Materials / Bruce's Final Prep Flashcards
Durometer
Hardness of tubing
Spallation
Cracking failure especially at point of flexion
Memory
Flexibility and resilience
Wear was invariably found on the luminal surfaces at the junction of
-inner and outer walls of PVC and silicone rubber tubing -no differences between normal and tight occlusions
The grooves in the PVC tubing were narrow and continuous with occasional deep cracks in the tubing after
> 3 hrs. on pump
Tygon material after 3.67 million compressions at full occlusion
crack formation did not occur
If the Tygon tubing was over-occluded, cracks did appear within ____.
24 h
A visible change of tubing diameter was generally noticeable by around 250 psi of arterial line pressure, which was already very high. By 1,500 psi what were the results of PVC and Silicone ?
PVC diameter ↑ by 5% to 10%
Silicone rubber tubings diameter ↑ between 20% to 25%
Silicone rubber tubings of all sizes showed?
greater distensibility than PVC tubings of equivalent size
1 PSI =
52 mmHg
Filtered reservoirs included 3 things?
- Sponge filter
- defoaming agent
- Screen filters
Unfiltered reservoirs are known as what ?
Collapsible bags
Historic filters were made of what ?
Dacron, wool, felt and nylon screens.
Current ECC Materials ?
– Polyvinylchloride
– Polycarbonate
– Polypropylene
– Stainless Steel
INFLAMMATION: Initiators-
-Systemic cytokine signaling and -compliment system activation -Expression of cell adhesion molecules
INFLAMMATION:
Effectors-
Margination of neutrophils, monocytes and platelets Release of granule proteases
INFLAMMATION by Effectors- & Initiators can lead to what ?
Organ Failure:
SIRS =
Systemic Inflammatory Response System
Cytokine =
Molecules released from inflammatory cells
that are signaling agents.
ATN
Acute Tubular Necrosis which results from
↑ surface contact
↑ hemolysis
= organ failure.
Coagulation /
Fibrinolysis cascade
1:17
Biological cascade influenced by contact of blood with a foreign surface.
Compliment activation
proteins (5)
1:19
C5 C6 C7 C8 C9 less compliment proteins is good
Complement proteins lead to what ?
1:20
a hole in the cell membrane leading to destruction of the cell
Ways of reducing contact activation ?
1:21
–Smaller components –Reduced air interface
4 Surface Treatments by
Heparin bonding
– Carmeda
– Duroflow
– Bioline
– Trillium
4 Surface Treatments by Surface modification
– SMART
– PC
– X-coating
– Softline
Carmeda
Covalent end- point attachment of heparin to ECC surface
does not wash off
Duroflow
Ionic end-point attachment of heparin to ECC material
washes off
SMART
1:28
- Cobe Product
- Molecule added to the plastic before extrusion - passively moves to surface of material
- Alternating hydrophobic and hydrophilic surfaces
- Designed to occupy all of fibrinogens binding sites, disabling it from binding platelets
Trillium
1:30
Binds a linker molecule to the PVC then binds heparin and other molecules to the linker to create a heparinized boundary layer
X Coating™ (PMEA)
1:31
poly(2-methoxyethylacrylate)
•Non-heparin / organic polymer
• Used in plasma pheresis in early 1990’s
• Amphiphilic: hydrophobic / hydrophilic
• Reduces protein adsorption / denaturation
• Reduces platelet adhesion / activation
Phosphorylcholine (PC)
- a molecule in plasma membranes of the body’s cells
- creates a hydrated boundary layer between the blood and the tubing
Marketed as
“Mimesys coating”
Classic complement pathway is activated by ?
Interaction with antigen-antibody complexes.
Alternative complement “properdin pathway” is activated by ?
Exposure of blood to foreign surfaces
An additional, potential mechanism for excessive bleeding following cardiopulmonary bypass is that ?
heparin activates the fibrinolytic system, which in turn, adversely affects hemostasis.
heparin induces activation of the
fibrinolytic system
Bubble trap works on what 2 principles?
Buoyancy
Bubble point pressure
