“… 46 More recently, a significant improvement in 6MWD, heart rate recovery, dyspnoea and lower limb fatigue was seen in 30 ES patients who received acute 40% oxygen supplementation. 47 There was, however, no benefit after two years of nocturnal oxygen therapy on mortality, exercise capacity, erythrocytosis or quality of life in an RCT involving 23 patients with ES and a post-tricuspid defect. 48 The routine prescription of oxygen therapy is, thus, not supported by the current literature, and the use of oxygen should be considered on a case-by-case basis and continued only if there is clear subjective or objective benefit.…”