Assessing the dose of supplemental oxygen: let us compare methodologies.

Supplemental oxygen is a marvelous “drug,” with several rather unique beneficial physiologic effects. It produces well-documented long-term benefits when administered to hypoxemic patients. A multi-billion-dollar industry has been established to provide supplemental oxygen to those for whom it is indicated. Nevertheless, research into the effectiveness (especially in the long term) of different delivery techniques has been sparse. Therefore the work of Wettstein et al,1 in this issue of RESPIRATORY CARE, is welcome, in that it explores the effectiveness of higher-flow devices than are generally used currently. There is clearly a dose-response relationship to supplemental oxygen delivery,2 and we are remarkably casual in clinical practice about how we assign supplemental oxygen dose. In part this is because the predominant mode of oxygen delivery is by nasal cannula. By choosing to deliver oxygen supplementation via only one of the 2 orifices through which we inspire, we guarantee variability in the relationship between the nasal oxygen flow and the dose of oxygen that is delivered. Newer modes of delivery, such as pulse-dose oxygen conservers, make the relationship between the quantity of oxygen supplied and its effects even more difficult to predict.