I had a blood gas test and the oxygen levels were normal :). What I don't understand is that the carbon dioxide levels were high. The doctor put it down to anxiety and asked me if I hyperventilate. I don't believe I do hyperventilate, although I do experience anxiety and depression. I also experience frequent tiredness, dizziness and headaches. I have had asthma for over 40 years and experience frequent shortness of breath. Does anyone else experience this?