1. Presented byDr. S. M. Monir hossainIntern doctorKhulna Medical College Hospital

2. DefinitionIt is a clinical condition characterizedby bluish or purple discoloration ofskin and mucous membrane due toincreased amount of reduced ordeoxygenated hemoglobin (Hb) inthe blood. Cyanosis is not seen until theamount of deoxygenated Hb is >5g% 3. Types of cyanosis1. Peripheral cyanosis2. Central Cyanosis 4. Peripheral cyanosisIt occurs due to localised reduction ofblood flow on exposure tocold, causing capillaryvasoconstriction. Also occurs inreduced cardiac output i.e. Heartfailure or Shock. Peripheral cyanosisis also seen in peripheral vasculardisease like Raynauds disease.Tongue is spared in peripheralcyanosis. 5. Central cyanosisThis is either due to imperfect oxygenationof blood in lung or admixture of venousand arterial blood. It is evident when O2saturation falls below 80% to 85%.Central cyanosis is best evident in tongue.Tongue is not involved because tongue isalways warm and circulation is good intongue. 6. Mechanism ofcyanosis 7. Mechanism of cyanosis 8. Mechanism of cyanosis 9. Where to look for cyanosis 10. Causes of Central Cyanosis In newborn:Birth asphyxiaIntracranial hypertension, hemorrhageOversedation (direct or through maternalroute)SeizuresRespiratory distress syndromeMeconium aspirationPneumonia (sepsis)PneumothoraxCongenital diaphragmatic herniaPulmonary hypoplasia 11. Causes of Central Cyanosis Defect in oxygenation of blood in lungs.Fibrosing alveolitisSevere pneumoniaCOPDSevere acute bronchial asthmaPulmonary infarction Shunt anomaly in heart (right to left)Transposition of great vesselsTotal anomalous pulmonary venous returnTruncus arteriosusTetralogy of FallotEbstein malformation of the tricuspid valveTricuspid atresia 12. Causes of Central Cyanosis Heart failure/Cardiogenic Shock Polycythemia Methemoglobinemia High altitude (physiological) 13. Differences between central and peripheral cyanosisPoints Central Peripheral1. Cyanosis Generalised Localised2. Affected part Warm Cold3. Application ofwarmDoes not disappear Disappears4. Oxygen Cyanosis may disappear in pulmonary case (Exceptin right to left shunt)Disappears5. Tongue Always involved Never involved 14. There is no cyanosis in Severe anemiabecause Hb is low and fully saturated,leaving no excess deoxygenated Hb.Similarly in Polycythemia cyanosis mayoccur even in mild hypoxia. 15. When cyanosis is present only in thetoes but not in the fingers, it is calledDifferential cyanosis. It is seen inPDA. In newborns, it can also occur inpre-ductal coarctation of aorta alongwith PDA.