Cyanosis presentation. Bluish discoloration of skin and its causes are discribed in presentation.

1. Cyanosis
Dr Kevin Zammit MD FRCEM
Emergency Medicine Consultant
Lister Hospital, Stevenage

2. Cyanosis

3. Cyanosis

4. What is Cyanosis?

5. Cyanosis
• Abnormal bluish discolouration of the skin and
mucous membranes.
• Increased amounts of bluish-coloured
haemoglobin – deoxygenated haemoglobin.
• Superficial vessels of the skin.
• Best appreciated – lips, nose, cheeks, oral cavity
(vessels abundant and overlying dermis is thin).
• Central vs Peripheral – bedside decision – implies
different aetiologies.

6. History
• 1761 – Morgagni described cyanosis first in
relation to pulmonary stenosis.
• 1869 – Bernard described the qualitative
difference in blood gases between blue
venous blood and red arterial blood.
• 1919 – Lundsgaard quantified how much
deoxygenated haemoglobin is needed to
produce cyanosis.

7. The blue colour
• Minimal amount of deoxygenated blood is
reached (2.38g/dL in arterial blood).
• Blue blood can be seen through the opaque
dermis.
• Cyanosis will remain if absolute amount of
deoxygenated blood stays the same –
oxyhaemoglobin concentration irrelevant.
• Colour of skin depends on colour of blood flowing
through dermal capillaries.
• Blanches in response to pressure on skin.

8. The blue colour
• Appearance of cyanosis depends on the absolute
quantity of deoxyhaemoglobin NOT the relative
amount.
• If anaemic, a patient has less haemoglobin and
will reach the minimal amount of
deoxyhaemoglobin later than a polycythaemic
patient!
• Cyanosis appears later in anaemic patients than
in polycythaemic patients.
• Anaemic patient will be more hypoxic once
cyanosis appears.

9. Cyanosis and Haemoglobin
Concentration
Haemoglobin
Concentration (g/dL)
CYANOSIS APPEARS
Oxygen Sats (%)
CYANOSIS APPEARS
Arterial PO2 (KPa)
6 60 4.1
8 70 4.8
10 76 5.3
12 80 6.0
14 83 6.26
16 85 6.66
18 87 7.19
20 88 7.47

10. Central vs Peripheral
CENTRAL
• Blood leaving heart
coloured blue.
• Lips, hands, feet.
• Long standing – associated
clubbing.
PERIPHERAL
• Blood leaving heart is red
but becomes blue by the
time it reaches peripheries.
• Hands and feet.
• Increased extraction of
oxygen by peripheral
tissues.
• Deoxygenated blood in
capillaries increases.
• Rubber band around finger.
• Warming.

11. Pulse oximetry / ABGs
• Central cyanosis – abnormal ABGs and pulse
oximetry readings.
• Peripheral cyanosis – normal ABGs (proximal
sampling) BUT abnormal oximetry readings.

12. What causes Cyanosis?

13. Causes of cyanosis
• ANY DISORDER CAUSING HYPOXAEMIA
enough to achieve the minimum absolute
amount of abnormal haemoglobin (>2.38 g/dL
arterial deoxyhaemoglobin).
• INTRACARDIAC RIGHT TO LEFT SHUNTS
• PERIPHERAL – low cardiac output, arterial
disease, Raynaud’s disease, venous disease.
• ABNORMAL HAEMOGLOBINS

14. Methemoglobinaemia
The Fugates of Kentucky (“The Blue Fugates”)

15. Methemoglobinaemia
• Congenital or Acquired
• Chocolate cyanosis
(brownish hue)
• ABGs will show normal
PaO2.
• Does not improve with
oxygen therapy.
• Severity of symptoms
depends on quantity,
rapidity of onset and
presence of comorbidities.
• Reversible with Methylene
blue.

16. Sulfhemoglobinaemia

17. Causes
Sulfhemoglobinaemia
• Phenacetin
• Industrial aniline
compounds
• Rare due to improved
occupational health
standards
• Irreversible.
Methemoglobinaemia
• Hereditary – NADH
methemoglobin
reductase
• Benzocaine
• Nitrates
• Nitrites

18. Carboxyhaemoglobinaemia
• Does not cause real cyanosis
• Cherry red colour of the skin?

19. Flexman AM. Dark green blood in the operating theatre. Lancet. 2007 Jun 9;369(9577)1972

20. Pseudocyanosis

21. Pseudocyanosis
• “Papa Smurf”
• Drank and applied
colloidal silver for a skin
condition.

22. Pseudocyanosis

23. Pseudocyanosis
• Does not blanch with pressure.
• Colour is not from abnormally coloured blood but
from abnormal deposition of blue pigments in
the skin.
• Mucous membranes of mouth are pink.
• Normal ABGs and normal pulse oximetry
readings.
• Causes include – silver therapy, gold therapy,
amiodarone, minocycline, chloroquine.

25. Summary
• LATE SIGN – prevent it if possible.
• OXYGEN!
• If no improvement with oxygen, think of
differential diagnosis.