Embolic Events- Exam 2

Question 1

What is the incidence of clinically obvious strokes post CPB?

Answer 1

~1-5%

Question 2

MRI suggests could be new cerebral infarcts in what percent of same patients?

Answer 2

~30%

Question 3

What is the source of strokes not necessarily?

Answer 3

CPB

Question 4

What is a major contributor to strokes?

Answer 4

Patient

Question 5

What percent of CABG patients experience cerebral infarct prior to surgery?

Answer 5

~50%

Question 6

Subclinical

Answer 6

hard to detect

Question 7

Types of emboli

Answer 7

Biologic (bloodborne)
Foreign material (circuit, manufacturing)
Gaseous

Question 8

What are the main targets of emboli? What size?

Answer 8

Micro vessels; 3 to 500 um in diameter

Question 9

What is the period of greatest risk?

Answer 9

Insertion of arterial cannula
Initiation of bypass
XC application/ removal
Use of centrifugal pump

Question 10

Why is initiation of bypass one of the riskiest periods for emboli?

Answer 10

Hypotension; most circuit “junk”

Question 11

Why is XC application/removal one of the riskiest periods for emboli?

Answer 11

Manipulation of the aorta; trauma to aorta can contribute to brain infarctions for up to 1 month

Question 12

When does the use of a centrifugal pump become a risk for developing emboli?

Answer 12

Any time you have a decrease in blood flow

Question 13

Biologic Emboli

Answer 13

Fibrin/fibrinogen microthrombi
Fat or lipids
protein
cold-reacting antibodies
calcium fragments
bone fragments
muscle fragments
platelet aggregates
neutrophil aggregates
RBC aggregates
inadequate anticoagulation
contact with foreign surface

Question 14

Formation of biologic emboli in homologous transfused blood increases with what?

Answer 14

Storage time

Question 15

What areas are at risk with the formation of biologic emboli?

Answer 15

Minimal flow
Stagnant areas
Turbulence
Cavitation
Rough surfaces

Question 16

What areas of the circuit can form biologic emboli? (higher risk areas)

Answer 16

Connectors
Bubble oxygenators
Arterial line filters
cardiotomy (venous) reservoir
intraluminal projections

Question 17

What kind of trauma can cause biologic emboli?

Answer 17

Trauma to fat cells of epicardium and trauma to tissue to the surgical wound

Question 18

What, besides bypass, can produce fat emboli?

Answer 18

Median sternotomy

thoractotomy

Question 19

What fraction of fat/lipid emboli within a circuit come from cardiotomy suction? What size particles?

Answer 19

2/3; 4-200 micron particles

Question 20

Biologic Emboli found in what organs post bypass?

Answer 20

Kidney, lungs, heart, brain, liver, spleen

Question 21

Platelet count drops what percent with initiation of bypass?

Answer 21

30-50%

Question 22

What drops with initiation of bypass

Answer 22

Platelet count and # of functional platelets

Question 23

Platelets related to…

Answer 23

Post op bleeding, neurologic dysfunction, release of histamine (membrane permeability), release of serotonin/thromboxane (vasoconstriction)

Question 24

Neutrophils related to…

Answer 24

Aggregation, interaction with endothelial cells, change in permeability

Question 25

Foreign Particle Emboli

Answer 25

``` Cotton fibers Plastic particles Filter material Tubing fragments (spallation) Metal Talc Thread Bone wax Microfibrillar collagen Silicone antifoam ```

Question 26

Bubbles of what size are associated with CPB mortality and morbidity?

Answer 26

35-40 um size

Question 27

What are in the bubbles that cause gaseous microemboli?

Answer 27

Mainly oxygen

Question 28

What causes formation of gaseous microemboli?

Answer 28

Bubble oxygenator Temperature gradients Surgical air Pump/Circuit problems

Question 29

What causes surgical air

Answer 29

Heart contracts before chambers completely de-aired Surgeon cuts into chamber of beat heart Placement of arterial, venous, or LV vent cannula

Question 30

What is present in heart how long post-bypass?

Answer 30

30-40 minutes

Question 31

Flush with Co2, what percent of bubbles are gone within 1 minute?

Answer 31

86%

Question 32

Why do you co2 flush?

Answer 32

Helps with air solubility, some of that CO2 transfers to the blood and PaCo2 will increase, increases vasodilation. Any type of embolism makes it easier to go to the brain

Question 33

What, involving the venous reservoir, can lead to pumping air?

Answer 33

Inattention to level in venous reservoir Vortexing of blood in venous reservoir at low volume levels Pressurized cardiotomy reservoir

Question 34

What involving the pump can lead to pumping air?

Answer 34

``` Reversed roller pump retrograde flow through centrifugal pump runaway pump mechanical jarring of circuit components over occluded arterial pump head ```

Question 35

What involving the tubing can lead to pumping air?

Answer 35

Tubing reversed in roller head cavitation leak/kink in tubing on negative side of the roller pump disconnection/breakage, detachment of tubing

Question 36

What involving the oxygenator can lead to pumping air?

Answer 36

disconnection/breakage detachment of oxygenator | pulsatile flow through microporous membrane oxygenator

Question 37

What involving the arterial filter can lead to pumping air?

Answer 37

Inadequate debubbling, especially the arterial filter

Question 38

What involving drugs can lead to air?

Answer 38

Drug injections into circuit and perfusion interventions

Question 39

What involving volume can lead to air?

Answer 39

Inattention while transfusing volume to patient post bypass

Question 40

What was the highest incidence of CPB emergency? Second highest?

Answer 40

Inattention to reservoir level (37%) | Aortic root air during CPS aminitration (29%)

Question 41

What has the highest proportion of total emboli?

Answer 41

Drug | then blood samples

Question 42

Blood-Bubble Interactions

Answer 42

``` Adsorption/denaturation plasma proteins Adsoprtion phospholipids Adsorption fibrinogen Complement activation Clumping red blood cells Leukocyte activation/adherence Lipid peroxidation Microthrombi production Platelet activation/adherence Thrombin activation Phospholipase activation Endothelial wall damage ```

Question 43

Safety Devices

Answer 43

``` Low level alarm Air bubble detector Arterial line filter (cardiotomy filter) one-way purge line form arterial line filter to cardiotomy reservoir one-way valve in vent line one-way valve in arterial line clear lines of ocmmunication use of protocols, policies and procedures Use of prebypass checklist ```

Question 44

How do you minimize biologic emboli formation?

Answer 44

``` use of transfusion filters adequate anticoagulation design of circuit components minimize surface area of circuit use of membrane oxygenator minimize complement/ immune activation minimize platelet activation minimize neutrophil activation ```

Question 45

How do you minimize introduction of foreign particle emboli?

Answer 45

Componnet design and manufacturing circulate crystalloid solution through entire circuit flush circuit with cystalloid solution in conjuction with a pre-bypass filter in AV loops don't use silicone tubing in arterial pump head use medical grade tubing

Question 46

How do you minimize formation of gaseous microemboli?

Answer 46

Check all equipment for proper operation ensure all tubing/ component connections are secure flush circuit with co2 prior to priming careful priming of arterial filter warm prime- then let it cool check circuit for proper alignment of tubing and components proper use of all safety devices open one=way purge line form arterial filter to cardiotomy reservoir use of pressure relief valve on venous reservoir when using VAVD test vent line prior to attachment to vent catheter Continual circuit scan while on bypass continual monitoring of centrifugal pump flow and RPM-ensure forward flow at all times avoid air in venous line