There was a good article eons ago in Nursing______(year?) Google the following: "Blue Bloater" and "Pink puffer" I think these articles will give you some physiology info that may help you. I agree with Granny, each COPD pt is different,(and she would know!!) You do not want to over oxygenate these folks nor do you want to under oxygenate them, their cells need O2 to function!!! Use the guidelines of your facility and if this area is lacking then bring it to the attention of your nurse educator. COPD is an umbrella term for various respiratory conditions, do a little more research and you will find your answers. This is a very complex condition and usually does require a good understanding of the specific condition and the other conditions that may contribute to someone going into respiratory distress. FYI, the winter is usually prime time for these patients to come into the hospital because of the agravation of underlying respiratory issues. You will see a lot of these type of patients this time of year. It can be a scarey situation, just remember, they need oxygen also and if you can maintain their SPO2 88-90% you are doing OK and so are they.