Patients with moderate to severe acute exacerbation of chronic obstructive pulmonary disease are often complicated with hypercapnia and respiratory failure, so they need to be admitted to ICU for monitoring and respiratory support treatment. Noninvasive ventilation has become the first-line respiratory support for the treatment of AECOPD with hypercapnia and respiratory failure. However, 26-54% of AECOPD patients with hypercapnia and respiratory failure eventually fail to receive noninvasive ventilation and need endotracheal intubation and invasive ventilation to maintain effective gas exchange. For these patients, the in-hospital survival rate is only 31-76%, and the prognosis is poor. In AECOPD patients with high risk of noninvasive ventilation failure and expected need of intubation, timely giving other ways of respiratory support to reduce blood CO2 may avoid patients receiving tracheal intubation and invasive ventilation, thus avoiding related complications and adverse prognosis. As a new type of respiratory support technology, ECCO2R is worthy of attention in monitoring and evaluation of support effect in AECOPD patients with respiratory failure. It is urgent that ECCO2R can effectively alleviate respiratory failure, avoid complications related to tracheal intubation, improve quality of life and reduce mortality.

Inclusion Criteria:

• AECOPD patients.
• The patients with hypercapnia respiratory failure were admitted to ICU and needed noninvasive ventilation.
• The results of blood gas analysis showed pH <7.30, PaCO2> 50 mmHg.
• There were high risk factors for failure of noninvasive ventilation: after receiving continuous 2 hours of noninvasive ventilation, the arterial blood pressure showed the pH value was ≤ 7.30, while PaCO2 was 20% higher than the baseline value, and any one or more of the following conditions were combined: respiratory rate ≥ 30 times / min, assisted respiratory muscle breathing; contradictory breathing.
• Informed consents were sighed.

Exclusion Criteria:

• The mean arterial pressure was less than 60 mmHg after volume and vasoactive drug treatment.
• There were anticoagulant contraindications.
• Weight over 120kg.
• Patients with malignant tumor or other complications, the expected survival time was less than 30 days.
• It could not cooperate with noninvasive ventilation or has contraindication of noninvasive ventilation.