Best fast source of O2 is aviation oxygen. You can get it mail order quickly. Cylinders are small, meant for individual use in light aircraft. Did my father a world of good when he needed it.. There are also the filter type oxygen concentrates using a zeolite as a filter that gets periodically back-flushed. These are pricey though, couple hundred $.

Best fast source of O2 is aviation oxygen. You can get it mail order quickly. Cylinders are small, meant for individual use in light aircraft. Did my father a world of good when he needed it..