1. Blood cardioplegia
a) Buckberg system
b) Various mixing ratios (eg 4:1)
c) Via double tubing in one pump head, or single tubing in double pump head
d) Double pump head offers ability to vary cardioplegia concentration during case
2. Crystalloid cardioplegia
a) Bag of crystalloid cardioplegia pressurised by hand or more usually by a pressure bag
b) Pump chamber of blood giving set acts as a bubble trap
c) May be infused via the standard Y-piece into aortic root
3. Oxygenated crystalloid
a) Bag of crystalloid oxygenated (by bubbling oxygen)
b) Limited oxygen content
1.
Membrane filtration
a) Clear fluids (crystalloids & colloids) do not contain cellular elements, therefore filtration can be taken to a much lower level
b) Includes removal of submicron particles & microbes
c) Formed rigid structures, appear like paper
d) Have a relative depth for microbes
i) Eg: 0.2 micron filter thickness is approximately 250 x diameter of bacteria
e) Mechanism of direct interception & adsorption
f) Increased resistance to flow
i) Resistance to flow is improved by:
a) Increasing the density of pores
b) Increasing the surface area (pleating)
g) Used in prebypass & cardioplegia filtration
2.
Hydrophilic
a) Having an affinity for water
b) A hydrophilic filter can be wetted with virtually any liquid
3.
Hydrophobic
a) Repels water
b) Cannot be wetted by aqueous solutions or by liquids with high surface tensions without first prewetting with agents of low surface tension, such as alcohol or subjecting them to high pressure
c) Hydrophobic filters are best suited for gas & solvent filtration & venting
4. Gas filtration filters tend to be hydrophobic
a) If water wets a filter medium that is ‘wettable’
i) A liquid channel will form preventing normal gas filtration mechanisms occurring thereby allowing passage of contaminants
ii) Sharp rise in resistance to gas flow
b) Hydrophobic material used:
i) Keeps liquid on one side of the filter
ii) Resistance to flow occurs only when a large percentage of the filter surface area is occluded
iii) Filtration efficiency is not affected even when wetted
5. Studies with isolated rat hearts after infusion of commonly used cardioplegia solutions
a) 50% reduction in coronary blood flow
i) Mechanism of reduced blood flow
a) Not by direct occlusion by particles
b) By several non-specified mechanisms
b) This effect abolished with use of 0.8 micron cardioplegia filter
6. Screen sizes
a) Most of the particles found in clear fluids used prebypass & cardioplegia are < 5 microns
b) 0.5 microns
i) Allows adequate flow rates
ii) Removes significant number of particles & microbes
c) 0.2 microns
i) Provides full bacterial retention
ii) Removes endotoxins
7. Pall cardioplegia plus filter
a) 0.2 microns
b) High flow
c) Protection against particulates, gas emboli and bacteria
d) Enhanced myocardial protection
e) Cannot be used with blood
f) Must be installed prior to mixing with blood in Buckberg system
1.
Aortic Root
a) Medtronic DLP
i) Description
a) Aortic root cannula
b) Standard tip with side holes
c) Includes introducer & stabber
d) 12 Fg
e) Also includes a longer tip version
ii) Comments
a) Connected to a cardioplegia delivery set with vent
2.
Coronary ostia
a) Pilling
i) Description
a) Coronary perfusion cannula
b) 13/32 cuff diameter
c) Silastic
d) Malleable wire along tip for forcep manipulation
ii) Comments
3.
Coronary sinus
a) Research medical
i) Description
a) RetroplegiaÒ coronary sinus cannula
b) RetractaguardÔ anti-retraction lumen
c) 3 tier balloon
d) Manual inflated
ii) Comments