ABSTRACT
The role of supplemental oxygen in the relief of dyspnea is both physiologi-
cally interesting and clinically important. Despite the almost parallel advances in our understanding of the mechanisms of dyspnea (1) and the
pathophysiology of hypoxemia, the precise relationship between them
remains unclear. The extent to which an increase in inspired oxygen con-
centration will improve the PaO2 will vary depending on the magnitude
of the mismatch between ventilation and perfusion. Understanding the sig-
nificance of an increase in PaO2 as part of the management of dyspnea is all
the more challenging as many profoundly dyspneic patients have only mini-
mal hypoxemia. Most countries have developed programs for domiciliary oxygen
therapy in which supplemental oxygen is funded according to established
criteria, derived mainly from two well designed multicenter randomized
controlled trials involving chronic obstructive pulmonary disease (COPD)
patients with resting hypoxemia (2,3). Although resting hypoxemia is a
clearly stated criterion for domiciliary oxygen therapy, some clinicians
prescribe supplemental oxygen for patients with only minimal resting hypoxemia in an effort to alleviate their incapacitating dyspnea, increase
their functional exercise capacity and improve their health status.