Supplemental Oxygen

About

What is the problem? 100% oxygen (O2) therapy is widely used in patients with Chronic obstructive pulmonary disease (COPD) and Congestive heart failure (CHF). Supplementary oxygen is seldom recommended for exercise Paradoxically, in CHF patients, supplementary O2 has been shown to worsen heart function, cause peripheral vasoconstriction and thereby reduce tissue O2 supply. There is no consensus on whether O2 during exercise is beneficial. Such findings have led to several reviews cautioning the use of O2 in acute medicine, in long-term therapy and “as needed”. Our new Solution? Provision of 40% O2 during exercise. Benefits of the new approach 40% O2 improves the O2 supply to exercising muscles in a way that facilitates aerobic metabolism, reduces fatigue but there is no significant increase in oxidative stress as occurs with 100% O2. Background Results indicate that administering 40% O2 to healthy young people during exercise improves the O2 supply to exercising muscles in a way that facilitates aerobic metabolism and limits anaerobic metabolism, thereby decreasing the accumulation of prostaglandins, adenosine and lactate. Thus, with 40% O2, a given level of exercise can be undertaken with a smaller vasodilatation but with less fatigue and this is achieved without significant oxidative stress. Importantly, PGs, adenosine and lactate are known to stimulate sensory nerves that evoke the exercise reflex and have been implicated in exercise dyspnea in CHF. It is anticipated that 40% O2 will diminish the exaggerated exercise reflex including the dyspnea particularly in CHF and COPD, but also in older people generally. The research group is now undertaking studies with 40% O2 in older men (60-70 years). Ageing is accompanied by oxidative stress, blunted exercise hyperaemia and in some, by exercise intolerance. These studies will allow direct comparisons with CHF or COPD patients and extend the study to whole body exercise, to establish whether 40% O2 will help improve exercise tolerance in all these groups. There is already fragmentary evidence suggesting 40% O2 will prove beneficial and which indicate that it is the deleterious effects of high O2 concentrations that have cast doubts on the use of O2. For example, in COPD patients who were normoxic at rest and mildly hypoxic during submaximal cycle exercise, ~30% O2 prevented the increases in several markers of inflammation and oxidative stress that otherwise occurred. Also, COPD patients who became mildly hypoxic in exercise, and were given graded levels of O2 (20-100%) during cycling exercise, showed significant improvement at 30% O2 and maximum benefit on exercise duration and dyspnea at 50% O2. Further, patients with CHF who undertook cycling exercise showed smaller increases in cardiac output but less severe dyspnea and fatigue when breathing 30 or 50% O2, whereas a similar study on CHF patients using O2 at the higher, 60% concentration showed no benefits.   Commercial Status The researchers have developed significant know-how and the evidence discussed above indicates there is a niche to be exploited, particularly in older people and in those with COPD or CHF, simple devices that can deliver such “health promoting” O2 in rehabilitation centres, sports clubs and the home, should be a highly commercial prospect.