cyanosis

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Cyanosis this, like any word with the prefix cyan, derives from the Greek for dark blue. It refers to a blue tinge seen on the surface of the whole or part of the body, due to lack of oxygen in the blood. The apparent colour of the skin depends on the state of oxygenation of the blood in the microscopic vessels below the surface. Blood in the arteries is normally bright red, the colour of red blood cells when the haemoglobin they contain is carrying its full quota of oxygen. In conditions of hypoxia due to altitude, lung disease, heart defects, or heart failure, the blood leaves the lungs without being fully oxygenated, and the arterial blood is less red. The degree of desaturation of haemoglobin at which such ‘central cyanosis’ is detectable varies between observers as well as between patients. Detection also depends on the superficial blood vessels being well-filled; if they are largely ‘shut down’ the skin is simply pale whatever the colour of the blood. Undoubtedly, however, if blueness is evident, there is significant hypoxia.

When arterial oxygen saturation is normal, the extent to which the blood becomes desaturated as it flows through the skin depends on the rate of blood flow. If blood flow is sluggish, a larger fraction of the oxygen is removed than if it is florid. Thus when cheeks are flushed, increased blood flow brings bright red blood near the surface; the oxygen supply is far in excess of need, with very little being removed. But when hands and feet are cold, the reflex constriction of blood vessels — to conserve heat as part of body temperature regulation — reduces the flow, so a higher proportion of the oxygen is removed to supply the skin tissue, and the blood becomes bluer before it moves on. Hence we can become ‘blue with cold’ — but only superficially. The arterial blood itself remains bright red, if everything else is normal. For similar reasons of diminished blood flow, cyanosis is seen locally in a part of the body — say a leg or a big toe — when the circulation in that part is compromised by arterial disease.

— Sheila Jennett

See also breathing; haemoglobin; hypoxia; lungs; oxygen.

Bluish discoloration of the skin and mucous membranes caused by lack of oxygen.

A bluish discoloration of the skin and mucous membranes due to excessive concentration of reduced hemoglobin in the blood. Used wrongly by clinicians describing skin lesions in pigs where there is severe congestion of cutaneous vessels and some leakage of blood into perivascular tissues.

• central c. — that due to arterial unsaturation, the aortic blood carrying reduced hemoglobin.
• enterogenous c. — a syndrome due to absorption of nitrites and sulfides from the intestine, principally marked by methemoglobinemia and/or sulfhemoglobinemia associated with cyanosis.
• peripheral c. — that due to an excessive amount of reduced hemoglobin in the venous blood as a result of extensive oxygen extraction at the capillary level.

A characteristic bluish tinge or color of the skin and mucous membranes associated with reduction in hemoglobin brought about by inadequate respiratory change (5 gm/100 ml are necessary for color to be perceptible).

• Signs and Symptoms - cyanosis: bluish discoloration of skin and mucous membrane due to inadequate oxygenation of blood

"Cyanotic" redirects here. For the band, see Cyanotic (band).

Cyanosis

Cyanosis of the hand in someone with low oxygen saturations
ICD-10	R23.0
ICD-9	782.5
eMedicine	med/3002

Cyanosis is the appearance of a blue or purple coloration of the skin or mucous membranes due to the tissues near the skin surface being low on oxygen. The onset of cyanosis is 2.5 g/dL of deoxyhemoglobin.^[1] The bluish color is more readily apparent in those with high hemoglobin counts than it is with those with anemia. Also the bluer color is more difficult to detect on deeply pigmented skin. When signs of cyanosis first appear, such as on the lips or fingers, intervention should be made within 3–5 minutes because a severe hypoxia or severe circulatory failure has induced the cyanosis.

The name cyanosis, literally means "the blue disease" or "the blue condition". It is derived from the color cyan, which comes from kyanos, the Greek word for blue.^[2]

Human blood is always a shade of red,^[3] and the more oxygenated the blood the brighter the shade of red. The more deoxygenated the blood, the darker red it is within the blood vessels, and the more bluish it appears on the skin. This color shift occurs because the optical properties of skin shift the darker red colors towards the bluer.^[4]

Contents 1 Definition 2 Differential diagnosis 2.1 Central cyanosis 2.1.1 Causes 2.2 Peripheral cyanosis 2.2.1 Causes 2.3 Differential cyanosis 3 See also 4 References 5 External links

Definition

A baby with a heart condition. Note purple nailbeds.

Acute arterial thrombosis of the right leg

Cyanosis is defined as a bluish discoloration, especially of the skin and mucous membranes due to excessive concentration of deoxyhemoglobin in the blood.

Differential diagnosis

Cyanosis is divided in to two main types: central (around the core and lips) and peripheral (only the extremities are affected). Cyanosis can occur in the fingers, including underneath the fingernails, as well as other extremities (called peripheral cyanosis), or in the lips and tongue (central cyanosis).

Central cyanosis

Central cyanosis is often due to a circulatory or ventilatory problem that leads to poor blood oxygenation in the lungs. It develops when arterial saturation of blood with oxygen is ≤85%. Cyanosis may not be detected until saturation is 75% in dark-skinned individuals.

Acute cyanosis can be a result of asphyxiation or choking, and is one of the surest signs that respiration is being blocked.

Causes

1. Central Nervous System:

• Intracranial hemorrhage
• Cerebral anoxia
• Drug overdose (e.g. Heroin)

2. Respiratory System:

• Bronchiolitis
• Bronchospasm (e.g. Asthma)
• Lung disease
• Pulmonary Hypertension
• Pulmonary embolism
• Hypoventilation
• COPD (emphysema and chronic bronchitis)
• Respiratory syncytial virus

3. Cardiac Disorders:

• Congenital heart disease (e.g. Tetralogy of Fallot, Right to left shunts in heart or great vessels)
• Heart failure
• Heart valve disease
• Myocardial infarction

4. Blood:

• Methemoglobinemia
• Polycythaemia

5. Others:

• High altitude
• Hypothermia
• Congenital cyanosis (HbM Boston) arises from a mutation in the α-codon which results in a change of primary sequence, H → Y. Tyrosine stabilises the Fe(III) form (oxyhaemoglobin) creating a permanent T-state of Hb.
• Obstructive sleep apnea

Peripheral cyanosis

Peripheral cyanosis is the blue tint in fingers or extremities, due to inadequate circulation. The blood reaching the extremities is not oxygen rich and when viewed through the skin a combination of factors can lead to the appearance of a blue color. All factors contributing to central cyanosis can also cause peripheral symptoms to appear, however peripheral cyanosis can be observed without there being heart or lung failures. Small blood vessels may be restricted and can be treated by increasing the normal oxygenation level of the blood.

Causes

• All common causes of central cyanosis
• Arterial obstruction
• Cold exposure (due to vasoconstriction)
• Raynaud's phenomenon (vasoconstriction)
• Reduced cardiac output (e.g. heart failure, hypovolaemia)
• Vasoconstriction
• Venous obstruction (e.g. deep vein thrombosis)

Differential cyanosis

Differential cyanosis is the bluish coloration of the lower but not the upper extremity and the head. This is seen in patients with a patent ductus arteriosus. Patients with a large ductus develop progressive pulmonary vascular disease, and pressure overload of the right ventricle occurs. As soon as pulmonary pressure exceeds aortic pressure, shunt reversal (right-to-left shunt) occurs. The upper extremity remains pink because the brachiocephalic trunk, left common cartoid trunk and the left subclavian trunk is given off proximal to the PDA.

See also

• Blue baby syndrome
• Raynaud's phenomenon
• Blue Fugates

References

1. ^ Mini Oxford Handbook of Clinical Medicine (7th ed.). p. 56. 
2. ^ Mosby’s Medical, Nursing and Allied Health Dictionary. Mosby-Year Book (4th ed.). 1994. p. 425. 
3. ^ Except in rare cases of hemoglobin-related disease.
4. ^ Kienle, Alwin; Lothar Lilge, I. Alex Vitkin, Michael S. Patterson, Brian C. Wilson, Raimund Hibst, and Rudolf Steiner (March 1, 1996). "Why do veins appear blue? A new look at an old question" (PDF). Applied Optics 35 (7): 1151–60. doi:10.1364/AO.35.001151. PMID 21085227. http://www.imt.liu.se/edu/courses/TBMT36/pdf/blue.pdf. 

External links

• Cyanosis definition, types, causes, and general details

v d e Symptoms and signs: skin and subcutaneous tissue (R20–R23, 782) Disturbances of skin sensation/ somatosensory disorder Hypoesthesia · Paresthesia (Formication) · Hyperesthesia Hypoalgesia · Hyperalgesia Circulation Cyanosis · Pallor/Livedo (Livedo reticularis) · Flushing · Petechia Edema Peripheral edema · Anasarca Other Rash · Desquamation · Induration · Diaphoresis · Mass (Neck mass) M: INT, SF, LCT anat/phys/devp noco(i/b/d/q/u/r/p/m/k/v/f)/cong/tumr(n/e/d), sysi/epon proc, drug (D2/3/4/5/8/11) M: SKA anat/phys/devp noco/cong/tumr, sysi/epon proc, drug(D10)

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Dansk (Danish)
n. - cyanose, blåsyge

Nederlands (Dutch)
blauwzucht

Français (French)
n. - cyanose

Deutsch (German)
n. - (Med.) Cyanose (bläuliche Verfärbung der Haut)

Ελληνική (Greek)
n. - (παθολ.) κυάνωση

Italiano (Italian)
cianosi

Português (Portuguese)
n. - cianose (m) (Med.)

Русский (Russian)
цианоз

Español (Spanish)
n. - cianosis

Svenska (Swedish)
n. - cyanos

中文（简体）(Chinese (Simplified))
苍白病, 黄萎病

中文（繁體）(Chinese (Traditional))
n. - 蒼白病, 黃萎病

한국어 (Korean)
n. - 청색증, 치아노오제

日本語 (Japanese)
n. - 紫藍症, チアノーゼ

العربيه (Arabic)
‏(الاسم) تزرق لون الجلد بسبب نقص الأوكسجين‏

עברית (Hebrew)
n. - ‮כיחלון, צבע עור כחול‬

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