ECMO (Extra-Corporeal Membrane Oxygenation)

Reviewed and revised 7 February 2014

OVERVIEW

  • ECMO is extra-corporeal membrane oxygenation
  • extracorporeal life support (ECLS) may be a better term
  • The extracorporeal circuit allows for the oxygenation and removal of carbon dioxide from blood
  • used as a supportive strategy in patients who have a high risk of death despite conventional therapy

HISTORY

Neonates

  • 1974 – used in the setting of meconium aspiration with severe hypoxaemia
  • first RCT (Bartlett) – benefit shown but methodology was highly criticized
  • 1993-1995, UK: ECMO vs conventional care -> trial stopped early due to benefit (NNT 3)

Adults

  • 1972 – first survivor (NEJM) – young patient with post-traumatic respiratory failure
  • 1979 – VA ECMO (ECMO with ventilation) vs ventilation alone -> high mortality in ECMO group
  • 1986 — Gattinoni’s case series, VV, used for CO2 removal, increased survival but large blood loss/day

TYPES

  • VV = veno-venous
  • VA = veno-arterial: peripheral or central
  • Veno-pulmonary artery ECMO (provides short-term right ventricular and respiratory support following LVAD insertion)
  • high (2 venous cannulae) vs low flow (1 venous cannula)

INDICATIONS

acute, severe REVERSIBLE respiratory or cardiac failure with a high risk of death that is refractory to conventional management

  • poor gas exchange
  • compliance < 0.5mL/cmH2O/kg
  • P:F ratio < 100
  • shunt fraction > 30%

GENERAL CONTRAINDICATIONS

Absolute

  • progressive non-recoverable cardiac disease (not transplant candidate)
  • progressive and non-recoverable respiratory disease (irrespective of transplant status)
  • chronic severe pulmonary hypertension
  • advanced malignancy
  • GVHD
  • >120kg
  • unwitnessed cardiac arrest

Relative

  • age > 75
  • multi-trauma with multiple bleeding sites
  • CPR > 60 minutes
  • multiple organ failure
  • CNS injury

VV ECMO

  • most common mode
  • venous drainage from large central veins -> oxygenator -> venous system near RA
  • support for severe respiratory failure (no cardiac dysfunction)
  • pathology:

-> pneumonia
-> ARDS
-> acute GVHD
-> pulmonary contusion
-> smoke inhalation
-> status asthmaticus
-> airway obstruction
-> aspiration
-> bridge to lung transplant
-> drowning

  • specific contraindications:
    — unsupportable cardiac failure
    — severe pulmonary hypertension
    — cardiac arrest
    — immunosuppression (severe)

  • oxygenated blood returned to right side of heart so oxygen loss can take place through the lungs

Advantages

  • normal lung blood flow
  • oxygenated lung blood
  • pulsatile blood pressure
  • oxygenated blood delivered to root of aorta
  • must be used when native cardiac output is high

Disadvantages

  • no cardiac support
  • local recirculation though oxygenator at high flows
  • reverse gas exchange in lung if FiO2 low
  • limited power to create high systemic arterial oxygen tension

Ventilation

  • no need to ventilate at normal level
  • must maintain alveolar volume and oxygenation
  • RR 8-10, PEEP 15, TV 3-4mL/kg, PIP < 30, FiO2 0.4
  • mandatory bronchoscopy and normal ventilation before decannulation

DETERMINATES OF FLOW WITH VENOUS LINES

  • cannula size
  • patency of vein
  • suck down and kicking of line (vein collapsing around cannula)
    -> fluid load
    -> check intra-abdominal pressure
    -> add a second drainage line
    -> return cannula advanced into right ventricle (rare)

VA ECMO

  • venous drainage from large central veins -> oxygenator -> arterial system in aorta
  • support for cardiac failure (+/- respiratory failure)
  • pathology:

-> graft failure post heart or heart lung transplant
-> non-ischaemic cardiogenic shock
-> failure to wean post CPB
-> bridge to LVAD
-> drug OD
-> sepsis
-> PE
-> cardiac or major vessel trauma
-> massive pulmonary haemorrhage
-> pulmonary trauma
-> acute anaphylaxis

  • specific contraindications:
    — aortic dissection and severe AR

Peripheral VA ECMO

  • back flow cannula used to prevent limb ischaemia
  • oxygenated blood returned to aorta so lungs get little O2 rich blood -> may exacerbate lung ischaemia
  • lower body receives better perfusion

Advantages

  • good Q
  • can create high oxygen tensions

Disadvantages

  • relative lung ischaemia
  • non-pulsatile blood flow
  • possible poor perfusion of coronaries and cerebral vessels
  • distal limb ischaemia
  • risk of lung overventilation -> tissue alkalosis (monitor with ETCO2)

Central VA ECMO

  • cannula into the ascending aorta or subclavian artery (needs back flow cannula)

Advantages

  • no preferential perfusion to lower body
  • no possibility of hypoxic perfusion of cerebral vessels
  • can use very large cannulae (high flows)

Disadvantages

  • need sternotomy and tissue dissection
  • predisposes to severe bleeding

CIRCUIT

  • cannulae
  • tubing
  • pump
  • membrane oxygenator and heat exchanger
  • gas blender

Cannulae

  • 15-23 Fr
  • arterial
  • venous
  • back flow
  • bicaval cannulae (available)

Tubing

  • therapeutic anticoagulation required (ACT 180-200)
  • all tubing is heparin bonded
  • blood must be kept flowing

Pump

  • centrifugal or roller
  • patients on VV don’t require a pump as patients heart is working

Oxygenator

  • large surface area
  • integrated heat exchange

MANAGEMENT

Patient

  • assessment if ECMO is no longer required:

VA

  • PAC to assess pulmonary pressures
  • TOE
  • increasing pulsatility visible on arterial trace or increased MVO2
  • turn down gas flow to oxygenator to assess respiratory function

VV

  • CXR
  • improved compliance
  • reduced PaCO2
  • turn off gas flow to oxygenator and increase ventilation
  • minimise lung injury: ventilate to recruit but minimize VALI, measure ETCO2 to assess native lung recovery

ECMO

  • optimise circuit function: pressure measurement before and after oxygenator
  • optimise ‘gas exchange’: set flow to provide adequate O2 delivery and CO2 elimination, mixed venous saturation monitoring, adjust blood volume to influence MAP
  • anticoagulation: Hb 120-130, ACT 140-180, platelets > 80
  • removal of cannulae: surgical or compression depending on type of insertion

Mechanical ventilation initial seeting for VV-ECMO (consensus guidelines and expert opinion)

  • Tidal volume: < 4 ml/kg predicted body weight
  • Plateau pressure: < 25 cmH2O
  • PEEP: 10-15 cmH2O
  • FiO2: titrated to maintain sats > 85%
  • RR: 4 to 6 breaths per minute

COMPLICATIONS

  • clot formation
  • haemolysis (plasma free Hb < 0.1g/L)
  • suck down and kicking (due to vessel collapse around access cannulae)
  • air embolism
  • bleeding
  • pump failure
  • decannulation
  • circuit rupture
  • cardiac arrest
  • oxygenator failure
  • VA: left ventricular overdistension -> APO, cardiac damage, pulmonary haemorrhage, pulmonary infarction, aortic thrombosis, cardiac or cerebral hypoxia, CVA 15%
  • VV: cardiac arrest -> perform CPR

SUMMARY

  • well established in neonates
  • adults and VV:
    -> CESAR trial showed improved survival @ 6 months (63% vs 47%) in adults with severe acute respiratory failure
    -> ANZ ECMO Influenza investigators showed a mortality rate of 21% (lower than previous published studies)
    -> Systematic review on ECMO in H1N1 pandemic (Crit Care Med, 2010) found insufficient evidence for ECMO use among patients with H1N1
  • adults and VA: little evidence so far
  • CPR: used successfully in cardiac arrest
  • retrieval: used successfully in retrieval medicine

-> established treatment
-> can decrease mortality
-> patient selection paramount
-> should be used in centres with appropriate expertise, experience and resources.

References and Links

LITFL

Journal articles

  • Bartlett RH, Gattinoni L. Current status of extracorporeal life support (ECMO) for cardiopulmonary failure. Minerva Anestesiol. 2010 Jul;76(7):534-40. PubMed PMID: 20613694. [Free Full Text]
  • Baud FJ, Megarbane B, Deye N, Leprince P. Clinical review: aggressive management and extracorporeal support for drug-induced cardiotoxicity. Crit Care. 2007;11(2):207. Review. PubMed PMID: 17367544; PubMed Central PMCID: PMC2206443.
  • Chauhan S, Subin S. Extracorporeal membrane oxygenation, an anesthesiologist’s perspective: physiology and principles. Part 1. Ann Card Anaesth. 2011 Sep-Dec;14(3):218-29. doi: 10.4103/0971-9784.84030. Review. PubMed PMID: 21860197. [Free Fulltext]
  • Chauhan S, Subin S. Extracorporeal membrane oxygenation–an anaesthesiologist’s perspective–Part II: clinical and technical consideration. Ann Card Anaesth. 2012 Jan-Mar;15(1):69-82. doi: 10.4103/0971-9784.91485. Review. PubMed PMID: 22234027. [Free Fulltext]
  • Ensminger SL, et al. The role of extracorporeal mechanical assists. (ECLS et al.) Applied Cardiopulmonary Pathophysiology 16: 192-201, 2012 [Free Fulltext]
  • Gattinoni L, Carlesso E, Langer T. Clinical review: Extracorporeal membrane oxygenation. Crit Care. 2011;15(6):243. doi: 10.1186/cc10490. Epub 2011 Dec 8. Review. PubMed PMID: 22188792; PubMed Central PMCID: PMC3388693.
  • Lindstrom SJ, Pellegrino VA, Butt WW. Extracorporeal membrane oxygenation. Med J Aust. 2009 Aug 3;191(3):178-82. Review. PubMed PMID: 19645652. [Free Fulltext]
  • Pellegrino VA, Davies AR. CESAR: deliverance or just the beginning? Crit Care Resusc. 2010 Jun;12(2):75-7. PubMed PMID: 20513213. [Free Fulltext]
  • Schmidt M, et al. Mechanical ventilation during extracorporeal membrane oxygenation. Crit Care 2014;18:203.
  • The Alfred ICU ECMO Guidelines (2013)

FOAM and web resources

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  1. […] Mechanical Cardiopulmonary Resuscitation is likely to have an increasing role in the future of CPR.  Despite a lack of a current evidence base for its use it may be useful in selected cases especially  where prolonged CPR is required.  For example, it may be helpful to use Mechanical CPR in patients with refractory VF, Thrombolysis for Massive PE, Toxicological Arrest, Hypothermic Arrest and in arrested patients who are being transferred onto rescue VA ECMO. […]

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