September 23, 1920] 



NATURE 



125 



Physiological Effects of Insufficient Oxygen Supply.* 

 By J. Barcroft, C.B.E., M.A., F.R.S. 



PROMINENT among the pathological conditions 

 which claimed attention during the war was 

 that of insufficient oxygen supply to the tissues, or 

 anoxaemia. The statement has been made that 

 ■' anoxxmia not only stops the machine, but wrecks 

 the machinery." This phrase is so apposite that I 

 shall commence by an inquiry as to the limits within 

 which it is true. 



.\nything like complete anoxaemia stops the machine 

 with almost incredible rapidity. Though the breath 

 can be held for a time, it must be borne in mind that 

 the lungs nonnally contain about half a litre of 

 oxygen, and that this will suffice for the body at rest 

 for upwards of two minutes. But get rid of the 

 residual oxygen from the lungs even to the extent 

 possible by the breathing of nitrogen, and you will 

 find that only with difficulty wilt you endure half a 

 minute. It seems doubtful whether complete absence 

 of oxygen would not bring the brain to an instan- 

 taneous standstill. So convincing are the experi- 

 mental facts to anyone who has tested them for him- 

 self that I will not further labour the power of 

 anoxemia to stop the machine. I will, however, say 

 a word about the assumption which I have made that 

 th<; machine in this connection is the brain. 



It cannot be stated too clearly that anoxaemia in 

 the last resort must affect every organ of the body 

 directly. Stoppage of the oxygen supply is known 

 to bring the perfused heart to a standstill, to caus9 a 

 cessation of the flow of urine, to produce muscular 



Haldane was not so. I gather that he has no recol- 

 lection of what took place ; that whenever he was 

 consulted about the pressure he gave a stereotyped 

 answer which was the same for all questions ; and 

 that even with a little more oxygen present he was 

 sufficiently himself to wish to investigate the colour 

 of his lips in the glass, but insufficiently himself to 

 be conscious that he was looking into the back, and 

 not the front, of the mirror. Dr. Kellas, who could 

 make observations, never discovered Dr. Haldane 's 

 mental condition, though bo.xed up with him for an 

 hour, and went on consulting him automatically. A 

 somewhat similar experiment was performed on the 

 other two observers, with results differing only in 

 degree. 



Yet the after-effects are summed up in the fol- 

 lowing sentence: ".■\ll four observers suffered some- 

 what from headache for several hours after these 

 experiments, but there was no nausea or loss of 

 appetite." 



Of real importance in this connection are the results 

 of carbon monoxide poisoning. Of these a large 

 number might be cited. Those interested will find 

 •eome very instructive cases described in a volume 

 entitled "The Investigation of Mine .•\ir," by the late 

 Sir C. Le Neve Foster and Dr. Haldane.' The cases in 

 question were those of a number of officials who 

 went to investigate the mine disaster on Snaefell, in 

 the Isle of Man, in May, 1897. Of the five cases 

 cited all suffered some after-effects, by which I mean 



fatigue, and at last immobility, but from our present i that by the time the blood was restored sufficiently 



point of view these effects seem to me to be out of 

 M" picture because the brain is so much the most 

 • tisitive to oxygen want. 



To what extent does acute anoxemia in a healthy 

 subject wreck the machinery as well as stop the 

 machine? By acute anoxaemia I mean complete or 

 almost complete deprivation of oxygen which, in the 

 matter of time, is too short to prove fatal. No doubt 

 many data might be quoted of men who have re- 

 covered from drowning, etc. Such data are com- 

 plicated by the fact that anoxaemia has onlv been a 

 factor in their condition. These data, therefore, have 

 a value in so far as they show that a very great 

 degree of anoxaemia, if acute and of short duration, 

 may be experienced with but little wreckage to the 

 machine. They have but little value in showing that 

 ich wreckage is due to the anoxaemia, becau.se the 

 ;iox.tmia has not been the sole disturbance. 

 Cases in which the anoxaemia has been uncom- 

 ■licated are to be found among those who have been 

 vnosod to low atmospheric pressures; for Instance, 

 illoonists and aviators. Of these quite a consider- 

 le number have suffered from oxvgen want to the 

 tent of being unconscious for short intervals of 

 ■ii«. 



No scientific observer has pushed a general condi- 

 n of anoxaemia either on hims<'lf or on his fellows 



• the extent of complete unconsciousness. The most 

 \ere experiments of this nature are those carried out 



Dr. H.Tldane and his colleagues. One rxperimrnt in 

 irtirular demand* attention. Dr. Haldane and Dr. 

 Kellas ' together spent an hour in a chamber in which 

 the air was reduced to between 370 mm. and iqj mm. 

 It \% diflRruIt to sav how far they were conscious, 

 riearlv each believed the other to be complete master 

 of his own faculties, but it is evident that Dr. 



• Ffom Ih. o,.-. ; i.i..„ of ihi> Pra-Mcfii or Sfclion I rPhvualon) 



•*• •"«' •< »•" "« of th. Briti.h AMoci«.ion (fi An(ii<l #4/ 



' H«l.l«nt. K- iiiwajr. /!•• tnti <•/ Pkyticltft, tvl VJi. 



NO. 2C)5(), VOL. 106] 



to its normal condition for the tissues to get the 

 amount of oxygen which they required, the effects of 

 the asphyxia had not passed off, and to this extent 

 the machine suffered. 



To sum up, then, what may be said of the per- 

 manent damage caused by acute anoxaemia, it seems 

 to me to be as follows: No degree of anoxannia 

 which produces a less effect than that of complete 

 unconsciousness leaves anything more than the most 

 transient effects; if the anox.xmia be pushed to the 

 point at which the subject is within a measurable 

 distance of death, the results may take days or weeks 

 to get over, but only in the case of elderly or un- 

 sound persons is the machine wrecked beyond repair.' 



Chrome Anoxaemia. 



And now to pass to the consideration of what I 

 may call chronic anoxaemia — that is to say, oxygen 

 want which perhaps is not very great in arnounti but 

 is of long duration. The most obvious instances of 

 men subject to chronic anoxaemia are the dwellers at 

 high altitudes. In these the anoxa-mia does not wreck 

 the machine. On what I may c^tII the average healthy 

 man anoxasmia begins to tell at about i8,o(xi ft. .\t lower 

 altitudes no doubt he will have some passing trouble, 

 but it seems to me from my own experienix; that this 

 altitude is a very critical one. Yet there are mining 

 c^mps at such heights in South .\mcrica at which 

 the work of life is carried on. The machine is kept 

 going by a process of compensation, in part carried 

 out bv a modification in the chemical properties of 

 the blood, in which both the carbonic acid and the 

 alkali diminish. The result, according to mv inter- 

 pretation of my own observations on the Peak of 



'thikI HaldsiM. "The Innxlfaiion of Mim Air." (Orifla aad 



) 

 - th« uddrMa wa« written Dr. Hal(tan« ttu told ma of a natqlwr of 

 viiiini^ n( tlia •ama arcklani who war* lirouiht out aliva by tha tearrh 

 party, hut in whgaacaa* lb« taachina wai wradiad bayond rafMir, Thay 

 lOo-i died. 



