Acute respiratory distress syndrome (ARDS) is a common acute and critical disease in clinic. The clinical mortality is as high as 30%-40%. At present, there is no specific treatment. Erythropoietin (EPO), also known as erythrocyte- stimulating factor, erythropoietin, has a certain amount in normal human body, mainly synthesized by liver in infants and kidneys in adults, which can stimulate erythropoiesis. In recent years, more and more studies have shown that high-dose exogenous EPO administration has benefit effects on multi-organ protection. Therefore, we designed this prospective, double-blind, placebo-controlled trial for defecting EPO on the alveolar fluid clearance of ARDS. The study mainly answers the following questions: Does human erythropoietin accelerate the resolution of alveolar edema in ARDS? Is there any effect on hospital survival? The study will draw conclusions by comparing the control group with the experimental group.

This study was designed as a double-blind, randomized controlled trial. Neither the subject nor the investigator knew the allocation of treatment drugs. Subjects signed the informed consent form, completed all screening assessments, and were randomized in the order of screening eligibility after screening eligibility. The investigator or designee generated the corresponding case number and drug number using a simple randomization method. Information about the subject's trial product allocation was placed in an emergency envelope and retained by the investigator for use in an emergency. Randomised subjects who withdraw from the clinical trial for any reason, regardless of whether they have taken the trial medication, will retain their case number and medication number and will not be allowed to re-enter the trial.

The investigator participating in this trial is a clinician with appropriate experience, who can make treatment decision based on the clinical response and laboratory test results of the subject. The specific process of the study is as follows:

1. The subjects of this study were patients with ARDS admitted to ICU.
2. After signing the informed consent form, complete medical history collection, vital signs and detailed physical examination will be performed. Patients meeting the inclusion criteria but not meeting the exclusion criteria will be randomized into the study.
3. Patients with ARDS who met the inclusion criteria were connected to PiCCO, randomly assigned to the following two groups, and monitored continuously for 3 days. Group A: Erythropoietin, 40000 IU, single intravenous injection. Group B: 0.9%NaCl group, with the same volume as group A, single intravenous injection.
4. The baseline values of extravascular lung water index (EVLWI) and pulmonary vascular permeability index (PVPI) were monitored by PiCCO after recording the general conditions of the subjects included in the study before intervention. After EPO or 0.9% NaCl intervention, EVLWI and PVPI at 0, 6, 12, 24, 48 and 72h after EPO or normal saline administration, and blood gas analysis, CRP, PCT, blood routine, inflammatory factors (TNF-a,IL-6,IL-8,IL-1β), endothelial cell injury marker (s-ICAM-1), alveolar epithelial cell injury marker (sRAGE,SP-D) and other laboratory indicators and clinical indicators such as peak airway pressure, mean airway pressure and positive end-expiratory pressure (PEEP) at 0, 1, 2 and 3 days after administration were recorded. The hospital survival rate and 28-day survival rate were compared between the experimental group and the control group.

Inclusion Criteria:

• Age≥18 years;
• Meeting diagnostic criteria for sepsis 3.0;
• Tracheal intubation and mechanical ventilation;
• Meeting the diagnostic criteria of ARDS Berlin;
• Willing to accept treatment and sign an informed consent form;

Exclusion Criteria:

• Age <18 years;
• Pregnancy or lactation;
• Patients with malignant tumors;
• Recombinant human erythropoietin (rhEPO) allergic patients;
• Hemoglobin (Hb) ≥120g/L;
• have recently taken rhEPO (within 3 months) or participated in other clinical trials;
• History of thromboembolic disease (pulmonary embolism, heart attack, cerebral infarction, arteriovenous thrombosis);
• Inability or unwillingness to provide informed consent or to comply with the requirements of the study;