after birth to a more aerobic metabolism.

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12
Q

The immature myocardium uses several substrates - what are they?

A

carbohydrates, glucose, medium, and long-chain fatty acids, ketones, and amino acids.

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13
Q

In the mature (3-12 mo) heart, what are the primary substrates?

A

Primary - long-chain fatty acids

enzymes and an increased number of mitochondria are needed.

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14
Q

Because of the increased ability of the immature myocardium to rely on _________ better than an adult myocardium can.

A

anaerobic glycolysis, it can withstand ischemic injury

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15
Q

Why are the Effects of hemodilution is enhanced in neonates (2)

A
  • decreased plasma proteins, coagulation factors, and Hgb

- reduction increases organ edema, coagulopathy, and transfusion requirements

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16
Q

Things that cause premature infants to be prone to hypocalcemia?

A

hypoxia, infection, stress, diabetes

mom

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17
Q

Infants/neonates have high oxygen-consumption rates
require flow rates as high as ___mL/kg/min at
normal temperature (kg based flow rates)

A

200 mL/kg/min

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18
Q

Adult: on bypass you have to Control high blood sugar

CPB -> ___ -> ____

A

CPB => stress response => hyperglycemia

Studies link hyperglycemia with adverse outcomes

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19
Q

Peds: On bypass you have to Control low blood sugar about it ?

A
  • -Hyperglycemia has not been linked to adverse outcomes in pediatric CPB
  • -more common on pediatric CPB is hypoglycemia ( ↓ glycogen stores)
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20
Q

Pediatric: Hematologic Response

A

Exaggerated response to surgery/CPB

Inflammatory response inversely proportional to age

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21
Q

The Inflammatory response is _____ to age in pediatrics

A

inversely proportional

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22
Q

The events that trigger stress: (4)

A

Ischemia
Hypothermia
Anesthesia
Surgery

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23
Q

CPB causes hormone release and also releases: (5)

A 
Catecholamines
Cortisol
ACTH
TSH
Endorphins

Immature organs affect the release!!!!

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24
Q

Adult Cardiac response to CPB?

A

Less ischemia tolerance
May/may not be preconditioned to ischemia
More tolerant of overfilling

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25
Q

Pediatrics Cardiac response to CPB?

A

Tolerate ischemia
Higher lactates seen (cost of tolerating ischemia)
Prone to stretch injury (overfilling)

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26
Q

Adult CNS response to CPB?

A

More neurological injuries
Multifaceted etiology
Stem from disease processes

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27
Q

Pediatrics CNS response to CPB?

A

Neuro problems rare with routine CPB

Increased with DHCA (?25%)

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28
Q

Adult Pulmonary response to CPB?

A

Lungs fully developed
Less reactive vasculature
May have preexisting disease

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29
Q

Pediatrics Pulmonary response to CPB?

A

Lungs not fully developed
More reactive vasculature
Usually without existing disease

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30
Q

Adults

The normal urine output ml/min , ml/hr

A

can be 0.5 to 1 ml/min, regardless of weight. That translates to 60 ml/hr.
Average 70kg adult would be expected to produce 35-70 mL/hour of urine

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31
Q

Peds - normal expected U.O.? ml/kg/hr, ml/hr

A

closer to 1ml/kg/hour of urine.
Average 5 kg child would be expected to
produce 5 mL/hour

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32
Q

Warm temps?

A

36-37°C

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33
Q

Mild Hypothermia temps?

A

32-35°C

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34
Q

Moderate Hypothermia temps?

A

28-31 °C

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35
Q

Deep Hypothermia temps?

A

18-27°C

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36
Q

Profound Hypothermia temps?

A

< 18°C

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37
Q

7°C Principle
This reduction in metabolic rates can be
summarized as follows:

A 
•Every 7°C drop in temperature will result in a 50% decrease in oxygen consumption 37°C
Normothermic
34°C 25% decrease (MILD)
30°C 50% decrease (MODERATE)
23°C 75% decrease (DEEP)
16°C 87.5% decrease (PROFOUND)
9°C  94% decrease (ALMOST FROZEN)
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38
Q

Temperature monitoring locations:

I. Core (central) - 5

A 
Bladder (not on small children)
Nasopharyngeal
Tympanic
Esophageal
Venous -- MOST COMMON
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39
Q

Temperature monitoring locations:

II. Shell (peripheral) - 2

A

Rectal

Skin

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40
Q

Excitatory neurotransmitter release is _____ with hypothermia

A

reduced

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41
Q

Hypothermia helps to protect organs against injury caused by the compromised what??

A

compromised substrate supply to tissues resulting from reduced flow

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42
Q

Protective effects of hypothermia is from what??

A

This protection occurs because of a reduced metabolic rate and decreased oxygen consumption.

43
Q

The metabolic rate is determined by enzymatic activity, which, in turn, depends on what?

A

temperature

44
Q

The safe period of hypothermic cardiopulmonary bypass (CPB) is ___ than the period predicted on the basis of reduced metabolic activity alone

A

longer

45
Q

PHCA/DHCA “Safe period durations”

>32 ⁰C = – mins?

A

<10 minutes

46
Q

PHCA/DHCA “Safe period durations”

28 ⁰ C = minutes?

A

10 - 20 minutes

47
Q

PHCA/DHCA “Safe period durations”

18⁰C = minutes?

A

20 - 45 minutes

48
Q

PHCA/DHCA “Safe period durations”

<18⁰C = mins?

A

45 - 60 minutes

49
Q

Negative effects of hypothermia

A
  • -brain BF loses autoregulation at extreme temp which makes BF highly dependent on extracorporeal perfusion
  • -this uncoupling of autoregulation is a serious issue
50
Q

CPB is started and cooling is begins for how long?

A

at least 20-30 mins. The pt’s body temp is monitored.

After adequate cooling is achieved, the circulation is arrested.

51
Q

The desired duration of DHCA is what?

A

limited to the shortest time possible.

After circulation is resumed, the final repairs are done on warming

52
Q

Cannulation for PHCA/DHCA is usually what?

A

a SAC

The heart is not opened until circulatory arrest

53
Q

Cannulation for PHCA/DHCA can and will be done with BICAVAL also:
when is heart opened with this?

A

The heart is can be opened before circulatory arrest

54
Q

Positives about DHCA (4)

A

Allows exposure
Reduces metabolic rate and molecular movement
Allows cessation of circulation

55
Q

Negatives about DHCA (5)

A 
Neurologic injury & morbidity
Brain is at the most risk
>60 min arrest is detrimental
>40 min increases risk
MUST monitor temp gradients closely
56
Q

DHCA or HLFB have demonstrated lowered rates of neural dysfunction in patients?

A

HLFB

57
Q

Combined DHCA with INTERMITTENT LOW FLOW BYPASS (ILFB) for what time frames?

A

1-2 minutes every 15-20 minutes

58
Q

The secret formula for how to flow may very well be what???

A

lie in the mixture of these techniques and not the techniques alone
i.e. DHCA w/intermittent perfusion

59
Q

Antegrade Cerebral Perfusion

A

Perfusing the head vessels in an antegrade fashion to perfuse the brain during DHCA
Via head vessels/shunt

60
Q

Retrograde Cerebral Perfusion

A

Perfusing the head vessels in an retrograde fashion to perfuse the brain during DHCA
Via SVC

61
Q

The concept of Retrograde Cerebral Perfusion originated from what?

A

in the treatment of massive air embolism during CPB.

62
Q

When Retrograde Cerebral Perfusion is started

the cannula pressure in the SVC is maintained at what ??

A

at 15-20 mm Hg

(the SVC is snared, antegrade arterial flow is terminated, and the arterial cannula is connected to the arterial return line to the SVC)

63
Q

Mechanisms with which retrograde cerebral

perfusion may accomplish neuroprotection include: (3)

A
  • -the flushing of air and atheromatous embolic material from the cerebral circulation
  • -the maintenance of cerebral hypothermia, and the provision of nutritive cerebral flow
  • -RCP can be given continuously or intermittently
64
Q

However, incidents of cerebral edema after retrograde cerebral perfusion are reported especially when perfusion pressure exceeds what?

A

particularly when the perfusion pressure exceeds 25 mm Hg,

65
Q

the amount of perfusate that provides cerebral nutrition is low, corresponding to what % of total retrograde flow

A

only about 5%

66
Q

the amount of perfusate that provides cerebral nutrition is only 5% of total retrograde flow – WHY ???

A

Most of this flow is drained from the SVC into the IVC given the rich network of collaterals between the veins

67
Q

Which is more common - Antegrade or Retrograde Cerebral Perfusion in the pediatric pop?

A

RCP technique is used less commonly than ACP in the pediatric population.

68
Q

Antegrade cerebral perfusion can be achieved by using what in peds that require arch reconstruction??

A

by using an open end of a modified Blalock-Taussig (BTT) shunt after the proximal anastomosis is constructed in neonates who require arch reconstruction
(i.e Norwood operation).

69
Q

For Antegrade Cerebral Perfusion Peds:
Perfusate temperature is set at what?
Flow is set at what?
R. Radial Artery Pressure maintained at what?

A

The perfusate temperature is usually set at 18°C, and the flow is set at 10-20 mL/kg/min or adjusted to maintain a pressure of 40-50 mm Hg in the right radial artery.

70
Q

For Antegrade Cerebral Perfusion for neonates:

What flows are recommended

A

Higher flows of 30-40 mL/kg/min are recommended for neonates

71
Q

Drawbacks related to Antegrade Cerebral Perfusion cannulae techniques are mainly related to what complications?

A

complications of direct cannulation of arch vessels

72
Q

Negatives to Antegrade Cerebral Perfusion ?

6

A
  • dissection of the arterial wall
  • air
  • atheromatous plaque embolization
  • malposition of the cannula
  • overcrowding of the operative field with cannulas
  • ACP can be given continuously or intermittently
73
Q

incidents of cerebral edema antegrade cerebral perfusion, when what are
reported???

A

particularly when the perfusion pressure exceeds 25 mm Hg,

74
Q

During hypothermia, the solubility of CO2 in blood does what?

A

increases, and for a given concentration of CO2 in blood, PCO2 decreases and the blood becomes alkalotic

75
Q

pH stat leads to lower or higher pCO2 (respiratory acidosis), and increased cerebral BF

A

HIGHER
(which aims for a pCO2 of 40 and pH of 7.40 at the patient’s actual temperature)

Higher pCO2 = respiratory acidosis and increased cerebral BF

76
Q

CO2 is deliberately added to maintain a pCO2 of 40 mmHg during hypothermia with what style of acid base management?

A

pH

to maintain the hypothermic pH at 7.40 and the
PCO2 at 40 mm Hg

77
Q

When blood samples are warmed to room temperature, blood gases are what two things?

A

are hypercapnic and acidotic

78
Q

CDI – what do you read at?

A

Read ABG’s are Perfusate’s temp

79
Q

Why is pH stat better for kids reasoning? (4)

A

Improved neurologic outcome, hastened EEG recovery times, and reduced number of postop seizures

  • Increased cortical oxygen saturation before arrest,
  • Decreased cortical oxygen metabolic rates during arrest
  • Increased brain-cooling rates.
  • CBF during reperfusion increases by using a pH-stat management strategy
80
Q

Negatives about pH stat?? (3)

A

—⬆️ CBF that can ⬆️ embolic events, high CBF during reperfusion, and reperfusion injury
–Acid load induced by pH-stat strategy may impair enzymatic function and metabolic recovery. To retain the benefits of the pH-stat method on cooling and to eliminate its negative effect on enzymatic function
–Lose autoregulation
perfusion pressure then rules

81
Q

During alpha-stat what is maintained?

A

the ionization state of histidine is maintained by managing a standardized pH (measured at 37C)

82
Q

During Alpha stat what happens to the pCO2 has pts temp falls?

A

Apha-stat pH management is not temperature-corrected as the patient’s temperature falls, the partial pressure of CO2 decreases (and solubility increases)

83
Q

With Alpha Stat what happens to the pH during cooling?

A

The alpha-stat method allows blood pH to increase during cooling, which leads to hypocapnic and alkalotic blood in vivo

Furthermore, the increase in pH parallels the increase in the hydrogen ion dissociation constant of water during cooling, which can maintain a constant ratio of OH- ions to H +ions

84
Q

Alpha Stat: Blood samples warmed to room temperature have a pH of 7.4 and a PCO2 of 40 mm Hg. These conditions allow what??

A

the alpha-imidazole group of the histidine moiety on blood/cellular proteins to maintain a constant buffering capacity, which enhances enzyme function and metabolic activity

85
Q

Positives with Alpha Stat (3)

A

-Cerebral Blood Flow (CBF) autoregulation is maintained, which allows for metabolism and blood flow coupling. CBF can be adjusted depending on the patient’s cerebral metabolic activity and oxygen needs.
•Autoregulation is intact
•Normal enzyme function

86
Q

Negatives with Alpha Stat (2)

A

Vasoconstriction

•Poor Cooling, which potentates problems at the cellular level

87
Q

When using pH stat and alpha stat in combination, when do some perfusionists switch to alpha stat management in the pump run?

A

—-some do it on the last gas before arrest—-

initial cooling is accomplished with the pH-stat method, which is then switched to alpha-stat method to normalize the pH in the brain before ischemic arrest is induced

88
Q

INVOS System by ?

A

Somanetics Corporation (Troy, Michigan)

89
Q

NONIN EQUINOX Regional Oximeter by?

A

Nonin Medical Incorporated (Plymouth, MN)

90
Q

FORE-SIGHT Cerebral Oximeter by?

A

CASMED Medical Systems (Branford, Connecticut)

91
Q

Retrograde CPG needle (coronary Sinus)

Neonatal – type? size?

A

DLP Neonatal 6 French

92
Q

Retrograde CPG needle (coronary Sinus)

Pediatric - type? size?

A

DLP Pediatric 10 French

93
Q

Retrograde CPG needle (coronary Sinus)

small adult - type? size?

A

DLP Small adult 13 French

94
Q

Retrograde CPG needle (coronary Sinus)

Adult - type? size?

A

DLP Adult 15 French

95
Q

Coronary Ostia CPG Cannula

Hard Tip Sizes?

A

10, 12, 14 French

96
Q

Coronary Ostia CPG Cannula

Soft Tip Sizes?

A

Universal

97
Q

Aortic Root CPG Cannula

DLP - 18 Gauge goes with what wt range?

A

0-7 kg

98
Q

Aortic Root CPG Cannula

DLP - 16 Gauge goes with what wt range?

A

7-20 kg

99
Q

Aortic Root CPG Cannula

DLP - 14 Gauge goes with what wt range?

A

20-35 kg

100
Q

Aortic Root CPG Cannula

DLP - 14 Gauge goes with what wt range?

A

> 35 kg

101
Q

Antegrade CPG - how much to you deliver? mL/kg

A

30 mL/kg in pediatric patients.

Flow is variable depending on patient size

102
Q

Antegrade CPG — pressures to maintain?

A

Line pressure depends on the pressure drop across the cardioplegia system (the goal is to maintain root pressure approximately 70 mmHg).
Look at your pre-op pressures
Flow is variable depending on patient size

103
Q

Retrograde cardioplegia is given into the coronary sinus

A balloon is inflated or self inflated and provides what two functions?

A

Prevents backflow

Holds cannula in place

Congenital Defects (exam 1) (4 decks)

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