Cyanosis is a condition of bluish, grayish, slate-like or dark purple discolouration of the skin, seen particularly about the face and extremities (nails, tips of ears). It accompanies states in which the blood is not properly oxygenated in the lungs or there is reduced haemoglobin in the blood. In Chinese medicine blue-green colouration indicates stagnation or obstruction of blood and qi. It also appears where there is liver disharmony or wind disharmony.
Cyanosis may be due to blockage of the air passages, or to disease in the lungs, or to a feeble circulation, as in heart disease. Dr. Douglas Model of Eastbourne in England added the term smoker's face to the medical lexicon in 1985 after surveying 116 patients and correctly identifying roughly half of the current smokers by their facial features alone. A smoker's face is inclined to appear older than its years, etched and wrinkled, with gaunt-looking features, prominent underlying bones, shriveled skin, gray with purplish blotches.