Cyanosis specifically refers to a bluish tone visible in
the mucous membranes and skin when desaturated or
abnormal hemoglobin is present in the peripheral
Central cyanosis occurs when poorly oxygenated
blood enters the systemic circulation
right-to-left” shunt and may occur within the heart or
in the pulmonary circulation itself.
When there is primary parenchymal lung disease or
neurologic disease causing alveolar
hypoventilation, an “intrapulmonary” right-to-left
shunt can occur.
3. Causes of cyanosis
Abnormal hemoglobins may be fully saturated with oxygen, yet
unable to release it to the tissues like Methemoglobinemia
Anemia at hb= 3-5gm/dl cyanosis will be visible
Typical cyanotic lesions are the “five Ts” of congenital heart disease (
tetralogy of Fallot,
transposition of the great vessels,
total anomalous pulmonary venous return,
tricuspid atresia, and
truncus arteriosus), but others may also be present.
Pulmonary diseases like
upper airway obstructive problems (croup, epiglottitis)
lower airway diseases (bronchiolitis, asthma, cystic
fibrosis, pneumonia with lobar consolidation).
4. Differentiating cardiac from pulmonary causes
Differentiating cardiac from pulmonary etiologies is critical
breath sounds are usually normal in cardiac disease
while wheezes, rhonchi, and chest wall abnormalities usually
accompany a pulmonary process.
cyanotic cardiac disease
little response to increased ambient
the saturation increase may be dramatic
ABG may also be useful, since an elevated pCO2 indicating
impaired ventilatory status, usually not seen with cyanotic congenital
heart disease unless there is associated pulmonary congestion.
The chest X-ray may reveal
an abnormal pulmonary circulatory pattern, or
overt pulmonary parenchymal abnormalities such as atelectasis
The absence of a heart murmur does not rule out cyanotic
cardiac disease; in most conditions with right-to-left shunting
there is no murmur.
Tachypnea may be present with most pulmonary diseases
Hyperpnea, or deep breathing with only a mild increase in
rate, is more characteristic of a primary cardiac disorder where
alveolar ventilation is maximized but pulmonary blood flow is
Hyperpnea can also reflect metabolic acidosis or elevated
6. Cyanotic (Tet) spells
Acute hypoxemic attacks represent a true emergency and initial
treatment is crucial to long term outcome.
Usually, the underlying diagnosis is tetralogy of Fallot.
In a Tet spell,
an acute increase in obstruction to pulmonary blood flow (either in heart or
in pulmonary circulation) results in increase in right-to-left shunting through
an intracardiac septal defect.
Alternatively, if systemic perfusion is reduced, as with hypovolemia or the
development of a tachyarrhythmia, right-to-left shunting will also increase
and a cyanotic spell develop.
7. Clinical presentation and diagnosis
They are characterised by:
Period of uncontrollable crying / panic,
Rapid and deep breathing (hyperpnoea),
Deepening of cyanosis,
Decreased intensity of heart murmur,
Limpness, convulsions and rarely, death.
common in the early morning, shortly after the patient awakens,.
Prolonged agitation and crying are also cited as precipitants,
Also, noxious stimuli, such as phlebotomy or a bee sting, or any circumstance which
leads to enhanced catecholamine output can precipitate a spell in a susceptible child.
A decrease in systemic vascular resistance (SVR) during exercise, bathing, or fever
potentiates a right-to-left shunt and precipitates hypoxemia
In such cases(tet spells), the absence of a heart murmur is a worrisome
indicator that pulmonary blood flow is severely compromised.
Hemoglobin and hematocrit values are usually elevated in proportion to
the degree of cyanosis. Prolonged cyanosis causes reactive polycythemia
that increases the oxygen-carrying capacity. While in cyanosis due to
Anemia hb is 3-5g/dl
results show varying oxygen saturation, but pH and partial pressure of
carbon dioxide (pCO2) are normal, unless the patient is in extremis, such
as during a tet spell.
Oximetry is particularly useful in a dark-skinned patient or an anemic
patient whose level of cyanosis is not apparent. Generally, cyanosis is not
evident until 3-5 g/dL of reduced hemoglobin is present.
Echocardiograms will usually reveal a large VSD with an overriding aorta and
variable degrees of right ventricular (RV) outflow tract obstruction (RVOTO)
The hallmark of tetralogy of Fallot is the classic boot-shaped heart
11. Emergency management
Management is directed at manipulating the relative resistances of the systemic and
vascular beds, as well as maintenance of appropriate circulating volume and heart rate
1. Knee-to-chest / Squatting:
Placing the child in the knee-chest position either lying supine or over the parent’s
shoulder (see below). This calms the infant, reduces systemic venous return and
increases systemic vascular resistance.
. Some older patients will instinctively squat to achieve the same result.
12. 2. Oxygen (100%) can be administered which also increasessystemic
resistance and may help enhance oxygen delivery
but usually has minimal effect.
3. Morphine: 0.1-0.2 mg/kg IM. (Caution in infants under 3 months).
morphine may cause pulmonary vasodilatation and also provide a beneficial
sedative effect, with consequent reduction of catecholamine secretion.
13. If the above procedures are ineffective or have suboptimal effect, the following
treatments may need to be given.
Establish IV access and discuss with a senior colleague.
4. Crystalloid or colloid fluid bolus: 10-20ml/kg by rapid IV push.
give an IV fluid bolus of 20 mL/kg normal saline
Obtain an ABG.
Treat metabolic acidosis with sodium bicarbonate, 1–2 mEq/kg slowly IV, only if
ventilation is adequate
(low or normal pCO2)
5. . phenylephrine
If cyanosis persists, give phenylephrine (10 mcg/kg by slow IV push)
to pharmacologically increase the systemic vascular resistance
14. 5. beta blocker (e.g. propranolol or esmolol)
In severe episodes, IV propranolol (Inderal) may be administered, which
relaxes the infundibular muscle spasm causing right ventricular (RV) outflow
tract obstruction (RVOTO)
Esmolol (BREVIBLOC®) 500 mcg/kg over one minute IV, then maintenance of
50 mcg/kg/min can be increased in steps of 50mcg/kg/min to maximum dose
ultra-short acting cardioselective beta blocker, reducing dynamic muscular
stenosis of the right ventricular outflow tract and increasing pulmonary blood
The availability of these medications may be limited in some centres.
. Progressive hypoxemia and the occurrence of cyanotic spells are
indications for early surgery.
15. For chronic cyanotic
congenital heart conditions
supportive treatment is all that can be done until a surgical
or catheter-directed intervention can be accomplished.
Give supplemental oxygen, even though dramatic changes
in saturation will not occur with oxygen alone.
Secure IV access and give fluid to maintain an adequate
Treat systemic acidosis once adequate ventilation is
Most of all, immediately consult with a cardiologist to
arrange for more definitive treatment and to prevent