Chapter LV

DISEASES DUE TO DIMINISHED ATMOSPHERIC PRESSURE:
PURE AND IMPURE GASES

_Mountain Climbers; Military Balloonists._

Increased atmospheric pressure causes unpleasant and sometimes serious symptoms in divers and in caisson workers, but to an extremely rarefied atmosphere can also be traced effects that are nearly equally serious. It is difficult to say at what height above the ordinary surface level of the earth man can live with comparative comfort. The Andes and the Himalayas have been scaled to from 15,000 to 23,000 feet above the sea level, and men are said to have gone as high as six miles in balloons. The difficulties of remaining at great altitudes are the excessive cold and the low barometric and oxygen pressures. In order to compensate for this low oxygen pressure, nature endows men living at great heights by increasing the number of the red corpuscles of their blood. It is these corpuscles that carry oxygen to the tissues. In ascending a very high mountain the individual experiences not only great difficulty of breathing and violent palpitation of the heart, but a sense of great physical fatigue and faintness. A set of symptoms not unlike those observed in sea-sickness occurs, hence the name given to the illness, “mal de montagnes,” although vomiting and nausea are not always present. In climbing mountains people generally put forth a great amount of muscular effort, and in consequence an increased amount of chemical change takes place within their body, a circumstance which reduces the resistance of these individuals to the influences of a falling barometric pressure. Aeronauts do not experience this sense of muscular fatigue, because they are not making any muscular effort, but they ascend to great heights with greater rapidity than climbers, and to this circumstance must be attributed many of the unpleasant symptoms they experience.

Since in the act of climbing it is upon the heart and lungs that the greatest strain is thrown, it is these organs that principally have their functional activity increased. The palpitation of the heart may be very distressing. There is throbbing in the head, accompanied by extreme muscular exhaustion, so that after reaching a great height the individual may be so overcome that he throws himself on the ground, unable to proceed further. He lies there for a time panting, trying to get more oxygen into his system and to rid it of the excess of carbonic acid. He may bleed at the nose or from the gums. He perspires freely, and there is great thirst. There may be deafness and earache owing to the bulging outwards of the drum of the ear. Although it cannot be stated that in man death has been caused by diminished atmospheric pressures at great heights, yet it has been shown experimentally in animals that coma is induced which may end in death. The animal passes into a state of cadaveric rigidity very shortly after death. It is just a question how far the sudden supervention of cardiac and cerebral symptoms in mountain climbers may not be responsible for some of the fatal accidents that we read of from time to time as occurring on the Alps.

_Military Balloonists._--In the _Archiv. de Med. Milit._, February 1900, Dr Maljean reports that in a company of balloonists belonging to the 1st Regiment of Engineers he found several of the soldiers suffering from a toxæmic form of jaundice, the nature of which was obscure. Ultimately he demonstrated that the jaundice was due to poisoning by inhalation of arseniuretted hydrogen gas mixed with hydrogen that had been used for filling the balloons. The hydrogen employed for military balloons is obtained by acting upon granulated zinc with sulphuric acid. The sulphuric acid is generally obtained from pyrites, and this is known to contain sometimes as much as from 2 to 5 per cent. of arsenic combined with iron. Commercial zinc also often contains arsenic. In filling balloons, therefore, it would appear that not only is there frequently an escape of this impure hydrogen from the valves of the balloon, but that during the operation of filling the balloon, the officers and men are in the habit of smelling the tube to ascertain whether by the garlicky odour of the impure hydrogen this gas has replaced the ordinary atmospheric air. At a single filling an officer may smell several times the open tube of the balloon and suffer in consequence.

According to Maljean the symptoms of poisoning commence with a sense of great malaise and nausea, followed later on by jaundice, often of a very pronounced yellow-green tint, urine scanty, and often as dark as coffee, but not giving the reaction of biliary pigment. The urine stains the linen like the blood-coloured urine of patients suffering from hæmoglobinuria, and it may contain both albumen and a few tube-casts. In a few days these symptoms disappear, but they leave behind them anæmia and loss of flesh, which persist. It has for long been known that if animals are given arseniuretted hydrogen gas to inhale, they rapidly become jaundiced and pass a blood-coloured urine. A similar set of symptoms has been observed in men working in chemical and mineral industries in which arsenic is present.

In the balloon service of the French army an endeavour is now being made to use only pure hydrogen. In most of the military balloons the valve which allows the gas to escape is placed in the upper part of the machine. The balloons are filled in the open by hydrogen from metallic cylinders which have been charged under a pressure equivalent to 120 atmospheric pressures. It is stated by some authorities that under such very high pressure the impure gas may be decomposed and rendered less harmful, but this requires confirmation.

Poisoning of aeronauts by arseniuretted hydrogen in connection with military balloons on the Continent is not confined to the French army alone. In the _Deutsche Milit. Zeitschrift_, 1900, p. 139, is an account of two German soldiers, who, after being poisoned by this gas, died at the end of three days.

Persons ascending in balloons should dress warmly, and they ought to take with them cylinders filled with compressed oxygen.

THOMAS OLIVER.