Cyanosis

Cyanosis is a medical term that describes a bluish or purplish discoloration of the skin, nails, and mucous membranes. This color appears when the blood circulating near the surface of the skin does not carry enough oxygen.

Depending on how it manifests, there are two main types of cyanosis:

• Central cyanosis: affects the entire body because the blood leaves the heart with a low oxygen content. It is clearly visible in areas with greater blood flow, such as the lips, tongue, oral mucosa, trunk, and extremities.
• Peripheral cyanosis: blood oxygenation is normal when it leaves the heart, but blood flow slows in the extremities, causing tissues to require a greater amount of oxygen. The bluish discoloration is mainly seen in the hands, feet, ears, and the tip of the nose. It is referred to as distal cyanosis when it affects areas furthest from the trunk, such as the hands and feet.

Cyanosis is a clear sign of an underlying disease that prevents proper oxygenation. The prognosis varies depending on the underlying condition. Identifying the specific cause is essential in order to apply appropriate treatment in a timely manner. Cyanosis in babies is a medical emergency that should be treated as soon as possible.

Symptoms

The characteristic symptom of cyanosis is the bluish or purplish discoloration of the skin and mucous membranes. In addition, patients may present other signs related to the underlying disease, including:

• Central cyanosis: primarily visible on the face (facial cyanosis), the tongue (lingual cyanosis), the lips, around the mouth (perioral cyanosis), and the trunk.
  • Warm skin on palpation.
  • Weakness.
  • Fatigue.
  • Dyspnea: difficulty breathing.
  • Tachypnea: rapid breathing.
  • Chest pain.
  • Confusion.
  • In chronic cases, digital clubbing: deformity of the fingertips.
• Peripheral cyanosis: usually observed in the hands, feet, and nails (nail cyanosis).
  • Pallor before the bluish color develops.
  • Cold skin on palpation.
  • Purple-colored nails.
  • Symptoms generally improve with warmth.
  • Numbness or paresthesia: a sensation of "pins and needles" or tingling.

Infants may experience difficulty breathing or feeding when cyanosis is caused by a serious disease.

Causes

Cyanosis occurs when hemoglobin in venous blood loses oxygen and may be caused by a variety of disorders:

• Central cyanosis:
  • High altitude: lower oxygen pressure may cause inadequate oxygenation.
  • Pulmonary embolism: blood clots in the pulmonary arteries.
  • Bronchitis: infection and inflammation of the bronchi (airways connecting the trachea to the lungs).
  • Pneumonia: infection causing inflammation of the alveoli (air sacs where oxygen and carbon dioxide exchange occurs), which may fill with fluid or pus.
  • Chronic obstructive pulmonary disease (COPD): alveolar damage and bronchial inflammation that obstructs airflow in the lungs.
  • Asthma: inflammation and narrowing of the airways.
  • Interstitial lung disease: fibrosis of the tissue surrounding the alveoli.
  • Drowning: respiratory impairment caused by submersion.
  • Choking: upper airway obstruction caused by a foreign body.
  • Epiglottitis: inflammation of the epiglottis, the cartilage that covers the trachea.
  • Cardiac abnormalities, usually congenital:
    • Tetralogy of Fallot: pulmonary stenosis, ventricular septal defect, overriding aorta, and right ventricular hypertrophy occurring simultaneously.
    • Eisenmenger syndrome: pulmonary hypertension and reversal of cardiac blood flow.
    • Transposition of the great arteries: the aorta arises from the right ventricle and the pulmonary artery from the left ventricle.
  • Myocardial infarction: interruption of blood supply to part of the heart muscle due to blockage of a coronary artery.
  • Cardiomyopathies: disorders of the heart muscle that impair its ability to pump blood.
  • Heart failure: the heart cannot pump enough blood to meet the body's needs.
  • Acute decompensated heart failure: sudden loss of the heart's pumping ability, causing fluid accumulation in the lungs and throughout the body.
  • Mitral stenosis: narrowing of the mitral valve opening.
  • Aortic stenosis: narrowing of the aortic valve that impairs blood flow to the rest of the body.
  • Severe cardiac arrhythmia: abnormally rapid heart rhythm.
  • Cardiac arrest.
  • Drug overdose.
  • Poisoning.
  • In infants:
    • Congenital heart diseaseHeart DiseaseHeart Disease : defects or malformations that alter normal blood flow and are present at birth.
    • Bronchiolitis: infection and obstruction of the bronchioles, the small branches of the bronchi.
    • Hypoventilation: shallow or excessively slow breathing.
    • Methemoglobinemia: a blood disorder characterized by abnormally high levels of methemoglobin, a form of hemoglobin that does not effectively release oxygen to the tissues.
• Peripheral cyanosis:
  • Cold exposure.
  • Arterial obstruction: blockage of an artery supplying an extremity.
  • Venous insufficiency: disorders that impair venous return to the heart.
  • Raynaud's phenomenon: excessive temporary constriction of the small blood vessels in the fingers.
  • Shock: a drop in blood pressure causing inadequate organ perfusion.
  • In infants: immaturity of the circulatory system.
• Acrocyanosis: a benign form of cyanosis that causes persistent bluish discoloration of the hands and feet due to vasoconstriction when the body is exposed to cold.

Risk Factors

The risk of cyanosis increases in the following situations:

• Smoking.
• Infections that may affect the respiratory system.
• Airway obstruction.
• Pulmonary fibrosis: scarring and thickening of lung tissue.
• Pneumothorax: presence of air between the lungs and the chest wall.
• Neuromuscular disorders that restrict respiratory capacity:
  • Amyotrophic lateral sclerosis (ALS): destruction of motor neurons prevents the brain from controlling voluntary muscles, including the respiratory muscles.
  • Myasthenia gravis: chronic autoimmune disease causing muscle weakness because the immune system mistakenly blocks chemical signaling between nerves and muscles.
  • Traumatic brain injury.
• Hypothermia: body temperature falls below 35°C.
• Peripheral arterial disease (PAD): narrowing of blood vessels outside the heart.
  • Arteriosclerosis: buildup of fatty plaques within the arteries.
  • Buerger disease (thromboangiitis obliterans): inflammatory disease that blocks small- and medium-sized blood vessels in the hands and feet.
• Polycythemia vera: a type of cancer in which the bone marrow produces excessive red blood cells, causing the blood to thicken and impair flow.
• Qualitative hemoglobinopathies: genetic mutations that produce abnormal hemoglobin molecules.
• High altitude: living in areas with low oxygen pressure.

Complications

Complications of cyanosis depend on the underlying disease. The most common are:

• Chronic hypoxia: tissues receive less oxygen than required. To compensate, the body increases red blood cell production, causing blood thickening.
• Organ damage: oxygen deprivation may impair the function of the brain, heart, and other vital organs.
• Neurological damage: when blood oxygen levels drop abruptly, seizures, loss of consciousness, or stroke may occur.
• In severe cases or when treatment is delayed, death.

Which specialist treats cyanosis?

Cyanosis is treated within the specialties of Cardiology, Pulmonology, Pediatrics and Emergency department.