Does prone ventilation make them less prone to​ ECMO in severe ARDS?

Extracorporeal membrane oxygenation (ECMO) is widely used in patients with severe acute respiratory distress syndrome (ARDS) and refractory hypoxemia. With the technological refinement of pumps and circuitry, along with increasing clinical expertise, many centers across the world seem to have adopted ECMO as an early treatment strategy. However, is this necessarily the most optimal management of patients with severe ARDS?

Li et al. analyzed 17 studies that utilized veno-venous ECMO between 1995–2017.(1) A total of 672 patients were included in these studies. The vast majority of patients (69%) did not undergo a trial of prone ventilation prior to the initiation of ECMO. In 2013, the PROSEVA study was published, which revealed improved survival with prone ventilation in severe ARDS.(2) However, bewilderingly, the utilization of prone ventilation before initiation of ECMO was even lower in studies published after PROSEVA.

The EOLIA study compared early ECMO with conventional care and rescue ECMO.(3) At the time of randomization, only 56% of patients had received prone ventilation in the “early” ECMO group. Would it be possible that the results may have been different had prone ventilation been resorted to more often among these patients? The study was stopped early for futility; besides, it aimed to demonstrate a fairly unrealistic 20% absolute mortality reduction. Crossover to rescue ECMO was largely based on clinician judgment, which may have led to bias. Although the results were eagerly awaited, the EOLIA study probably raised more questions than it could answer; importantly, would a more liberal proning strategy be advisable prior to initiation of ECMO?

An observational study from 11 intensive care units in Korea compared patients who received prone ventilation prior to ECMO with those who did not.(4) The 30-day mortality was similar among both groups of patients. Successful weaning from ECMO and from mechanical ventilation was more frequent in patients who were prone ventilated prior to ECMO. This study suggests that a trial of prone ventilation may be appropriate prior to consideration of ECMO; such a strategy may even have a protective effect.

Why are some clinicians reluctant to prone ventilate their patients with ARDS? Unfamiliarity and unjustified concerns regarding device dislodgement may be one of the factors. However, no study of prone ventilation has reported harm that could be directly attributed to this technique. Insertion of cannulae and overall management of ECMO would appear to be far more complex than adopting the prone position. Perhaps there is a general tendency to believe that a more complex treatment modality may be more efficacious. Perhaps the ready availability of equipment, skills, and possible financial incentive from an expensive treatment strategy are inevitable inducements.

After several randomized controlled trials (2,5–7) and two meta-analyses,(8,9) there is fairly robust evidence that prone ventilation saves lives in ARDS. It is needless to emphasize that ECMO will play an increasing role in the future in the management of the sickest of patients with ARDS. However, perhaps we should consider prone ventilation prior to contemplating ECMO therapy in every patient with severe ARDS.

References

1. Li X, Scales DC, Kavanagh BP. Unproven and Expensive before Proven and Cheap: Extracorporeal Membrane Oxygenation versus Prone Position in Acute Respiratory Distress Syndrome. Am J Respir Crit Care Med. 2018 Apr 15;197(8):991–3.
2. Guérin C, Reignier J, Richard J-C, Beuret P, Gacouin A, Boulain T, et al. Prone positioning in severe acute respiratory distress syndrome. N Engl J Med. 2013 Jun 6;368(23):2159–68.
3. Combes A, Hajage D, Capellier G, Demoule A, Lavoué S, Guervilly C, et al. Extracorporeal Membrane Oxygenation for Severe Acute Respiratory Distress Syndrome. N Engl J Med. 2018 May 24;378(21):1965–75.
4. Kim W-Y, Kang BJ, Chung CR, Park SH, Oh JY, Park SY, et al. Prone positioning before extracorporeal membrane oxygenation for severe acute respiratory distress syndrome: A retrospective multicenter study. Med Intensiva [Internet]. 2018 Jul [cited 2019 Jan 21]; Available from: https://linkinghub.elsevier.com/retrieve/pii/S0210569118301608
5. Guerin C, Gaillard S, Lemasson S, Ayzac L, Girard R, Beuret P, et al. Effects of systematic prone positioning in hypoxemic acute respiratory failure: a randomized controlled trial. JAMA. 2004 Nov 17;292(19):2379–87.
6. Mancebo J, Fernández R, Blanch L, Rialp G, Gordo F, Ferrer M, et al. A multicenter trial of prolonged prone ventilation in severe acute respiratory distress syndrome. Am J Respir Crit Care Med. 2006 Jun 1;173(11):1233–9.
7. Taccone P, Pesenti A, Latini R, Polli F, Vagginelli F, Mietto C, et al. Prone positioning in patients with moderate and severe acute respiratory distress syndrome: a randomized controlled trial. JAMA. 2009 Nov 11;302(18):1977–84.
8. Sud S, Friedrich JO, Taccone P, Polli F, Adhikari NKJ, Latini R, et al. Prone ventilation reduces mortality in patients with acute respiratory failure and severe hypoxemia: systematic review and meta-analysis. Intensive Care Med. 2010 Apr;36(4):585–99.
9. Gattinoni L, Carlesso E, Taccone P, Polli F, Guérin C, Mancebo J. Prone positioning improves survival in severe ARDS: a pathophysiologic review and individual patient meta-analysis. Minerva Anestesiol. 2010 Jun;76(6):448–54.