Cyanosis 379828 224232547 2008-07-07T22:30:05Z 96.246.91.38 {{SignSymptom infobox | Name = Cyanosis | Image = Cyanosis.jpg | ICD10 = {{ICD10|R|23|0|r|20}} | ICD9 = {{ICD9|782.5}} }} '''Cyanosis''' is a blue coloration of the [[skin]] and mucous membranes due to the presence of deoxygenated [[hemoglobin]] in [[blood vessel]]s near the skin surface. It occurs when the [[oxygen saturation]] of arterial blood falls below 85-90% (1.5g/dl deoxyhemoglobin). Although human blood is always a shade of red (except in rare cases of hemoglobin-related disease), the optical properties of skin distort the dark red color of deoxygenated blood to make it appear bluish<ref>{{cite journal |last=Kienle|first=Alwin|authorlink= |coauthors=Lothar Lilge, I. Alex Vitkin, Michael S. Patterson, Brian C. Wilson, Raimund Hibst, and Rudolf Steiner |date= [[March 1]] [[1996]]|title=Why do veins appear blue? A new look at an old question|journal=Applied Optics |volume=35 |issue=7 |pages=1151–60 |id= |url=http://www.imt.liu.se/edu/courses/TBMT36/pdf/blue.pdf}}</ref>. The elementary principle behind cyanosis is that deoxygenated hemoglobin is more prone to the optical bluish discoloration, and also produces vasoconstriction that makes it more evident. The scattering of color that produces the blue hue of veins and cyanosis is similar to the process that makes the sky and large bodies of water appear blue: some colors are refracted and absorbed more than others. During cyanosis, tissues are uncharacteristically low on oxygen, and therefore tissues that would normally be filled with bright oxygenated blood are instead filled with darker, deoxygenated blood. Darker blood is much more prone to the blue-shifting optical effects<ref>1</ref>, and thus oxygen deficiency - [[Hypoxia (medical)|hypoxia]] - leads to blue discoloration of the lips and other [[mucous membranes]]. The name is derived from the color [[cyan]], the Greek word for blue. ==Types== Cyanosis can occur in the [[finger]]s, including underneath the [[nail (anatomy)|fingernails]], as well as other extremities (called ''peripheral cyanosis''), or in the [[lip]]s and tongue (''central cyanosis''). === Central cyanosis === Central cyanosis is often due to a circulatory or ventilatory problem that leads to poorer blood [[oxygenation]] in the lungs or greater oxygen extraction due to slowing down of blood circulation in the skin's blood vessels. Acute cyanosis can be a result of asphyxiation or choking, and is one of the surest signs that respiration is being blocked. ==== Common causes of central cyanosis ==== * Abnormal [[hemoglobin]] levels * [[Bronchospasm]] * [[Congenital heart disease]] * [[Heart failure]] * [[Heart valve]] disease * High [[altitude]] * [[Hypothermia]] * [[Hypoventilation]] * [[Lung disease]] * [[Myocardial infarction]] * [[Polycythaemia]] * [[Pulmonary embolism]] * [[Chronic obstructive pulmonary disease|COPD (Emphysema and Chronic Bronchitis)]] * [[Asthma]] * [[Methemoglobinemia]] * [[Tetralogy of Fallot]] * [[Right to left shunts in heart or great vessels]] === 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 [[Blood#Color|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. ==== Common causes of peripheral cyanosis==== * All common causes of central cyanosis (see above) * [[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]]) ==References== {{reflist}} ==See also== * [[Blue baby syndrome]] * [[Raynaud's phenomenon]] ==External links== * [http://www.emedicine.com/med/topic3002.htm eMedicine] * [http://skin-care.health-cares.net/cyanosis.php Health-cares.net] * [http://www.tmc.edu/thi/cyanosis.html Texas Heart Institute] {{Skin and subcutaneous tissue symptoms and signs}} [[Category:Medical signs]] [[cs:Cyanóza]] [[de:Zyanose]] [[fa:کبودی پوست]] [[fr:Cyanose]] [[it:Cianosi]] [[nl:Cyanose]] [[ja:チアノーゼ]] [[no:Cyanose]] [[nn:Cyanose]] [[pl:Sinica]] [[pt:Cianose]] [[sk:Cyanóza]] [[sl:Cianoza]] [[sv:Cyanos]] [[uk:Ціаноз]] [[zh:發紺]]