II. Pathophysiology

  1. Blood components responsible for Cyanosis
    1. Deoxygenated Hemoglobin > 5 g/dl or
    2. Methemoglobin >1.5 g/dl or
    3. Sulfhemoglobin >0.5 g/dl

III. Precautions

  1. Cyanosis appears when at least 5 g/dl of Hemoglobin is deoxygenated (desaturated)
    1. Anemic patients (e.g. Hemoblobin <10 g/dl)
      1. May not appear cyanotic despite Hypoxia
    2. Polycythemic patients (e.g. Hemoblobin >17-20 g/dl) such as those with COPD or Pulmonary Hypertension
      1. May appear cyanotic in mild Hypoxia

IV. Signs

  1. Blue coloration to skin and mucous membranes

V. Causes: Central Cyanosis (Cyanosis of the trunk and head)

VI. Causes: Peripheral Cyanosis (local Cyanosis or extremity Cyanosis)

  1. Early in course of Central Cyanosis causes (that will progress to Central Cyanosis without intervention)
  2. Hypovolemia
  3. Cold extremities
  4. Raynaud Syndrome
  5. Peripheral Arterial Disease
  6. Deep Vein Thrombosis
  7. Venous Stasis

VII. Differential Diagnosis

VIII. References

  1. Degowin (1987) Diagnostic Examination, p. 335-6

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