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1、发 绀 Cyanosis,原南京中大附属医院神内科主任、硕士生导师 佛山大学医学院医学系孟红旗教授、主任医师 Professor、Doctor director 、Neurologist,Definition,Cyanosis refers to a bluish(带蓝色的；带青色的)color of the skin and mucous membranes resulting from an increased quantity of reduced hemoglobin(亚铁血红蛋白；还原血红蛋白), or of hemoglobin derivatives, in the small
2、blood vessels of those areas. It is usually most marked in the lips, nail beds, ears, and malar(颧骨的；颊的)eminences(隆起).,定义,发绀是指血液中还原血红蛋白增多，或出现异常血红蛋白衍化物（高铁血红蛋白、硫化血红蛋白）时，皮肤粘膜呈青紫色现象。 发绀在皮肤较薄、色素较少和毛细血管丰富的部位，如唇、舌、两颊、鼻尖、耳垂和甲床等处较明显易于观察。,发绀（紫绀）血液中还原血红蛋白增多皮肤、粘膜呈青紫色,Mechanism of Cyanosis,Cyanosis, especially if
3、 developed recently, is more commonly detected by a family member than the patient. The florid(鲜红色的；气色好的) skin characteristic of polycythemia vera(真性红细胞增多症) must be distinguished from the true cyanosis discussed here. A cherry(樱桃)-colored flush(潮红), rather than cyanosis, is caused by COHb (Carboxyhe
4、moglobin 碳氧血红蛋白).,The degree of cyanosis is modified by the color of the cutaneous(皮肤的) pigment and the thickness of the skin, as well as by the state of the cutaneous capillaries. The accurate clinical detection of the presence and degree of cyanosis is difficult, as proved by oximetric(血氧定量法的)stud
5、ies,In some instances, central cyanosis can be detected reliably when the SaO2 has fallen to 85%; in others, particularly in dark-skinned persons, it may not be detected until it has declined to 75%. In the latter case, examination of the mucous membranes in the oral cavity and the conjunctivae(结膜)r
6、ather than examination of the skin is more helpful in the detection of cyanosis.,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
7、 venules(小静脉) and venous ends of the capillaries or by a reduction in the SaO2 in the capillary blood.,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
8、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 reduce
9、d, 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
10、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.,HbO2,HHb,2.6g/dl,正常,发绀 (cyan
11、osis),Normal Polycythemia Anemia,g/dl,Mechanisms of Cyanosis Caused by absolute increase of amount of reduced Hb in blood, usually 5g/dl (capillary) The higher the hemoglobin concentration, The greater tendency toward cyanosis.,发病机制,当毛细血管中脱氧血红蛋白浓度增加到5g/dl时，可使皮肤与粘膜呈青紫色，称为发绀(cyanosis)。循环性缺氧时，因血液流经毛细血管
12、时间延长，从单位容量血液弥散给组织的氧量增加，故静脉血氧含量明显降低。毛细血管中脱氧血红蛋白含量可超过5g/dl，所以可出现发绀。血液性缺氧无发绀，严重贫血的病人，Hb数量减少，面色苍白，毛细血管中脱氧血红蛋白达不到5g/dl，不会出现发绀。在因Hb与O2亲和力增强引起的血液性缺氧时，动脉血氧容量和氧含量可不低，甚至还稍高于正常,毛细血管中脱氧血红蛋白含量不会超过5g/dl，所以不会引起发绀。,发病机制,碳氧血红蛋白血症 (Carboxy hemoglobinemia) HbCO: 亲和力高; 抑制糖酵解; 樱桃红色 CO中毒，因HbCO呈樱桃红色，但重度中毒，严重缺氧，由于皮肤血管收缩，皮肤
13、、粘膜可呈苍白色。,高铁血红蛋白使皮肤、粘膜呈现咖啡色或青石板色，但不是发绀。,高铁血红蛋白血症 （methemoglobinemia),肠源性紫绀 (enterogenous cyanosis),（咖啡色）,Clinical Classification & Etiology,True Cyanosis (increased amount of reduced Hb) Central Type Peripheral Type Mixed Type Cyanosis due to abnormal Hb derivatives Methemoglobinemia(高铁血红蛋白血症) Sulfh
14、emoglobinemia(硫化血红蛋白血症),病因与临床表现,1. 血液中还原血红蛋白增多： (1) 中心性发绀 (2) 周围性发绀 (3) 混合性发绀 2血液中存在异常血红蛋白衍化物 (1)先天性高铁血红蛋白血症 (2)硫化血红蛋白血症,Impaired pulmonary function 1. Airway obstruction 2. Pulmonary diseases 3. Pleural(胸膜的)diseases,Right-to-left shunting of blood,Tetralogy of Fallot,Central Cyanosis,Central Cyanos
15、is,Seriously impaired pulmonary function, through perfusion(灌注) of unventilated(通气不畅) or poorly ventilated areas of the lung or alveolar hypoventilation, is a common cause of central cyanosis. This condition may occur acutely, as in extensive pneumonia or pulmonary edema, or chronically with chronic
16、 pulmonary diseases .In the last situation, secondary polycythemia(红血球增多症) is generally present, and clubbing(杵状指)of the fingers may occur.,clubbing,The selective bullous(大疱的,大泡的) enlargement of the distal segments of the fingers and toes due to proliferation of connective tissue, particularly on the dorsal surface, is termed clubbing; there is increased sponginess(海棉质) of the soft tissue at the base of the nail.,中心性发绀,呼吸系统疾病：呼吸系统是使血红蛋白能够和氧结合，成为氧合血红蛋白的地方
