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

Question 1

Infant CPB parameters;

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

Answer 1

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

Question 2

Early Manifestations of brain injury in children include:

Answer 2

Seizure
Stroke
Choreothasis
Coma

Question 3

Choreothasis definition ?

Answer 3

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

Question 4

Late Manifestations of brain injury in children include:

Answer 4

• Delayed neurodevelopment

- Motor abnormalities

Question 5

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

Answer 5

25%

Question 6

Deep hypothermia post-CPB effects:

Answer 6

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

Question 7

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

Answer 7

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

Question 8

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

Neonate ?

Answer 8

Brain Weight = 300 g

Body Weight = 3500 g

Question 9

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

Answer 9

9 %

Question 10

The first truly scientific document in hypothermia was written by ?

Answer 10

1797 - Dr. James Currie

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

Question 11

Two Distinct Open-Heart Surgery Strategies Emerged

in 1950, what were they ?

Answer 11

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

Question 12

Who discovered hypothermia with inflow occlusion ?

Answer 12

Dr. W.G. Bigelow

Question 13

Dr. John F. Lewis

Answer 13

• 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

Question 14

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

Answer 14

• ASDs

- Isolated aortic/pulmonic stenosis

Question 15

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

Answer 15

1958, WC Sealy, Duke University Medical Center

Question 16

Surface Cooling/Immersion work in what order?

Answer 16

Environment
Skin / Tissues
Blood Vessels

Question 17

Extracorporeal Blood Cooling worked in what order ?

Answer 17

Blood vessels
Skin / Tissues
Environment

Question 18

Hypothermia and cardiopulmonary bypass has effects on what 3 sectors?

Answer 18

Biochemical Reactions
Blood Viscosity
Changes in blood gases

Question 19

CPB + Hypothermia permits

Answer 19

lower pump flows,
less blood trauma,
better organ protection

Question 20

The concept of Q10

Answer 20

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

Question 21

Levels of Hypothermia

Mild:
Moderate
Deep
Profound

Answer 21

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

Question 22

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

Answer 22

Neonatal heart surgery
Aortic arch reconstruction
Neuro-surgical procedures

Question 23

Hypothermia ___ blood viscosity.

Answer 23

Increases

Question 24

Viscosity of blood ____ per °C

Answer 24

2 %

Question 25

Cooling and Warming gradients ?

Answer 25

Do not exceed 8-10°C

Question 26

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

Answer 26

perfusate and core temp

Question 27

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

Answer 27

venous blood and heater cooler waterbath

Question 28

3 Neuroprotective strategies in children undergoing CPB ?

Answer 28

- Deep hypothermia - Avoidance of long circulatory arrest times - Blood chemistries

Question 29

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

Answer 29

- HCT levels - COP - Blood Gas Strategies - Hyperoxia

Question 30

Change in the oxygen-hemoglobin dissociation curve. | Greater affinity = less efficient release of O2 at tissue level, what can we do?!?

Answer 30

Consider HYPEROXIA prior to circulatory arrest

Question 31

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

Answer 31

Decreases Decreases Increases

Question 32

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

Answer 32

Temperature Corrected

Question 33

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

Answer 33

Temperature Uncorrected

Question 34

An Essential Amino Acid | that plays an important part of catalytic sites in certain enzymes ?

Answer 34

Histidine

Question 35

Histidine Contains a positivily charged ? | The charge state can dictate the structure of the active site.

Answer 35

imidazole functional group

Question 36

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

Answer 36

protein buffering, largely due to the imidazole group of histidine

Question 37

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

Answer 37

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

Question 38

Alphastat Hypothesis

Answer 38

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

Question 39

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

Answer 39

- CO2 may counteract oxy-hemoglobin disassociation . curve | - CO2 is a potent cerebral vasodilator and promotes high CBF

Question 40

high CBF promotes ?

Answer 40

- More complete and homogeneous cooling | - Prevents cerebral steal due to aorto-pulmonary collateral's

Question 41

pH-stat method Goal:

Answer 41

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

Question 42

Alpha-stat method Goal:

Answer 42

Maintain pH = 7.40 in UNCORRECTED SAMPLE eg 37C degrees. Technically easy. Run normal ABG based upon results of sample

Question 43

Blood gas strategy for mild/moderate hypothermia?

Answer 43

Alpha-stat

Question 44

Blood gas strategy for deep hypothermia (pediatrics) ?

Answer 44

pH-stat

Question 45

Blood gas strategy for deep hypothermia (adult)

Answer 45

Alpha stat

Question 46

Blood gas strategy for all populations ?

Answer 46

Consider hyperoxia pre-arrest

Question 47

Careful attention during rewarming to avoid ?

Answer 47

cerebral hyperthermia

Question 48

Maintain hematocrits at ?

Answer 48

> 25%

Question 49

What are the 4 different modes ?

Answer 49

- Deep Hypothermic Circulatory Arrest (DHCA) - Selective Antegrade Cerebral Perfusion (SACP) - Regional Low flow - Retrograde cerebral perfusion (RCP)

Question 50

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

Answer 50

Alpha-Stat pH management

Question 51

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

Answer 51

ASD patients use Alpha Stat

Question 52

cross-over technique

Answer 52

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

Question 53

Update on Pediatric Perfusion Practice | in North America Minimal acceptable Hct ?

Answer 53

24 - 30%

Question 54

Update on Pediatric Perfusion Practice | in North America Termination Hct (cyanotic defects) ?

Answer 54

28 - 45%

Question 55

Update on Pediatric Perfusion Practice | in North America Termination Hct ( non cyanotic ) ?

Answer 55

21 - 35%