Question 18

College answer

Not available.

Discussion

ECPR has never been seen in the CICM exams until this paper.

Rationale

• Survival from cardiac arrest remains poor even in well-resourced urban medical systems where bystander CPR is common.
• This is partly because conventional CPR yields a meagre 50% of normal cardiac output at best
• This poor cardiac output results in a low flow state which progressively diminishes the chances of a successful resuscitation
• Many causes of cardiac arrest (MI, massive PE, overdose, primary arrhythmia) are amenable to intervention, if only the patient could be sustained for long enough to benefit from it
• From this, it follows that mortality from cardiac arrest could be improved by the early use of VA ECMO to support the circulation while the cause of cardiac arrest is being found and reversed. 

Advantages

• Rapid restoration of circulation on ECMO should protect from organ system damage
• Facilitates coronary and endovascular interventions
• Carefully selected patients have had good outcomes:
  • 22% survival at 180 days for Belohlavek et al, 2022
  • 43% for Yannopoulos et al, 2020
  • 44% for Dennis et al, 2020
  • 54% for Stub et al, 2015
  • This is compared to 3-10% survival for conventional CPR
• The cost of the program is comparatively lower than the cost of similarly low-yield interventions which still associate with high mortality (eg. radiation therapy and chemotherapy).

Disadvantages

• Expensive, mainly in terms of staff (in the sense that not everybody is trained in VA ECMO cannulation, and not everybody trained in it is willing to go on a 24/7 roster)
• May facilitate the survival of patients with profound neurological disabilities
• May prolong the dying process in some patients, preventing the "good death".
• Though ethically withdrawal of ECMO support is equivalent to the decision to stop CPR when the patient is not expected to make any recovery, practically it may be difficult to contemplate discontinuing ECMO support from the viewpoint of the family.
• The availability of this technique in only dense urban areas may increase the inequality in healthcare availability between metropolitan and rural populations

Patient selection

• ELSO criteria:
  • Age < 70 years
  • Witnessed cardiac arrest
  • Initial cardiac rhythm of VT/VF (PEA)
  • Low flow (cardiac arrest to initiation of full ECMO flow) of <60 minutes
  • EtCO₂ > 10mmHg
• 2CHEER criteria:

  • age 12-70 years

    AND meets ALL of the following criteria:

    • the cardiac arrest is likely to be of primary cardiac or respiratory cause

    • the cardiac arrest was witnessed by a bystander or paramedic or hospital staff member

    • chest compressions commenced within 10 minutes

    • initial cardiac rhythm of ventricular fibrillation (VF)

    • immediate availability of a mechanical CPR device with paramedic staff

    • the cardiac arrest duration (collapse to arrival at ED) has been < 60minutes

  • OR meets ONE of the following criteria:

    • Severe hypothermia (<32°C) due to accidental exposure

    •  Severe overdose with β-blockers, tricyclic antidepressants, digoxin or other agents causing profound reversible myocardial depression and/or cardiac rhythm disturbance

    • Any other cause where there is likely to be reversibility of the cardiac arrest if an artificial circulation can be provided (e.g. massive pulmonary embolism)