Pediatric emergency medicine trisk 0508 0508
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FIGURE 21.1 Evaluation of cyanosis. EKG, electrocardiogram; CNS, central nervous system.
Location of cyanosis helps determine its cause. Cyanosis may be either central
or peripheral in location. Central cyanosis is noted in the mucous membranes,
tongue, trunk, and upper extremities. It is most often the result of decreased PaO2
but can also result from severe methemoglobinemia or polycythemia. If the
cyanosis is peripheral only (hands, feet, lips), moderate cold exposure, newborn
acrocyanosis (
e-Figs. 21.1 and 21.2 ), shock states, or mild
methemoglobinemia may be the cause. Local blue discoloration of a single
extremity corresponds to compromise of distal circulation or autonomic tone as
seen in traumatic vascular lesions or complex regional pain syndrome. Cyanosis
and swelling of just the head may be seen with superior vena cava syndrome. In
addition, a local blue hue to the skin may also be a result of simple phenomena
such as pigmentary lesions or blue clothing dye. If blue coloring appears on an
alcohol swab wiped across the discolored area of skin, dye is responsible ( eFig. 21.3 ). Differential cyanosis of the lower body versus the upper body may
indicate high pulmonary vascular resistance with right-to-left shunting via the
ductus arteriosus. Transposition of the great arteries with pulmonary-to-aortic
