ECMO

Question 1

What is ECMO tubing coating with

Answer 1

Heparin

Question 2

What are the constituents of an ECMO machine

Answer 2

Outflow cannula, membrane oxygenator, pump, return cannula

Question 3

How does the membrane oxygenator of ECMO add O2 and what is it dependant on

Answer 3

Via a semipermeable membrane
Dependant on rate of blood flow, fiO2, Hb, membrane surface area
(To increases pO2 then increase pump flow)

Question 4

How does the membrane oxygenator remove CO2 and what is it dependant on

Answer 4

Via countercurrent exchange
Dependant on rate of countercurrent gas, flow rate, membrane integrity
(To increase CO2 removal, increase O2 sweep gas)

Question 5

Compare VA and VV ECMO in terms of exit and entry cannula sites

Answer 5

VA: out of femoral vein and back in to femoral artery
VV: out of femoral vein and back in to internal jugular vein

Question 6

Describe blood flow in VA ECMO

Answer 6

Retrograde blood flow back up the aorta (depending on the CO depends where the “cloud” of mixing of blood occurs)

Question 7

Describe what VA ECMO is used for and why

Answer 7

Cardiac problems including arrest, cardiogenic shock, open cardiothoracic surgery
Used because the pump is able to maintain a high flow state throughout the entire body

Question 8

Describe when VV ECMO is used and why

Answer 8

Respiratory problems eg ARDS

The pump only moves blood around the circuit not the body so still need good cardiac function to perfuse the body

Question 9

What are the contraindications for VA and VV ECMO

Answer 9

VA: aortic dissection, aortic regurgitation
VV: cardiac arrest, severe LV failure

Question 10

What are the proposed inclusion criteria for prehospital ECMO

Answer 10

Age 18-65
Witnessed arrest with bystander cpr
VF/pVT
No flow time <5 minutes
Ability to put on ECMO within 60 minutes