Hi Cram glad it all worked out and you are fine. Would just like to clear up a few points that have been raised.
I think your doctor made a very reasonable diagnosis of hyperventilation syndrome. This occurs under exertion, (I had a friend who gets it while playing squash, and takes a paper bag onto the court), or when anxious, or in pain, or I have even seen people with very mild asthma present this way. What happens is you breath too deep and/or fast, and blow off CO2. This causes "acral paraesthesiae" ie. lips, nose, hands and feet go numb and have pins and needles. You can have chest pain as well. This usually provokes extreme anxiety as you feel you are having a heart attack, feel awful and tend to hyperventilate more (vicious cycle). The treatment is to rebreath into a paper bag to build up the CO2 in the blood stream again. So I have never heard of CO2 deprivation, we are all deprived of it because air has about 0.03% CO2. The easiest way to confirm or refute the diagnosis is a blood gas sample, in which arterial blood is taken and passed through a machine that tells the exact pCO2 and pO2 in the blood if it is low confirmation, if normal or high look for another cause. What sways me to hyperventilation is the global nature of the paraesthesiae,ie. all limbs, you had just done some unusual exertion.