ARDS and PROne position NETwork: APRONET study 



APRONET is a ONE-day prevalence study initiated by the ESICM Acute Respiratory Failure Section, which will be repeated four times during a one year period. It is a multicentre observational prospective study with no patient follow-up.


Prone position is used in almost 14% of severe ARDS patients according to the results of the LUNG-SAFE study. This rate is rather low given the results of the most recent trial that showed a beneficial effect of proning on patient outcome, a finding which is in line with previous meta-analyses. The reasons why the use of proning is still limited are unclear. One reason could be that the dissemination of the last scientific results was not complete at the time of the LUNG-SAFE study was carried out. Other reasons may include lack of expertise, preference of clinicians to alternate treatments, such as inhaled nitric oxide, higher PEEP, extracorporeal membrane oxygenation, high frequency oscillation ventilation among others.

Therefore, our goal is to explore the extent to which prone positioning is used in the current daily practice in ARDS patients by deciphering the following aims:

The primary objective of this study is to determine the prevalence of the use of the prone position in ARDS.

The secondary objectives are to determine:

–  The prevalence of the use of the prone position in ARDS according to the stage of ARDS from the Berlin definition.

–  The baseline characteristics of patients with ARDS, who are treated with prone position and of those who are not.

–  The characteristics of the patients with ARDS, at the time of the day of the study, who are treated with prone position as compared to those who are not.

–  The reasons why the prone position is not used in ARDS.

–  The physiological response to the prone position session the day of the study.

–  The duration of the prone position session the day of the study.

–  The complications occurring during the prone session the day of the study.

–  The use of adjunct concomitant therapies the day of the study.

–  The potential temporal trend in the rate of use of prone position and in the characteristics of ARDS patients


Data collection began in April 2016.

Each centre will select one date in each period across the 4 proposed dates for each of the 4 periods.

Study periods:

Period 1

APRIL 2016

Period 2

JULY 2016

Period 3


Period 4


Tuesday 5 Tuesday 5 Wednesday 5 Thursday 5
Tuesday 12 Tuesday 12 Wednesday 12 Thursday 12
Tuesday 19 Tuesday 19 Wednesday 19 Thursday 19
Tuesday 26 Tuesday 26 Wednesday 26 Thursday 26

The day of the study, all patients with ARDS present in the centre are screened and data are captured in the eCRF.

What data is required?


Inclusion criteria: adult patients (age ≥ 18 years) with ARDS criteria according to the Berlin definition (PaO2/FIO2 ≤300 mmHg), intubated and mechanically ventilated in the participating ICU.

Non-inclusion criteria: non-intubated patients and no criteria for ARDS the day of the study even though ARDS criteria were met from ICU admission to day of study.

Data Collection:

e-CRF includes variables to assess the general characteristics of patients including comorbidities at the time of ICU admission, the cause of ARDS, the date of ARDS diagnosis, SOFA, PaO2, and ventilator settings (tidal volume, FIO2, PEEP) and plateau pressure the day of the study, whether or not ARDS patients were treated by prone position and reasons for not using proning, PaO2, ventilator settings (tidal volume, FIO2, PEEP) and plateau pressure before and at the end of prone position session the day of the study, concomittent treatments the day of the study.

Do I need IRB approval?

The protocol has been approved by the IRB of Lyon, France (IRB number 9118) on July 9th 2015. It waived informed consent according to French law. This acceptance is valid for all centres in France. Centres in other countries should use their own local IRB.

How is the data that is collected managed?

All data is annonymised and cannot be linked to individual subjects. The data is stored securely and all procedures regarding data management will comply with EU directive on data protection 95/46/EC.

Who owns and can access the collected data? 

Each site investigator is responsible for his own data and may request an export of his data after the database is locked. The request should be addressed to the Principal Investigator.

Is there any financial compensation?

No. Participation in the trial is completely voluntary.

What about authorship? 

Authors: members of the steering committee

The primary investigators in each centre will be listed as coauthors.

How do I participate?

Registration is now closed.

Any further Questions?

If you have additional questions regarding APRONET, please contact the principal Investigator  Pr Dr Claude Guérin


Claude Guérin et al. A prospective international observational prevalence study on prone positioning of ARDS patients: the APRONET (ARDS Prone Position Network) study. Intensive Care Med. 2017 Dec 7. doi: 10.1007/s00134-017-4996-5.




For more information, please contact Guy FRANCOIS at