Bypass shannon lecture and apex Flashcards
5 components of the cbp machine
venous reservoir
main pump
oxygenator
heat exchanger
artificial filter
What is the role of an accessory pump
cardioplegia delivery
How does blood drain from the patient to the reservoir
gravity
Roller vs centrifuge pump
Roller- propels blood forward, non pulsatile flow, flow remains the same regardless of afterload, traumatic to blood cells
Centrifuge- safer for RBCs, flow varies with afterload, high afterload can cause a back up of blood towards venous circulation
Explain membrane oxygenator
tightly wound fibers
o2 can be controlled by changing fio2
co2 can be controlled by changing liter gas flow rate (sweep)
What is the purpose of the arterial filter
filter blood before returning to the arterial cannula in the ascending aorta
Prevents thrombi, fat globules, calcium and tissue debris
What is the significance of aortic regurg
Blood and cardioplegia can backflow and fill the LV, distend the lv, raise lvedp, and oppose cardioplegic flow
Standard cardiac dose of heparin
300-400u/kg
ACT level for CABG
> 400 to initiate cpb
When to draw act for cpb
Prior to heparin
3 minutes after administration
q30 min
When would you suspect heparin resistant
recent exposure
ACT <480 despit 500u/kg IV heparin
Treatment for heparin resistance
2 units FFP, AT3 concentrate, recombinant AT3
CMRO2 decreases ___ for every degree celsius decrease in brain temperature
7%
Anterograde vs retrograde cardioplegia
anterograde- coronary arteries, aortic root
retrograde- coronary sinus and cardiac veins, RA, watch for dysrhthmias and hotn
Blood conservation meds
Amicar 50mg/kg over 20 min followed by 25mg/kg infusion
TXA 10mg/kg over 20 min followed by 1mg/kg infusion
Blood salvage does what to the blood?
Removes serum, coagulation factors and platelets
HCT 55-70
Large quantities of salvaged blood can cause what
dilutional coagulopathy
ABX 1st and 2nd choice
1- beta lactams, q3-4 hours
2- vanco and amg, no redosing, within 2 hours of incision
What happens if vessel damage in a redo cabg
emergently give 300-400u/kg heparin and cannulate
Goal BP before cannulation
SBP <100, MAP <70
to prevent disseciton