Extracorporeal Life Support: Overview and Practice Questions

Extracorporeal Life Support is an advanced form of support where blood is pumped outside the body for oxygenation and then returned to circulation.

Respiratory Therapists are often involved in this type of therapy which is why it’s an important topic to learn about. Hopefully, this study guide can help make that process easier for you.

Below, we have provided practice questions for your benefit as well. So if you’re ready, let’s get started.

What is Extracorporeal Life Support?

Extracorporeal Life Support is a form of therapy used for providing cardiac and respiratory support to patients who are unable to perform gas exchange or perfusion with their own organs.

It involves pumping blood out of the body into a machine where oxygenation takes place. Then, the blood can be pumped back into circulation in the body.

This is a severe type of support that should only be used in life-threatening situations where conventional forms of treatment were unsuccessful.

Types of Extracorporeal Life Support:

Here is a list of the types of Extracorporeal Life Support that you should be familiar with:

• Extracorporeal Membrane Oxygenation (ECMO)
• Venoarterial (VA)
• Venovenous (VV)
• Extracorporeal CO2 Removal (ECCO2R)

In general, ECMO is considered to be the most common type of Extracorporeal Life Support. The others can, technically, be classified as types of ECMO.

What is ECMO?

Extracorporeal Membrane Oxygenation (ECMO) is a type of extracorporeal life support that involves pumping blood out of the body through a membrane for gas exchange of oxygen and carbon dioxide to occur.

It can be used for the management of severe, life-threatening respiratory failure or cardiogenic shock in patients who have not responded well to conventional types of treatment.

Respiratory therapists are often involved with this type of treatment, although state licensure laws may limit involvement in some states.

Venoarterial Extracorporeal Membrane Oxygenation

Venoarterial ECMO is a type of extracorporeal life support where venous blood is drained from the patient and run through the machine for oxygenation. The blood becomes saturated with oxygen and can be returned to the patient’s body via arterial circulation.

This type of ECMO is typically used in patients with cardiovascular failure and provides hemodynamic support. It’s most commonly indicated for the treatment of cardiogenic shock.

Venovenous Extracorporeal Membrane Oxygenation

Venovenous ECMO is a type of extracorporeal life support where venous blood is drained from the patient and run through the machine for gas exchange. However, with this type of support, the blood is returned to the patient’s body via venous circulation.

This type of ECMO is typically indicated for the treatment of acute respiratory failure that is due to viral or bacterial pneumonia. Unlike venoarterial ECMO, venovenous ECMO provides no hemodynamic support.

Extracorporeal Life Support Practice Questions:

1. When is ECMO indicated?
It can be used for the management of severe, life-threatening respiratory failure or cardiogenic shock in patients who have not responded well to conventional types of treatment.

2. What are the three types of ECMO?
Venovenous, venoarterial, and arteriovenous

3. In hypoxic respiratory failure due to any cause, ECLS should be considered when?
It should be considered when the risk of mortality is greater than 50% and is indicated when the risk of mortality is greater than 80%.

4. A 50% mortality rate is associated with a P/F of what?
With a P/F of greater than 150 on an FiO2 of greater than 90%

5. An 80% mortality risk is associated with a P/F of what?
Less than 100 on an FiO2 of greater than 90%

7. Gas flow in an ECMO circuit is referred to as what?
Sweep flow

8. The higher the sweep flow, the more?
The more CO2 is eliminated

9. Which form of ECMO involves a complete lung bypass?
Venoarterial ECMO

10. In order for venovenous ECMO to support oxygenation and CO2 removal, the patient must have what?
Adequate cardiac function

11. Patients with an acute lung injury and preserved cardiac function would be considered for which type of ECMO?
Venovenous ECMO

12. Which form of ECMO should be considered for patients with cardiogenic shock, with or without an acute lung injury?
Venoarterial ECMO

13. What form of ECMO is best indicated for patients with COPD and pre-lung transplant patients?
Arteriovenous EMCO

14. Which group has the best survival rate treated with ECMO?
Neonates with respiratory support

15. What is the key reason for making ECMO so successful in newborns?
Most clinical conditions treated with ECMO in newborns are reversible.

16. What are the different uses of ECMO?
It is mostly used for neonatal hypoxemic respiratory failure. Some examples of clinical conditions include PPHN, MAS, RDS, sepsis, and air leak syndrome.

17. Which of the following strategies is greatly responsible for decreasing the need for ECMO in neonates?
HFOV

18. Which condition is considered the 1st contraindication for neonatal ECMO?
Less than 2 kg of body weight

19. What are the suggested indications for pediatric ECMO?
PaO2/FiO2 greater than 75, oxygen index greater than 35, and a pre-ECMO pH less than 7.20

20. What are the cardiac applications of ECMO?
ECPR, CDH, fulminant myocarditis, and cardiomyopathy

21. What statement describes venoarterial ECMO?
A cannula is inserted into the right common carotid artery for arterial return

22. During the administration of venovenous ECMO, the therapist notices that the SvO2 is greater than the SaO2. What is the best explanation of this phenomenon?
The native cardiac output has increased

23. During venovenous ECMO, what effect does the cardiac output have on oxygenation?
Changes in cardiac output, either way, will have little influence on the patient’s oxygenation.

24. What are the major advantages of venovenous ECMO?
Cardiovascular support is not involved

25. What mechanisms affect the output of venovenous ECMO?
The size of the tubing, the rotations per minute, and the tension of the rollers

27. What is the advantage of having the centrifugal pump automatically respond to resistances against which it is pumping?
It maintains regulated flow through the system.

28. In the gas membrane exchanger, what is one of the limiting factors to the transfer the rate of oxygen across the membrane?
The thickness of the blood film between the membrane layers

29. Because the minimum flow rate required to remove condensation in the gas compartment usually results in excessive elimination of carbon dioxide, what should the respiratory therapist do?
Blend sweep gas with a carbogen mixture

30. What are the most common causes of a decrease in venous return in ECMO?
Hypovolemic state, malpositioning of the venous cannula, kinking of the cannula, and shifting of the mediastinum

31. It is not uncommon for patients undergoing ECMO to experience renal failure. What can be done to enhance renal function?
Perform hemofiltration

32. The ECMO specialist has noticed excessive clotting in the circuit despite increased doses of heparin. What is the most feasible explanation for this event?
Deficiency of ATIII

33. The respiratory therapist in charge of a patient on ECMO is monitoring the ACT every 30 minutes. The last ACT was 100 seconds. What should the therapist suggest at this time?
Increase the heparin dose

34. The respiratory therapist in charge of a patient on ECMO has noticed an increase in pre-membrane pressures. What is the most probable explanation?
Clotting in the circuit

35. How can membrane malfunction be suspected?
Narrowing of the pre-membrane and post-membrane PaCO2

36. What ventilator settings are typically used in ECMO for respiratory support?
A tidal volume of 5-7 ml/kg, PIP 25-25 cmH2O, and a frequency 10-12.

37. What ECMO flow is considered as minimal support?
30 mL/Kg

38. What is considered the most concerning complication of ECMO in a newborn?
Intracranial hemorrhage

39. What are the main uses of ECMO?
Neonatal Hypoxemic Respiratory Failure, i.e. Persistent pulmonary HTN of the newborn (PPHN), Meconium aspiration syndrome (MAS), Respiratory distress syndrome (RDS), sepsis, and air leak syndromes

40. What are the uses of ECMO for cardiac applications?
Congenital heart disease, fulminant myocarditis or cardiomyopathy, and extracorporeal cardiopulmonary resuscitation (ECPR)

41. What needs to be monitored in the circuit function?
Water temperature, venous saturation, circuit integrity, pre- and post-membrane blood gases, air bubbles, hemodynamics, organ perfusion, lab tests, and a neurologic assessment

42. When can ECMO be used in neonates?
ECMO can be used at greater than 32 weeks gestation with no intraventricular hemorrhage.

43. What are the cardiac applications for ECMO?
Congenital heart disease, myocarditis or cardiomyopathy, and extracorporeal cardiopulmonary resuscitation (ECPR)

44. How much of the cardiac output is supported by ECMO?
80%

45. What is used for anticoagulation?
Heparin

46. What is the main goal of ECMO?
The main goal is to discharge the patient without any disability.

47. What is the survival rate for ECMO?
Greater than 65% in infants

48. What is the most common mechanical complication that can occur during ECMO?
Clot formation

49. How can you wean a patient from ECMO?
Weaning occurs by gradually turning down the pump flow in VA or by turning down the sweep flow in VV.

50. During venoarterial ECMO, how is blood returned to the patient’s body?
It is returned to the body via arterial circulation.