1. Presented by
Dr. S. M. Monir hossain
Intern doctor
Khulna Medical College Hospital

2. Definition
It is a clinical condition characterized
by bluish or purple discoloration of
skin and mucous membrane due to
increased amount of reduced or
deoxygenated hemoglobin (Hb) in
the blood.
• Cyanosis is not seen until the
amount of deoxygenated Hb is >5
g%

3. Types of cyanosis
1. Peripheral cyanosis
2. Central Cyanosis

4. Peripheral cyanosis
It occurs due to localised reduction of
blood flow on exposure to
cold, causing capillary
vasoconstriction. Also occurs in
reduced cardiac output i.e. Heart
failure or Shock. Peripheral cyanosis
is also seen in peripheral vascular
disease like Raynaud’s disease.
Tongue is spared in peripheral
cyanosis.

5. Central cyanosis
This is 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%.
Central cyanosis is best evident in tongue.
Tongue is not involved because tongue is
always warm and circulation is good in
tongue.

6. Mechanism of
cyanosis

7. Mechanism of cyanosis

8. Mechanism of cyanosis

9. Where to look for cyanosis

10. Causes of Central Cyanosis
• In newborn:
Birth asphyxia
Intracranial hypertension, hemorrhage
Oversedation (direct or through maternal
route)
Seizures
Respiratory distress syndrome
Meconium aspiration
Pneumonia (sepsis)
Pneumothorax
Congenital diaphragmatic hernia
Pulmonary hypoplasia

11. Causes of Central Cyanosis
• Defect in oxygenation of blood in lungs.
Fibrosing alveolitis
Severe pneumonia
COPD
Severe acute bronchial asthma
Pulmonary infarction
• Shunt anomaly in heart (right to left)
Transposition of great vessels
Total anomalous pulmonary venous return
Truncus arteriosus
Tetralogy of Fallot
Ebstein malformation of the tricuspid valve
Tricuspid atresia

12. Causes of Central Cyanosis
• Heart failure/Cardiogenic Shock
• Polycythemia
• Methemoglobinemia
• High altitude (physiological)

13. Differences between central and peripheral cyanosis
Points Central Peripheral
1. Cyanosis Generalised Localised
2. Affected part Warm Cold
3. Application of
warm
Does not disappear Disappears
4. Oxygen Cyanosis may disappear in pulmonary case (Except
in right to left shunt)
Disappears
5. Tongue Always involved Never involved

14. There is no cyanosis in Severe anemia
because Hb is low and fully saturated,
leaving no excess deoxygenated Hb.
Similarly in Polycythemia cyanosis may
occur even in mild hypoxia.

15. • When cyanosis is present only in the
toes but not in the fingers, it is called
Differential cyanosis. It is seen in
PDA. In newborns, it can also occur in
pre-ductal coarctation of aorta along
with PDA.