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Perfusion Circuits > Pumps and Heat Exchangers > Flashcards

Pumps and Heat Exchangers Flashcards

1
Q

In an ideal pump, the flow should be able to reach up to ____?

A

7 Liters/minute

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2
Q

what are other ideal characteristics to have on a pump?

A
  • minimal blood hemolysis
  • limited turbulence or stasis
  • disposable if direct contact with blood
  • exact and reproducible flow calibration
  • manual hand crank
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3
Q

Roller displacement pumps have a ___ raceway with ____ _____ tubing

A

curved raceway

length flexible tubing

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4
Q

Describe the set up of roller displacement pumps

A

two rollers mounted ends rotating arms, 180 degrees apart allowing contact of tubing at one location at all times

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5
Q

how does the roller displacement pumps move fluid

A

roller compresses tubing against racing pushing fluid ahead of moving roller

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6
Q

what three things determine fluid flow of roller displacement pumps

A
  1. occlusion of roller
  2. revolutions per minute (RPM)
  3. tubing size
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7
Q

how do you change occlusions?

A

by adjusting rollers compress tubing

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8
Q

what can over occlusion cause?

A

cause hemolysis and tubing wear

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9
Q

what can under occlusion cause?

A

it can compromise forward flow to patient

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10
Q

what are the three different methods to test roller pump occlusion?

A
  1. fluid drop method
  2. pressure drop method
  3. Dynamic occlusion method
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11
Q

how do you conduct the fluid drop method?

A
  • arterial line raised 30 inches above pump head
  • slightly loosen occlusion let fluid fall slowly
  • gently tighten occlusion until fluid just stops falling
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12
Q

what should the drop rate be for the roller pump occlusion?

A

drop rate 1 inch/min

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13
Q

when testing the roller pump occlusion, you should _____ and check in ___ locations

A

rotate rollers and check in 6 locations

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14
Q

fluid column for fluid drop method is how high above pump

A

30 cm

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15
Q

Describe the pressure drop method

A

build pressure in system and watch pressure in transducer 180-300 mmHg
turn the pump off and watch the pressure drop

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16
Q

what do you have to have in order to move the blood forward?

A

have to have occlusion in order to compress the tubing to move the blood forward

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17
Q

what is the roller displacement pump also known as?

A

positive displacement pump

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18
Q

how will wrong occlusion affect displacement

A

wrong occlusion will not displace amount of blood

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19
Q

what is runaway pump

A

motor staff comes disconnected from machine and just continues to spin faster and faster

  • no safety devices can stop it
  • must turn circuit breaker off
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20
Q

definition of cavitation of air

A

sucking air out of solution

-different from air from the atmosphere because caveated air will just go back into solution

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21
Q

name complications of roller pumps (7)

A 
improper occlusions
calibration errors
sapallation
loss of power
runaway pump 
over pressurization 
cavitation of air
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22
Q

what is the centrifugal rotary pumps used for

A

main arterial head

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23
Q

the ____ the resistance in the centrifugal rotary pumps, the _____ flow

A

higher the resistance, less flow

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24
Q

what kind of pump does a centrifugal rotary pump have?

A
  • non occlusive pump
  • smooth plastic cones or vane impeller contained in polycarbonate housing
  • magnet located in both disposable pump and in pump console
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25
Q

____ causes fluid movement in centrifugal pump

A

rotation

26
Q

centrifugal pumps are ____ and ____ dependent

A

pre load and after load dependent

27
Q

what kind of flow probe does the biomedicus use?

A

electromagnetic

everything else uses ultrasonic

28
Q

how does ultrasonic flow measurement work?

A
  • no direct blood contact

- measures flow based on Doppler principle or ultrasound transit-time

29
Q

How does electromagnetic flow measurement work?

A
  • direct blood contact

- flow measured by electromagnetic flow principle

30
Q

what is essential to have for the McKay rotoflow pump?

A

gel for pump

-pump usually built into the base of the machine

31
Q

what are complications with the centrifugal pump?

A

power loss
depriming of cone
magnet decoupling
inadvertent outflow obstruction, kink line or clamp results in no/low flow of patient
retrograde flow = exsanguination of patient with no/low RPMs or line clamp

32
Q

what does depriming of cone in centrifugal pump mean

A

air in cone, will not generate flow

33
Q

what is retrograde flow

A

flow reverse back into the body

34
Q

how were heat exchangers used in the early days?

A

only used to keep patient warm

35
Q

in the early days, how did you lose heat from patient?

A

open chest
respiration
perfusion circuit with no integral heat exchanger

36
Q

early model heat exchangers were ____ and made out of what three things?

A

were reusable

made out of glass, steel, and other materials

37
Q

what were the development of disposable heat exchangers due to

A

pyrogenic reactions

difficulty in cleaning

38
Q

how does heat transfer work on the heat exchanger?

A

energy is transferred into and out of HE by non sterile water that is circulated by a Heater Cooler unit attached to the oxygenator by tubing or “lines”

39
Q

how is the water heated in the heat exchanger?

A

by heating unit in H/C

40
Q

how is the water cooled?

A

ice is added to cool

41
Q

water provides _____ of temperature with no _____

A

provides even distribution of temperature with no hot spots

42
Q

what materials are used

A

stainless steel
pvc tubing coil
polyurethane
polyethylene terephthalate (PET)

43
Q

what is the surface area of the heat exchanger

A

large size
folding of material increases surface area
could tube (PVC in ice bucket)

44
Q

what does having a larger surface area help?

A

better transfer

45
Q

what is conduction method

A

takes place where when there is a difference in temperature (temp gradient)

  • is proportional to the difference in temperature
    ex: a spoon in cup of hot water
46
Q

what is convection method

A
  • mass movement of molecules from one place to another
  • great effect on patient in OR from a cold room with open chest
    ex: ovens
47
Q

what are the two mechanisms of heat exchanger during CPB

A
  • forced convection as water and blood flow past stainless steel interface
  • conduction within the stainless steel components
  • heat exchanged into or out of blood and thus into or out of patient
48
Q

the rate or warming is limited during CPB due to

A
  • microair formation
  • as any fluid is heated, any air dissolved in solution will become less soluble which will result in air coming out of solution when fluid temperature increases rapidly
49
Q

blood damage is caused due to blood protein denaturation as temperatures reach

A

42”

50
Q

increasing temperature may cause ______ while trying to warm ______

A

may cause neurological damage while trying to warm peripheral vascular beds

51
Q

periphery warms ____ than major organs

A

slower than

52
Q

the brain has been shown to be about ______ warmer than the _________ temperature

A

2” warmer than the nasopharyngeal temperature

53
Q

what are the water sources for the heat exchanger

A
  • wall water, but can be difficult to regulate temperature and pressure
  • units have one water bath for both heating and cooling
54
Q

what are the separate compartments on dual heater cooler units

A

heating & cooling

  • some make own ice
  • some add ice to
55
Q

Explain the Sarns Dual Cooler Heater operation

A
  • cooling mode has 4 settings which will change water flow
  • water travels through ice tank
  • recirculation mode is a sing setting: water travels through heating manifold with the heating element off
  • heating mode has 4 temperature settings that are preset
56
Q

what are the 4 preset temperature setting on the Sarns

A

30, 38, 40, 42 (+ or -2 degrees)

57
Q

what is important to remember about LivaNova Sorin 3T

A

powered on its own circuit breaker (20 amp) for bother heater cooler and pump

58
Q

Features of the Sorin 3T

A
  • separate warm and cold cardioplegia tanks
  • compressor based cooling
  • independent safety system that prevents water temperature from reaching critical values
  • two chamber pumps minimize any pressure inside the heat exchanger
  • water evacuation feature enables emptying of the heat exchanger and tubing for a spill proof clean up
59
Q

Features of Cardioquip MCH 1000

A
  • 1600W heater delivers efficiency and performance
  • patented adaptive temperature control TM technology
  • insulated and valved cold water tank
  • temperature precision to 0.1 degree
  • customizable pump speeds
  • open water path
60
Q

Precautions using Heater/Cooler systems

A
  • do not turn on unit to recirculate unless the water lines are connected
  • H/C requires its OWN electrical outlet of 20 AMP

Perfusion Circuits (5 decks)

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