Cardiac Flashcards
How do you calculate CaO2?
CaO2 = (Hgb x 1.34 x SaO2) + (0.003 x PaO2)
How do you calculate CBF (coronary blood flow)?
CBF = CPP/CVR (CVR stands for coronary vascular resistance)
Coronary blood flow is autoregulated between what MAPs?
50-150mmHg
How do you calculate CPP?
CPP = diastolic - LVEDP
What causes the O2 dissociation curve to shift to the right?
Increases in “CADET” (CO2, Acidity, 2-3 DPG, Exercise, Temperature)
What are the three cardiac factors that contribute to myocardial O2 demand?
HR, contractility, wall stress
How is wall stress calculated?
wall stress = (P x r)/(2 x wall thickness)
Define preload. What is it a result of? What does it reflect?
Preload is the load placed on myocardium before contraction. It’s a combination of diastolic volume and filling pressure. Reflects stretch of ventricular myofilaments.
What is afterload? What does it reflect?
Afterload is the load placed on myocardium DURING contraction. Reflects distensibility of aorta and SVR.
What drugs are given for post-CPB bleeding? What class are they?
amicar or TXA; anti-fibrinolytics
What drugs are typically set up as infusions for cardiac cases?
epi & NE
What EKG leads are most important to look at prior to induction for cardiac anesthesia?
ST segments of leads II and V5
What lines should you have for CPB?
a-line, central line +/- PAC
What are some advantages to having a central line?
monitor CVP, enable volume replacement, enable pharmacologic therapy, insert PAC or other monitors
What is the most common vein for CVP?
R internal jugular
What are some of the things a TEE can assess?
valvular abnormalities, preload, contractility, pulmonary HTN, RWMA, EF, pericardial effusion, cardiac abnormalities
What must occur before cannulation for CPB?
anticoagulation
What is the dosage of heparin for CPB?
300U/kg
how is heparin metabolized?
50% liver, 50% unchanged and renal excretion
What’s a normL ACT? What is needed for CPB?
90-120sec normal; for CPB minimum 300s, 400s< preferred
What factor does heparin bind to? What factors does it inhibit?
binds to antithrombin III; inhibits II, IX, X, XI, XII, XIII
Where is the arterial cannula placed for CPB?
ascending aorta
Where is the venous cannula placed for CPB?
dual stage IVC/RA for external procedures; single stage (one bifurcating tube) bicaval cannula in SVC/IVC for valvular procedures
What’s in cardioplegia?
KCl, mannitol, glucose, blood with other additives
What is antegrade cardioplegia?
needle placed below aortic clamp/above aortic valve and cardioplegia administered into coronary arteries via aortic root
What is retrograde cardioplegia?
balloon-tipped cannula placed into coronary sinus and administered into coronary veins
What MAP range is typically maintained during CPB?
50-70mmHg (below that perfusion suffers, above that you start to get noncoronary collateral bloodflow into heart)
What are the 6 “C’s” for CPB termination?
cold (>36*C), conduction (HR 70-100), Ca++ (available), CO, cells (>7g/dL), coagulation (anticipate)
What are the 4 “V’s” for CPB termination?
ventilation, vaporizer, volume expanders, visualization
What are the 6 “P’s” for CPB termination?
predictors (difficulty weaning from pump), protamine (drawn up), pressure, pressors, pacer (external available), potassium
Why can’t protamine be given when patient is on the pump?
blood will coagulate and clog the circuit
When is protamine given?
typically before aortic cannula removal; coordinate with surgeon!
What are signs of a mild protamine reaction?
isolated HoTN, normal-low filling pressures, normal airway pressures
What are signs of severe protamine reaction?
HoTN, tachycardia, elevated PA pressure, evidence of acute RV failure
Turning up desflurane quickly can cause what response?
(sympathetic) tachycardia, HTN, bronchospasm
What CV effects does CAD have?
decreased HR and contractility
The dicrotic notch corresponds with what?
aortic valve closure
A rapid upstroke on an arterial blood pressure curve indicates what?
good contractility
What size ETT is used for cardiac surgeries?
8.0mm
How long does it take for ischemia to show up on the EKG? TEE?
60-100s; immediately
What are the three most popular vessels used in bypass and in what order?
saphenous vein > internal mammary artery > radial artery
What is the purpose of priming the CPB?
to remove air from the circuit
Which cannula should be placed first in CPB and why?
arterial - venous runs risk of hemorrhage and blood can be transfused through arterial
How frequently is cardioplegia re-dosed?
every 15-20 min
What BP (MAP) should be maintained during CPB? Why?
50-70mmHg; below is inadequate, above and too much blood returns to heart and washes out cardioplegia
What happens to blood glucose in diabetics when they are taken off CPB?
increases dramatically
