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Scientific Proceedings (125) 



The general term, or, even its gradations spoken of as marked, 

 moderate, or a mild degree of cyanosis, conveyed no accurate 

 idea of the condition under observation. Furthermore, it was 

 noted that when an observer had been with a patient for some 

 time, his appreciation or registration of a color witnessed be- 

 came less acute. It is a common occurrence for a spectator to 

 enter an operating room and be struck by the patient's cyanosis, 

 the condition having been imperceptibly increased under the color 

 wearied gaze of the anaesthetist. A standard measure of cyan- 

 osis, therefore, serves two purposes. It provides data relative 

 to the degree of cyanosis present and provides a criterion for 

 the color wearied vision of the constant observer. 



That there has been a general failure to meet the demand for 

 a measure of cyanosis is possibly due to a rather unique and 

 widely accepted impression that where there is cyanosis there 

 must be an increased tension of carbon dioxide. This accidental 

 association of carbon dioxide and cyanosis has so complicated 

 the matter of measuring cyanosis that, to the average medical 

 mind, the solution was quite out of the question. To brush away 

 the cobwebs of carbon dioxide as an element affecting the color 

 of the blood is to reduce the problem to its simplest terms. 



The observations which follow are based upon the assumption 

 that the color of the blood, where the haemoglobin is approxi- 

 mately normal, is directly dependent upon the amount of oxygen 

 present as oxyhaemoglobin. Complete oxygen saturation (0 no 

 cyanosis) representing one extreme; complete oxygen unsatura- 

 tion (100 per cent, or complete cyanosis) representing the other. 



Through the courtesy of Dr. Van Slyke of the Rockefeller 

 Institute, numerous specimens of venous blood taken from the 

 distal portions of ligated veins, after 5, 10, 15, 20 minutes 

 stagnation, were subjected to quantitative analysis. The longest 

 exposure resulted in oxygen unsaturation (cyanosis) of not 

 more than 30 per cent. An attempt to secure a completely un- 

 saturated specimen from an amputated leg also proved a failure. 

 It became evident that it would not be possible to secure a com- 

 pletely unsaturated specimen from the blood while in the blood 

 vessels, the oxygen tension being probably upheld by a flow 

 of oxygen from the tissues, and possibly from atmospheric 

 absorption from the mucous membranes. 



