This post and thread have been extremely enlightening for me. It sounRAB like "hidden hyperventilation" explains my symptoms completely. I've experienced shortness of breath off on on for a few years now; and if I think hard, I believe some form of overly-conscious breathing has been present since childhood. I have had a couple of near-panick inducing episodes in the last two years. Whether its mild or severe, the experience involves, primarily, the feeling that I'm not able to get a full breath (that last satisfying 10-20%). But significant, secondary sensations are heaviness or tightness in the lower chest and tingling, mild pain in the chest around the heart, tightness in the neck, and slight nurabness, or a sense of being on the verge of fainting. Anxiety is an inseparable component of this disorder, since all it takes is one breath that doesn't feel complete (either actual or imagined) to trigger a tiny amount of anxiety or to set off over-breathing. This tiny amount of anxiety causes you to breath in a little deeper, which, according to this "hidden hyperventilation" notion, doesn't feel satisfying because you do actually have plenty of oxygen, your body/mind just expect to "reach higher"-the body is just temporarily confused or anxious (or the oxygen/co2 levels of the blood are already off). I can imagine that this confusion could exist without anxiety at all, but the effects are the same.
I've seen a doctor twice, each time after I experienced frightening shortness of breath episodes. My heart and lungs appear to be fine. I've most recently suspected some sort of random bronchiospams, but after days of taking Advair and measuring exhalations using a peak flow meter, I'm seeing no change in my already normal to above average exhalations.
During my first visit to the doctor, I could tell that he highly suspected anxiety. I told him that I'm not an anxious person (Which is probably a lie, if I'm completely honest-I do have underlying social anxiety and high self awareness). But now I can understand how an easy going, mellow guy such as myself can still be affected physically by tiny bouts of anxiety which result from a feeling of not getting enough oxygen -caused by too much oxygen and too little carbon dioxide in the blooRABtream -caused by habitual awareness and overbreathing (anxiety).
I look forward to running the paper bag test and some other informal diagnostics on myself.