1. Title: Study of Biomarkers in Blood and Alveolar Lavage Fluid Samples of Sepsis Patients Complicated With Acute Respiratory Distress Syndrome (ARDS)
2. Research center: Single-center study.
3. Design of the research: A prospective and cohort study.
4. Object of the research: Patients（age≥18 years）those who meet the diagnostic criteria of sepsis complicated with ARDS and grouped into ARDS group and non-ARDS adults receiving mechanical ventilation as control.
5. Sample size of the research: Not less than 30 patients in each group.
6. Research approach: After admission to ICU, patients who meet the criteria are divided into mild group and moderate/severe group according to the severity of ARDS. In addition, blood and alveolar lavage fluid were collected within 24 hours for metabonomics analysis, and differential metabolites were screened out to prove the differentiation ability of differential metabolites between mild and moderate/severe ARDS patients. Then, MSEA and STITCH analysis were performed, and the relationship between different metabolites, HO-1 protein, oxidative stress and inflammatory markers in serum and alveolar lavage fluid were determined. And whether differential metabolites are associated with 28-day mortality in patients with moderate/severe ARDS.
7. Aim of the research: The metabolomics techniques were used to compare the differences between sepsis patients with mild ARDS and moderate/severe ARDS. And determine the relationship between different metabolites, HO-1 protein, oxidative stress and inflammatory markers, as well as the predictive effect of metabolites on 28-day mortality in patients.
8. Statistical analysis: Analytical study.
9. The estimated duration of the study：1-2 years.

This study is a single-center, prospective, retrospective study. In this study, the serum samples and alveolar lavage fluid of patients with sepsis complicated with ARDS were studied by using high performance liquid chromatography (HPLC) tandem electrospray four-stage rod time-of-flight mass spectrometry (LC-ESI-Q-TOF-MS). Aim to screen out the different metabolites between patients with mild and moderate/severe sepsis complicated with ARDS. HO-1 protein, oxidative stress and inflammatory markers in serum and alveolar lavage fluid were measured simultaneously to explore the relationship between HO-1, oxidative inflammatory markers and metabolic markers. In addition, a biomarker model was established to provide an important reference for assisting ARDS disease management and predicting the adverse outcome of patients with sepsis complicated with ARDS.

Inclusion Criteria:

• At least 18 years old
• Patients with sepsis who meet the criteria for sepsis -3
• Patients complicated with Acute Respiratory Distress Syndrome who meet the Berlin diagnostic criteria
• Agree to participate in this study and sign informed consent

Exclusion Criteria:

• Refuse to participate in this study
• Patient with HIV infection, patients in pregnancy or breast stage
• Patient had chronic respiratory ailments
• Patients are now being included in another study
• In the opinion of the attending physician or researcher, there are other conditions that are not appropriate for the study

Adult patients with sepsis complicated with ARDS

All of the individual participant data collected during the trial,after deidentification will be shared.And anyone who wishes to acess the date will be available for any purpose.