144 THE GASES OF THE BLOOD IN DISEASE. [BOOK I. 



physical conditions of the patients, we can often surmise the way in which 

 the gaseous exchanges of the blood must be affected. Thus from the 

 amount of haemoglobin found in cases of anaemia and chlorosis, we can, 

 with considerable accuracy, calculate the maximum amount of oxygen 

 which such blood can contain, and we arrive at the conclusion that the 

 amount is much below the normal. 



Thus a healthy man's blood contains on an average say 13*5 grammes 

 of haemoglobin in one hundred parts. Such blood in virtue of its haemo- 

 globin would, if saturated with oxygen, be capable of absorbing 22-55 c.c. 

 of oxygen measured at C. and 760 mm. pressure. 



On the other hand the blood in cases of chlorosis may contain as little 

 as 5 '3 grammes of haemoglobin per 100 of blood. Such blood could in 

 virtue of its haemoglobin only take up 8 '85 c.c. of oxygen if fully 

 saturated. We see therefore that the respiratory capacity of such blood 

 is reduced to less than one half that of healthy blood. 



Again in cases where mechanical causes exist which interfere with the 

 due amount of the gaseous exchanges in the lung, the cyanosis and the 

 dyspnoea, sometimes culminating in asphyxia, point to a condition in which 

 the oxygen of the blood is greatly diminished and the carbonic acid greatly 

 increased. Actual determinations are, however, almost entirely wanting 1 . 



Attempts have been made by certain observers to determine the 

 changes which the gases of the blood undergo in disease. Unfortunately 

 the methods employed have been such as to deprive the results of all 

 value. Thus Quinquaud determined the amount of oxygen in the blood 

 of various diseases by means of a standard solution of sodium hydrosulphite 2 . 

 The results obtained by this method are unfortunately in no way 

 comparable with those obtained by the mercurial pump. Again, Brouardel 3 

 has published analyses of the gases of the blood in variola and scarlatina 

 which would appear to shew that in these diseases the proportion of oxygen 

 which the blood can absorb is very much diminished. As, however, the 

 amount of nitrogen found is much greater than could possibly have been 

 held in solution by the quantity of blood analysed, the legitimate conclusion 

 to be drawn is that the analyses possess no value. Regnard 4 has attempted 

 to determine the so-called ' respiratory capacity' of blood in disease, i. e. 

 the maximum amount of oxygen which a given quantity of blood will 

 absorb. Blood is shaken with air and then subjected to analysis in the 

 mercurial pump. According to Regnard the respiratory capacity of blood 

 is not affected even by putrefaction ; i. e. blood which is decomposed can 

 absorb as much oxygen, as it did before the process of putrefaction 

 set in. Regnard's observations were all performed with blood taken 

 from the dead body, the clot being broken up artificially. They led 

 to the conclusion that in many diseases the respiratory capacity is immensely 

 diminished ; were the results reliable they would indicate that under the 



1 In a case of cyanosis due to a cardiac lesion Lupine found that 100 c.c. of 

 venous blood contained 64 c.c. of C0 2 . Gazette Medic, de Paris, 1873, p. 128. 



2 Quinquaud, "Sur un proc6d6 de dosage de 1'he'moglobine dans le sang" 

 Comptes Rendus, Vol. LXXVI. p. 1489. " Sur les variations de 1'h^moglobine dans les 

 maladies. " Comptes Eendus, Vol. LXXVII. p. 447. 



3 Brouardel: "Des gaz du sang dans diffe'rentes maladies." Societe medicale des 

 hopitaux, 1870, quoted by Bernard. 



4 P. Bernard: Eecherches experimental sur les variations pathologiques des combus- 

 tions respiratoires. These pour le Doctorat en Mddecine. Paris, 1878 109 et seq. 



