Saturday, December 14, 2013

Extracorporeal life support (ECLS)

This refers to either extracorporeal membrane oxygenation (ECMO) or extracorporeal CO2 removal (ECCO2R), for a variety of indications but mainly ARDS. Here is a recent review.

The status of ECLS is evolving. In the 70s, following an early wave of enthusiasm for ECMO as treatment for ARDS, research evidence was disappointing. By the time of my early interest in critical care the idea was almost rejected out of hand. Subsequently it began to emerge as a rescue modality for ARDS in cases of therapeutic desperation. Technology improved and offered variations of the technique as additional options. Out of necessity considerable positive experience was gained during the 2009 pandemic. Also, as quoted from the review:

Also that same year, the conventional ventilatory support versus ECMO for severe adult respiratory failure (CESAR) study was published. The investigators used a “pragmatic” study design and were criticized for the inability to standardize mechanical ventilation management in the conventional care group.[30] Importantly, the CESAR trial demonstrated that protocolized care that included ECMO in an expert center for ARDS care yielded higher survival than the best standard care in tertiary intensive care units in the UK.[30]

Here is the CESAR study. It concluded:

We recommend transferring of adult patients with severe but potentially reversible respiratory failure, whose Murray score exceeds 3.0 or who have a pH of less than 7.20 on optimum conventional management, to a centre with an ECMO-based management protocol to significantly improve survival without severe disability.

So ECLS is making its way into clinical practice. The Extracorporeal Life Support Organization has published guidelines. The indications section reads:

Acute severe heart or lung failure with high mortality risk despite optimal conventional therapy. ECLS is considered at 50% mortality risk, ECLS is indicated in most circumstances at 80% mortality risk. Severity of illness and mortality risk is measured as precisely as possible using measurements for the appropriate age group and organ failure. See patient- specific protocols for details. 
Most contraindications are relative, balancing the risks of the procedure (including the risk of using valuable resources which could be used for others) vs. the potential benefits. The relative contraindications are: 1) conditions incompatible with normal life if the patient recovers; 2) preexisting conditions which affect the quality of life (CNS status, end stage malignancy, risk of systemic bleeding with anticoagulation); 3) age and size of patient; 4) futility: patients who are too sick, have been on conventional therapy too long, or have a fatal diagnosis. See patient-specific protocols for details.

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