The International Nocturnal Oxygen (INOX) Trial (INOX)

Inclusion Criteria:

• Patients with a diagnosis of COPD supported by a history of past smoking and obstructive disease: FEV1<70% predicted, FEV1/FVC<70% and a total lung capacity by body plethysmography >80% predicted;
• Stable COPD at study entry, as demonstrated by (1) no acute exacerbation and (2) no change in medications for at least 6 weeks before enrollment in the trial;
• Non-smoking patients for at least 6 months before enrollment in the trial;
• SpO2 at rest < 95%;
• Patients fulfilling the current definition of nocturnal oxygen desaturation, i.e., >=30% of the recording time with transcutaneous arterial oxygen saturation <90% on at least one of two consecutive recordings;
• Ability ot give informed consent.

Exclusion Criteria:

• Patients with severe hypoxemia fulfilling the usual criteria for continuous oxygen therapy at study entry: PaO2 <=55 mmHg; or PaO2 <= 59 mmHg with clinical evidence of at least one of the following: (1) with right ventricular hypertrophy (P pulmonale on ECG:3 mm leads ll, lll, aVf); (2) right ventricular hypertrophy; (3)Peripheral edema (cor pulmonale); (4) hematocrit >=55%;
• Patients with proven sleep apnea (defined by an apnea/hypopnea index of >=15 events/hour) or suspected sleep apnea on oximetry tracings;
• Patients currently using nocturnal oxygen therapy;
• Patients with known left heart or congenital heart diseases, interstitial lung diseases, bronchiectasis as the main cause of obstructive disease, lung carcinoma, severe obesity (body mass index >= 40 kg/m²), or any other disease that could influence survival.