Carbon monoxide poisoning: optics and histology of skin and blood.

In 10 fatal cases of carbon monoxide poisoning an optical study of the skin colour was made by reflectance spectrophotometry, and the values converted to their visual equivalents. Several circumstances contribute to the difficulty of identifying the cherry-red colour in the skin, such as a low CO concentration, skin pigmentation, washing out of a previously high concentration of CO, and deep venous dilatation with superficial vasoconstriction producing the impression of cyanosis. The colour of the altered blood depends on the way the red cells are massed together, their depth below the surface, and the brightness of the background against which they are viewed. These phenomena were compared with the dichroism of oxyhaemoglobin. Damage to eccrine sweat acini was noted early in CO-poisoning. It was probably intensified, in those surviving longer, at skin sites of intermittent pressure anoxia.