The goal of this observational study is to integrate existing clinical cohorts from the research team to establish dedicated cohorts for ARDS and high-risk ARDS patients (primarily SCAP patients), then systematically collect comprehensive clinical data and multi-omics biological samples to construct a high-quality multimodal ARDS database. Building upon this foundation, the research will develop an ARDS-specific large-scale disease model to assist clinical decision-making in early warning, diagnosis, and prognosis prediction. The main question it seeks to address is: Can the establishment of specialized ARDS cohorts and multimodal databases, combined with the development of an ARDS-specific large-scale disease model, effectively improve ARDS prediction rates, diagnostic accuracy, and reduce mortality rates, thereby enhancing overall clinical management standards?

ARDS is a common critical illness in ICUs with high mortality rates. Its prognostic factors are complex and multifaceted, including challenges in precise early warning, lack of early diagnostic biomarkers due to complicated pathogenesis, and difficulties in personalized precision treatment owing to high heterogeneity. Interventions targeting any single aspect are unlikely to improve overall outcomes. Only through systematic interventions addressing key aspects of ARDS - including assessment, early warning, diagnosis, phenotyping and treatment - can its mortality be significantly reduced.

This study is a multicenter, retrospective and prospective observational cohort study with the following objectives:

1. To integrate existing ARDS-related cohorts from the research team (comprising 5,000 patients enrolled between January 1, 2014 and September 1, 2024) and prospectively recruit an additional 1,500 ARDS patients and ARDS high-risk individuals. This will establish a comprehensive cohort of no fewer than 6,500 cases, primarily including patient populations with conditions such as severe community-acquired pneumonia (SCAP) and other ARDS-associated disorders;
2. To collect comprehensive clinical data and multi-omics biological samples from these patients, constructing a high-quality multimodal ARDS database through rigorous data governance;
3. Based on this foundation, to develop and clinically validate an ARDS-specific large-scale disease model to assist in clinical decision-making for early warning, diagnosis, and prognosis prediction, thereby improving the overall standard of ARDS management.

Inclusion Criteria:

1. ARDS Group: ( 1 ) Admitted to the ICU; ( 2 ) Age ≥18 years; ( 3 ) Meets the 2024 Global New Definition of ARDS (diagnosis confirmed by at least two experienced physicians; in case of disagreement, a third physician will adjudicate):Diagnostic Criteria:

1. Risk Factors & Origin of Pulmonary Edema:Acute risk factors (e.g., pneumonia, non-pulmonary infection, trauma, transfusion, aspiration, shock).

   Pulmonary edema not fully or primarily attributable to cardiogenic pulmonary edema/fluid overload.Hypoxemia/gas exchange abnormalities not primarily due to atelectasis.Exception: ARDS can still be diagnosed if predisposing risk factors exist, even with concurrent conditions.

2. Timing:Acute onset or worsening of hypoxemic respiratory failure within 7 days of risk factor exposure or new/worsening respiratory symptoms.

3. Chest Imaging (X-ray/CT/US):Bilateral opacities (not fully explained by effusions, atelectasis, or nodules/masses)；Ultrasound findings: Bilateral B-lines and/or consolidations.

4. Oxygenation Status:

   1. Non-intubated ARDS:PaO₂/FiO₂ ≤300 mmHg OR SpO₂/FiO₂ ≤315 (if SpO₂ ≤97%). High-flow nasal oxygen (HFNO) ≥30 L/min or NIV/CPAP ≥5 cm H₂O.

   2. Intubated ARDS (all enrolled patients assessed via PaO₂/FiO₂):

      Mild: 200 < PaO₂/FiO₂ ≤300 OR 235 ≤ SpO₂/FiO₂ ≤315 (if SpO₂ ≤97%). Moderate: 100 < PaO₂/FiO₂ ≤200 OR 148 < SpO₂/FiO₂ ≤235 (if SpO₂ ≤97%). Severe: PaO₂/FiO₂ ≤100 OR SpO₂/FiO₂ ≤148 (if SpO₂ ≤97%).

   3. Resource-limited settings:No PEEP/minimum oxygen flow required; SpO₂/FiO₂ ≤315 (if SpO₂ ≤97%).

( 4 ) Signed informed consent.

2. ARDS High-Risk Group: ( 1 ) Admitted to the ICU; ( 2 ) Age ≥18 years; ( 3 ) Does not meet ARDS criteria at ICU admission but has high-risk factors for ARDS development, including: SCAP, sepsis, high-risk trauma, post high-risk surgery, acute pancreatitis, shock, aspiration.The primary etiology in this cohort is SCAP.

SCAP Diagnostic Criteria (≥1 major or ≥3 minor criteria):

1. Major Criteria:

   1. Requires mechanical ventilation (intubation).
   2. Septic shock requiring vasopressors after fluid resuscitation.

2. Minor Criteria:

   1. Respiratory rate ≥30 breaths/min.
   2. PaO₂/FiO₂ ≤250 mmHg.
   3. Multilobar infiltrates.
   4. Altered mental status/disorientation.
   5. BUN ≥20 mg/dL (7.12 mmol/L).
   6. Leukopenia (WBC <4×10⁹/L).
   7. Thrombocytopenia (platelets <100×10⁹/L).
   8. Hypothermia (core temp <36°C).
   9. SBP <90 mmHg requiring aggressive fluid resuscitation.

( 4 ) Signed informed consent.

Exclusion Criteria:

1. Patients without ARDS or ARDS high-risk factors.
2. Age <18 years.
3. Incomplete clinical data.
4. Refusal to sign informed consent.
5. Long-term nursing home residents.
6. Tracheostomy patients.
7. Currently enrolled in another clinical trial.

1. ARDS ptients;
2. ARDS high-risk patients