Developmental Pathophysiology, Develop. Physiol., Dr. D. Penney
Table 4.09. Cyanosis.
- "A bluish discoloration, applied especially to such discoloration of skin, mucous membranes and nail beds due to excessive concentration of 'reduced' hemoglobin in the blood".
- Caused by 4 or more g/dL of deoxygenated Hb in arterial blood, regardless of total hemoglobin conc.; arterial O2 saturation below 85%.
- Types -
- Central or Shunt Cyanosis - caused by some forms of congenital heart disease (>25% shunt), and right and left heart failure.
- Peripheral Cyanosis - caused by extensive O2 extraction at capillary level, extreme peripheral constriction (Raynaud's).
- Accompanying conditions - polycythemia, clubbing of fingers and toes (especially when cyanosis marked), cerebral thrombosis, etc.
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