CPB Flashcards
What is CPB
Blood bypasses the heart and lungs
Explain the physical steps of CPS
Venous blood flows into the reservoir via gravity drainage
Blood flows through an oxygenator and a filter
Blood is pumped back into the aorta via the aortic cannula
A heat exchanger allows heating and cooling
Left heart bypass
Used for defending aorta surgery
Blood flows from the left atrium and is pumped back into the femoral artery
No oxygenator; May have heater/cooler
Extracorporeal Membrane Oxygenation (ECMO) Types
Veno-atrial (VA) and Veno-venous (VV)
VA vs. VV
VA: Post surgical patients, cardiac support
VV: Clears CO2 better than it adds O2, background ventilation needed
Both: Require systemic heparinization and ICU care
CPB Monitoring
ECG, arterial pressure, temperature, perfusion, volume
CPB Anticoagulation
Heparin, ACT
CPB Cannulas
Arterial, venous, vent, tack
CPB ECG Monitoring
Confirm asystole after cardioplegia and while the cross clamp is on
ST changes can occur due to air or ischemia
CPB Arterial Pressure Monitoring
Necessary because arterial pressure will not be pulsatile and therefore NIBP monitoring won’t work
Right radial arterial line issue during CPB
May not be accurate when right axillary is cannulated
Left radial arterial line issue during CPB
May be lost during high clamp in defending procedures
CPB Temperature Monitoring
Hypothermia is utilized to improve tolerance of non-pulsatile flow and decrease ischemic injury to brain, heart, and kidneys
CPB Target Temperature
Related to expected duration of the procedure
Mild/tepid 34-36, moderate 30-34, DHCA 18
What part of the body is most sensitive to ischemic insult?
CNS
CPB Profusion Monitoring
BIS/cerebral oximetry, ECG/filling pressures, Urine output, MVO2, Labs!
Best way to assess volume status during CPB?
Reservoir volume
Ultrafiltration
Removes excess volume and some electrolytes (like dialysis)
How does CPB effect anticoagulation?
It generates contact activation
Heparin works how?
It inhibits thrombin via antithrombin III
Anticoagulation options for patients with HIT
LMWH, danaparoid, lepirudin, ancrod, argatroban
Heparin Resistance
ATIII deficiency
Requires therapy for CPB
Normal ACT
100-140
ACT adequate to go on CPB
380-480
ACT in impacted by…
Temperature, platelet function and hemodilution
CPB Arterial Cannulas
Blood is pumped back in to the arterial system after being oxygenated and cleared of CO2
CPB Arterial Cannulas: Common Placement
Ascending aorta, dital to the pulmonary artery
Alternatives: Axillary or femoral artery
CPB Venous Cannulas
Placed in a large vein and allowed to drain into the CPB reservoir via gravity drainage
CPB Venous Cannulas: Common Placement
Sternotomy
Dual or tri stage venous: Cannula placed through the right atrial appendage and down in to the IVC, drains RA and IVC
Bicaval cannulation
Separate cannulas in SVC and IVC
Maximal drainage of the heart
SVC cannula
Placed by anesthesiology via RIJ
Vent
Catheter placed in the RUPV and in the left atrium to remove blood that accumulates in the heart in order to prevent injury
Tack
A small catheter placed in the assenting aorta to facilitate clearance of intracardiac air
Retrograde cardioplegia
A catheter is placed by the surgeon into the coronary sinus directly, or sometimes percutaneously by anesthesiologist via the RIJ with TEE guidance
The infusion pressure is measured in order to prevent injury to the sinus
Antegrade vs. Retrograde cardioplegia
Antegrade - follows path of normal blood flow
Retrograde - flows from the sinuses to the coronary veins and out of the aorta
Choice between the two depends on the surgical procedure and on the ventricular function status
Axillary Cannulation
Used for major aortic surgical procedures
MUST have an a-line
Protamine
Used to reverse heparin
Will clot the CPB circuit!
Never give until the surgeon asks and always tell the perfusionist
Protamine Reactions
Rare, but can be fatal
Pulmonary HTN/systemic hypotension
What blood products can be given during CPB?
PRBCs and FFP
