CPB Cannulation Flashcards
1
Q
The arterial cannula is normally inserted ____ the venous cannula for CPB cases
A
BEFORE
2
Q
Arterial cannula is usually the ____ part of the CPB Circuit
A
narrowest
3
Q
what does high flow through narrow cannulas cause?
A
high pressure gradients, high velocity flow (jets), turbulence and cavitation
4
Q
what does the performance index tell?
A
describes the relationship between pressure gradient and OD at any given flow
5
Q
what should the pressure gradients always be less than?
A
less than 100 mmHg
6
Q
If pressure gradients are greater than 100 mmHg, what is likely to happen
A
hemolysis and protein denaturation
7
Q
small cannulas produce a jetting effect that do what 4 things
A
- may damage the interior aortic wall
- dislodge atheroemboli (sandblasting)
- cause arterial dissection
- disturb the flow into nearby vessels
8
Q
what are the three arterial cannula tip designs?
A
tapered tip
curved tip
beveled straight tip
9
Q
what are the 4 main sites of cannulation
A
- ascending aorta
- axillary or innominate artery
- femoral artery
- abdominal artery
10
Q
what is the most common site for arterial cannulation
A
ascending aorta
11
Q
what is the flow in ascending aorta arterial cannulation
A
flow is antegrade
12
Q
why is the ascending aorta the most common site for arterial cannulation
A
easily accessible and low risk of dissection
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
14
Q
where does arterial cannulation occur if the ascending aorta is diseased?
A
innominate or axillary artery
15
Q
what does innominate artery arterial cannulation require
A
requires separate incision
16
Q
what is the risk of cannulating in the innominate artery
A
risk for damage to brachial plexus and are ischemia
17
Q
what kind of flow is running through the innominate artery
A
selective antegrade perfusion
18
Q
what cannulation site is used for arterial cannulation in emergent situations and redo chest cases?
A
femoral artery
19
Q
what is the arterial flow for cannulation in the femoral artery
A
arterial flow of blood is retrograde
20
Q
what is the risk of cannulation in the femoral artery
A
retrograde dissection of aorta, limb ischemia, femoral artery laceration
21
Q
what is abdominal arterial cannulation site used for
A
return of blood to lower body during left heart bypass
22
Q
venous drainage is usually via _____ _____
A
gravity siphon
23
Q
for gravity siphon to occur, what two things must you have
A
- reservoir must be below the level of the patient
2. venous lines must be fluid filled to prevent an “air lock”
24
Q
the amount of venous drainage is determined by what two things
A
- patients CVP (patients blood volume)
2. heigh difference between top of blood level in venous reservoir and the table height at RA
25
the greater the height difference of the venous reservoir, the greater the ______
negative pressure of the siphon
26
patients CVP (patients blood volume) is affected by what two things
1. intravascular volume
| 2. venous compliance, which is affected by medications, sympathetic tone, anesthesia
27
excessive venous drainage can also be looked at as
excessive negative pressure
28
what can excessive venous drainage cause
can cause the compliant veins to collapse around tip of the venous cannula
- obstructs the venous blood from entering the cannula
- decreases venous return
29
when you see "chattering" or "flutter" in the venous lines, what is happening?
venous drainage excessive, causing the veins to be sucked and collapsed around the venous cannula, therefore the venous blood can not enter the cannula
30
what can resolve "chattering" or "flutter" in the venous lines
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
31
how much of blood volume is in the veins
2/3 of blood volume is in veins
32
what are the types of venous cannulas
- single stage: straight or angled
| - multi-stage: most common is the two-stage
33
what is the most common multi-stage venous cannula
two-stage (Cavo-Atrial)
| 1/3 flows from the SVC and 2/3 flows from IVC
34
what does the "M" number of cannulas tell us
the M number compared flow-pressure relationships in vascular devices
35
a cannula with a low M number indicates what
lower resistance and higher potential flows
36
ideal cannula should be: (4 things)
1. thin walled
2. stiff enough for insertion
3. kink resistant
4. marked to determine length
37
what are the different cannula tip designs
- swirl tip
- beveled, right angered tip
- straight, multi port tip
- basket tip
38
what are the sites for central venous cannulation
1. bicaval
2. cavoatrial
3. single atrial
39
what are the sites for peripheral venous cannulation
1. neck
| 2. femoral vein
40
what cannulation site is used whenever the right heart is going to be open
bicaval venous cannulation
2 separate cannulas, 1 in SVC and 1 in IVC
used with and without caval tapes
41
what does "total CPB" or "caval occlusion" mean?
when caval tapes are "cinched down", all systemic venous blood enters the 2 cannulas
42
Describe what cavoatrial venous cannulation consist of
single cannula with 2 ports into RA and IVC
| -purse string placed into right atrial appendage
43
what is cavoatrial venous cannulation most commonly used for?
CABG, AVR, AATA surgeries
44
describe what single atrial venous cannulation is and when it is most commonly used
1 cannula into RA appendage
| -more commonly used in pediatric cases
45
what venous cannulation is used for ECMO
neck peripheral venous cannulation
46
Describe femoral vein venous cannulation and when it is used
- multiport long thin cannula
- inserted all the way to RA or into SVC
- used for ECMO, redo sternotomy, minimally invasive (access) surgeries
47
LSVC is present in ____% of the population and ____% with _____
LSVC is present in 0.3-0.5% of the population and 2-10% of CHD patients
-sometimes no RSVC present
48
where does the LSVC drain into
coronary sinus and then into right atrium
| -10% drain into left atrium (most have an associated ASD)
49
what are problems during CPB that come with LSVC (4)
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
what are the 3 methods of augmented venous return
1. Roller pump
2. Kinetic (centrifugal)
3. vacuum assisted
51
where is the roller pump in the perfusion circuit
between the venous cannula and the venous reservoir
52
why is the roller pump no longer used
high risk of generating excessive negative pressure and collapsing the RA or caves
-pulls air out of solution and into cardiotomy
53
describe kinetic (centrifugal) pump
systemic (centrifugal) pump positioned between the venous cannula and venous reservoir actively pumps blood from the pt into the venous reservoir
54
what should be done before intiating CPB on a centrifugal pump
eliminate all air in the venous circuit
55
on centrifugal pump, the negative pressure should be monitored _____ to the venous pump
monitored 10 cm before the inlet to the venous pump
56
what kind of reservoir is used during vacuum assisted venous drainage
closed hard shell venous reservoir
57
when using a vacuum assisted drainage, the negative pressure should not exceed how many mmHg?
-60- -100
58
when should vacuum not be applied?
when there is no forward flow through the oxygenation to prevent air being pulled across the microporous oxygenator into the blood path
59
the total negative pressure (gravity and applied vacuum) should not be more than
-100 mmHg
60
complications associated with achieving venous drainage (7)
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
How do the cavas become obstructed in regards to venous drainage
if there is venous drainage, the cava can become obstructed when purse-string sutures placed in cava are closed after cannula is removed
62
what are the causes of low venous return (4)
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
what are normal sources of blood returning to LV
- 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
abnormal sources of blood returning to LV
- persistent LSVC
- patent ductus arteriosus (PDA)
- systemic - to - PA shunt
- ASD or VDS
- anomalous systemic venous drainage
- aortic regurgitation
65
when the cannula is inside the heart, what do you go on
go on green
66
Venting the right heart must be done via what
decompression is usually via venous cannulas
67
when bicaval cannulation with caval tapes is used, the ______ must be released or a ______ must be used in venting the right heart
the caval tapes must be released or a RA vent must be used
68
venting the left heart is important to....
- prevent LV disention
- reduce myocardial rewarming (reduce myocardial oxygen demand)
- prevent cardiac ejection of air
- prevent pulmonary venous hypertension
- facilitate surgical exposure
69
where are the 5 methods of venting the left heart
1. ascending aorta
2. indirect LV vent
3. direct LV vent
4. direct LA appendage
5. pulmonary artery vent
70
how is venting the left heart through the descending aorta done
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
the ascending aorta is used to vent the left heart but it is also used to vent what
vent air when aorta is unclamped and when LV start to eject
72
what can the ascending aorta vent be used to monitor
AO root infusion pressure
73
ascending aorta vent only works when....
the aorta is cross clamped
74
the ascending aorta vent does not work during....
antegrade CPG infusion
75
Where is the indirect LV vent placed
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
what is the indirect LV vent best used for
BEST for AI (aortic insufficiency)
| -handles all sources of blood causing LV distention
77
the indirect LV vent provides optimal ______ of the LV
decompression
78
pro and con of indirect LV vent
pro: avoids problems of direct LV vent
con: potential air entry into LV
79
where is the direct LV vent placed in venting the left heart
cannula is placed directly in apex of LV
80
what is the pros of direct LV vent
- avoids getting across prosthetic mitral valve
| - handles all sources of blood causing LV distension
81
what is the cons of DIRECT LV vent
- tip may become obstructed
- bleeding for LV incision site
- potential for embolism if clots in LA
- potential for air entrainment into left heart
82
pros and cons of direct LA appendage vent
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
Where is the pulmonary art vent placed to help with venting the left heart
inserted into the pulmonary artery
84
pros and cons of Pulmonary art vent
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
what are complications associated with venting left heart (3)
1. introduction of air into left heart
2. errors in function of the vent
3. bleeding and damage to heart
86
when does air into left heart usually occur
- 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
what must happen in order to prevent air into left heart
fill the heart before insertion and removal of vent
88
what are errors in the function of the vent that could happen
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
