Cyanosis

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Contents 1 More Specific Terms 2 Introduction 3 Etiology 4 Pathology 5 Clinical-manifestations 6 More General Terms 7 References

More Specific Terms

• acrocyanosis

Introduction

• Bluish discoloration of the skin & mucous membranes that occurs when the capillary content of reduced hemoglobin is > 5 g/ dL.

Etiology

• central cyanosis

• severe hypoxia ( pO2 < 55 mm Hg)
• mild hypoxia with

• polycythemia (red cyanosis)
• shock
• hemoglobin with low affinity for oxygen

• decreased atmospheric pressure (high altitude)
• impaired pulmonary function

• alveolar hypoventilation
• ventilation-perfusion mismatch
• impaired oxygen diffusion

• anatomic shunt

• congenital heart defect
• pulmonary arteriovenous fistula
• multiple small intrapulmonary shunts

• pseudocyanosis

• methemoglobinemia
• sulfhemoglobinemia
• argyria (from silver nitrate)
• hemochromatosis
• carboxyhemoglobin causes cherry red flush, not cyanosis

• peripheral cyanosis

• reduced cardiac output
• cold exposure
• redistribution of blood flow from extremities
• arterial obstruction
• venous obstruction

• anemia does not cause cyanosis

Pathology

• unsaturation of arterial hemoglobin
• high tissue extraction of oxygen
• decreased perfusion

Clinical-manifestations

• bluish discoloration of the skin & mucous membranes
• clubbing of fingers may be present in patients with pulmonary disease or congenital heart disease
• massage or warming of cyanotic extremity with resolve peripheral, but NOT central cyanosis

More General Terms

• sign/symptom

References

1. Mayo Internal Medicine Board Review, 1998-99, Prakash UBS (ed) Lippincott-Raven, Philadelphia, 1998, pg 720
2. Harrison's Principles of Internal Medicine, 13th ed. Isselbacher et al (eds), McGraw-Hill Inc. NY, 1994, pg 182
3. Harrison's Principles of Internal Medicine, 14th ed. Fauci et al (eds), McGraw-Hill Inc. NY, 1998, pg 209

cyanosis