This investigator-initiated, prospective, single center, randomized, controlled clinical trial enrolled patients with stable Global Initiative for Chronic Obstructive Lung Disease stage II-IV chronic obstruction pulmonary disease. The primary outcome was 2-year acute exacerbation rates.

Pulmonary rehabilitation (PR) has been suggested to be positive effects on 6 min walking distance (6MWD), muscle force, cycle exercise endurance time, and quality of life. However, the literature still could not explain the role of PR in reducing systemic inflammation of chronic obstruction pulmonary disease (COPD) patients. A recent study found that PR with negative pressure ventilation (NPV) improved lung function, exercise capacity and reduced acute exacerbation rates in COPD patients. The objectives of this research are to design a prospective, randomized controlled trial to determine the clinical outcome of NPV-PR in COPD patients and to investigate if NPV-PR reduces systemic inflammation in patients with COPD.

This investigator-initiated, prospective, single center, randomized, controlled clinical trial enrolled patients with stable Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage II-IV COPD. NPV was targeted to reduce baseline blood carbon dioxide by at least 20% during NPV titration. Patients were randomly assigned (in a 1:1 ratio) to continue optimised standard treatment (control group) or to receive additional NPV-PR for at least 24 months (intervention group). The primary outcome was 2-year acute exacerbation rates. The lung function and walking distance will be assessed by six-minute walking tests and the severity of disease will be evaluated by high resolution computed tomography scores. Peripheral blood sample will be collected to analyze the inflammatory cytokines and oxidative markers.

In the present prospective study, investigators hypothesize that NPV-PR would be superior to usual care in reducing the risk for acute exacerbations of COPD, hospitalisations and emergency visits over a 24-month period. This research will provide evidence for the role of NPV-PR in the management of COPD, and evidence for a role of systemic inflammation in disease progression of COPD. The results may provide certain insights into more effective treatments to inhibit the disease progression of COPD.

Inclusion Criteria:

• Diagnosis of COPD ((post-bronchodilation forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) <0.7)
• Optimal medical treatment according to the Global Initiative for Chronic Obstructive Lung Disease (GOLD)) at least 3 months before screening

Exclusion Criteria:

• abnormalities of the thorax or the lung other than COPD,
• acute exacerbation within one month
• obesity with a body-mass index (BMI) ≥35 kg/m²,
• malignant co-morbidities, severe heart failure (New York Heart Association stage IV), unstable angina, severe arrhythmias, neuromuscular diseases and/or impairment of basal brain nerve function with disturbed swallowing and choking and impaired general condition that could preclude regular follow-up visits.

The IRB of Chang Gung Memorial Hospital does not permit to share IPD in this project.