In general, cvanosis becomes apparent when the mean capillary concentration ot reduced hemoglobin exceeds 50 g/l (5g/dL). It is the absolute rather than the relative quantity of reduced hemoglobin that is important in producing cyanosis
In general, cyanosis becomes apparent when the mean capillary concentration of reduced hemoglobin exceeds 50 g/L (5g/dL). It is the absolute rather than the relative quantity of reduced hemoglobin that is important in producing cyanosis
Thus in a patient with severe anemia. the relative amount of reduced hemoglobin in the venous blood may be very large when considered in relation to the total amount of hemoglobin in the blood. However since the concentration of the latter is markedly reduced the absolute quantit of reduced hemoglobin may still be small and therefore patients with severe anemia and even marked arterial desaturation(稀释 )do not display cyanosis
Thus, in a patient with severe anemia, the relative amount of reduced hemoglobin in the venous blood may be very large when considered in relation to the total amount of hemoglobin in the blood. However, since the concentration of the latter is markedly reduced, the absolute quantity of reduced hemoglobin may still be small, and therefore patients with severe anemia and even marked arterial desaturation(稀释 )do not display cyanosis
Conversely the higher the total hemoglobin content. the greater is the tendency toward cyanosis thus, patients with marked polycythemia(红细胞增多症) tend to be cyanotic at higher levels of Sao, than patients with normal hematocrit(红细胞压积 values
Conversely, the higher the total hemoglobin content, the greater is the tendency toward cyanosis; thus, patients with marked polycythemia(红细胞增多症)tend to be cyanotic at higher levels of SaO2 than patients with normal hematocrit(红细胞压积) values
Likewise, local passive congestion which causes an increase in the total amount of reduced hemoglobin in the vessels in a given area, may cause cyanosIS
Likewise, local passive congestion, which causes an increase in the total amount of reduced hemoglobin in the vessels in a given area, may cause cyanosis
yanosis also is observed when nonfunctional hemoglobin such as methemoglobin(正铁血红蛋 白,高铁血红蛋白)or sulfhemoglobin(硫化血红蛋白 ) is present in blood
Cyanosis also is observed when nonfunctional hemoglobin such as methemoglobin(正铁血红蛋 白，高铁血红蛋白)or sulfhemoglobin(硫化血红蛋白 ) is present in blood