An interventional study of Daily prone position sessions and Prolonged prone position sessions in Acute Respiratory Distress Syndrome, sponsored by Pontificia Universidad Catolica de Chile. Recruiting at 38 sites in 6 countries. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-05-18.
Sponsored by Pontificia Universidad Catolica de Chile · Not applicable, Interventional, and Other
Prone position (placing the patient on his abdomen) has been shown to be an effective intervention to decrease mortality in adults connected to mechanical ventilation for moderate to severe Acute Respiratory Distress Syndrome (ARDS). Patients may require one or more sessions of prone position. However, the optimal duration of prone sessions is unknown. The goal of this clinical trial is to learn if applying prone position in prolonged sessions (> 48 hours - prolonged prone position) is more effective than applying it in daily sessions (16 to 24 hours - intermittent prone position). The trial will also learn about the safety of prolonged prone position compared to intermittent prone position. The main questions it aims to answer are:
Researchers will compare prolonged versus intermittent prone position to see which approach is better to treat moderate to severe ARDS.
Participants will:
Acute Respiratory Distress Syndrome (ARDS) is a severe condition with a 40% mortality rate. The management of ARDS still relies largely on supportive therapy. The cornerstone of this support is protective mechanical ventilation to prevent ventilator-induced lung injury (VILI). For patients with moderate-to- severe forms of ARDS, specifically mechanically ventilated patients with PaO2/FiO2 ratios below 150, the use of prone position has shown to be a fundamental intervention which became one of the most relevant pillars of the ICU management during the Covid-19 pandemics. Several studies have shown that prone position not only improves oxygenation, but can attenuate the mechanisms of VILI, which would explain its benefit in terms of mortality. The physiologic benefits of prone position are progressive along time, but they can be lost rapidly after returning to supìne position.
Since the publication of the landmark PROSEVA study (Guerin 2013), which showed that ventilating patients in prone position decreased mortality, the standard approach to prone position has been the use of daily sessions of 16 to 20 hours. With this approach most patients usually require 3 to 4 prone sessions (intermittent daily prone position). However, due to the excessive workload of ICU staff during the Covid-19 pandemics, several centers decided to extend the sessions beyond 24 hours to decrease the frequency of position changes in patients with Covid-19 associated ARDS. Several centers reported their experience with prolonged sessions showing that it was feasible and that the rate of adverse events appeared to be similar to those previously reported with the standard daily sessions. The largest experience reported up to now was a retrospective study which included 417 patients from 15 centers in Chile, where a continuous prolonged prone position was applied as a nationwide strategy (Cornejo 2022). Most patients required a single prone session of 4 (3-5) days. Although the study lacked a control group, the mortality and rate of adverse events was rather low compared to other series of patients with similar characteristics. A non-randomized controlled study from 3 hospital in US even showed that compared to patients treated with standard prone sessions (\< 24 hours), patients treated with prolonged sessions had a lower risk of mortality (Okin 2023). However, other reports have shown conflicting results regarding the potential benefit associated to prolonging prone position sessions beyond 24 hours. Recent guidelines have acknowledged that the optimal duration of prone position sessions is unknown and must be further investigated (Grasselli 2023). Prolonging prone position sessions may ensure that this lung protective intervention is maintained throughout the acute phase of ARDS.
The goal of the present study is to compare the effects of a continuous prolonged prone position versus an intermittent daily prone position on mortality and other relevant outcomes, as well as on the incidence of adverse events potentially related to prone position, in mechanically ventilated patients with moderate-to-severe ARDS.
The study will be a randomized, multicenter, two-arm parallel-group, investigator-led clinical trial with allocation concealment and intention-to-treat analysis. Patients allocated to the experimental arm (prolonged prone position) will receive prone position sessions for a minimum of 48 hours, which will be further extended until PaO2/FiO2 is ≥ 200, or until reaching the maximum of 120 hours. Patients allocated to the control arm (intermittent prone position) will receive prone position sessions for a minimum of 16 hours and a maximum of 24 hours. In both groups prone sessions may be repeated if PaO2/FiO2 ratio falls below 150 after being returned to supine position during the first 7 days (intervention period).
1,387 studies on the registry are indexed under Respiratory Distress Syndrome; 283 are open to participants now.
This study's planned enrollment of 780 is above the median of 60 across 822 interventional studies indexed under Respiratory Distress Syndrome.
Browse Respiratory Distress Syndrome studies →Pontificia Universidad Catolica de Chile is the lead sponsor of 224 studies on the registry; 59 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Moderate-severe ARDS defined as:
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Contraindication
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
This arm will receive prone position sessions as applied in the PROSEVA trial (Guerin 2013)
Procedure: Daily prone position sessions
This arm will receive prone position sessions as applied in a previous multicenter study during the COVID-19 pandemics (Cornejo 2022)
Procedure: Prolonged prone position sessions
Prone position sessions will be extended at least 16 hours, but no longer than 24 hours. Prone sessions will be repeated if PaO2/FiO2 ratio decreases to \< 150 after returning to supine position within the first 7 days after randomization. The extension of repeated prone sessions will follow the same criteria.
Prone position sessions will be extended at least 48 hours AND until PaO2/FiO2 ratio is ≥ 200, but no longer than 120 hours. Prone sessions will be repeated if PaO2/FiO2 ratio decreases to \< 150 after returning to supine position within the first 7 days after randomization. The extension of repeated prone sessions will follow the same criteria.
28-day mortality
All-cause mortality
Time frame: 28 days
90-day mortality
All-cause mortality
Time frame: 90 days
Ventilator-free days
Days-free from mechanical ventilation and alive up to day 28
Time frame: 28 days
Hospital-free days at day 28
Days-free from Hospital and alive up to day 28
Time frame: 28 days
Plan to share: Yes — anonymized data will be shared among reasonable request to the corresponding author.
Supporting information: Study protocol, Statistical analysis plan
Time frame: will become available after the main paper is published, for 10 years.
Access criteria: among reasonable request to the principal investigator
Started Apr 2025 (actual). Primary completion is estimated for Oct 2027, 30 months after the start.
Of 263 non-industry interventional studies with no phase under Respiratory Distress Syndrome, half reached primary completion within 24 months of starting (the median), counting those still running; a quarter within 12 and three quarters within 42. This study's planned 30 months is above that.
Counting every sponsor, half of 270 studies reached it within 24 months; a quarter within 12 and three quarters within 42.
How these figures are worked out, and which studies are left out of them.
Eligibility is decided by the study team. Share this record with your doctor or contact the team directly.
Contact study teamGet an email when the registry record changes — status, dates, results — or when someone posts here.
Sign in to followQuestions and observations about this study, from anyone following it. Not medical advice, and not a channel to the study team — their contact details are on the registry record.
Sign in to join the discussion. Reading takes no account; posting does. You choose a display name, and a pseudonym is the default.
Nothing here yet. If you are running this trial, taking part in it, or weighing whether to, this is the place to say so.
Respiratory Distress Syndrome →
Pontificia Universidad Catolica de Chile →