End-expiratory Transpulmonary Pressure-guided vs Electrical Impedance Tomography-guided PEEP Titration Methods in Patients With Intra-abdominal Hypertension Combined With Acute Respiratory Distress Syndrome: a Randomized Crossover Controlled Study

Inclusion Criteria: 1. age: 18-80 years; 2. meets IAH ≥12 mmHg; 3. meets the diagnostic criteria of the new global definition of ARDS in the 2023 edition; 4. PaO2/FiO2 ≤ 150; 5. within 36 hours of invasive mechanical ventilation; 6. patients or their family members were consulted, agreed to participate in the trial, and signed an informed consent form. Exclusion Criteria: 1. Age \<18 years or age \>80 years; 2. uncorrected shock of any type; 3. chronic obstructive pulmonary disease, interstitial lung disease, pulmonary embolism, right heart failure, pulmonary hypertension, or severe cardiac arrhythmia; 4. pneumothorax or bronchopleural fistula or lobectomy or other surgery of the lungs within 2 weeks of surgery; 5. non-invasive ventilation or transnasal high-flow oxygen; 6. with relevant contraindications to the application of EIT (large chest skin injuries, infections, pacemaker implanters, in vivo automatic defibrillator implantation, etc.) pneumothorax, mediastinal emphysema, massive pleural effusion; 7. oesophageal obstruction, oesophageal perforation, severe oesophageal variceal bleeding, upper gastrointestinal surgery, and other factors that make it impossible to place an oesophageal pressure catheter; 8. diaphragmatic hernia, thoracic deformity; patients with obvious pulmonary hernias; 9. prolongation of prothrombin time (PT), activated partial thromboplastin time (APTT) to two times the high limit of normal values or with active bleeding in the nasopharynx; 10. severe neurological disease: intracranial hypertension or neuromuscular disease, etc; 11. pregnant and lactating women; 12. patients to be treated with ECMO; 13. re-admission to the ICU of patients who have already been included in this study, or who are participating in other clinical studies;