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CPB Cannulation > CPB Cannulation > Flashcards

CPB Cannulation Flashcards

1
Q

The arterial cannula is normally inserted ____ the venous cannula for CPB cases

A

BEFORE

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2
Q

Arterial cannula is usually the ____ part of the CPB Circuit

A

narrowest

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3
Q

what does high flow through narrow cannulas cause?

A

high pressure gradients, high velocity flow (jets), turbulence and cavitation

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4
Q

what does the performance index tell?

A

describes the relationship between pressure gradient and OD at any given flow

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5
Q

what should the pressure gradients always be less than?

A

less than 100 mmHg

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6
Q

If pressure gradients are greater than 100 mmHg, what is likely to happen

A

hemolysis and protein denaturation

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7
Q

small cannulas produce a jetting effect that do what 4 things

A
  1. may damage the interior aortic wall
  2. dislodge atheroemboli (sandblasting)
  3. cause arterial dissection
  4. disturb the flow into nearby vessels
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8
Q

what are the three arterial cannula tip designs?

A

tapered tip
curved tip
beveled straight tip

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9
Q

what are the 4 main sites of cannulation

A
  1. ascending aorta
  2. axillary or innominate artery
  3. femoral artery
  4. abdominal artery
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10
Q

what is the most common site for arterial cannulation

A

ascending aorta

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11
Q

what is the flow in ascending aorta arterial cannulation

A

flow is antegrade

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12
Q

why is the ascending aorta the most common site for arterial cannulation

A

easily accessible and low risk of dissection

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13
Q

what must be avoided when cannulating the ascending aorta with arterial cannula

A

avoid directing flow into head vessels

- can cause over perfusion of brain, stroke, and brain edema

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14
Q

where does arterial cannulation occur if the ascending aorta is diseased?

A

innominate or axillary artery

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15
Q

what does innominate artery arterial cannulation require

A

requires separate incision

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16
Q

what is the risk of cannulating in the innominate artery

A

risk for damage to brachial plexus and are ischemia

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17
Q

what kind of flow is running through the innominate artery

A

selective antegrade perfusion

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18
Q

what cannulation site is used for arterial cannulation in emergent situations and redo chest cases?

A

femoral artery

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19
Q

what is the arterial flow for cannulation in the femoral artery

A

arterial flow of blood is retrograde

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20
Q

what is the risk of cannulation in the femoral artery

A

retrograde dissection of aorta, limb ischemia, femoral artery laceration

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21
Q

what is abdominal arterial cannulation site used for

A

return of blood to lower body during left heart bypass

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22
Q

venous drainage is usually via _____ _____

A

gravity siphon

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23
Q

for gravity siphon to occur, what two things must you have

A
  1. reservoir must be below the level of the patient

2. venous lines must be fluid filled to prevent an “air lock”

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24
Q

the amount of venous drainage is determined by what two things

A
  1. patients CVP (patients blood volume)

2. heigh difference between top of blood level in venous reservoir and the table height at RA

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25
Q

the greater the height difference of the venous reservoir, the greater the ______

A

negative pressure of the siphon

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26
Q

patients CVP (patients blood volume) is affected by what two things

A
  1. intravascular volume

2. venous compliance, which is affected by medications, sympathetic tone, anesthesia

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27
Q

excessive venous drainage can also be looked at as

A

excessive negative pressure

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28
Q

what can excessive venous drainage cause

A

can cause the compliant veins to collapse around tip of the venous cannula

  • obstructs the venous blood from entering the cannula
  • decreases venous return
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29
Q

when you see “chattering” or “flutter” in the venous lines, what is happening?

A

venous drainage excessive, causing the veins to be sucked and collapsed around the venous cannula, therefore the venous blood can not enter the cannula

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30
Q

what can resolve “chattering” or “flutter” in the venous lines

A
  1. partially occluding venous line which keeps move cones blood in RA or caves
  2. increasing systemic blood volume by adding blood, crystalloid, albumin
  3. giving a vasoconstrictor to SVR, which increases blood in venous system
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31
Q

how much of blood volume is in the veins

A

2/3 of blood volume is in veins

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32
Q

what are the types of venous cannulas

A
  • single stage: straight or angled

- multi-stage: most common is the two-stage

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33
Q

what is the most common multi-stage venous cannula

A

two-stage (Cavo-Atrial)

1/3 flows from the SVC and 2/3 flows from IVC

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34
Q

what does the “M” number of cannulas tell us

A

the M number compared flow-pressure relationships in vascular devices

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35
Q

a cannula with a low M number indicates what

A

lower resistance and higher potential flows

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36
Q

ideal cannula should be: (4 things)

A
  1. thin walled
  2. stiff enough for insertion
  3. kink resistant
  4. marked to determine length
37
Q

what are the different cannula tip designs

A
  • swirl tip
  • beveled, right angered tip
  • straight, multi port tip
  • basket tip
38
Q

what are the sites for central venous cannulation

A
  1. bicaval
  2. cavoatrial
  3. single atrial
39
Q

what are the sites for peripheral venous cannulation

A
  1. neck

2. femoral vein

40
Q

what cannulation site is used whenever the right heart is going to be open

A

bicaval venous cannulation
2 separate cannulas, 1 in SVC and 1 in IVC
used with and without caval tapes

41
Q

what does “total CPB” or “caval occlusion” mean?

A

when caval tapes are “cinched down”, all systemic venous blood enters the 2 cannulas

42
Q

Describe what cavoatrial venous cannulation consist of

A

single cannula with 2 ports into RA and IVC

-purse string placed into right atrial appendage

43
Q

what is cavoatrial venous cannulation most commonly used for?

A

CABG, AVR, AATA surgeries

44
Q

describe what single atrial venous cannulation is and when it is most commonly used

A

1 cannula into RA appendage

-more commonly used in pediatric cases

45
Q

what venous cannulation is used for ECMO

A

neck peripheral venous cannulation

46
Q

Describe femoral vein venous cannulation and when it is used

A
  • multiport long thin cannula
  • inserted all the way to RA or into SVC
  • used for ECMO, redo sternotomy, minimally invasive (access) surgeries
47
Q

LSVC is present in ____% of the population and ____% with _____

A

LSVC is present in 0.3-0.5% of the population and 2-10% of CHD patients
-sometimes no RSVC present

48
Q

where does the LSVC drain into

A

coronary sinus and then into right atrium

-10% drain into left atrium (most have an associated ASD)

49
Q

what are problems during CPB that come with LSVC (4)

A
  1. confounds passage of PA catheter due to large size of LSVC
  2. interfere with retrograde CPG delivery due to size of coronary sinus - washout of CPG
  3. Blood will enter RA and flood the field of view
  4. RA will distend during total CPB if not adequately vented
50
Q

what are the 3 methods of augmented venous return

A
  1. Roller pump
  2. Kinetic (centrifugal)
  3. vacuum assisted
51
Q

where is the roller pump in the perfusion circuit

A

between the venous cannula and the venous reservoir

52
Q

why is the roller pump no longer used

A

high risk of generating excessive negative pressure and collapsing the RA or caves
-pulls air out of solution and into cardiotomy

53
Q

describe kinetic (centrifugal) pump

A

systemic (centrifugal) pump positioned between the venous cannula and venous reservoir actively pumps blood from the pt into the venous reservoir

54
Q

what should be done before intiating CPB on a centrifugal pump

A

eliminate all air in the venous circuit

55
Q

on centrifugal pump, the negative pressure should be monitored _____ to the venous pump

A

monitored 10 cm before the inlet to the venous pump

56
Q

what kind of reservoir is used during vacuum assisted venous drainage

A

closed hard shell venous reservoir

57
Q

when using a vacuum assisted drainage, the negative pressure should not exceed how many mmHg?

A

-60- -100

58
Q

when should vacuum not be applied?

A

when there is no forward flow through the oxygenation to prevent air being pulled across the microporous oxygenator into the blood path

59
Q

the total negative pressure (gravity and applied vacuum) should not be more than

A

-100 mmHg

60
Q

complications associated with achieving venous drainage (7)

A
  1. atrial dysrhythmias
  2. lacerations and bleeding of right atrium
  3. air embolism (especially if RA pressure is low)
  4. lacerations of vena cava
  5. malposition of tips of cannulas
  6. cava tapes can cause lacerations
  7. cavae may become obstructed
61
Q

How do the cavas become obstructed in regards to venous drainage

A

if there is venous drainage, the cava can become obstructed when purse-string sutures placed in cava are closed after cannula is removed

62
Q

what are the causes of low venous return (4)

A
  1. reduced venous pressure
  2. inadequate height of patient above venous reservoir
  3. malposition of venous cannulas
  4. obstruction or excessive resistance in lines or cannulas (kinks, air locks, too small of cannula)
63
Q

what are normal sources of blood returning to LV

A
  • bronchial blood (normally drains into pulmonary veins - 140 ml/min)
  • thebesian veins (about 50 ml/min)
  • blood returning to RA that gets around venous cannulas and passes through pulmonary circuit
  • coronary venous return
64
Q

abnormal sources of blood returning to LV

A
  • persistent LSVC
  • patent ductus arteriosus (PDA)
  • systemic - to - PA shunt
  • ASD or VDS
  • anomalous systemic venous drainage
  • aortic regurgitation
65
Q

when the cannula is inside the heart, what do you go on

A

go on green

66
Q

Venting the right heart must be done via what

A

decompression is usually via venous cannulas

67
Q

when bicaval cannulation with caval tapes is used, the ______ must be released or a ______ must be used in venting the right heart

A

the caval tapes must be released or a RA vent must be used

68
Q

venting the left heart is important to….

A
  • prevent LV disention
  • reduce myocardial rewarming (reduce myocardial oxygen demand)
  • prevent cardiac ejection of air
  • prevent pulmonary venous hypertension
  • facilitate surgical exposure
69
Q

where are the 5 methods of venting the left heart

A
  1. ascending aorta
  2. indirect LV vent
  3. direct LV vent
  4. direct LA appendage
  5. pulmonary artery vent
70
Q

how is venting the left heart through the descending aorta done

A

one limb of the “Y” is connected to the cardioplegia admin system and the other limb to suction (siphon or roller pump) for venting left heart

71
Q

the ascending aorta is used to vent the left heart but it is also used to vent what

A

vent air when aorta is unclamped and when LV start to eject

72
Q

what can the ascending aorta vent be used to monitor

A

AO root infusion pressure

73
Q

ascending aorta vent only works when….

A

the aorta is cross clamped

74
Q

the ascending aorta vent does not work during….

A

antegrade CPG infusion

75
Q

Where is the indirect LV vent placed

A

inserted into the ruction of the right superior pulmonary veins (RSPV) and left atrium and advanced through the left atrium and mitral valve into the left ventricle

76
Q

what is the indirect LV vent best used for

A

BEST for AI (aortic insufficiency)

-handles all sources of blood causing LV distention

77
Q

the indirect LV vent provides optimal ______ of the LV

A

decompression

78
Q

pro and con of indirect LV vent

A

pro: avoids problems of direct LV vent
con: potential air entry into LV

79
Q

where is the direct LV vent placed in venting the left heart

A

cannula is placed directly in apex of LV

80
Q

what is the pros of direct LV vent

A
  • avoids getting across prosthetic mitral valve

- handles all sources of blood causing LV distension

81
Q

what is the cons of DIRECT LV vent

A
  • tip may become obstructed
  • bleeding for LV incision site
  • potential for embolism if clots in LA
  • potential for air entrainment into left heart
82
Q

pros and cons of direct LA appendage vent

A

pros: avoids getting across MV
cons: does not handle AI, potential for embolism if LA clots present, potential for air entry into left heart

83
Q

Where is the pulmonary art vent placed to help with venting the left heart

A

inserted into the pulmonary artery

84
Q

pros and cons of Pulmonary art vent

A

pros: reduces risk of air entry into left heart
cons: does not handle AI, can’t measure PA pressure accurately, risk of damage and bleeding from pulmonary artery

85
Q

what are complications associated with venting left heart (3)

A
  1. introduction of air into left heart
  2. errors in function of the vent
  3. bleeding and damage to heart
86
Q

when does air into left heart usually occur

A
  • during insertion and removal of vent if the left heart volume is low
  • excessive suction by air being drawn from around the purse string sutures
87
Q

what must happen in order to prevent air into left heart

A

fill the heart before insertion and removal of vent

88
Q

what are errors in the function of the vent that could happen

A
  1. sucker in reverse direction causing a pumping of air and not sucking of air
  2. positive pressure in venous reservoir, therefore 1-way valve must be used

CPB Cannulation (1 decks)

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