Clinical Measurement of Cyanosis 



3 



At the suggestion of Dr. Van Slyke a specimen of oxalated 

 blood was artificially unsaturated by passing hydrogen gas over 

 it. It was found that the lower percentages of oxygen were 

 displaced with difficulty. Finally, a specimen exposed to hydro- 

 gen gas for an hour and 15 minutes was found by quantitative 

 analysis to be completely unsaturated (100 per cent, cyanosis). 

 Before submitting this specimen for examination, the mass color 

 was carefully matched by a color expert and recorded in non- 

 fading ink. Complete saturation (0 cyanosis) was easily ar- 

 rived at by passing oxygen gas through a specimen of oxalated 

 blood. The two extremes of the mass color of the blood thus 

 secured formed the basis for the intermediate percentages. This 

 scale based upon the mass color of the circulating blood provides 

 a fixed and optically accurate means of determining the percent- 

 age of specimens collected from blood vessels under the usual 

 airtight precautions. It also offers a measure for the degree of 

 oxygenation of blood escaping from a fresh incision when the 

 skin and mucous membranes are not available for estimation, 

 as for example, in operations for brain tumors, glands of the 

 neck, thyroidectomies, etc. 



The basic extremes representing the actual mass color of the 

 blood having been secured, the next problem was to so modify 

 this scale that the resultant color would faithfully represent the 

 actual color seen in the nails, skin and mucous membranes. 



It soon became apparent that the skin color depended upon the 

 volume of the capillary circulation as well as upon the quality, hue 

 or oxygen percentage of this circulation, i.e., the normal in- 

 dividual at rest shows a delicate skin color whose variations are 

 read with difficulty. The same individual after physical exer- 

 tion or under anaesthesia will fall into a totally different range 

 of color whose variations are much more clearly defined. While 

 convinced that the skin and mucous membrane colors were 

 fundamentally dependent upon basic blood scale already arrived 

 at, the writer, nevertheless, essayed a determination of actual 

 skin color under anaesthesia by enlisting the assistance of a color 

 expert. What was his chagrin to find that it was not possible 

 to accurately match the colors under observation? For there 

 appeared to be a constant undulation of color value due to the 

 respiratory complications of anaesthesia. Had it not been the 



