Steve is right to a point. People who are on O2 at home can develop excess CO2, but some rather specific conditions need to exist for it to be worrisome. For most of us, who are active and live our lives with as much movement as possible, it's not a issue. If you re exercising, for instance, and your O2 sats go down, don't be afraid turn your O2 up. As long as you are moving and your O2 sats are down, you can turn it up safely, even if you are a known, diagnosed, CO2 retainer. Just remember to turn to O2 down when you're done.. Like most issues with COPD, this one can be safely managed with the necessary information. B the way, it' carbon dioxide......

Good answer Jean! oxygen/O2 is breathed in, used in our blood system to feed every cell, then is ready to discard after as carbon dioxide/CO2 slow, Pursed lip breath to help get all the 'old' air out ......... Hypercapnia, also known as CO2 retention, hypercapnea, and hypercarbia, is a condition of abnormally elevated carbon dioxide (CO2) levels in the blood. Carbon dioxide is a gaseous product of the body's metabolism and is normally expelled through the lungs., more @ https://en.wikipedia.org/wiki/Hypercapnia

This is a condition where too little CO2 is removed from blood by the lungs. Medical term is hypercapnia. It causes, headaches, drowsiness, lethargy, confusion and in some cases can lead to cooma and death. People on oxygen that receive toi high an input can develop this problem

I try and not use the word ''Retainer'' as there are very few ''real'' retainers...When in the hospital situation, patients are treated as if they retain but when they leave, doctors do not tell them that it is just a temporary situation and they then call themselves ''Retainers'' which is really Respiratory Acidosis when the lungs cannot remove all of the carbon dioxide produced by the body. Only an ABG can determine if you retain oxygen and how acidic your blood is...

COPD patients do NOT retain carbon dioxide when given too much oxygen unless they have advanced disease process. Treating chronic lung patients as well as heart failure patients require that you meet the blood oxygen need in order to address cause and buy time without causing harm. Low blood oxygen saturation is harmful.

The real issue is that with deterioration of lung function, you can still take in more than enough oxygen but your heart can no longer work hard enough to do this exchange anymore and you will end up in Cardiac Arrest.....That is where Pulmonary Hypertension enters the playing field to counter what too much Carbon Dioxide in your blood will do to you eventually.......

Way to go team for your answer to this question as I had no idea. Have a happy breathing day and blessings to everyone.

Berny