The mechanism behind<unk>  is different depending on whether it is central or peripheral. Central<unk>  Central<unk>  is caused by a decrease in arterial oxygen saturation (SaO2) and begins to show once the concentration of deoxyhemoglobin in the blood reaches a concentration of ≥ 5.0 g/dL (≥ 3.1 mmol/L or oxygen saturation of ≤ 85 %). Causes of central<unk>  are discussed below. Peripheral<unk>  Peripheral<unk>  happens when there is increased concentration of deoxyhemoglobin on the venous side of the peripheral circulation. In other words,<unk>  is dependent on the concentration of deoxyhemoglobin. Patients with severe anemia may appear normal despite higher than normal concentrations of deoxyhemoglobin. On the other hand, patients with increased amounts of red blood cells (e.g. polycythemia vera) can appear cyanotic even with lower concentrations of deoxyhemoglobin.A baby with a heart condition. Note purple nailbeds.
Cyanosis
Polycythemia
Acrocyanosis
Myxedema
Retinopathy
Lipedema
Tooth discoloration
Color blindness