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CVPR 326 Pediatric Perfusion > Flow reduction and cessation in infant and pediatric cardiac surgery / Pedi Test 2 > Flashcards

Flow reduction and cessation in infant and pediatric cardiac surgery / Pedi Test 2 Flashcards

1
Q

Ground squirrel

– Respiratory rate drops from 200 per min to

A

4 to 5 per min, HR from

150 to 5.

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2
Q

Wood Chuck Drops its body temperature more than ?

A

30°

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3
Q

Jumping Mouse

– Reduce heart rate from 500 to 600 BPM to

A

30 BPM

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4
Q

O2 Consumption Vs. Temperature
y axis = O2 comsumption
x axis = Perfusion flow rate

What is the summary of this graph?

A

The colder we make he patient, the less requirements for oxygen, which allows us to decrease our flow rate.

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5
Q

Myocardial oxygen uptake of the
Beating heart at 37° celcius?

Beating heart:
Fibrillating heart:
Arrested heart:

A

Beating heart: 5.5 L/m
Fibrillating heart: 6.5 L/m
Arrested heart: 1 L /m

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6
Q

Myocardial oxygen uptake of the
Beating heart at 32° celcius?

Beating heart:
Fibrillating heart:
Arrested heart:

A

Beating heart: 5.0 L/m
Fibrillating heart: 4 L/m
Arrested heart: .75 L /m

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7
Q

Myocardial oxygen uptake of the
Beating heart at 28° celcius?

Beating heart:
Fibrillating heart:
Arrested heart:

A

Beating heart: 4 L/m
Fibrillating heart: 3 L/m
Arrested heart: .50 L/m

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8
Q

Myocardial oxygen uptake of the
Beating heart at 22° celcius?

Beating heart:
Fibrillating heart:
Arrested heart:

A

Beating heart: 3 L/m
Fibrillating heart: 2 L/m
Arrested heart: .25 L/m

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9
Q

What does CMRO2 stand for ?

A

Cerebral Metabolic Rate of O2

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10
Q

CMRO2 drops as the temperature drops from 37 to 14 degrees. What is the drop of CMRO2

A

from 100% to 10%

then goes back up to 100% as we return to 37 degrees.

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11
Q

The fundamental effects of hypothermia is

A

the progressive reduction of molecular movement through, passive transport and active transport.

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12
Q

Q10

A

reaction rate changes for every 10°C change in temperature

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13
Q

Simple diffusion

A

Through solution, down the gradient

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14
Q

Facilitated diffusion:

A

across a membrane, down the gradient, via membrane carriers

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15
Q

Active Transport :

A

Transport across membranes, up concentration gradient, via pumps and ATP

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16
Q

Hypothermia reduces metabolic rate and facilitates:

A

– Reduced blood flow
– Reduced blood trauma
– Reduced surface contact (blood to circuit)
– Safety buffer

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17
Q

Hypothermia reduces metabolic rate and facilitates a safety buffer that could be caused by :

A
  • Accident

* Regional perfusion deficits

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18
Q

The virtues of hypothermia come at a cost, Disruptions may occur due to differential
reduction of transport mechanisms such as ?

A
  • Electrochemical gradients

* Osmotic gradients

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19
Q

A technical reason for reducing flow is the presence of collateral blood flow caused by ?

A

– Wash out cardioplegia

– Increase tissue temperature – Cerebral steal

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20
Q

A technical reason for reducing flow is a small playing field ?

A

Tiny hearts with big
cannulas make for poor visualization and
unsuccessful surgeries

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21
Q

Congenital Heart Defects with reduced pulmonary blood flow ?

A 
Tricuspid Atresia 
Tetralogy of Fallot
TAPVR
Pulmonary Stenosis
Ebstein's Malformation
22
Q

2 Technical approaches to reducing flow ?

A

Low Flow Cardiopulmonary Bypass (LFCPB)

Deep Hypothermic Circulatory Arrest (DHCA)

23
Q

During the clinical testing of LFCPB vs. DHCA, what were the findings:

A

DHCA had a significantly higher incidence of seizure

24
Q

The estimated probabilities of definite seizures in infants following repair of transposition of the great arteries with VSD or intact ventricular septum (IVS). Which group had a higher incidence for seizures post circulatory arrest ?

A

Patients with VSDs

25
Q

Ictal definition ?

A

relating to or caused by a stroke or a seizure

26
Q

In regards to our biochemical parameters, we can expect an increased Lactate release during?

27
Q

In regards to our biochemical parameters, we can expect an increased release of isoenzyme ______ 6 degrees s/p surgery.

A

CK an enzyme marker of myocellular injury

28
Q

CMVO2 definition ?

A

Cerebral mixed venous oxygen saturation.

29
Q

CMVO2 returns to normal in ?

A

2-4 hours after profound hypothermia

30
Q

Cerebral vascular resistance (CVR) Remains elevated for ?

A

6-8 hour after

profound hypothermia

31
Q

What where the outcomes for Children randomized to DHCA (especially with VSD) ?

A

lower developmental scores at 1 year and 2.5 years

32
Q

During LFCPB with flows less than 30 ml/kg, what can we expect ?

A 
– Undetectable flow using 
   Trans Cranial Doppler
– Reduced cerebral oxygen  
   consumption 
– Development of Oxygen debt in the brain
33
Q

During LFCPB with flows less than 30 ml/kg, why can we expect a development of Oxygen debt in the brain?

A

results from anaerobic metabolism

34
Q

4 Proper techniques for LFCPB ?

A 
• Even Cool (long time)
• Use appropriate blood gas 
  strategy 
• Pack head in ice ?
• Maintain blood flow greater 
  the 30 ml/kg
35
Q

If blood flow is creating a real problem for the surgeon what can we do ?

A

DHCA may be better than a sub-par surgical repair

36
Q

Proper techniques for LFCPB maintains continuous blood flow but may expose brain to ?

A

increased embolic load (bad)

37
Q

In an attempt to avoid DHCA and try to palliate a CHD patient, what will delaying the surgery lead to ?

A

• Increased collateral vessel development
• the patient continues to
suffer from secondary effects on the central nervous system, the pulmonary arteries, the airways, and the heart itself.

38
Q

In the safe circulatory arrest times vs. temperatures graph, we can assume that ?

A

The colder we get down to 18 degrees, the longer the duration of total circulatory arrest.

At 18 degrees = 45 min of safe total circulatory arrest with 70% probability.

39
Q

The predicted safe duration of HCA at 15 degrees C is only

40
Q

Subjects were reperfused for 20 minutes at 20°C and then rewarmed with (cold reperfusion). This study resulted in what?

A

↓ cerebral edema &
↓ Intracranial pressures

Diastolic flow velocity returns after 20 min

41
Q

With DHACA we may reduce the embolic load on the brain (good), but ?!?!?

A

DHCA interrupts cerebral blood flow (bad)

42
Q

7 proper techniques for DHCA?

A 
• Even cooling 
• Pack head in ice
• Appropriate blood gas  
  management
• Pharmacology
– steroids and/or barbiturates
• Minimize arrest time (periodic reperfusion?) 
• Cold reperfusion
• Respect the 6 degree temperature gradients when warming.
43
Q

HCT vs. Cerebral blood flow graph conclusion ?

A

Hgb concentration of 7 to 9 produced a higher cerebral blood flow.

44
Q

During Hypothermia Blood viscosity increases (capillary sludging), Therefore CBF would ?

A

↓ CBF

↓ CDO2 (O2 delivery)

45
Q

During Hypothermia, how can we Counteract temperature mediated increased viscosity ?

A

By decreasing HCT to

Maintain CBF which would lead to ↑ CDO2.

46
Q

Cerebral ischemia does not result from

A

low Hct perfusion

47
Q

Severe hemodilution (10%) results in what?

A

inadequate cerebral tissue oxygenation during cooling

48
Q

Higher Hcts greatly reduced priming of

A

leukocytes

49
Q

Higher Hct does not impair CBF

A

( 10,20, and 30% Hct)

Greater Oxygen delivery is good

50
Q

During Hct. Vs. Temp the Difference between 15 and 25 degrees was ?

51
Q

Blood is appropriate solution for

A

buffering ischemic environment

52
Q

Cerebral ischemia has been shown, following what?

A

low hct perfusion

CVPR 326 Pediatric Perfusion (23 decks)

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