4 g/dL) orMethemoglobin (>1.5 g/dL) Q orSulfhemoglobin (>0.5 g/dLQ) CYANOSIS | | | Centralcyanosis Peripheralcyanosis # Central cyanosis is caused by in adequate oxygenation of systemic arterial blood due to decreased arterial oxygenQ saturation or Hemoglobin abnormalities# It results from cardiac shunting, pulmonary diseases or hematological disorders (Hb abnormalities)# Central cyanosis is charachterized by cyanosis affective both mucous membranes and skin5 # Peripheral cyanosis is caused by slowing of blood flow and increased extraction of oxygen from normally saturated blood# It results from vasoconstriction or decreased peripheral blood flow, reduced cardiac output or vascular occlusion# Peripheral cyanosis is characterized by cyanosis of skin alone and sparing of mucous membranes*3">