Four prospective observational studies of ventilation in critically ill patients were harmonized and pooled.

The individual data from four observational studies ('Epidemiology of Respiratory Insufficiency in Critical Care study' [ERICC], the 'Large Observational Study to Understand the Global Impact of Severe Acute Respiratory Failure' [LUNG SAFE], 'PRactice of VENTilation in critically ill patients without ARDS' [PRoVENT], 'PRactice of VENTilation in critically ill patients in Middle-income Countries' [PRoVENT-iMiC]) were harmonized and pooled into a database named 'PRoPERLy II'. This database will be used to address various issues in diverse patient categories.

ERICC included patients aged 18 years or older that received ventilatory support for at least 24 hours during the first 48 hours of ICU admission at the participating ICUs. ERICC excluded patients with a tracheostomy, patients admitted for routine uncomplicated postoperative care, readmissions and patients with a terminal condition. ERICC enrolled patients during 2-months period.

LUNG SAFE included patients aged 16 years or older that received invasive or noninvasive ventilation. LUNG SAFE excluded patients without informed consent. LUNG SAFE enrolled patients during a 4-week period in the winter months.

PRoVENT included patients aged 18 years or older that received invasive ventilation. PRoVENT excluded patients in whom ventilation was started before the study recruitment week, patients receiving only noninvasive ventilation, and patients that were transferred to the ICU from another hospital under ventilation. PRoVENT enrolled patients during 4-week period.

PRoVENT-iMiC included patients aged 18 years or older that started with invasive ventilation. They excluded patients that received only noninvasive ventilation, patients whose invasive ventilation started before the inclusion phase of the study, and patients transferred from another hospital while under ventilation. PRoVENT-iMiC enrolled patients during 4-week period.

All patients in the PRoPERLy II database are eligible for this and future analyses. For this first analysus, patients without reported SpO2 values and patients with SpO2 values and PaO2 values not simultaneously recorded are excluded.

For this, interested investigators will have to provide a detailed analysis plan, containing a testable hypothesis, clearly described endpoints and an analysis plan. After approval, investigators will be provided with a mock database that will allow them to write an analysis script in R. PROVE network investigators will then run the script on the PRoPERLy II database and provide the investigators with the results. Any publication from an additional analysis must follow the rules for publication denoted by the PROVE network

Notably, after this initial analysis of PRoPERLy II, the database will be available for additional analysis, till for ever

For this, interested investigators will have to provide a detailed analysis plan, containing a testable hypothesis, clearly described endpoints and an analysis plan. After approval, investigators will be provided with a mock database that will allow them to write an analysis script in R. PROVE network investigators will then run the script on the PRoPERLy II database and provide the investigators with the results. Any publication from an additional analysis must follow the rules for publication denoted by the PROVE network