I 2t> 



NATURE 



[September 23, 1920 



Tenerifle, which appeared to be confirmed by the 

 experiments in a partially vacuous chamber in 

 Copenhagen,* was this : The hydrogen-ion concen- 

 tration ot the blood increased slightly, the respiratory 

 centre worked more actively, and the lung became 

 better ventilated with oxygen, with the natural result 

 that the blood became more oxygenated than it would 

 otherwise have been. 



The difference which this degree of acclimatisation 

 made was very great. On Monte Rosa in one case 

 15 mm. of oxygen pressure were gained in the lungs. 

 To put the matter another way, the amount of 

 oxygen in our lungs at the summit was what it 

 would otherwise have been 5000 ft. or 6000 ft. lower 

 down. 



The body, then, had fought the anoxaemia and 

 reduced it very much in degree, but at the same time 

 the anoxaemia had in a subtle way done much to 

 stop the powers of the body, for this very acclimatisa- 

 tion is effected at the expense of the ultimate reserve 

 which the body has at its disposal for the purpose of 

 carrying out muscular or other work. The oxygen 

 in the lungs was obtained essentially by breathing 

 at rest as you would normally do when taking some 

 exercise. Clearly, then, if you are partly out of 

 breath before vou commence exercise you cannot 

 undertake so much as you otherwise would do. As a 

 friend of mine — who has camped at 23,000 ft.. If 

 higher altitude, I believe, than any other man — put 

 it to me : " So great was the effort that we thought 

 twice before we turned over in bed." 



One of the interesting problems with regard to 

 chronic anoxaemia is its effect upon the mind. Sir 

 Clement Le Neve Foster's account of himself during 

 CO poisoning shows loss of memory, some degree 

 of intelligence, and a tendency to repeat what is said. 

 The whole train of his symptoms strongly suggests 

 some form of intoxication, and is not dissimilar to 

 that produced by alcoholic excess. Here it may be 

 noted that, so far as isolated nerves are concerned, 

 there is very good evidence that alcohol and want 

 of oxygen produce exactly the same effects, i.e. they 

 cause a decrement in the conducting power of the 

 nerve. And herein lies a part of its interest, for 

 pharmacologists of one school, at all events, tell me 

 that the corresponding effects of alcohol are really 

 due to an inhibition of the higher centres of the 

 mind; you can, therefore, conceive of the mental 

 mechanism of self-control being knocked out either 

 because it has not oxygen enough with which to 

 "carry on," or because it is drugged by some poison 

 as a secondary result of the anoxaemia. 



To pass now to the results of more chronic 

 anoxaemia, if I were to try to summarise them in a 

 sentence I should say that, just as acute anoxaemia 

 simulates drunkenness, chronic anoxaemia simulates 

 fatigue. 



A page in mv note-book written at the Alta Vista 

 Hut, at an altitude of 12,000 ft., commences with a 

 scrawl which is crossed out, then "6 Sept.," the 

 word "Sept." is crossed out and "March" is in- 

 serted, "March" shares th,€ same fate as "Sept.," 

 and "April," the correct month, is substituted, and 

 so on, more crossings out and corrections. All. this 

 you joight sav with justice is the action of a tired 

 man. The other pages written at lower altitudes do 

 not, however, bear out the idea that I was out of 

 health at the time, and there was no reason for tired- 

 ness on that particular day. Another symptom fre- 

 quently associated with mental fatigue is irritability. 

 Anvone who has experience of high altitudes knows 

 to his cost that life does not run smoothly at 

 To,ooo ft. If the trouble is not with one's own 



* Hasselh^ch and Lindhard, onoted by Rainbridge. 



NO. 2656, VOL. 106] 



temper, it is with those of one's colleagues; and so 

 it was in many cases of gas poisoning and in the 

 case of aviators. In these subjects the apparent 

 fatigue sometimes passed into a definitely neuras- 

 thenic condition. At this point an issue appeared to 

 arise between the partisans of two theories. One 

 camp said that the symptoms were definitely those of 

 anoxaemia, the other that they were due to nerve- 

 strain. As I have indicated later on, it is not clear 

 that these two views are mutually exclusive. It takes 

 two substances to make an oxidation, the oxygen and 

 the oxidised material. If the oxidatiort does not take 

 place, the cause may lie in the absence of either or 

 of both, in each case with a similar effect. The 

 subject really is not ripe for controversy, but it is 

 amply ripe for research — research in which both the 

 degree of anoxaemia and the symptoms of fatigue are 

 clearly defined. 



So much, then, for the injury to the machine 

 wrought by chronic anoxaemia. 



Types of Anoxaemia. 



Anoxaemia is by derivation want of oxygen in the 

 blood. Suppose you allow your mind to pass to some 

 much more homely substance than oxygen — such, for 

 instance, as milk — and consider the causes which may 

 conspire to deprive your family of milk, three obvious 

 sources of milk deficiency will occur to you at once : 

 (i) There is not enough milk at the dairy; (2) the 

 milk is watered or otherwise adulterated so that the 

 fluid on sale is not really all milk; and (3) the milk- 

 man from that particular dairy does not come down 

 your road. 



These three sources of milk deficiency are typical 

 of the types of oxygen deficiency. 



The first is insufficient oxygen dispensed to the 

 blood by the lungs. An example of this type of 

 anoxaemia is mountain-sickness. The characteristic 

 of it is insufficient pressure of oxygen in the blood. 

 In mountain-sickness the insufficiency of pressure in 

 the blood is due to insufficient pressure in the air. 

 But this type of anoxaemia may be due to other 

 causes. In such cases, either caused by obstruction, 

 by shallow respiration, or by the presence of fluid in 

 the alveoli, the blood leaving the affected areas will 

 contain considerable quantities of reduced haemo- 

 globin. This will mix w-ith blood from unaffected 

 areas which is about 95 p>er cent, saturated. The 

 oxygen will then be shared round equally among the 

 corpuscles of the mixed blood, and if the resultant 

 is onlv 85-90 per cent, saturated the pressure 

 of oxygen will only be about half the normal, and, 

 as I said, deficiency of oxygen pressure is the charac- 

 teristic of this type of anoxaemia. 



The second type involves no want of oxygen pres- 

 sure in the arterial blood; it is comparable to the 

 watered milk. The deficiency is really in the quality 

 of the blood, and not in the quantity of oxygen to 

 which the blood has access. The most obvious 

 example is anaemia, in which the blood contains too 

 low a percentage of htemoglobin, and because there 

 is too little haemoglobin to carry the oxygen, too 

 little oxygen is carried. Anaemia is. however, only 

 one example of this type of anoxaemia. The haemo- 

 globin may be useless for the purpose of oxygen 

 transport ; it mav be turned in part into methaemo- 

 globin, as in several diseases, e.g. among workers 

 in the manufacture of some chemicals, and in some 

 forms of dysentery contracted in tropical climates, or 

 it mav be monopolised by carbon monoxide, as in 

 mine-air. 



Thirdly, the blood may have access to sufficient 

 oxvffen and mav contain sufficient functional haemo- 

 globin, but owing to transport trouble it may not be 



