In respiratory school, instead of harping on this theory of knocking out a COPDers hypoxic drive, we are told time and time again to NEVER withold oxygen from a patient of any kind at any time if they are in need of it. I feel like nurses have this hypoxic drive fear drilled into their heads that a lot of times can have a negative impact on patient care. I don't ever blame the nurses because I understand that they are treating the patient to the best of their ability with the knowledge they have available to them, but as far as RT's go, the hypoxic drive is a non-issue. I will not hesitate to slap a COPder on 100% oxygen if I feel they need it.
With that said, there can be a huge misconception about exactly when a patient needs additional oxygen. Seeing as your COPD patient walked to the bathroom without her cannula (or whatever she was wearing) on, but that her sat's were 93% when you checked them and they were complaining of SOB, in my professional opinion, the patient's oxygen flow didn't need to be bumped up at all (though you did not hard the patient by doing that).
A lot of healthcare workers do not understand the complexities involved with the entire "SOB" syndrome. It is NOT always due to low O2 levels in the blood (as estimated by the SpO2 readings). It can simply be a patient needing more airflow (as would be the case in someone with already restricted lungs walking to the bathroom and back). Another reason that is typically not widely understood at my hospital is that sometimes patients are SOB because their RBC's are unable to properly transport the O2 (think anemia or CO poisoning). Finally, of course there is SOB caused by a lack of O2 in the air (like being high in the mountains). Because there are lots of different reasons for SOB, it's important to understand that it can be a complex issue, and that just upping the O2 isn't always the answer. Additional liter FLOW may help the COPD patient in the short term after walking to the bathroom, but it's the extra FLOW, not the O2 that is helping them out!