Cyanosis
Cyanosis is the blue-purple discoloration of the skin and mucous membranes caused by elevated blood concentration of deoxygenated hemoglobin, of at least 4 g/dL.
Central cyanosis results from desaturated blood flowing from the aorta. The vermillion of the lips (the area lipstick goes) is a fairly good approximation, but the inside of the mouth or eyelids are the best. In children, cyanosis around the mouth can be a normal response.
Peripheral cyanosis results from peripheral vasoconstriction (occurring in the arterioles).
This corresonds to an arterial O2 saturation of 85% or less in someone with normal oxygen levels.
If someone is anemic, someone will need to have a much lower oxygen saturation.
(In children at least,) cyanosis does not necessarily lead to.
Do not trust your eyes for oxygen saturation, especially in babies.
check sats on babies with murmurs!
Hypercyanotic (Tet) spells
Differential cyanosis
lower cyanosis - occurs with coarctation of the aorta and a patent ductus arteriosus. Differential upper cyanosis can occur with coarctation and transposition of the great vessels.