Abstract/Text: BACKGROUND: Long-term treatment with supplemental oxygen has unknown efficacy in patients with stable chronic obstructive pulmonary disease (COPD) and resting or exercise-induced moderate desaturation.
METHODS: We originally designed the trial to test whether long-term treatment with supplemental oxygen would result in a longer time to death than no use of supplemental oxygen among patients who had stable COPD with moderate resting desaturation (oxyhemoglobin saturation as measured by pulse oximetry [Spo2], 89 to 93%). After 7 months and the randomization of 34 patients, the trial was redesigned to also include patients who had stable COPD with moderate exercise-induced desaturation (during the 6-minute walk test, Spo2 ≥80% for ≥5 minutes and <90% for ≥10 seconds) and to incorporate the time to the first hospitalization for any cause into the new composite primary outcome. Patients were randomly assigned, in a 1:1 ratio, to receive long-term supplemental oxygen (supplemental-oxygen group) or no long-term supplemental oxygen (no-supplemental-oxygen group). In the supplemental-oxygen group, patients with resting desaturation were prescribed 24-hour oxygen, and those with desaturation only during exercise were prescribed oxygen during exercise and sleep. The trial-group assignment was not masked.
RESULTS: A total of 738 patients at 42 centers were followed for 1 to 6 years. In a time-to-event analysis, we found no significant difference between the supplemental-oxygen group and the no-supplemental-oxygen group in the time to death or first hospitalization (hazard ratio, 0.94; 95% confidence interval [CI], 0.79 to 1.12; P=0.52), nor in the rates of all hospitalizations (rate ratio, 1.01; 95% CI, 0.91 to 1.13), COPD exacerbations (rate ratio, 1.08; 95% CI, 0.98 to 1.19), and COPD-related hospitalizations (rate ratio, 0.99; 95% CI, 0.83 to 1.17). We found no consistent between-group differences in measures of quality of life, lung function, and the distance walked in 6 minutes.
CONCLUSIONS: In patients with stable COPD and resting or exercise-induced moderate desaturation, the prescription of long-term supplemental oxygen did not result in a longer time to death or first hospitalization than no long-term supplemental oxygen, nor did it provide sustained benefit with regard to any of the other measured outcomes. (Funded by the National Heart, Lung, and Blood Institute and the Centers for Medicare and Medicaid Services; LOTT ClinicalTrials.gov number, NCT00692198 .).

Abstract/Text: BACKGROUND AND OBJECTIVE: The optimal oxygen supplementation needed to avoid tissue hypoxia in patients with pulmonary hypertension (PH) remains unclear. This study aimed to identify the arterial oxygen tension (PaO2 ) level needed to avoid tissue hypoxia which results in a poor prognosis in patients with PH.
METHODS: We retrospectively analysed the data for 1571 right heart catheterizations in patients suspected of having PH between 1983 and 2017 at our institution. Examinations were classified according to mean pulmonary arterial pressure (mPAP), cardiac index (CI) and the presence of lung disease, pulmonary arterial hypertension (PAH) or chronic thromboembolic PH (CTEPH). The PaO2 levels needed to avoid tissue hypoxia were compared in each subgroup.
RESULTS: The estimated PaO2 equivalent to a mixed venous oxygen tension (PvO2 ) of 35 mm Hg (tissue hypoxia) was 63.2 mm Hg in all patients, 77.0 mm Hg in those with decreased CI (<2.5 L/min/m2 ) and 57.0 mm Hg in those with preserved CI. Multivariate regression analysis identified mPAP, CI and PaO2 to be independent predictors of extremely low PvO2 . Similar results were observed regardless of the severity of PH or the presence of lung disease, PAH or CTEPH. The PaO2 level needed to avoid tissue hypoxia was higher in patients with mild PH and decreased CI than in those with severe PH and preserved CI (70.2 vs 61.5 mm Hg).
CONCLUSION: These findings indicate that a decreased CI rather than increased mPAP induces tissue hypoxia in PH. Patients with PH and decreased CI may need adjustment of oxygen therapy at higher PaO2 levels compared with patients with preserved CI.

© 2019 Asian Pacific Society of Respirology.