Long-term Oxygen Therapy in Patients With Chronic Obstructive Pulmonary Disease Who Live at High Altitude

A clinical, prospective, randomized controlled trial to determine the effect of prescribing oxygen in a group of COPD (chronic pulmonary disease) patients with PaO2 (arterial oxygen tension) ≥50 and ≤55 mmHg who do not have erythrocytosis or pulmonary hypertension on echocardiogram (which are considered manifestations of chronic hypoxia)

A clinical, prospective, randomized controlled trial to determine the effect of prescribing oxygen in a group of COPD patients with PaO2 ≥50 and ≤55 mmHg who do not have erythrocytosis or pulmonary hypertension on echocardiogram (which are considered manifestations of chronic hypoxia). It will be included 220 patients of the Fundación Neumológica Colombiana living in Bogotá who accept their participation by signing an informed consent.

The subjects will be randomly assigned to receive or not LTOT and they will be followed for 20 to 30 months. At baseline and then at 10, 20 and 30 months, they will be clinically evaluated with arterial blood gases, pulse oximetry, echocardiography, spirometry with bronchodilator, diffusion capacity, quality of life (SGRQ), neurocognitive performance (MMSE) and six minutes walk test. The primary outcome will evaluate the ratio of occurrence of erythrocytosis or pulmonary hypertension. Secondary outcomes will be evaluated quality of life, lung function, neurocognitive performance and exercise tolerance by comparing the groups with and without LTOT.

Eligibility Criteria:
Inclusion Criteria:

* Men and women between ≥ 40 years and \< 85 years living in Bogotá or in a high - altitude city (\>2.500 - \<3.500 m).
* Diagnosis of COPD defined by FEV1 / FVC \<LLN (Lower limit of normal value) and significant exposure to cigarette ≥ 10 packs / year or woodsmoke ≥ 10 years.
* Diagnosis of ACO defined by FEV1 / FVC post BD \<70%, significant exposure to cigarette or woodsmoke and asthma diagnosed before 40 years and/or wheezing, cough with spirometry with a high respond to bronchodilator (FEV1 or FVC ≥ 15% and 400 ml) or eosinophil \>300 cels.
* PaO2 ≥ 50 and ≤ 55 mmHg or oxygen desaturation during the six-minute walk test (at least in three of the measurements performed during the exam) or during sleep (SpO2 ≤ 85% in ≥ 30% of the total time of sleep)
* No clinical signs of cor pulmonale
* Clinically stable COPD defined as no exacerbations in the last three months.
* Signature of informed consent.

Exclusion Criteria:

* BMI ≥40.
* Paraclinical findings of chronic hypoxemia and pulmonary hypertension:

  * Hematocrit ≥ 55%.
  * Pulmonary hypertension (PH) defined by transthoracic echocardiography systolic pulmonary artery pressure \> 40 mmHg or indirect signs of PH: Pulmonary artery acceleration time \<100ms associated with a meso-systolic notch and flattening of the septum interventricular in systole.
* Echocardiographic findings that could lead to pulmonary hypertension.

  * Left ventricular systolic dysfunction defined by an ejection fraction \<40%
  * Left ventricular diastolic dysfunction higher than grade I.
  * Valvular disease higher than moderate
* Use of oxygen \> 12 hours a day for more than six months in the last year.
* Comorbidities not controlled or deemed medically that can contribute to mortality during the study follow-up.
* Diagnosis of severe sleep apnea-hypopnea syndrome without treatment
* Plan of transfer of residence below 2.500 meters.
* Medical, psychiatric, social and administrative conditions that define high probability of poor adherence to therapy with oxygen.
* Active smoking