This presentation is about the causes and mechanisms of central and peripheral cyanosis. It also contain some general information about different scenarios of cyanosis.

2. Cyanosis
The causes and mechanisms of central and peripheral cyanosis

3. Definition
 Cyanosis is defined as a bluish discoloration of the skin
and mucous membranes, resulting from an increased
amount of reduced hemoglobin (more than 5 g/dL), or
of hemoglobin derivatives in the capillary blood.
 Smaller concentrations of methaemoglobin and
sulphmethaemoglobin (1.5 and 0.5 g/dL, respectively)
may also evoke cyanosis.
 Cyanosis is most marked in the lips, nail beds, ears
and malar eminences.

4. TypesofCyanosis
andtheir
Mechanisms
 Cyanosis can be subdivided into two
 Central cyanosis
 Peripheral cyanosis.
 Central cyanosis is due to decreased arterial oxygen
saturation (most of the cases) or the presence of an
abnormal hemoglobin derivative (rarely).
 Peripheral cyanosis is due to slowing of blood flow to
an area, resulting in greater extraction of oxygen from
normally saturated arterial blood. This results from
vasoconstriction or diminished peripheral blood flow
(reduced cardiac output).

5. Causes
Central cyanosis Peripheral cyanosis
• Due to decreased arterial
oxygen saturation
• Cardiac causes
Fallot's tetralogy
Eisenmenger's syndrome
Congestive cardiac failure
• Pulmonary causes
Chronic bronchitis
Interstitial lung disease
Pulmonary arteriovenous
fistula
• High altitude
• Cirrhosis of liver
• Due to abnormal hemoglobin
derivatives
• Methaemoglobinaemia
• Sulphaemoglobinaemia
•Due to diminished peripheral
blood flow resulting from reduced
cardiac output
• Mitral stenosis
• Congestive cardiac failure
• Shock
•Due to local vasoconstriction
• Cold exposure
• Raynaud's disease
• Peripheral vascular disease

6. Differentiation
BetweenCentral
andPeripheral
Cyanosis
Feature Central cyanosis Peripheral
cyanosis
• Site Mucous
membranes and
skin are both
involved
Mucous
membranes of the
oral cavity or
those beneath the
tongue spared
• Tongue Affected Unaffected
• Temperature of
limb
Warm Cold
• Clubbing Present(Shunts) Absent
• Polycythemia Present(Shunts) Absent
• Local warming Cyanosis remains Cyanosis
• Breathing pure
oxygen
for 10 minutes
Cyanosis may
disappear
disappears
Cyanosis remains
• Arterial blood
gas studies
Abnormal Normal

7. General
Information
aboutCyanosis
 Cyanosis in cardiac failure is often of a mixed type due
to both central and peripheral causes.
 "Differential cyanosis" is cyanosis occurring in the
lower limbs, but not in the upper limbs. This occurs in
patients with patent ductus arteriosus with a reversal
of shunt.
 Cyanosis of only upper limbs can occur in patients with
patent ductus arteriosus with reversal of shunt in
combination with transposition of great vessels.
 Cyanosis of left-upper limb and both lower limbs
(sparing right upper limb) can occur in patients with
patent ductus arteriosus with reversal of shunt in
combination with a pre-ductal coarctation of aorta.
 Intermittent cyanosis in Ebstein's anomaly.