IABP/ECMO Flashcards
What are the major functions of an IABP?
Improve myocardial O2 supply + decrease O2 demand + increased CO + improve coronary perfusion
Does the IABP balloon completely occlude the aorta with inflation?
No, it should only be 85-90% occlusive
What are the indications for IABPs?
Acute cardiogenic shock + prior to high-risk CABG or PCI + inability to separate from CPB + unstable angina
What are contraindications for IABPs?
Aortic regurgitation + aortic dissection + aortic aneurysm + severe sepsis + vascular access issues
When does inflation occur for an IABP?
During diastole (triggered by the dicrotic notch/AV closure or middle of the T wave)
What are the physiologic effects of an IABP?
Decreased LV afterload/LVEDP/wall tension
What are complications of IABPs?
Limb ischemia + hemorrhage + atheromatous emboli (CVA) + thrombocytopenia + hemolysis + helium embolization
What is synchronized counter-pulsation?
The mechanism by which IABPs work: inflates during diastole and deflates during systole
What’s the only parameter you can change on an ECMO circuit?
The RPMs
What does the pump inlet pressure or venous pressure measure? What is it affected by?
The amount of pressure needed to drain blood; affected by cannula size, length, patient volume status, venous resistance
What does an increasing negative venous pressure indicate?
Can indicate that the patient is volume down (more pressure needed to drain the required blood)
What is the delta pressure or pressure drop in ECMO?
The pressure gradient across the membrane/oxygenator
What does an increasing pressure drop or delta P indicate?
Might be due to thrombosis in the oxygenator
What 4 factors affect the ECMO flows?
- Pump speed 2. Drainage cannula size 3. Preload 4. Afterload
What are the key differences between ECMO and CPB?
ECMO can be used for days to months + No venous reservoir or blood/air interface + no arterial filter + lower heparin dose + only centrifugal pump + less hemodilution
How are lipophilic anesthetic meds affected by ECMO?
ECMO circuit adds about 400-800cc of blood so volume of distribution is increased; highly lipid soluble agents require higer doses
What drugs do you need a higher amount while on ECMO?
Propofol + benzos + precedex + ketamine + opioids (particularly fentanyl) + volatile anesthetics
How are NMBs and succinylcholine affected while on ECMO?
NMBs may require a higher initial dose but you might see prolonged effects; succinylcholine will have a prolonged effect (pseudocholinesterase levels are lower in critically ill patients)
Where are the cannulas located for fem-fem VV ECMO?
The drainage cannula is in the mid IVC and the return cannula is in the RA
What is ultra-protective ventilation?
The type of ventilation that should be used while on ECMO: Low driving pressures (10-15 cmH2O) + low RR (<12) + low plateau pressures (<25 cmH2O); these values are lower than the standard ARDS protective ventilation
What are the determinants of O2 sats while on VV ECMO?
ECMO flow + O2 fraction of circuit + ratio of ECMO flow to native cardiac output + recirculation + metabolic demand + native lung function
What is recirculation while on VV ECMO?
Post oxygenator blood is sent out the return cannula but then taken back into the drainage cannula
What should you worry about if you see a decrease in O2 sats with increasing VV ECMO flows?
Recirculation
What are the steps for weaning off VV ECMO?
- Reduces FiO2 2. Reduce sweep gas 3. Off-sweep gas challenge 4. Prepare for decannulation
What is North-South syndrome?
AKA Harlequin syndrome: Only seen with peripheral VA ECMO: patient’s native heart function recovers but lung function has not -> heart pumps deoxygenated blood into the body normally -> mixing zone present
Where should the arterial line be while on VA ECMO?
Right upper extremity: this is to diagnose North-South or Harlequin syndrome (mixing zone)
How do you treat North-South Syndrome?
Decrease inotropes (make the heart do less) + optimize vent settings + increased VA ECMO flows to move mixing zone closer to the aortic root + VAV ECMO
What is the only clinical predictor of weaning success from VA ECMO?
Pulse pressure (other things that can be looked at include aortic VTI + LV EF + lateral mitral TDI + >10% improvement in TV annular velocity (RV function))
What is VAV ECMO?
Blood is drained from the IVC (femoral venous cannula) and returned to the femoral artery and the RA (usually via the RIJ)
