Flashcards in Materials / Bruce's Final Prep Deck (37)
Hardness of tubing
Cracking failure especially at point of ﬂexion
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 ____.
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 =
Filtered reservoirs included 3 things?
Unfiltered reservoirs are known as what ?
Historic filters were made of what ?
Dacron, wool, felt and nylon screens.
Current ECC Materials ?
-- Stainless Steel
signaling and -compliment system
-Expression of cell
Margination of neutrophils, monocytes and platelets Release of granule proteases
can lead to what ?
Systemic Inflammatory Response System
Molecules released from inflammatory cells
that are signaling agents.
Acute Tubular Necrosis which results from
↑ surface contact
= organ failure.
Biological cascade influenced by contact of blood with a foreign surface.
less compliment proteins is good
Complement proteins lead to what ?
a hole in the cell membrane leading to destruction of the cell
Ways of reducing contact activation ?
–Smaller components –Reduced air interface
4 Surface Treatments by
4 Surface Treatments by Surface modiﬁcation
Covalent end- point attachment of heparin to ECC surface
does not wash off
Ionic end-point attachment of heparin to ECC material
• 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