The purpose of this study is to investigate the feasibility of using electric impedance tomography (EIT) to monitor lung perfusion during veno-venous (VV) extracopreal membrane oxygenation (ECMO) support, as well as the effect of different ECMO flows on lung perfusion monitored by EIT.

This is a monocentric obsevensional study that uses EIT to monitor lung perfusion during VV ECMO support and the effect of different ECMO flows on lung perfusion as measured by EIT. Patients on VV ECMO who meet the withdrawal criteria as determined by clinical experts will have their ECMO flow gradually reduced. EIT lung ventilation and perfusion monitoring were performed at various ECMO flows.

Inclusion Criteria:

1. Patients aged ≥ 18 and ≤ 70 years；
2. Patients supported with VV ECMO for respiratory failure；
3. Patients are intubated and mechanically ventilated.

Exclusion Criteria:

1. EIT contraindications such as chest wound dressing, pacemaker installation, defibrillator, etc;
2. Patients who did not sign the informed consent form;
3. Pulmonary embolism;
4. Pneumothorax;
5. Medium to plenty of chest water;
6. Atrial fibrillation or other malignant arrhythmia leads to a decrease in cardiac output;
7. Refractory shock;
8. Severe chronic heart and lung disease has existed in the past;
9. BMI>35 kg/m2;
10. Intra-abdominal pressure >20mmHg.

Patients with respiratory failure supported on VV ECMO