I recall being told by an instructor during my nursing clinicals that a patient can be on up to 4L of O2 but no more due to the retention of CO2 and loss of respiratory drive if they have COPD. A colleague of mine today told me that she was told that it shouldn't go over 2 Liters however. What is the correct answer, or is it one of those things that is more individualized to meet the needs of the specific patient? Also if anybody has any good sources or links to studies for this info it would be a bonus.