Without enough oxygen people die. Period. The main reason that people are hospitalized with COPD is because their CO2 level is elevated. If this CO2 level rises too high then they are in danger of respiratory acidosis which ultimately result in coma and death. The solution for respiratory acidosis is assisted ventilation by mechanically pumping more "air" to and from the lungs NOT by reducing oxygen levels. The assisted ventilation is given by non-invasive positive pressure ventilation (nippv) also known as bi-pap, or by intubation and this assisted ventillation includes supplemental oxygen to maintain a minimum SaO2 of 92%. Reference www.goldcopd.org/guidelines-global-strategy-for-diagnosis-management.html These are the globally accepted guidelines for the treatment of COPD including acute COPD exacerbations. To the best of my knowledge this is the basis for all national COPD Guidelines.
Simply reducing oxygen flow might help some people, but has been shown to result in more deaths.
Please do not be afraid to use oxygen. It is the only drug proven to help those with COPD to live longer.
The article described by Al is really only of interest to those researchers who study lung structure at the cell level.
Respirologists (pulmonologists) who are really knowledgeable about oxygen typically prescribe supplemental oxygen to maintain an SaO2 level at a minimum of 92% (normal for someone with good lungs at normal elevations is 97% or better). I have been on oxygen for over ten years now and I sit here very comfortably with my SaO2 at 96%