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CVPR 326 Pediatric Perfusion > Differences beweeen adult and pediatric CPB, Hypothermia, Nero, Blood gas / Pedi test 2 > Flashcards

Differences beweeen adult and pediatric CPB, Hypothermia, Nero, Blood gas / Pedi test 2 Flashcards

1
Q

Infant CPB parameters;

  1. ) Hemodilution:
  2. ) Perfusion Pressures:
  3. ) Hypothermic Temps:
  4. ) TCA / DHCA:
A

1.) 150 - 300%
2.) 20 - 50 mmHg
3.) 15 - 20 degrees celcius
common
4.) Common

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2
Q

Early Manifestations of brain injury in children include:

A

Seizure
Stroke
Choreothasis
Coma

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3
Q

Choreothasis definition ?

A

Occurrence of involuntary movements in a combination of chorea (irregular migrating contractions) and athetosis (twisting and writhing).

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4
Q

Late Manifestations of brain injury in children include:

A
  • Delayed neurodevelopment

- Motor abnormalities

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5
Q

Reports suggest that transient deficits occur in ______% of all infants undergoing CPB

A

25%

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6
Q

Deep hypothermia post-CPB effects:

A
  • Reduced cerebral blood flow.
  • Disordered brain metabolic activity
  • Delayed functional recovery
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7
Q

Cold is a perfusionist’s best friend, cold temperatures serve as a ?

A

PROTECTIVE mechanism that reduces metabolism & from a TECHNICAL perspective gives a greater safety margin for emergency scenarios

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8
Q

Adult
Brain Weight = 1300 g
Body Weight = 75,000 g

Neonate ?

A

Brain Weight = 300 g

Body Weight = 3500 g

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9
Q

Adult brain represents <2% of total body weight. Neonatal brain represents what % of total body weight?

A

9 %

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10
Q

The first truly scientific document in hypothermia was written by ?

A

1797 - Dr. James Currie

  • Royal College of Surgeons
  • Recorded temps 94º F
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11
Q

Two Distinct Open-Heart Surgery Strategies Emerged

in 1950, what were they ?

A
  1. Cardiopulmonary bypass: maintain normal physiology
  2. Hypothermia with inflow occlusion
    * No Cardiopulmonary Bypass
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12
Q

Who discovered hypothermia with inflow occlusion ?

A

Dr. W.G. Bigelow

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13
Q

Dr. John F. Lewis

A
  • September 2, 1952 successfully closed a secundum ASD in a 5-year old girl under direct vision.
  • Published on a series of ASD closures with 12% mortality
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14
Q

Benefits of Hypothermia w/inflow occlusion were obvious but were limited to?

A
  • ASDs

- Isolated aortic/pulmonic stenosis

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15
Q

What institution incorporated a modified General Motors radiator into the extracorporeal circuit to combine Cardiopulmonary bypass + Hypothermia ?

A

1958, WC Sealy, Duke University Medical Center

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16
Q

Surface Cooling/Immersion work in what order?

A

Environment
Skin / Tissues
Blood Vessels

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17
Q

Extracorporeal Blood Cooling worked in what order ?

A

Blood vessels
Skin / Tissues
Environment

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18
Q

Hypothermia and cardiopulmonary bypass has effects on what 3 sectors?

A

Biochemical Reactions
Blood Viscosity
Changes in blood gases

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19
Q

CPB + Hypothermia permits

A

lower pump flows,
less blood trauma,
better organ protection

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20
Q

The concept of Q10

A

The multiple by which a reaction rate changes for every 10°C change in temperature

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21
Q

Levels of Hypothermia

Mild:
Moderate
Deep
Profound

A

Mild: 32 -36º C
Moderate 28 - 32º C
Deep 18 - 28º C
Profound < 18º C

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22
Q

Who are the smaller subset of patients using deep hypothermia ± TCA ?

A

Neonatal heart surgery
Aortic arch reconstruction
Neuro-surgical procedures

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23
Q

Hypothermia ___ blood viscosity.

A

Increases

24
Q

Viscosity of blood ____ per °C

A

2 %

25
Q

Cooling and Warming gradients ?

A

Do not exceed 8-10°C

26
Q

Do not exceed 8-10°C gradient During cooling between:

A

perfusate and core temp

27
Q

Do not exceed 8-10°C gradient During rewarming between:

A

venous blood and heater cooler waterbath

28
Q

3 Neuroprotective strategies in children undergoing CPB ?

A
  • Deep hypothermia
  • Avoidance of long circulatory arrest times
  • Blood chemistries
29
Q

4 Neuroprotective strategies in children undergoing CPB that involve Blood chemistries ?

A
  • HCT levels
  • COP
  • Blood Gas Strategies
  • Hyperoxia
30
Q

Change in the oxygen-hemoglobin dissociation curve.

Greater affinity = less efficient release of O2 at tissue level, what can we do?!?

A

Consider HYPEROXIA prior to circulatory arrest

31
Q

Changes in solubility of O2 and CO2.
As temps ____ gases become more soluble in liquid.
This means that as temp ___ the solubility of gas ____. 
Therefore more gas will be dissolved in plasma and the partial pressure will drop. Much more significant for CO2

A

Decreases

Decreases

Increases

32
Q

Values that are calculated to actual temperature when the sample is drawn ?

A

Temperature Corrected

33
Q

Sample that is measured at normothermia (37º C) ?

A

Temperature Uncorrected

34
Q

An Essential Amino Acid

that plays an important part of catalytic sites in certain enzymes ?

A

Histidine

35
Q

Histidine Contains a positivily charged ?

The charge state can dictate the structure of the active site.

A

imidazole functional group

36
Q

What is responsible for maintaining the temperature-pH relationship in Alpha-stat ?

A

protein buffering, largely due to the imidazole group of histidine

37
Q

The imidazole has a degree of dissociation (referred to as alpha) of

A

0.55 in the intracellular compartment and this remains constant despite changes in temperature (ie the pK is changing with change in temperature).

38
Q

Alphastat Hypothesis

A

The degree of ionisation (alpha) of the imidazole groups of intracellular proteins remains constant despite change in temperature.

39
Q

Rationale for pH-stat; CO2 added to the circuit maintains pH = 7.40
May be beneficial because:

A
  • CO2 may counteract oxy-hemoglobin disassociation . curve

- CO2 is a potent cerebral vasodilator and promotes high CBF

40
Q

high CBF promotes ?

A
  • More complete and homogeneous cooling

- Prevents cerebral steal due to aorto-pulmonary collateral’s

41
Q

pH-stat method

Goal:

A

Keep arterial pH = 7.40 at any given temperature.

ACTUAL or TEMPERATURE CORRECTED SAMPLE

Remember:blood gas measure samples at 37 C.
To accomplish my goal, one must allow CO2 to accumulate

42
Q

Alpha-stat method

Goal:

A

Maintain pH = 7.40 in UNCORRECTED SAMPLE eg 37C degrees.

Technically easy. Run normal ABG based upon results of sample

43
Q

Blood gas strategy for mild/moderate hypothermia?

A

Alpha-stat

44
Q

Blood gas strategy for deep hypothermia (pediatrics) ?

A

pH-stat

45
Q

Blood gas strategy for deep hypothermia (adult)

A

Alpha stat

46
Q

Blood gas strategy for all populations ?

A

Consider hyperoxia pre-arrest

47
Q

Careful attention during rewarming to avoid ?

A

cerebral hyperthermia

48
Q

Maintain hematocrits at ?

A

> 25%

49
Q

What are the 4 different modes ?

A
  • Deep Hypothermic Circulatory Arrest (DHCA)
  • Selective Antegrade Cerebral Perfusion (SACP)
  • Regional Low flow
  • Retrograde cerebral perfusion (RCP)
50
Q

The clinical team should manage adult patients undergoing moderate hypothermic CPB with ?

A

Alpha-Stat pH management

51
Q

The clinical team should manage PEDIATRIC patients undergoing DEEP hypothermic CPB with ?

A

ASD patients use Alpha Stat

52
Q

cross-over technique

A

one cools pH stat and then just prior to arrest crosses back to alpha.

53
Q

Update on Pediatric Perfusion Practice

in North America Minimal acceptable Hct ?

A

24 - 30%

54
Q

Update on Pediatric Perfusion Practice

in North America Termination Hct (cyanotic defects) ?

A

28 - 45%

55
Q

Update on Pediatric Perfusion Practice

in North America Termination Hct ( non cyanotic ) ?

A

21 - 35%

CVPR 326 Pediatric Perfusion (23 decks)

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