Copd ---- what's considered a high concentration of required oxygen?

Copd: Generally COPD patients require only about 2-3 liters of oxygen. More concentrated oxygen will have a detrimental effect. It increases what is called partial pressure of co2. If the levels go beyond 40 then the patient may become lethargic, becomes short of breath.

Delivery: Perspective is that 21% is the concentration from the air we breath. 2-3% increase in concentration is from each liter of oxygen added. So 1 liter is about 24% and this can go through a nasal canula tube. Over 4-5 liters, you cannot get this from a canula and need continuous flow to maintain the concentration. This would be considered "high" in my book. Not sure if this answers your question.