This is a prospective study of patients diagnosed with chronic obstructive pulmonary disease (COPD) with respiratory failure and admitted in West China Hospital during April 2017 to March 2019. The following variables will be prospectively studied: age, sex, height, weight, respiratory function indicators, arterial blood gas analysis results, biochemical data, nutritional risk screening 2002 (NRS 2002) score, short-term and long-term prognostic outcomes. The purpose of this study is to assess whether NRS 2002 is a useful prognosis predictor in COPD patients with respiratory failure.

Inclusion Criteria:

• Newly diagnosis of COPD at West China Hospital during April 2017 to March 2019
• Partial pressure of O2 (PaO2) < 60 mmHg and/or partial pressure of CO2 (PaCO2) >50 mmHg
• Age ≥ 18 years
• Respiratory rates > 23 bpm

Exclusion Criteria:

• Pregnancy or during lactation
• Ventilatory dysfunction due to neuromuscular disorders, acute and chronic thromboembolic disease, severe illness in other systems
• Refused to participate in this study

Patients diagnosed with chronic obstructive pulmonary disease with respiratory failure during April 2017 to March 2019 at West China Hospital.