people with hvs may feel that they cannot get enough air. in reality, they have about the same oxygenation in the arterial blood (normal values are about 98% for hemoglobin saturation) and too little carbon dioxide (hypocapnia) in their blood and other tissues. while oxygen is abundant in the bloodstream, hvs reduces effective delivery of that oxygen to vital organs due to low--induced vasoconstriction and the suppressed bohr effect.