Table 5 summarizes my current perspective on home oxygen delivery systems in the United States. As I already indicated, scoring for cost and labor may be very different in other countries. As noted, all things considered, today the most reasonable system for home oxygen therapy is the concentrator. Problems with FIO2, liter flow, and portability are clearly overshadowed by cost, labor, ease of use, and lack of potential hazard, as well as potential for future innovation. I would expect with future development that the concentrator will score higher on FIO2, liter flow, and portability. As a result of the anticipated large number of patients worldwide expected to require home oxygen therapy, ongoing improvement in this technology will be evident in the next few years.