Effects Of Altitude On Aviators In 1917
Yandell Henderson, professor of physiology at Yale Medical School, explains the effects of altitude sickness in an article from Aviation Week 99 years ago.
He said that anyone can get an ‘aviator’s headache’ without ever leaving the ground if you breathed in less oxygen than is normal at sea level.
He cites the work of Paul Bert, a French physiologist, who had demonstrated that “the effects of lowered barometric pressure, or altitude, are wholly dependent on the increased pressure of oxygen. He [Bert] showed that in pure oxygen at 21 per cent of atmospheric pressure life goes on in practically the same manner as in the air, which contains 21 per cent of oxygen at the ordinary pressure.
“So also the breathing of an artificial gas mixture containing only 10.5 per cent of oxygen has the same untoward effects at sea level tht breathing pure air at an altitude of 20,000 feet where the barometer is reduced by one half. By breathing a mixture of gases deficient in oxygen one can get an aviator’s headache without ever leaving the ground.”
He notes this is an important consideration for the differentiation of the disorders caused by “rarified air” such as mountain sickness or aviator’s sickness from conditions resulting from work in compressed air.
He goes on to explain the dangers of compressed air causing the ‘bends’ among deep sea divers and says the disorders affecting aviators are of a ‘different class’. The topic of acclimatization to altitudes “forms one of the finest chapters in recent physiological advance”.
Henderson concludes his study by suggesting that if time is allowed for gradual acclimatization or if for some time before the ascent, mountaineers or aviators are subjected to gradually increasing degree of oxygen deficiency, the capacity of the lungs to secrete oxygen will develop to a degree sufficient in most cases, to afford protection against any altitude that a heavier than air machine has yet attained.”
He describes the effects of not having acclimatized by quoting the experiences of Tissandier, the sole survivor of a fatal balloon ascent in 1875, whose notes are characteristic of the mental condition when “oxygen-want is becoming dangerous”.
Tissandier described how he felt as he became starved of oxygen the higher the balloon rose: “At about 7500 metres the condition of torpor that comes over one is extraordinary.
“Body and mind become feebler, little by little, insensibly. There is no suffering. On the contrary one feels an inward joy. There is no thought of the dangerous position; one rises and is glad to be rising… This vertigo appears at the last moment, and immediately precedes extinction; sudden, unexpected and irresistible.”
Read the full article from March 1, 1917