Fig. 31:  This Figure is a summary of US Medicare coverage for long-term home oxygen provision^[21]; the O₂ values inside the added red highlight define Medicare’s coverage, based on the results of prospective randomized controlled trials showing that oxygen therapy can improve functional outcome or mortality.

These values reflect data from the Nocturnal Oxygen Treatment Trial (NOTT), which found that patients with a PaO₂ ≤55 mmHg or oxygen saturation ≤88% at rest should be prescribed supplemental oxygen, and Medicare will pay for oxygen supplementation based on those values 

For patients with a slightly higher degree of oxygen at rest, O₂ saturation 89%, PaO₂ 56–59 mmHg, and with secondary cor pulmonale, pulmonary hypertension, or secondary polycythemia on physical exam, then again, the NOTT results found that for those patients use of continuous oxygen therapy results in lower risk of mortality. 

Looking at other parameters for oxygen therapy, however – during exercise or sleep when PaO₂ values are > 60 mm Hg or saturation is >90% -- then none of the published studies have documented what patient groups would benefit from this.  In other words, these data are based on expert opinion alone, and there are no substantive peer reviewed data that consistently show that these patient groups benefit from supplemental oxygen therapy.