Mountain Sickness of Aviators.

Progress, Volume VI, Issue 5, 1 March 1911, Page 581

Mountain Sickness of Aviators.

Mountain climbers tell us that at great altitudes disagreeable physiological symptoms manifest themselves. Some assert that these can be detected at heights of a few thousand feet, and many say that they are unable to live in cities like Denver, Col., which its citizens are fond of reminding us is "a mile high." What would be the result if, instead of attaining these altitudes from sea-level by the slow process of climbing, we could be transported from one level to the other in a few minutes? This is precisely what happens in a lofty aeroplane flight, where the ascent takes but a short time and the descent is made in four or five minutes from an elevation of, perhaps 8000 feet. We know that quick transition from high to low pressure in the caisson of a subaqueous tunnel may have fatal results. Something of the same sort occurs in aviation, and may account for some of the mysterious accidents (we are told by a writer in The Lancet London, November 5) ; This new problem of the physiological effects upon the aviator seems to have

attracted little notice, he remarks. We read:— - • "The rapid ascent to great altitudes exposes the body to conditions different from any' terrestrial ones. Mountain-climbing offers some analogy, but it differs in the fact that the transition from the high atmospheric pressure of the sea-level to a low pressure takes place much more slowly. In the Gazette Hel)domadaire dcs Sciences Medicates de Bordeaux of September 25 Prof. R. Moulinier has reported some interesting observations on the bloodpressure of aviators who have ascended to high altitudes." On alighting after ascending to a height of four or five thousand feet, the aviator's hands and feet are blue, his eyes are bloodshot, and his pulse is high. He has headache and ringing in the ears. Sometimes there is a tendency to sleep, and this may be felt even during flight. After the flight the blood-pressure is always increased, sometimes by 30 to 40 per cent. To quote further: "This increase in pressure is all the more remarkable as the aviators were athletes in full training. The rise was less marked in aviators who were fatigued. These showed palpitation of the heart and marked acceleration of the pulse (108). In one case (symptoms) ... of functional insufficiency of the heart, and vertiginous movements, were observed in an aviator who, after a flight of an hour, had reached the height of 1000 meters (3200 feet. No rise in blood-pressure was found in aviators who flew at low altitudes, such as 100 to 150 meters. As to the cause of the rise in blood-pressure, Professor Moulinier puts forward the hypothesis that it is due to the sudden descent to earth in four or five minutes from a height of 1000 to 2000 meters which was attained in 20 to 25 minutes. ... In the short time of the descent the circulatory system had not time to become adapted to the change of pressure. He therefore advises aviators to descend more slowly. lie also points out the dangerous fatigue to which flight at high altitudes, exposes the circulatory apparatus by provoking increased and irregular activity of the heart and vessels. A sound heart and supple arteries are absolutely necessary to an aviator. The list of distressing fatalities to aviators has become comparatively long in a very short time. The accidents are always attributed to some mechanical cause—some breakdown in the machine or unexpected current of air. No doubt this is usually true, but it seems to us quite possible that in some cases the breakdown is personal, not of the material at all.