February 15, 2018


Treating ARDS: Are we using prone positioning?



Acute respiratory distress syndrome (ARDS) is a frequent cause of intensive care unit (ICU) admission and is associated with a significant mortality rate [1]. Prolonged sessions of prone positioning (PP) is one of the few strategies that have been proven to reduce mortality when PaO2/FiO2 ratio is lower than 150 mmHg [2, 3]. However, despite this evidence, it seems that PP continues to be underused [1]. Until now, no large-scale international studies had been conducted to solely examine the true prevalence of PP use in ARDS.  

In the APRONET study, C. Guérin et al. wanted to measure the prevalence of use of PP in ARDS with the hypothesis that the prevalence was actually higher than had been found previously [4]. They also wanted to identify the reasons for not applying PP. In this one-day prospective observational international study, prevalence was assessed and carried out four times; in April 2016, July 2016, October 2016 and January 2017 in 141 ICUs from 20 countries, which were participating on a voluntarily basis. In all participating ICUs, all intubated adult patients with ARDS according to criteria in the Berlin definition in the ICU on the study day were included.

Amongst the 6723 patients screened during the four study days, 735 (10.9%) fulfilled the ARDS criteria with a prevalence rate on each study day of 13.3%. One hundred and one (13.7%) patients with ARDS underwent PP at least one time. The prevalence of use of PP was 5.9% in mild ARDS, 10.3% in moderate and 32.9% in severe ARDS. The most frequent reason for not proning was not severe enough hypoxemia to justify it (64.3% of the cases).


This study enhanced that PP is much more used than previously reported in severe ARDS and that, as previously described, the major reason for not proning was related to the severity of hypoxemia. There are many reasons that might have led to these results: It may reflect a change in practice due to the mounting evidence and a better diffusion of the related recommendations and experts’ advice. However, this study did take place solely in volunteer ICUs, in which practitioners may be more self-motivated to apply PP in ARDS. Moreover, these ICUs were mostly across Europe where the rate of use of PP has already been found to be higher than elsewhere [1]. Although the rate of application of prone position seems to have increased over recent years with a lower rate of complications being reported, in clinical practice it seems to still be considered only as a rescue manoeuvre on par with ECMO. Indeed, Li et al. recently published a paper entitled “Unproven and Expensive before Proven and Cheap” where they have revealed that in most reports that described ECMO use in ARDS, patients had not received a trial of prone positioning before ECMO, even after the 2013 publication of the key paper from Guérin et al.’s positive RCT on prone positioning in these patients [3, 5].

Take Home Messages

Prone position is associated with an increase in arterial oxygenation and a significant decrease in driving pressure, two strong predictors of survival in ARDS. Furthermore, the rate of complications reported is much lower than previously reported in patients with ARDS possibly due to an improvement in practice. Proponents of this inexpensive and beneficial technique clearly need to keep dissemination of this important message: “With ARDS, let’s be prone to prone positioning our patients“.

Article review was prepared by Thomas Madelaine and Paul Abraham (Hospices Civils de Lyon, Hôpital Edouard Herriot, Lyon, France) on behalf of the EJRC.


  1. Bellani G, Laffey JG, Pham T, et al (2016) Epidemiology, Patterns of Care, and Mortality for Patients With Acute Respiratory Distress Syndrome in Intensive Care Units in 50 Countries. JAMA 315:788–70.
  2. Gattinoni L, Carlesso E, Taccone P, et al (2010) Prone positioning improves survival in severe ARDS: a pathophysiologic review and individual patient meta-analysis. Minerva Anestesiol 76:448–454.
  3. Guerin C, Reignier J, Richard J-C, et al (2013) Prone positioning in severe acute respiratory distress syndrome. N Engl J Med 368:2159–2168.
  4. Guérin C, Beuret P, Constantin JM, et al (2018) A prospective international observational prevalence study on prone positioning of ARDS patients: the APRONET (ARDS Prone Position Network) study. Intensive Care Med 44:22–37. (FREE ACCESS)
  5. Li X, Scales DC, Kavanagh BP. Unproven and Expensive Before Proven and Cheap – Extracorporeal Membrane Oxygenation vs. Prone Position in ARDS. Am J Respir Crit Care Med. 2018, Jan 9.
Related icTV Content

In this new icTV interview, Claude Guérin shares the encouraging results recently published in Intensive Care Medicine on large-scale observational study APRONET, which looked at the prevalence of ARDS and the use of prone positioning.

For more information on this ESICM Trials Group study, visit the APRONET webpage.

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