THE FACTORS INVOLVED IN CYANOSIS

Like several other signs of deviation from the normal, cyanosis has long been a familiar symptom meriting recognition from the physician, notably in diseases of the circulatory and respiratory systems. The bluish color of the skin and mucous membranes is by no means always manifest when respiration becomes impaired. Thus, in the coma of diabetes there may be asphyxial conditions without cyanosis. Strangely enough, despite the frequency with which this striking sign is observed in clinical experience, there has been no convincing and tenable explanation of precisely how cyanosis originates. Anatomic changes in the capillaries cannot be held to explain the characteristic changes in color. The production of blood pigments like methemoglobin having an unusual color has been postulated as a possible cause of cyanosis, particularly the so-called enterogenous cyanosis in which products of intestinal putrefaction have been held responsible for the alteration of the blood pigments.¹ Even if