II. Prerequisites

  1. Emergency ECMO is limited to tertiary institutions that have the equipment to perform cardiopulmonary bypass
  2. Emergency ECMO is time, training and resource intensive

III. Indications

  1. Cardiopulmonary Bypass
    1. Original indication dating back to its 1950 introduction
    2. Indicated in open heart surgery (CABG, Open Valve Replacement)
  2. Severe Hypothermia
    1. Core Temperature <32 C or 89.6 F) AND
    2. Cardiac instability (including Cardiac Arrest, Hypotension)
  3. Extracorporeal Life Support (ECLS)
    1. Severe, refractory Cardiogenic Shock (e.g. acute Myocardial Infarction, severe Viral Myocarditis)
    2. Obstructive shock (e.g. massive Pulmonary Embolism)
    3. Undifferentiated Hypotension refractory to fluid, Vasopressors, inotropes
    4. Poisoning (e.g. Carbon Monoxide Poisoning, Calcium Channel Blocker Overdose, Beta Blocker Overdose, Digitalis Toxicity)
  4. Extracorporeal Cardiopulmonary Resuscitation (ECPR)
    1. Periarrest support (Cardiac Arrest and severe Cardiogenic Shock)
    2. Refractory out-of-hospital Cardiac Arrest (>10 minutes of aggressive ACLS management)
      1. Ortega-Deballion (2016) Resuscitation 101:12-20 [PubMed]
    3. Combined with other Resuscitation measures
      1. Percutaneous Coronary Intervention (PTCA)
      2. Targeted Temperature Management (Therapeutic Hypothermia)
      3. Intra-aortic balloon pump

IV. Contraindications: Emergent ECMO - Extracorporeal Cardiopulmonary Resuscitation (ECPR)

  1. Age >75 years old (relative, depending on institution specific guidelines)
  2. Non-cardiac cause of arrest (except massive Pulmonary Embolism)
  3. Unwitnessed event or significant delay in initiating CPR
  4. Initial non-shockable rhythm (e.g. PEA or Asystole), not VT/VF
  5. Uncontrolled active Hemorrhage
  6. Departure from aggressive Resuscitation efforts
  7. Do not resuscitate order (DNR)
  8. Total arrest time >60 minutes
  9. Significant underlying comorbidities
    1. Significant CVA, Traumatic Brain Injury or Dementia
    2. Terminal illness (e.g. active advanced malignancy)
    3. End-stage renal disease on regular Dialysis
    4. Irreversible end-organ damage (e.g. Paraquat Poisoning)

V. Mechanism

  1. Blood Volume is removed from body via central venous catheter
  2. Blood circulates through machine that provides gas exchange including oxygenation
    1. Pump pushes blood forward, and creates negative pressure that draws blood from venous catheter
    2. Membrane oxygenator
  3. Blood is returned to the body via a central venous catheter (VV-ECMO) or arterial catheter (VA-ECMO)

VI. Types

  1. Venoarterial ECMO (VA-ECMO)
    1. Access with one central venous line (e.g. 21 F) and one central Arterial Line (e.g. 17 F)
    2. Typical ECMO that provides both pulmonary and cardiac support
  2. Venovenous ECMO (VV-ECMO)
    1. Access via one double lumen catheter
    2. Primarily indicated in ICU to manage refractory, decompensated Respiratory Failure

VII. Protocol: Example Emergent ECMO - Extracorporeal Cardiopulmonary Resuscitation (ECPR)

  1. Stage 1: Inpatient ECMO team places femoral central venous and Arterial Lines during ongoing CPR
  2. Stage 2: Venous and Arterial Lines are replaced with ECMO cannulae over guidewires
  3. Stage 3: Cardiopulmonary bypass initiated
  4. Urgent transfer to unit equipped to manage ECMO and its complications

VIII. Imaging

  1. Ultrasound
    1. Ultrasound-guided line placement
    2. Ultrasound confirmation of positioning of catheters (see xray for positioning landmarks)
  2. XRay confirms correct catheter placement
    1. Venous catheter at junction of inferior vena cava and right atrium
    2. Arterial catheter at descending aorta, proximal to the aortoiliac bifurcation

IX. Complications

  1. Arterial Gas Embolism
    1. Negative pressure generated by pump will pull air from any opening in the circuit
    2. Circuit is typically primed and ready for use in advance (30 day shelf life once primed)
    3. Prefill all tubing with Isotonic Saline prior to catheter insertion
    4. Confirm all connections are secure and stop cocks are inline to prevent air entrainment
    5. Starting ECMO requires at least 2 people to coordinate safe start
  2. Vascular Injury
    1. Catheter placement is complicated by performing during CPR, with a large bore ECMO cannula
    2. Risk of pseudoaneurysm, vascular dissection or tear
  3. Cerebral and cardiac hypoperfusion
    1. Retrograde Flow from a low aorta catheter may not adequately reach coronary and cerebral arteries
    2. Oxygenated blood in the aorta also mixes with deoxygenated blood in the low aorta
  4. Left ventricular distention
    1. Following ROSC, stunned Myocardium with reduced EF, will backfill and distend from aorta retrograde flow
    2. Risk of subendocardial ischemia, Pulmonary Edema, Pulmonary Hemorrhage
    3. Perform serial Echocardiograms
      1. Confirm aortic valve opening
      2. Evaluate for marked ventricular distention
        1. Manage with ECMO setting modification, inotropes, thoracic surgery interventions
  5. Superficial femoral artery obstruction
    1. ECMO catheters are large (15-25F art, 19-29F ven) by comparison with Central Lines (2.7F art, 7-9F ven)
    2. Large catheters may completely obstruct the femoral artery and block the superficial femoral artery
    3. Risk of Critical Limb Ischemia
  6. Compartment Syndrome
    1. Local inflammation from tissue Hypoxia results in increased Compartment Pressures
    2. Venous obstruction from large catheters also increase Compartment Pressures
  7. Hemorrhage
    1. ECMO increases thrombus risk (low flow rates through heart/lung, bypass circuit activates inflammatory response)
    2. ECMO requires large Heparin doses which increases risk of hemorrhagic complications

X. Efficacy

  1. Out-Of-Hospital Arrest and Refractory Ventricular Fibrillation
    1. Extracorporeal Cardiopulmonary Resuscitation (ECPR, VA-ECMO) may add significant intact survival benefit
      1. Yannopoulos (2020) Lancet 396(10265):1807-16 +PMID: 33197396 [PubMed]

XI. Resources

  1. Extracorporeal Life Support Organization (ELSO)
    1. https://www.elso.org/resources/guidelines.aspx

XII. References

  1. Kessler and Kurz in Herbert (2017) Crit Dec Emerg Med 31(5): 3-11
  2. Nordt, Swadron and Herbert in Herbert (2019) EM:Rap 19(9): 13-4

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