Cyanosis

1. بسم الله الرحمن الرحيم

2. Cyanosis mechanism and how to overcome

3. *Definition* Cyanosis is a blue discoloration of the skin and mucous membranes Due to: The presence of an abnormally great amount of reduced Hb in the superficial capillaries

4. Threshold of cyanosis It is the minimal concentration of reduced Hb In the capillary blood that leads to appearance of cyanosis . -It’s about 5gm% capillary blood Threshold cyanosis = 0.5 (reduced Hb in arterial blood + reduced Hb in venous blood ).

5. Cyanosis does not occur in:- 1-anemic hypoxia:- due to decrease hemoglobin content. 2-histotoxic hypoxia:- as smaller amount of reduced hemoglobin present in venous blood 3-co poisoning:- because of cherry red color of carboxy Hb

6. Cyanosis can be seen in: In Fingers Ear lobes Nails In lips

7. causes of cyanosis 1-hypoxic hypoxia 2-Stagnant hypoxia 3 -Asphxia

8. Mechanisms of cyanosis 1-Hypoxic hypoxia - Rate of diffusion of O2 to tissues is decreased . -O2 tension and O2 content decrease in arterial and venous blood

9. causes 1-Low O2 in inspired air : a)Breathing air with low O2 content at sea level(e.g. respiration of inert gases) b)High altitudes (lower total atmospheric pressure &then O2 tension) 2-hypoventilation a)Obstruction of air passages b)Emphysema c)Depression of respiratory center 3-alveo-capillary block : increase of the thickness of the alveo -capillary membrane leads to decrease of diffusion of gases through membrane 4-short circuit between right and left side of the heart a)Patent ductus arteriosus b) Interatrial or interventriclar septal defect

10. 2-stagnant hypoxia -it results from deficiency of blood flow through tissues -O2 tension & O2 content in arterial blood is normal -O2 tension & O2 content in venous blood decrease Causes and types:- 1 - generalized circulatory deficiency : as congestive heart failure 2- localized circulatory deficiency : as peripheral vascular spasm (e.g. Reynaud's disease

11. 3-asphyxia In which there is both hypoxia and hypercapina

12. * Types of Cyanosis* 1- peripheral 2-central Normal arterial blood saturation) (Low arterial blood saturation

13. Peripheral cyanosis It occurs due to localized 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 Reynaud's disease.

14. Central cyanosis This is either due to imperfect oxygenation of blood in lung or admixture of venous and arterial blood. It is evident when O 2 saturation falls below 80% to 85%.

15. Differences between central and peripheral cyanosis Peripheral Central Points *Arterial and venous diseases: Reynaud disease and thrombosis. *Polycythemia. *cold exposure. *congestive heart failure. Cardiac diseases e.g.: congestive heart failure and septal defect. *Diseases that interfere with ventilation or gas exchange in lung. causes Localised Generalised cyanosis Cold Warm . Affected part Disappears Does not disappear Application of warm Stagnation of the blood in the peripheral circulation. Blood pumped in the aorta contains more than 5 gm% reduced Hb. blood

16. Factors that affect cyanosis: 1-Capillary factors: Factors that increase the number of open capillaries or increase the diameters e.g. (heat – CO2 – acid metabolites) increase the depth of central cyanosis but improve peripheral cyanosis. 2-Skin thickness: Cyanosis is deeper in thin skin areas. 3-Skin pigmentation: It alters whether physiological( e.g. in yellow races) or pathological ( e.g. in jaundice). In dark races cyanosis in the skin is masked

17. 4-Blood composition : The presence of abnormally great amount of Met-Hb produces a cyanotic like colour . Other abnormalities in the blood composition also alter the depth of cyanosis (e.g. leukemia and lipaemia ) 5-The amount of reduced Hb and oxyHb : Cyanosis becomes deeper if the amount of reduced Hb is increased or the amount of oxyHb is decreased .

18. Overcoming cyanosis 1-Warming of the affected area: Peripheral cyanosis brought about by exposure to cold or by gentle warming of fingers and toes . 2-Oxygenation as a treatment for cyanosis: Initial stabilization requires . 3-Surgery as a treatment : Treatment of central cyanosis due to congenital heart disease.

19. 4-Intravenous fluids: Children who have difficulty in feeding due to cyanosis need fluids to be administrated. 5-Drugs as a treatment for cyanosis: Drugs are prescribed to reduce the excess accumulation of fluids such as Diuretics

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