Cyanosis is a blue discoloration of the skin and mucous membranes caused by low oxygen levels in the blood. There are two main types - peripheral cyanosis, caused by reduced blood flow and seen in the extremities, and central cyanosis, caused by issues with oxygenation in the lungs or mixing of arterial and venous blood with low oxygen saturation systemically. Peripheral cyanosis can be improved by warming the skin, while central cyanosis requires treatments like oxygen therapy, surgery for congenital heart defects, intravenous fluids, or diuretics to manage fluid accumulation. The document discusses the mechanisms, causes, signs, and treatments of both peripheral and central cyanosis in detail.

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:-
: asgeneralized circulatory deficiency-1
congestive heart failure
: as peripherallocalized circulatory deficiency-2
vascular spasm (e.g. Reynaud's disease

12. 3-asphyxia
In which there is both hypoxia and
hypercapina

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

14. 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.

15. 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%.

16. Differences between central and peripheral cyanosis
PeripheralCentralPoints
*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.
.1causes
LocalisedGeneralised.1cyanosis
ColdWarm. Affected part
DisappearsDoes not disappearApplication of
warm
Stagnation of the blood in
the peripheral circulation.
Blood pumped in the aorta contains more
than 5 gm% reduced Hb.
blood

17. Factors that affect cyanosis:
Capillary factors:-1
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.
Skin thickness:-2
Cyanosis is deeper in thin skin areas.
Skin pigmentation:-3
It alters whether physiological( e.g. in yellow races)
or pathological ( e.g. in jaundice). In dark races
cyanosis in the skin is masked

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

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

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

21. thanks