September 23, 1920] 



NATURE 



127 



cirfulateti in sufficient quantities to the tissues. The 

 quantity of oxygen which reaches the tissue in unit 

 time is too small. Literally, according to the strict 

 derivation of the word "anoxaemia," the third type 

 should perhaps be excluded from the category of 

 conditions covered by that word, but as the result is 

 oxygen starvation in the tissues it will be convenient 

 to include it. 



The obvious types of anoxaerr;ia may therefore be 

 classified in some such scheme as the following : 



Anox^mi.*. 



I 



I I I 



I. AnAxic Typ€. a. Anatmic Tyfi€. 3. Sta^ant Ty^, 



The preuure of oxygen in Th« quantily of fiioc- The blood is norma], 



the blood is too low. tional harmoglobin is but is supplied to the 



The hzmogtobin is not too sina<l. li&saesin insufficient 



saturated to the oornul The oxygen pressure is quantities, 



extent. normal. Examples : 



The blood is dark. The blood is normal in 1. Secondary result 



Examples: colour. of histamine shock. 



1. Rare atmospheres. Examples a. Haimorrliage. 



a. Areas of lung par- 1. Too little hxnio- 3. back pressure. 



tially unventiUted. gloUin. 



3. Fluid or tibrin on a. CO hemoglobin. 



surface of cells. 3. Methaemoglobin. 



Anoxic anoxaemia is essentially a general as 

 opposed to a local condition. Not only is the pressure 

 of oxygen in the blood too low, but the lowness of 

 the pressure, and not the deficiency in the quantity, 

 is the cause of the symptoms observed. 



The workers on Pike's Peak, for instance, 

 emphasised the fact that the increase of red-blood 

 corpuscles during their residence at 14,000 ft. was 

 due to deficient oxygen pressure. No doubt they were 

 right, but the point was rather taken from their 

 argument by their assertion in another part of the 

 paper that the oxygen pressure in their arterial blood 

 ■was anything up to about too mm. of mercury. Let 

 me, therefore, take my own case, in which the 

 alveolar pressures are known to be an index of the 

 oxygen pressures in the arterial blood. I will compare 

 my condition on two occasions, the point being that 

 on these two occasions the quantities of oxygen united 

 with the hamoglobin were as nearly as may be the 

 s.ime, whilst the pressures were widely different. 



.As I sit here the haemoglobin value of my blood 

 is 9fV-97, which corresponds to an oxygen rapacity of 



178 CO. of O, per c.c. of blood. In the oxygen 

 chamber on the last day of my experiment, to w'hich 



1 refer later,' the oxygen capacity of my blood was 

 0201 r.c. Assuming the blood to be 95 per cent, 

 'i.ituratcd now and 84 per rent, saturated then, the 

 i^-tual quantity of oxygen in the blood on the two 



occasions would be : 



Oxygen 

 content. 



o-i6g 

 0-169 



Hi- I am in my usual health. In the chamber I 

 v.,inii.-<l; my pulse was 86, it is now 56; my head 

 -Th. (| in a most distressing: fashion; it was with the 

 utnuwt difficulty that I could carry out routine gas 

 analyses, and when doing so the only objects which 

 I saw distinctly were those on which my attention 

 w.Ts r()nrontrat<'d. 



In itw> .nnoxic type of anoxaemia there mav then be 

 quite .1 ■-ufTirlcnt quantity of oxvgcn in the blood, but 

 a sufTu irnt quantity does not avail in the fare of an 

 insufTicient pressure. Indeed, as 1 shall show pre- 

 sentlv. the anoxic type of anoxaemia is the most 

 sorious. We are. therefore, confronted with some- 

 thing of a paradox in that the most severe type of 

 .-inox,-Bmi.T is one in which there is not necessarilv an 

 insuflirient quantity of oxygen in the blood at all. 



s Barcntft, C«olit, Hartridg*, ParaoM. ud Par«ent. Innml »f Pti,- 



'■' ••»tr, wl. Im., p. 4)1, ifao. 



NO . 2656, VO I.. 106] 



It is interesting and not uninstructive to try to 

 calculate the degree to which the tissues are pre- 

 judiced by being subjected to various types of 

 anoxaemia. Let us suppose that we have a piece of 

 tissue — muscle, for instance — which normally is 

 under the following conditions : 



(a) One cubic centimetre of blood per minute runs 

 through it. 



(b) The total oxygen capacity of this blood is 

 o-i88 c.c. of oxygen f>er c.c. of blood. 



(c) The percentage saturation is 97. 



(d) The oxygen pressure is 100 mm. 

 ie) The oxygen used is 0-059 c.c. 



(/) The oxy^n pressure in the tissues is half of 

 that in the vems, in this case 19 mm. 



My colleague, Mr. F. J. Roughton, has calculated 

 the amount of o.xygen which would penetrate this 

 tissue from the blood in each type of anoxaemia, if 

 the o.\ygen which reached it in the blood was reduced 

 to 66 per cent, of the quantity stated above. 



Measurement of Anoxaemia. 

 In the study of all physical processes there comes 

 a point, and that very early, when it becomes neces- 

 sary to compare them one with another to establish 

 some sort ot numerical standard and have some sort 

 of quantitative measurements. The study of 

 anoxaemia has reached that point. By what scale 

 are we to measure oxygen want? 



Let' us take the anoxic type first. There are two 

 scales which might be applied to it, both concerning 

 the arterial blood; the one is the oxygen pressure in 

 it, the other is the consequent percentage of the 

 hamoglobin which is oxyhaemoglobin. The important 

 thing is that there should be as little reduced haemo- 

 globin as possible. The more reduced haemoglobin 

 there is present, the less saturated is the blood; or, 

 as the .American authors say, the more unsaturated is 

 the blood. They emphasise the fact that it is the 

 quantity of rediiced haemoglobin that is the index of 

 the anoxic condition. They speak not of the per- 

 centage saturation, but of the percentage of unsatura- 

 tion. A blood which would ordinarily Se called 85 f>er 

 cent, saturated they speak of as 15 per cent, un- 

 saturated. 



Anoxic anoxaemia, in many cases of lung affection, 

 should be measured by tl>e direct method of arterial 

 puncture introduced by Stadie,* for the simple reason 

 that the relation between the alveolar air and the 

 arterial blood is quite unknown. Such, for instance, 

 are_ cases of many lung lesions of pneumonia in 

 which the lung may be functioning onlv in parts, of 

 pneumothorax, of pleural effusions, o( emphysema, 

 of multiple pulmonary embolism, in phases of 

 which the arterial blood has been found experi- 

 mentally to be unsaturated. In addition to these 

 definite lung lesions there is another tvpe of case on 

 which great stress has been laid ' bv Haldane. 

 Meakins, and Priestley, namely, cases ' of shallow 

 respiration.' A thorough investigation of the arterial 

 blood is such cases is urgently necessary. Indeed, in 

 all cases in which it is practicable, the method of 

 arterial punrture is desirable. But in the cases of 

 many normal persons — as, for instance, those of air- 

 men at different altitudes — alveolar>air determinations 

 would give a useful index. 



The ansemic type of anoxemia is f;aue«d by the 

 quantity of oxyh.-emoglobin in the blood. In the case 

 of simple anaemias this is measured by the scale in 

 which the normal man counts as ino, and the hsmo- 

 globin in the anaemic individual is expressed as a 

 percentage of this. This method has been stan- 



• Stadia. J«utn>ml ^ Kx^rimtnt^ MtMetmi, v«l. a«i., p. alt. lotf., 

 ' Haldan*. Maakins, and Prieuley. Itumat » PhfiMtgy, veL In. 

 p. 4»o, 191)-!^ 



