Cyanosis
OVERVIEW
- Cyanosis is a bluish hue that occurs in the presence of ~60 g/L deoxyhaemoglobin or dyshemoglobinaemia
- the differentials include treatment with methylene blue and new clothes that leach blue ink…
CENTRAL VERSUS PERPIHERAL CYANOSIS
- perpiheral causes will not of signs of central cyanosis
- central cyanosis is suggested clinically by bluish discolouration of the tongue and mucous membranes, rather than just the peripheries (e.g. fingers and nail beds)
CENTRAL CAUSES
- decreased arterial oxygen saturation
-> decreased FiO2 (altitude)
-> lung disease (COPD)
-> V/Q mismatch (PE)
-> right to left shunt (cyanotic congenital heart disease) - polycythaemia
- haemoglobin abnormalities (methaemoglobinaemia, sulphaemoglobinaemia)
PERIPHERAL CAUSES
- all causes of central cyanosis cause peripheral cyanosis
- exposure to cold
- reduced cardiac output (cardiogenic shock, LVF)
- arterial or venous obstruction
CAUSES OF CYANOTIC CONGENITAL HEART DISEASE
5 Ts
- Tetralogy of Fallot (TOF)
- Transposition of the Great Arteries (TGA) — PA and aorta are reversed
- Truncus Arteriosus — both RV and LV flow into one artery
- Tricuspid Atresia — leads to shunt through patent PFO, RV is non-functional)
- Total Anomalous Pulmonary Venous Connection (TAPVC) — APO results from obstructed pulmonary venous drainage, PGE1 doesn’t work for this
Other
- Pulmonary atresia (absent connection between RV and PA) is also a rare cause of cyanotic congenital heart disease)
- Eisenmenger syndrome (an acyanotic lesion causing left-to-right shunt can lead to pulmonary hypertension if untreated, the raised PA pressures ultimately cause shunt reversal and cyanosis)
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Critical Care
Compendium
Chris is an Intensivist and ECMO specialist at the Alfred ICU in Melbourne. He is also a Clinical Adjunct Associate Professor at Monash University. He is a co-founder of the Australia and New Zealand Clinician Educator Network (ANZCEN) and is the Lead for the ANZCEN Clinician Educator Incubator programme. He is on the Board of Directors for the Intensive Care Foundation and is a First Part Examiner for the College of Intensive Care Medicine. He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives.
After finishing his medical degree at the University of Auckland, he continued post-graduate training in New Zealand as well as Australia’s Northern Territory, Perth and Melbourne. He has completed fellowship training in both intensive care medicine and emergency medicine, as well as post-graduate training in biochemistry, clinical toxicology, clinical epidemiology, and health professional education.
He is actively involved in in using translational simulation to improve patient care and the design of processes and systems at Alfred Health. He coordinates the Alfred ICU’s education and simulation programmes and runs the unit’s education website, INTENSIVE. He created the ‘Critically Ill Airway’ course and teaches on numerous courses around the world. He is one of the founders of the FOAM movement (Free Open-Access Medical education) and is co-creator of litfl.com, the RAGE podcast, the Resuscitology course, and the SMACC conference.
His one great achievement is being the father of three amazing children.
On Twitter, he is @precordialthump.
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