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发 绀 Cyanosis - PowerPoint PPT Presentation

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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.

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发 绀 Cyanosis

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ProfessorDoctor director Neurologist


  • Cyanosisrefers to a bluish()color of the skin and mucous membranes resulting from an increased quantity of reduced hemoglobin(), or of hemoglobin derivatives, in the small blood vessels of those areas. It is usually most marked in the lips, nail beds, ears, and malar()eminences().

Mechanism of Cyanosis

  • Cyanosis, especially if developed recently, is more commonly detected by a family member than the patient. The florid() skin characteristic of polycythemia vera() must be distinguished from the true cyanosis discussed here. A cherry()-colored flush(), rather than cyanosis, is caused by COHb (Carboxyhemoglobin ).

  • The degree of cyanosis is modified by the color of the cutaneous() 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()studies

  • 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()rather than examination of the skin is more helpful in the detection of cyanosis.

  • The increase in the quantity of reduced hemoglobin in the mucocutaneous() 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() 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 absoluterather than the relativequantity 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, theabsolutequantity of reduced hemoglobin may still be small, and therefore patients with severe anemia and even marked arterial desaturation()do not display cyanosis.

  • Conversely, the higher the total hemoglobin content, the greater is the tendency toward cyanosis; thus, patients with marked polycythemia()tend to be cyanotic at higher levels of SaO2 than patients with normal hematocrit() 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.






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.


Normal Polycythemia Anemia

  • 5g/dl(cyanosis)5g/dlHb5g/dlHbO2,5g/dl

  • (Carboxy hemoglobinemia)

  • HbCO: ;

  • ;

  • COHbCO







Hb: 22


(enterogenous cyanosis)

Clinical Classification & Etiology

  • True Cyanosis(increased amount of reduced Hb)

    Central Type

    Peripheral Type

    Mixed Type

  • Cyanosis due to abnormal Hb derivatives




  • (1)

  • (2)

  • (3)


  • (1)

  • (2)

Central Cyanosis

Impaired pulmonary function

1. Airway obstruction

2. Pulmonary diseases

3. Pleural()diseases

Right-to-left shunting

of blood

Tetralogy of Fallot

Central Cyanosis

  • Seriously impaired pulmonary function, through perfusion() of unventilated() 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 pulmonary diseases .In the last situation, secondary polycythemia() is generally present, and clubbing()of the fingers may occur.


  • The selective bullous(,) 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() of the soft tissue at the base of the nail.

  • ()()

Central Cyanosis

  • Another cause of reduced SaO2 is shunting of systemic venous blood into the arterial circuit. Certain forms of congenital heart disease are associated with cyanosis.

  • Since blood flows from a higher-pressure to a lower-pressure region, for a cardiac defect to result in a right-to-left shunt, it must ordinarily be combined with an obstructive lesion distal to the defect or with elevated pulmonary vascular resistance.

Central Cyanosis

  • The most common congenital cardiac lesion associated with cyanosis in the adult is the combination of ventricular septal defect and pulmonary outflow tract obstruction (tetralogy of Fallot).

  • Pulmonary arteriovenous fistulae may be congenital or acquired, solitary or multiple, microscopic or massive. The severity of cyanosis produced by these fistulae depends on their size and number.

Peripheral Type

  • Probably the most common cause of peripheral cyanosis is the normal vasoconstriction resulting from exposure to cold air or water.

  • When cardiac output is low, as in severe congestive heart failure or shock, cutaneous vasoconstriction occurs.

Peripheral Type

  • Arterial obstruction to an extremity, as with an embolus, or arteriolar() constriction, as in cold-induced vasospasm(Raynauds phenomenon), generally results in pallor() and coldness, but there may be associated with cyanosis. Venous obstruction, as in thrombophlebitis(), dilates the subpapillary venous plexuses() and thereby intensifies cyanosis.

  • 12

Cyanosis due to abnormal Hb derivatives

  • Methemoglobinemia

    Hereditary: very rare

    Acquired: >3g/dl in blood

    - intake or exposure to some drugs or

    chemicals, such as sulfa drugs, nitrite

    salt. enterogenic cyanosis

  • Sulfhemoglobinemia

    Caused by some drugs or chemicals,

    Sulfhemoglobin > 0.5g/dl in blood

  • (1)

  • (2)

  • 1Fe++Fe+++

  • Vc

  • 2

  • 19301

Approach to Patients with Cyanosis

  • Differentiation of central as opposed to peripheral

Cyanosis Skin temp. Massage()or warming

Central Warm No change

Peripheral Cool Cyanosis fades

Associated symptomsANDINQUIRY

  • Certain features are important in arriving at the cause of cyanosis:1. The history, particularly the onset (cyanosis present since birth is usually due to congenital heart disease), and possible exposure to drugs or chemicals that may produce abnormal types of hemoglobin.

  • 2000vc2

  • 2. Clinical differentiation of central as opposed to peripheral cyanosis. Objective evidence by physical or radiographic examination of disorders of the respiratory or cardiovascular systems. Massage or gentle warming of a cyanotic extremity will increase peripheral blood flow and abolish peripheral but not central cyanosis

  • 3. The presence or absence of clubbing of the digits.

  • Clubbing without cyanosis is frequent in patients with infective endocarditis and ulcerative colitis; it may occasionally occur in healthy persons, and in some instances it may be occupational, e.g., in jackhammer()operators.

  • The combination of cyanosis and clubbing is frequent in patients with congenital heart disease and right-to-left shunting and is seen occasionally in persons with pulmonary disease such as lung abscess or pulmonary arteriovenous fistulae.

  • In contrast, peripheral cyanosis or acutely developing central cyanosis is not associated with clubbed digits.

  • 4. Determination of PaO2 tension and SaO2 and spectroscopic and other examinations of the blood for abnormal types of hemoglobin (critical in the differential diagnosis of cyanosis).

  • Cyanosis + Dyspnea()

    Disorders of respiratory or cardiovascular system

  • Cyanosis with mild or no dyspnea


    Sulfhemoglobinemia: Spectroscopy helpful

  • Cyanosis + clubbing

    Severe, long duration

  • Determination of arterial oxygen saturation

  • 70320

  • EKG 160mg12

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