Pediatric emergency medicine trisk 0507 0507
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presence of methemoglobin beneath the skin (see Chapter 93 Hematologic
Emergencies ).
Other conditions leading to a blue appearance of the skin may be confused with
cyanosis. A rare but perplexing presentation is that of the well-appearing child
with unusually localized cyanosis, which can be related to blue dye of clothing.
Slate blue discoloration of the face, neck, and arms has been noted in patients on
chronic amiodarone therapy. Certain pigmentary lesions such as Mongolian spots
(also known as slate gray nevi) can be confused with cyanosis, especially when
uncharacteristically large or in unusual locations. Adolescents will occasionally
tattoo areas of the body that may be misinterpreted as local cyanosis.
EVALUATION AND DECISION
A careful yet rapid history and physical examination are critical in the care of the
cyanotic patient because timely correction may be lifesaving. Many historical
features can help narrow the differential diagnosis and lead to prompt evaluation
and treatment. The onset and pattern, location, quality, temporal nature, and
presence of palliative or provocative features should be explored. Age of the
patient with respect to onset of cyanosis, whether at birth, shortly after birth, or
acquired later, is critical. In newborns, congenital cardiac and respiratory diseases
are the most common causes of cyanosis. Special attention must also be paid to
known pre-existing heart or lung disease that may predispose to the acute onset of
cyanosis. History of exposure to environmental conditions or toxins, such as cold,
trauma, smoke inhalation, confinement to an airtight space, drugs, or chemicals,
is crucial. Known patient or family history of methemoglobinemia may lead
directly to the cause of cyanosis. A history of sudden pain or fear with crying or
seizure occurrence should be sought.
The physical examination must include a complete general examination, with
special attention paid to the vital signs, oxygen saturation, and cardiovascular and
pulmonary systems. A key physical examination feature is the presence or
absence of respiratory distress. In general, children with respiratory distress are
likely to have respiratory dysfunction, and careful examination of the airway,
breathing, and circulation should be rapidly initiated. A temperature should be
obtained. Presence of cough, “sniffing position,” stridor, retractions, or fever
should be determined. Lung examination may reveal adventitious (e.g., wheezing
or rales) or diminished breath sounds. Presence of a cardiac murmur often
suggests cardiac disease. Careful attention to the peripheral circulation, including
pulses and capillary refill is also helpful. A rapid neurologic examination should
be performed.
