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CYANOSIS |
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central |
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R to L shunts: |
congenital heart disease pulmonary arteriovenous fistulas |
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COPD (usually with cor pulmonale; 'blue bloater')polycythaemia (high level of deoxyhaemoglobin despite normal pO2)severe pulmonary oedema massive pulmonary embolism severe acute asthma severe pneumonia shock from any cause diaphragmatic weakness severe acute pancreatitis any other cause of significant hypoxia |
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peripheral |
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physiological in cold weather peripheral vascular disease initially in Raynaud's phenomenon |
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methaemoglobinaemia (Fe3+ instead of Fe2+) |
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genetic: |
defect in NADH metabolism (autosomal recessive)defect in haemoglobin structure (Hgb M) |
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acquired: |
drugs / chemicals oxidising Fe 2+ to Fe3+: |
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aniline dyes chromates dapsone nitrites primaquine quinones |
chlorates nitrates (incl. GTN)phenacetin sulphasalazine and other sulphonamides |
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