This is common in babies and young children. It is usually
confined to the area around the mouth ("muzzle area") and the hands and
feet. Whilst it may occur when exposed to a cold environment (e.g. after a
long time in the bath) there is often no obvious reason and it may occur
on warm and sunny days. It usually lasts for a few minutes and the child
is asymptomatic and unaware of any problem. The technical term for this colour
change is acrocyanosis. It is probably caused by local variation in blood
flow through the skin - the longer the transit time the greater the
extraction of oxygen from the blood and the more intense the colour change. It is of no consequence and usually goes
away as the child gets older.
This is present when the tongue itself is
noted to be blue. This occurs when there is more than 5g of reduced
haemoglobin per 100 ml blood. It is therefore more easily seen in those
with polycythaemia and masked when anaemia is present. In general the
oxygen saturation needs to be below 85% for cyanosis to be detectable.
Central cyanosis may be due to cardiac, respiratory,
neurological or haematological disorders. The clinical situation usually
allows them to be distinguished however sometimes it can be difficult and
co-existing disease may be present.
When cyanosis has been present for more than 6 months then
clubbing almost invariable occurs.
The history together with the examination, chest X-ray and
capillary gas usually allows the diagnosis to be made. A cardiac diagnosis
is more likely if the respiratory rate is normal or only slightly
increased, the pulmonary vascular markings are abnormal on the X-ray or
the cardiac size or shape is abnormal. The pCO2 is usually normal or low.
Murmurs are often uncommon even in significant cardiac disease. The
hyperoxia test is still useful. Measure the oxygen saturation in as low an
oxygen concentration as possible and then again after ten minutes of an
oxygen concentration of 100%. In respiratory disease there will usually be
a significant rise in the oxygen saturation (15-20% or more) and an
adequate level reached (85% or more).
In infants the major cause
of central cyanosis is respiratory as most cyanotic cardiac disease has
already presented in the neonatal period. The exceptions are those
disorders with a normal or high pulmonary blood flow e.g. Tetralogy of
Fallot, Pulmonary atresia with MAPCAs, unobstructed TAPVC and single
Adolescence & Adult Period
There are a substantial number of severely cyanosed
patients in this age group who have either had definitive palliative
treatment for cyanotic cardiac disease (e.g. systemic-pulmonary shunts for
pulmonary atresia) or have developed Eisenmenger syndrome (e.g. unoperated
AV septal defects, Trisomy 21). Their chronic hypoxaemia leads to an
increase in erythropoietin production and hence an isolated increase in
red cell mass. For many patients therefore the increase in red cell mass
is appropriate, enhances oxygen delivery to tissues and is asymptomatic.
These usually occur in tetralogy of Fallot. The mechanisms
are uncertain but probably involve either an increased pulmonary vascular
resistance or decreased systemic vascular resistance. This leads to an
increased R-L shunt across the VSD and hence exacerbates the hypoxia,
hypercarbia and acidosis further increasing the pulmonary vascular
resistance and creating a downward spiralling process.
A spell usually occurs for no apparent reason, often early in the morning
although some may be precipitated by induction of anaesthesia, following a
bath or when upset). The infant becomes pallid or cyanosed, is irritable
with prolonged cry. If examined the intensity of the murmur may have
decreased as less blood is ejected across the pulmonary valve.
Spells may be brief (minute or two) and self correct or may progress with
the infant developing paroxysms of rapid, deep respirations, becoming
grey, floppy and unresponsive. Without appropriate treatment a severe
spell may be life threatening.
The treatment is to
administer 100% O2
place infant in knee-chest position or compress both
femoral arteries directly
give intramuscular morphine sulphate
give intravenous propranolol
If the spell continues full cardio-respiratory support may
Note Spells may occur even after a surgical shunt and may occur in other
conditions, e.g. Pulmonary atresia with MAPCAs, Eisenmenger syndrome.
The increase in red cell mass increases blood viscosity
and in some patients causes symptoms. These include headaches,
light-headedness, slow mentation, visual disturbance, paraesthesia,
tinnitus, fatigue, myalgia and muscle weakness. Iron deficiency is
commonly associated as the additional erythropoiesis necessitates an
increased iron requirement. Iron deficient red blood cells are microcytic
but despite being small are less deformable than normal cells and so also
increase the viscosity. Those symptomatic patients with an haematocrit <
65% are thus probably iron deficient.
Polycythaemic patients also have bleeding tendencies.
Usually this is mild – bleeding gums after teeth brushing, epistaxis but
may be life threatening in severe pulmonary haemorrhage (this was the fate
of the 32 year old man reported by Victor Eisenmenger in 1897). The
bleeding tendency appears to be a combination of reduced platelet counts
(usually they have an inverse relationship to the haematocrit) and a
reduction in von Willibrand factor. It may well be exacerbated by the
injudicious use of antiplatelet and anticoagulant medication and self
administration of NSAIDs.
The high red cell production (and hence destruction)
increase uric acid production which the kidneys are unable to readily
excrete as their function is depressed in polycythaemia. Gout is not
uncommon in this group of patients and may be exacerbated by diuretic
Patients vary in their tolerance of a high haematocrit and may be
asymptomatic even at levels > 70%. Recent evidence also suggests that
neither the haematocrit nor iron stores are linked to the risk of cerebral
arterial thrombo-embolism. Thrombosis can certainly occur but appears to
be related to abnormal vascular beds.
The rationale for treatment is therefore purely for
symptomatic relief. Phlebotomy, when indicated, should remove 250-500 ml
of blood with replacement of the same volume with normal saline. The
beneficial effects usually are manifest within 24 hours but only last for
as long as the erythropoietin production takes to increase the red cell
mass again. Frequent venesection will cause iron deficiency anaemia unless
supplementation is given. Pain relief and allopurinol is usually effective
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