Cardio Pulmonary Bypass Flashcards
During CPB, venous blood flows in a _______ via what type of drainage?
reservoir
gravity
Blood flows through ______ and _____ and is then pumped via aortic cannula into aorta
oxygenator
filter
Heat exchanger allows heating and cooling. True or false?
true
When is a left heart bypass used?
Used for descending aortic surgery
During a left heart bypass, where does flow out of and then reinfused?
out of left atrium
reinfused to femoral artery or middle aorta
Is there an oxygenator on left heart bypass?
No
Some may have heater/cooler.
What does ECMO mean?
extracorporeal membrane oxygenation
Note: There are 2 types: VA (venous-arterial) and VV (veno-venous).
Does the ECMO system need heparinization?
Yes
What types of monitoring do you need on CPB? (5)
- ECG–need to confirm asystole after cardioplegia/cross clamp.
- Arterial pressure–NIBP does NOT work
- Temperature
- Perfusion
- Volume
Right radial arterial line is not accurate with right axillary cannulation. True or false?
True.
Brain damage may occur due to inaccurate readings. Placement of art line is critical. Left radial art line may be lost during high clamp in descending procedures.
Hypothermia is utilized during CPB procedures to improve tolerance of prolonged non-pulsatile flow states and decrease ischemic injury to brain, heart and kidneys. True or false?
True
Hypothermia decreases CMOR.
What can temperature be as low as during circulatory arrest?
18ºC
What is most sensitive to ischemic insult?
CNS
Hypothermia increases tolerance during aortic arch procedures and periods of low flow.
Relating to perfusion
How do you know the brain, heart, kidneys, liver and GI tract are getting adequate cardiac output? (5)
- BIS/cerebral oximetry (frontal lobe perfusion)
- ECG (want asystole), filling pressures
- Urine output–best indicator for kidneys
- Mixed Venous O2 (total body perfusion)
- Labs galore- lactate, glucose, acid-base status, potassium
What drug do we administor to ensure urine production?
mannitol
What is the best intravascular volume estimate we have?
CPB reservoir
What is important to determine prior to CPB?
total body volume status
Ultrafiltration during CPB allows removal of excess volume, and some removal of electrolytes, similar to dialysis. True or false?
true
If the hemoglobin is 7 and reservoir volume is 1000ml, do you need add blood?
Basically need more information. What info do we need? (3)
Reservoir volume
Mixed venous
Temperature
What does heparin inhibit?
Thrombin via AT-III (antithrombin)
What do we give patients with HIT (heparin induced thrombocytopenia)? (3)
LMWH
ancrod (snake venom)
argatroban* (most common- shuts down platelet fxn)
Patients with ATIII deficiency–‘heparin resistance’ either acquired or inherited, requires therapy to ensure maximal anticoagulation for CPB, what do we give them? (2)
FFP
Emory happens to have recombinant ATIII
What is normal ACT?
What is ACT to go on bypass?
100 - 140
380 - 480
What impacts ACT?(3)
Temperature
Platelet function
Hemodilution
Where do you cross clamp for an arterial cannula?
below the cannula
Blood is pumped back into the arterial system via the cannula after being ______ and cleared of ____.
oxygenated
CO2
When they are sewing the aorta cannnula in, what do we need to be doing?
decrease BP from 160 to 100 systolic
Where are arterial cannulas normal placed? (3)
ascending aorta, distal to the PA (most common)
axillary artery
femoral artery
Where are dual or tri-stage venous cannulas normal placed?
Can be placed in any large vein that will allow gravity drainage of blood to the reservoir.
Cannula placed through right atrial appendage and down into SVC and IVC.
In what cases do we place venous cannulas? (3)
Sternotomy
CABG
Aortic valve replacement
What is bicaval cannulation?
separate cannulas in the SVC and IVC
(used for open chamber procedures, VSD repairs, transplants)
When is bicaval cannulation used?
In what cases is this needed? (2)
When maximal drainage of the heart is needed.
Open chamber procedures, transplant
Who places the SVC cannula when bicaval cannulation is needed and where is it placed?
anesthesiologist
RIJ
Note: the IVC cannula is placed in femoral.
Where is a vent placed?
A catheter typically placed in the right upper pulmonary vein (RUPV) and into the left atrium.
What is the function of a vent?
Vent removes blood that accumulates in the heart with a goal of preventing distention injury.
What is a tack?
A tack is a smaller catheter, sometimes a 14 gauge IV, placed in the ascending aorta to facilitate clearance of intracardiac air after open chamber procedures.
IThe tack is allowed to bleed in to the pericardial well until air is cleared.
Where is a retrograde cardioplegia catheter placed and what is it for?
By the surgeon into the coronary sinus directly, or percutaneously by anesthesia via RIJ with TEE.
Prevents injury to the coronary sinus by monitoring infusion pressure with the CVP transducer.
How is cardioplegia administered?
antegrade or retrograde
How is antegrade catheter placed?
Into ascending aorta or directly into coronary artery which follows path of normal blood flow
Can be the same line as tack line.
What is the direction of flow for retrograde cardioplegia?
Retrograde flows into coronary sinus, into coronary veins and out the aorta.
How is temperature monitored during CPB? (3)
nasopharyngeal
bladder
PA
What drugs are used to target MAP?
phenylepherine
vasopressin
NOT EPI because of beta agonist activity!
On what 2 factors is target MAP based on?
temperature
pt baseline
How low can Hgb trend as low as in most circumstances?
7
What technique of aortic cannulation is used for major aortic surgical procedures, including aortic dissections, aneurysms and arch procedures?
axillary cannulation
Note: Used often.
For a patient receiving axillary aortic cannulation, Where MUST the art line be placed to avoid neurologic damage?
OTHER arm or femoral artery
What must you ensure before weaning a patient off CPB? (3)
- Ensure the pt is appropriately rewarmed
- Venous line is incrementally clamped to prevent blood from returning to the reservoir (blood reenters heart and ejection returns)
- The arterial inflow rate is decreased as the blood pressure increases.
Heparin is a ______ charged glycosaminoglycan.
Protamine is an _____ rich base compound.
negatively
arginine
Note: This is a simple acid-base reaction.
What blood products can be given during CPB?
RBC and FFP
Note: Platelets and cryoprecipitate and other coagulation factors are withheld until CPB is no longer needed.
What is off pump heart surgery?
CABG can now be accomplished without CPB in many instances
Hemodynamic management of these patients can be difficult as we are allowing an ischemic state while grafts are completed.
TEVAR (thoracic endostent) is an example
When do we perform off pump heart surgery?
valve operations such as AVR, MVR, PVR, and even TVR
TEVAR (trans endo vascular aortic repair)
You are on CPB and the hemoglobin is 7. Which of these would lead you to transfuse?
A. Temperature 32C
B. MVO2 80
C. Reservoir volume 200ml
D. MAP 65
c
Which monitor is the most important for CPB?
A. ECG
B. Arterial line
C. Temperature
D. BIS
b
what is the main difference between VA and VV ECMO?
VA = some cardiac support
VV = clears CO2 better than it adds O2 (background ventilation needed)
What does the CPB oxygenator do?
delivers O2, Co2 and Isoflurane to patient while the patient is on bypass
What does DHCA stand for?
Deep Hypothermic Cardiac Arrest
- alternative to CPB
- commonly referred to as “circ arrest”
how does ultrafiltration during CPB work?
removal of fluid via counter-current exchange (NB… can decrease electrolytes by down shifting concentration)
what is cardioplegia and how does it work?
fluid is injected into the heart (antegrade or retrograde) that stops the heart from pumping.
K+ often the drug of choice. Stops heart in diastole
when a patient is on CPB, the perfusionist is roughly equivalent to the patient’s _____ while the anesthesia team is ______
Perfusionist = Cardiac output
Anesthesia = SVR
What must you always do before giving protamine?
ASK PERFUSIONIST
-protamine will clot CPB circuit (–> dead patient)
