The purpose of this international, multicenter service review is to describe and compare ventilation management in patients at risk of acute respiratory distress syndrome (ARDS) versus patients not at risk and patients with established ARDS, and to ascertain whether certain ventilator settings and ventilation parameters are associated with pulmonary complications or development of ARDS after start of ventilation in patients in intensive care units (ICUs) in Asian countries.

Participating centers will include adult patients undergoing mechanical ventilation in the ICU during a 28-day period. Patients' data will be collected during the first 7 days in the ICU, or until ICU discharge. Follow up is until ICU discharge. The primary outcome includes two main ventilator settings, i.e., tidal volume and the level of positive end-expiratory pressure. Secondary endpoints are development of ARDS in patients without ARDS at the onset of mechanical ventilation, worsening of ARDS in patients with ARDS at the onset of mechanical ventilation, pulmonary infection, other pulmonary complications, need for tracheostomy, duration of ventilation, length of ICU stay and ICU mortality.

Rationale: scarce information exists on management of mechanical ventilation in intensive care unit (ICU) patients in low- and middle-income countries.

Objective:The primary objective is to describe and compare ventilation management in patients at risk of ARDS versus individuals not at risk, and patients with established ARDS, and to ascertain whether certain ventilation settings are associated with a higher incidence of developing ARDS in patients in ICUs in Asia. PRoVENT-iMIC secondary objectives are to determine the epidemiological characteristics and clinical outcomes of patients at risk of ARDS in ICUs in Asia according to the ventilation practice applied.

Primary hypothesis: a large proportion of patients at risk of ARDS in ICUs in Asia do not receive so-called protective ventilation, defined as tidal volume < 8 ml/kg predicted body weight and a level of positive end-expiratory pressure of at least 5 cm H2O.

Secondary hypothesis: in ICUs in Asia a large proportion of patients is at risk of ARDS, as stratified by a Lung Injury Prediction Score of ≥4.

Study design: an international multicenter service review focusing on ICUs in selected middle-income Asian countries.

Population: consecutive intubated and ventilated ICU patients.

Methods: Patients in participating ICUs will be screened daily during a 28-day period. A registry of limited demographic data will be compiled on all screened patients. Collection of ventilation characteristics is restricted to the first three days. The first seven days or up to death, whichever comes first, will be used for collection of patient demographics (on day of admission), development of ARDS and other pulmonary complications. All patients will be followed until ICU-discharge to determine length of stay in ICU and ICU mortality. The inclusion period will be flexible for participating centers and determined at a later stage together with the study-coordinator. Data will be coded by a patient identification number of which the code will be kept safe at the local sites. The data will be transcribed by local investigators onto an internet based electronic case report form (https://www.project-redcap.org).

Centers: about 60 Asian ICUs from ten countries are expected to participate in this international multicenter study. Each participating center will recruit ~ 50 patients.

Ethics Approval: The Oxford Tropical Research Ethical Committee has evaluated the study and considered it exempt from ethical review on the 1st of June 2017. National coordinators will be responsible for clarifying the need for ethics approval and applying for this where appropriate according to local policy. Centers will not be permitted to record data unless ethics approval or an equivalent waiver is in place.

Monitoring: Due to the observational nature of the study, a Data Safety and Monitoring Board is not necessary.

Sample Size Calculation: a formal sample size calculation was not performed, seen the largely descriptive character of this investigation. 3000 patients are expected to be enrolled in the study period, which will be sufficient to test the hypotheses.

Statistical Analysis: Patient characteristics will be compared and described by appropriate statistics. Student's t-test or Mann-Whitney U-tests are used to compare continuous variables and chi-squared tests are used for categorical variables. Data are expressed as means (SD), medians (interquartile range) and proportions as appropriate. Comparisons between and within groups are performed using one-way ANOVA and post-hoc analyses for continuous variables.

The primary analysis concerns the determination of (variation of) tidal volume and PEEP levels in patients without ARDS. These are compared between predefined patient groups: patients at no risk for ARDS, patients at risk for ARDS, patients with mild ARDS, and patients with moderate or severe ARDS.

To identify potential factors associated with outcome like development of ARDS, or worsening of ARDS, development of pulmonary complications, duration of ventilation, or death, univariate analyses are performed. A multivariate logistic regression model is used to identify independent risk factors. A stepwise approach is used to enter new terms into the model, with a limit of p < 0.2 to enter the terms. Time to event variables are analyzed using Cox regression and visualized by Kaplan-Meier.

Organization: The study is conducted by the PROtective VEntilation Network (PROVENet). National co-ordinators will lead the project within individual nations and identify participating hospitals, translate study paperwork, distribute study paperwork and ensure necessary regulatory approvals are in place. They provide assistance to the participating clinical sites in trial management, record keeping and data management. Local coordinators in each site will supervise data collection and ensure adherence to Good Clinical Practice during the trial.

Inclusion Criteria:

• Admitted to an ICU participating in this study
• Intubated in the ICU, or in the emergency room, general ward, or operation room before the present ICU admission

Exclusion Criteria:

• Age < 18 years
• Patients under invasive mechanical ventilation previous to the 28-day period of inclusion
• Patients transferred from another hospital under invasive mechanical ventilation
• Receiving only non-invasive ventilation (i.e., patient never received invasive ventilation during the present admission)

consecutive intubated and ventilated intensive care unit patients