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Breathe in, breathe out
Anyone who has had the misfortune to hear me talk about aviation knows that I will invariably bring the discussion around to oxygen at some point. Well, it's that point again. I continue to receive emails and letters from all sorts of pilots about this topic and think it useful to once again set out the world of gases as perceived by your faithful correspondent.
Every cell in your body requires oxygen to survive; without it, cells are damaged and die. Folks know that if a coronary artery gets blocked, blood-carrying oxygen cannot get through and the heart muscle that should have received the blood is destroyed, manifesting as either a heart attack or, even worse, 15 minutes of unwanted fame and one column inch in the local newspaper. No one in his right mind would sign up for a major coronary. Similarly, if blood-carrying oxygen cannot get through due to partially or totally blocked arteries the organ at the other end is affected. If the brain, one suffers a stroke; if a limb or digit, gangrene; if a kidney, renal failure.
Well guess what: If the same volume of blood can get through, but it is carrying less oxygen, the same damage can occur. Those of us who ascend to the heights are potentially doing this to our bodies every time we go higher than the observation deck at the Empire State Building. The damage we do may lead to cognitive impairment as the effects are cumulative within and between flights. At the very least you will finish a flight with a headache or other aches and pains; at worst, possibly shorten your lifespan.
Many of the pilots who write to me proclaim that they are just fine at 10,000 feet; maybe they are if they live in the mountains or are an athlete who has enhanced oxygen carrying capacity. However, most people are oxygen-depleted even at that altitude. My position on this is simple—apart from a few bucks to buy an oxygen bottle, some nasal cannulae, and a pulse oximeter, what have you got to lose? Try a simple experiment: Measure your oxygen carriage with an oximeter (widely available) on the ground and when next flying at various altitudes. Bear in mind that a healthy person at sea level will be around 98- to 100-percent oxygenated and at around 70 percent or thereabouts will be unconscious. Anything below 91 percent, you are not functioning normally. If traveling on a commercial airliner, take the same measurements throughout the flight and think about how you feel after a few hours in the air. Remember, the cabin altitude is equivalent to being in Denver or higher—no wonder one feels jet-lagged. So again, please think this through; you will breathe easier and so will I.
March 27, 2012
