GENERAL TOPICS IN PERFUSION

Maria Helena L. Souza, CCP (Br)

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QUESTIONS

1. All of the following represent complications arising from the use of roller pumps, except:

miscalibration
runaway pumping
spallation
spontaneous retrograde flow
tubing fracture

2. All of the following statements concerning gas diffusion are true, except:

A. The rate of diffusion is proportional to the partial pressure gradient of the gas in the direction of diffusion
B. Diffusion of gases is dependent upon a constant of diffusivity
C. The diffusivity is constant for a particular gas and diffusion barrier material
D. The diffusivity is directly proportional to the square root of the molecular weight of the gas
E. The diffusivity of a gas is related to the solubility of the gas

A
B
C
D
E

3. Regarding gas transfer across a membrane oxygenator, all of the following statements are correct, except:

A. membrane oxygenators have much smaller surface area than the natural lungs
B. membrane oxygenators allow for gas diffusion as well as the natural lungs
C. Most membrane oxygenators actually use microporous membranes for gas transfer
D. Standards have been developed for assessing gas transport capacities of membrane oxygenators
E. The membrane oxygenators show absence of a direct blood-gas interface once the membrane develops a proteinaceous coating

A
B
C
D
E

4. A left superior vena cava is present in about 0.3% to 0.5% of the general population but in 2% to 10% of patients with congenital heart disease. It usually drains into the:

coronary sinus
left atrium
inferior vena cava
right superior vena cava
none of the above

5. Recently, there has been a renewed interest in use of regulated suction to overcome the resistance of longer and/or narrower venous cannulas used during limited cardiac access operations. Venous return in these circumstances can be augmented by:

A. a roller pump placed in the venous line between the venous cannula and the venous reservoir
B. a kinetic (centrifugal) pump placed in the venous line between the venous cannula and the venous reservoir
C. applying a regulated vacuum to a closed hard-shell venous reservoir attache tot he venous line
D. all of the above
E. none of the above

A
B
C
D
E

6. The arterial cannula is usually the narrowest part of the extracorporeal circuit. High flow through narrow cannulas may lead to all of the following, except:

high pressure gradients
platelet agglutination
high velocity of flow
turbulence
cavitation

7. During CPB a variety of acute changes can occur with some hormones. Considering thyroid function, the number of beta-adrenergic receptors and their sensitivity to agonists is regulated by:

T3
T4
thyrotropin
all of the above
none of the above

8. Before CPB, small increases in free T3 and free T4 hormones are produced by the administration of:

halothane
dopamine
heparin
beta blockers

9. Much like calcium, magnesium in the blood exists in three fractions, distributed as in:

A. ionized 55%, chelated 15%, protein bound 30%
B. ionized 30%, chelated 55%, protein bound 15%
C. ionized 15%, chelated 30%, protein bound 55%
D. ionized 20%, chelated 30%, protein bound 50%
E. ionized 10%, chelated 40%, protein bound 50%

A
B
C
D
E

10. During and after CPB potassium flux is influenced by all of the following conditions, except:

myocardial protectant solutions
priming solutions
arterial pH
hypothermia
hemoglobin concentration

11. A blood pump for animal and clinical use was developed in collaboration with the General Motors Co in Detroit. The device was designed as a right, left or combined heart bypass with autologous lung oxygenation. This resulted from the work of:

Dodrill
Helmsworth
Lillehei
Dennis
Clowes

12. Roller pumps contain a lenght of tubing located inside a curved raceway. All of the following are correct in respect to roller pumps, except:

A. The raceway is placed at the travel perimeter of rollers mounted on the ends of rotating arms
B. By compressing a segment of blood-filled resilient tubing, blood is pushed ahead of the moving roller, thereby producing continuous blood flow
C. The output of the rotary pump is determined by the revolutions per minute of the pump and the volume displaced with each revolution
D. The output of the roller pumps is independent of size and lenght of the track
E. Roller pumps may have one, two or three rollers

A
B
C
D
E

13. When considering the occlusiveness of roller pumps, all of the following statements are correct, except:

A. Occlusion can be adjusted by either increasing or decreasing the compression of the tubing by the rollers
B. Excessive compression induces hemolysis and tubing wear
C. Too little occlusion may produce hemolysis and compromise forward output
D. At nonocclusive settings, roller pump output can be sharply decreased, resulting in hypoperfusion
E. Adjusting tubing compression to be barely nonocclusive results in the most hemolysis

A
B
C
D
E

14. All of the following statements represent disadvantages of roller pumps, except:

A. occlusion variability does not affect flow rate and blood trauma
B. possibility of circuit disruption from excessive line pressure
C. particulate microemboli from tubing spallation
D. contraindicated for long-term use because of tubing wear
E. Increased blood trauma

A
B
C
D
E

15. Regardless of the type of oxygenator, gas transfer from the gas to the liquid phase (or the opposite direction) is driven by diffusion according to the partial pressure difference of the particular gas. Gas transfer is limited by the resistance to diffusion of the particular gas through the primary substance, whether it is a synthetic membrane, blood, or the gas phase itself.

True
False

16. Regarding the principles of heat transfer answer the question using the key outlined below:

A. if 1, 2, and 3 are correct
B. if 1 and 3 are correct
C. if 2 and 4 are correct
D. if only 4 is correct
E. if all four are correct

1. Heat transfer represents the transfer of kinetic energy from molecules with a higher energy to molecules with a lower energy.
2. Heat transfer actually represents the transfer of kinetic energy from the higher energy source to the lower.
3. Within CPB heat exchanger, the major forms of heat transfer are forced convection and conduction.
4. The flow of energy or heat is independent of temperature.

A
B
C
D
E

17. Regarding true membrane oxygenators answer the question using the key outlined below:

A. if 1, 2, and 3 are correct
B. if 1 and 3 are correct
C. if 2 and 4 are correct
D. if all four are correct

1. true membrane oxygenators provide a complete barrier between the gas and blood phases so that gas transfer depends totally on diffusion of gas through the membrane material.
2. true membranes oxygenators are costly to manufacture and have a large priming volume.
3. the only true membrane oxygenator in clinical use today is the Kolobow spiral coil membrane oxygenator.
4. the spiral coil membrane oxygenator is primarily indicated for long term extracorporeal oxygenation.

A
B
C
D
E

18. The ideal extracorporeal oxygenator transfers oxygen and carbon dioxide out of the body at physiologic blood flow rates with minimal blood trauma and a large priming volume.

True
False

19. All of the following may be due to the presence of a left superior vena cava during cardiac surgery, except:

A. it may confuse and complicate the passage of a pulmonary artery catheter
B. it may interfere with the administration of retrograde cardioplegic solution
C. it does not interfere with right heart drainage
D. the innominate vein may be absent in presence of a left superior vena cava
E. atrial surgery requires additional cannulation of the left superior vena cava

A
B
C
D
E

20. The highest acceptable pressure gradient across the arterial cannula is:

200 mmHg
150 mmHg
100 mmHg
50 mmHg
25 mmHg

C.E.Quiz is dedicated to the Continuing Education in Extracorporeal Technology.

Your comments on C.E. Quiz are appreciated. Please contact: Maria Helena L. Souza