CBP + IABP Flashcards
For what main two surgeries do we use CPB?
CABG and cardiac valve repair
Name the three essential functions performed by CPB:
1) Oxygenation of venous blood
2) Elimination of CO2
3) Maintenance of system perfusion
ECC stands for:
Extracorporeal circulation
Explain what CPB is.
A form of ECC in which the patient’s blood is rerouted outside the vascular system and the function of the heart, the lungs, and to a lesser extent the kidneys is temporarily assumed by surrogate technology
CPB has five physical components. What are they?
1) Blood reservoir
2) Oxygenators/ gas exchangers
3) Pumps
4) Heat exchangers
5) Filters
DHCA stands for?
Deep Hypothermic Circulatory Arrest = 18 *C
Normally, heat exchangers in CPB cool the body to:
30 *C
What is it called when you use heat exchangers in hypothermia to cool the body down to 18 *C?
Deep Hypothermic Circulatory Arrest
Blood reservoirs, Filters, Heat exchangers, pumps. What is missing from that list?
Oxygenators/gas exchangers
Oxygenators/gas exchangers, pumps, heat exchangers, filters. What is missing from that list?
Blood reservoir
How many cannulas are necessary to provide CPB?
2
Where is/are the CPB cannula(s) located?
One cannula is located in the right atrium–it provides venous drainage to the ECC.
Another arterial cannula placed in the ascending aorta allows arterial return to the patient from the ECC.
Under what circumstances who a surgeon perform CPB using a bicaval cannula?
For any procedure that required the isolation of the right ventricle or atrium
T/F: The majority of cardiac procedures are performed with venous cannulation through the right atrium, with a single two-stage cannula.
True
The majority of cardiac procedures are performed with venous cannulation through the right atrium using a:
single two-stage cannula
Single cannulation of the atria is also known as:
Cavoatrial
Which cannulation procedure allows complete CPB?
Bicaval
In two-vessel cannulation of the RA, the drainage holes are placed:
in the SVC and the IVC
The single “two-stage” cannula in CPB refers to the fact that:
The cannula has two sets of drainage holes: one in the right atrium and one in the IVC. This method bypasses the SVC entirely.
Which venous cannulation method includes the SVC?
Bicaval
Cardioplegia involves what two solutions?
A high-K+ containing crystalloid cardioplegia solution or a low-K+ containing crystalloid cardioplegia solution
Is cardioplegia solution crystalloid or colloid?
Crystalloid
By what means is perfusion of cardioplegia possible?
Antegrade through the coronary arteries or retrograde through a catheter in the coronary sinus
If cardioplegia flows antegrade, it does so via:
Coronary arteries
If cardioplegia flows retrograde, it does so via:
a catheter coronary sinus
When you think antegrade cardioplegia, think:
coronary arteries
When you think retrograde cardioplegia, think:
coronary sinus
When and where is the retrograde catheter for cardioplegia normally placed?
It is normally placed prior to CPB through the atrial wall to the coronary sinus.
Cardioplegia literally translates to:
Paralysis of the heart
T/F: the venous reservoir, heat exchanger, and oxygenator are all combined in one integrated, disposable unit.
True
What aspects of the CPB machine are all integrated as a single disposable unit?
Venous reservoir
Heat exchanger
Oxygenator
What mechanism is used to prevent LV distension due to high volume of return to the LV?
An LV vent and a roller pump
Why is it important that both heat exchanger and gas exchanger portions of the membrane lung contain manifolds that distribute blood flow evenly?
It minimizes the blood pressure drop at clinical flow rates.
Primary function of the small tubules in the gas exchanger?
Eliminates CO2 from blood
What controls the FiO2 delivered to the membrane oxygenator and therefore controls the oxygen partial pressure gradient between the gas and blood phases? Why is that significant?
An air-oxygen blender
In doing so, it alters the total amount of oxygen transfer by diffusion through the membrane, ultimately determining PaO2
In CPB, arterial PaO2 is independently controlled by:
gas flow (L/min) through the oxygenator (AKA sweep rate)
T/F: lower gas flow rates remove more CO2 from inner membrane surface than higher do.
False; higher remove more CO2 from the inner membrane surface.
What effects does removing CO2 form the inner membrane surface of the oxygenator have on PaCO2?
It decreases it because it establishes a diffusion gradient from the blood to the inside of the membrane.
By what means does an oxygenator encourage the removal of CO2 from blood?
High flows remove CO2 from the inner membrane of the oxygenator, creating a diffusion gradient by which CO2 tends to flow from higher concentration to lower concentration (blood to filter).
Might CPB circuits contain anesthetic vaporizors?
Yes.
What ultimately controls PaCO2?
Flow rate (sweep rate) of non-CO2 containing gases
What is lung surface area?
70m2
What is the surface area of current membranes in CPB filters?
2-4 m2
How do membranes of CPB filters compensate for the fact that they have significantly lower surface areas than the human lung?
Via increased contact or transit time of the blood with the membrane
What two types of pumps would you see on CPB?
Centrifugal pumps
Roller pump
Impeller
What type of blood flow does centrifugal pumps produce?
Semi-pulsatile (sinusoidal) blood flow
What type of blood flow does roller pumps produce?
Propels blood forward using surface tension of blood
Centrifugal pumps are primarily used for what type of bypass?
Venovenous bypass
Which is superior at generating pulsatile flow, roller pumps or centrifugal pumps?
Roller pumps
Which pump is dependent on afterload?
Centrifugal pumps. Roller pumps are independent of afterload.
Which type of pump is more likely to cause trauma to bypass tubing, roller or centrifugal?
Roller pumps
If the power goes out, which type of pump can you hand crank?
Roller pumps
Which type of pump is capable of reverse flow, roller or centrifugal?
Centrifugal
Which type of pump involves an increased risk of air embolism?
Roller pump
Where are some areas of CPB that filters are located?
Blood reservoir Priming fluids Blood from blood bank Cardioplegia Between oxygen and oxygenator Arterial filter for gas exchange
T/F: Patient’s lungs are considered a filter.
True
T/F: Hypothermia further causes complications during cerebral ischemia.
False; hyperthermia does
What are some benefits to hypothermia during cerebral ischemia?
Favorable balance between O2 supply and demand
Decrease in excitotoxic NT release
Decrease in BBB permeability
Decreased inflammatory response