Embolic Events- Exam 2 Flashcards Preview

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Flashcards in Embolic Events- Exam 2 Deck (46):
1

What is the incidence of clinically obvious strokes post CPB?

~1-5%

2

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

~30%

3

What is the source of strokes not necessarily?

CPB

4

What is a major contributor to strokes?

Patient

5

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

~50%

6

Subclinical

hard to detect

7

Types of emboli

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

8

What are the main targets of emboli? What size?

Micro vessels; 3 to 500 um in diameter

9

What is the period of greatest risk?

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

10

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

Hypotension; most circuit "junk"

11

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

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

12

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

Any time you have a decrease in blood flow

13

Biologic Emboli

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

14

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

Storage time

15

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

Minimal flow
Stagnant areas
Turbulence
Cavitation
Rough surfaces

16

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

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

17

What kind of trauma can cause biologic emboli?

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

18

What, besides bypass, can produce fat emboli?

Median sternotomy
thoractotomy

19

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

2/3; 4-200 micron particles

20

Biologic Emboli found in what organs post bypass?

Kidney, lungs, heart, brain, liver, spleen

21

Platelet count drops what percent with initiation of bypass?

30-50%

22

What drops with initiation of bypass

Platelet count and # of functional platelets

23

Platelets related to...

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

24

Neutrophils related to...

Aggregation, interaction with endothelial cells, change in permeability

25

Foreign Particle Emboli

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

26

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

35-40 um size

27

What are in the bubbles that cause gaseous microemboli?

Mainly oxygen

28

What causes formation of gaseous microemboli?

Bubble oxygenator
Temperature gradients
Surgical air
Pump/Circuit problems

29

What causes surgical air

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

30

What is present in heart how long post-bypass?

30-40 minutes

31

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

86%

32

Why do you co2 flush?

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

33

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

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

34

What involving the pump can lead to pumping air?

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

35

What involving the tubing can lead to pumping air?

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

36

What involving the oxygenator can lead to pumping air?

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

37

What involving the arterial filter can lead to pumping air?

Inadequate debubbling, especially the arterial filter

38

What involving drugs can lead to air?

Drug injections into circuit and perfusion interventions

39

What involving volume can lead to air?

Inattention while transfusing volume to patient post bypass

40

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

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

41

What has the highest proportion of total emboli?

Drug
then blood samples

42

Blood-Bubble Interactions

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

43

Safety Devices

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

44

How do you minimize biologic emboli formation?

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

45

How do you minimize introduction of foreign particle emboli?

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

46

How do you minimize formation of gaseous microemboli?

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