The increase in the quantity of reduced hemoglobin in the mucocutaneous(皮肤粘膜的) vessels that produces cyanosis may be brought about either by an increase in the quantity of venous blood as the result of dilatation of the venules(Jv 静脉) and venous ends of the capillaries or by a reduction in the Sao2 in the capillary bloodThe increase in the quantity of reduced hemoglobin in the mucocutaneous(皮肤粘膜的) vessels that produces cyanosis may be brought about either by an increase in the quantity of venous blood as the result of dilatation of the venules(小 静脉) and venous ends of the capillaries or by a reduction in the SaO2 in the capillary blood