Pediatric emergency medicine trisk 127

is congenital heart disease. Although most newborns with cyanotic congenital
heart disease are recognized in utero or while in the newborn nursery, on
occasion, such a newborn will initially present to the emergency department (ED)
in the first few days or weeks of life with cyanosis. One condition particularly
prone to such late presentation is tetralogy of Fallot with pulmonary atresia.
When the ductus closes, profound cyanosis ensues. Rarely, an infant with mild
tetralogy of Fallot (or “pink tet”) may present with intermittent cyanosis during a
“tet” or “hypercyanotic” spell. These self-limited episodes are caused by
increased right-to-left shunting and decrease in pulmonary blood flow. The causes
of cyanotic congenital heart disease are listed in Table 21.1 (II,A) .
TABLE 21.3
LIFE-THREATENING CAUSES OF CYANOSIS
I. Respiratory
A. Decreased inspired O2 concentration
B. Upper airway obstruction/disruption
C. Chest wall immobility
D. Tension pneumothorax
E. Massive hemothorax
F. Lung disease leading to hypoxemia
II. Vascular
A. Cardiac
1. Cyanotic congenital defects
2. Congestive heart failure
3. Cardiogenic shock
B. Pulmonary
1. Pulmonary edema
2. Primary pulmonary hypertension of the newborn
3. Pulmonary embolism
4. Pulmonary hemorrhage
C. Peripheral
1. Septic shock

III. Other
A. Neurologic conditions leading to hypoxemia
B. Severe methemoglobinemia
Cyanosis may also be caused by pulmonary congestion from cardiac failure or
left-to-right shunt lesions leading to increased pulmonary blood flow and


diminished diffusion of O2 across the blood–gas barrier (see Chapter 86 Cardiac
Emergencies ). Several pulmonary vascular abnormalities can also lead to
cyanosis. These include primary pulmonary hypertension of the newborn or
pulmonary hypertension from other causes. When pulmonary pressures are high,
blood is shunted away from the lungs and the child becomes hypoxemic.
Pulmonary embolism and pulmonary hemorrhage, although rare in children, also
impair lung perfusion and must be considered.
Low perfusion states may lead to local or peripheral cyanosis, particularly of
the hands, feet, and lips. Moderate cold exposure, for example, can result in local
blueness. Patients in septic or cardiogenic shock may have perfusion-related
cyanosis as a result of pump failure. Poor perfusion can also result from
hyperviscous states such as polycythemia or leukemia. Acrocyanosis, or blueness
of the hands and feet with preserved pinkness centrally, is seen commonly in
newborns and is related to variable perfusion in the extremities. It is seen in wellappearing babies and resolves within the first few days of life.
Neurologic conditions can also lead to Hb deoxygenation and cyanosis.
Patients who hypoventilate because of central nervous system (CNS) depression,
whether from primary CNS lesions or drugs/toxins that depress the respiratory
center, are often centrally cyanotic at presentation to the ED. Episodic blue spells
in infants and young children who are otherwise well may be caused by breath
holding, especially when associated with a sudden insult such as fear, pain,
frustration, or anger (see Chapter 126 Behavioral and Psychiatric Emergencies ).
Cyanosis may be noted as part of the picture in an infant with a brief resolved
unexplained event (BRUE). Seizures are often associated with cyanosis from

inadequate respiration during the convulsion. A variety of neuromuscular diseases
that affect chest wall or diaphragmatic function may ultimately lead to
hypoventilation.
With respect to the Hb molecule itself, methemoglobinemia is an unusual but
important reason for presentation to the pediatric ED. Methemoglobinemia can be
either congenital or acquired. Congenital methemoglobinemia is caused by either
Hb variants designated M hemoglobins or deficiency of NADH-dependent
methemoglobin reductase. The more common acquired form occurs when red
blood cells are exposed to oxidant chemicals or drugs. Methemoglobinemia has
also been associated with diarrheal illnesses in children. Young infants are
particularly susceptible to the development of methemoglobinemia as a result of
immature enzyme systems required to reduce Hb. Even at low levels, skin
discoloration is prominent, often with intense or “slate gray” cyanosis from the


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.


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