Case presentation & viva-voice of a cyanosis patient
Definition: It is the bluish discolouration of skin and mucous membrane due to increased amount of deoxygenated haemoglobin in the blood. Cyanosis is not seen until the amount of deoxygenated haemoglobin is >5 gm%.
Types of cyanosis: It is of 2 types—
Due to localized reduction of blood flow on exposure to cold causing capillary vasoconstriction (lip is blue in cold weather). Also, occurs in reduced cardiac output (heart failure or shock). Tongue is spared in peripheral cyanosis. Causes are:
• Exposure to severe cold, frostbite.
• Raynaud’s phenomenon.
• Heart failure.
• Shock and peripheral circulatory failure.
• Deep vein thrombosis.
Either due to imperfect oxygenation of blood in lung or admixture of venous and arterial blood. It is evident when O2 saturation falls below 80 to 85%. Best site to see is tongue.
Respiratory: There is defect in oxygenation of blood in the lungs:
• Chronic obstructive pulmonary disease (COPD).
• Severe pneumonia.
• Tension pneumothorax.
• Massive lung collapse.
• Acute severe bronchial asthma.
• Massive pulmonary embolism.
• Pulmonary infarction.
• Diffuse parenchymal lung disease (DPLD).
• Adult respiratory distress syndrome.
• Respiratory failure due to any cause.
• Cyanotic congenital heart disease: Fallot’s tetralogy, transposition of great vessels.
• Shunt anomaly (reversal of shunt, right-to-left shunt called Eisenmenger syndrome), causes are:
atrial septal defect, ventricular septal defect, patent ductus arteriosus.
• Acute left ventricular failure.
• Cardiogenic shock.
• High altitude (physiological).
Q: What are the differences between central and peripheral cyanosis?
- Imperfect oxygenation
- Cyanosis generalized
- Tongue always involved
- Affected part warm
- Capillary vasoconstriction
- Cyanosis localized
- Tongue spare
- Affected part cold
Q: Why tongue is not involved in peripheral cyanosis?
A: Because tongue is always warm and circulation is good in tongue.
Q: Why there is no cyanosis in severe anaemia?
A: Because in severe anaemia, Hb is low and fully saturated, so there is no deoxygenated Hb (deoxygenated haemoglobin should be >5 gm% for cyanosis to be evident). In polycythaemia, cyanosismay occur even in mild hypoxia.
Q: What is enterogenous cyanosis? How to diagnose?
A: Discolouration of skin due to the presence of abnormal pigments in blood. It occurs in sulphaemoglobinaemia
or methaemoglobinaemia. There may be history of intake of some drugs (sulphonamide, phenacetin and dapsone). No dyspnoea in enterogenous cyanosis or no other respiratory symptoms. This can be diagnosed by spectroscopic examination of blood.