title: Duration of veno-arterial extracorporeal life support (VA ECMO) and outcome: an analysis of the Extracorporeal Life Support Organization (ELSO) registry.
abstract: BACKGROUND
  Veno-arterial extracorporeal membrane oxygenation (VA ECMO) is an effective rescue therapy for severe cardiorespiratory failure, but morbidity and mortality are high. We hypothesised that survival decreases with longer VA ECMO treatment. We examined the Extracorporeal Life Support Organization (ELSO) registry for a relationship between VA ECMO duration and in-hospital mortality, and covariates including indication for support.
  
  
  METHODS
  All VA runs from the ELSO database from 2002 to 2012 were extracted. Multiple runs and non-VA runs were excluded. Runs were categorized into diagnostic groups. Logistic regression for analysis of the effect of duration on outcome, and multivariate regression for diagnosis and other baseline factors were performed. Non-linear models including piecewise logistic models were fitted.
  
  
  RESULTS
  There were 2699 runs analysed over 14,747 days. Logistic regression analysis of the effect of duration on outcome, and multivariate regression analysis of diagnosis and other baseline factors were performed. In-hospital survival was 41.4% (95% CI 39.6-43.3). 75% of patients were supported for less than 1 week and 96% for less than 3 weeks. Median duration (4 days IQR 2.0-6.8) was greater in survivors (4.1 (IQR 2.5-6.7) vs 3.8 (IQR 1.7-7.0) p = 0.002). The final multivariate model demonstrated increasing survival to day 4 (OR 1.53 (95% CI 1.37-1.71) p < 0.001), decreasing from day 4 to 12 (OR 0.86 (95% CI 0.81-0.91), p < 0.001) with no significant change thereafter (OR 0.98 (95% CI 0.94-1.02), p = 0.400).
  
  
  CONCLUSIONS
  ECMO for 4 days or less is associated with higher mortality, likely reflecting early treatment failure. Survival is highest when patients are weaned on the fourth day of ECMO but likely decreases into the second week. While this does not suggest weaning at this point will produce better outcomes, it does reflect the likely time course of ECMO as a bridge in severe shock. Patients with some underlying conditions (like myocarditis and heart transplantation) achieve better outcomes despite longer support duration. These findings merit prospective study for the development of prognostic models and weaning strategies.
authors.affiliation: Department of Intensive Care Medicine, St Vincent's Hospital, Sydney, NSW, Australia. myles.smith@unswalumni.com.
authors.forename: Myles
authors.identifier: http://orcid.org/0000-0002-9308-2230
authors.initials: M
authors.lastname: Smith
authors.affiliation: Department of Intensive Care Medicine, St Vincent's Hospital, Sydney, NSW, Australia.
authors.forename: Alexander
authors.initials: A
authors.lastname: Vukomanovic
authors.affiliation: Extracorporeal Life Support Organization (ELSO), Ann Arbor, MI, USA.|Columbia University Medical Center/NewYork-Presbyterian Hospital, New York, NW, USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Brodie
authors.affiliation: Extracorporeal Life Support Organization (ELSO), Ann Arbor, MI, USA.
authors.forename: Ravi
authors.initials: R
authors.lastname: Thiagarajan
authors.affiliation: Extracorporeal Life Support Organization (ELSO), Ann Arbor, MI, USA.
authors.forename: Peter
authors.initials: P
authors.lastname: Rycus
authors.affiliation: Department of Intensive Care Medicine, St Vincent's Hospital, Sydney, NSW, Australia.|Extracorporeal Life Support Organization (ELSO), Ann Arbor, MI, USA.|University of New South Wales, Sydney, NSW, Australia.
authors.forename: Hergen
authors.initials: H
authors.lastname: Buscher
mesh_terms: D000328:Adult; D015199:Extracorporeal Membrane Oxygenation / Q000379:methods* / Q000401:mortality / Q000592:standards*; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011446:Prospective Studies; D012042:Registries / Q000706:statistics & numerical data; D012189:Retrospective Studies; D013997:Time Factors; D016896:Treatment Outcome
keywords: Extracorporeal Life Support Organization; Extracorporeal membrane oxygenation; Outcomes; Refractory shock; Survival; Treatment duration