Cyanosis

CYANOSIS

Q. 1 Hypoxia without cyanosis is? 
 A Stagnant hypoxia
 B Hypoxic hypoxia 
 C

Anemic hypoxia

 D

Histotoxic hypoxia

Q. 1 Hypoxia without cyanosis is? 
 A Stagnant hypoxia
 B Hypoxic hypoxia 
 C

Anemic hypoxia

 D

Histotoxic hypoxia

Ans. C

Explanation:

Anemic hypoxia REF: Ganong’s physiology 22nd edition, chapter 37, Fundamentals of Human Physiology by Lauralee Sherwood page 371

See APPENDIX-16 for “Types of hypoxia” Indirect repeat from June 2008, June 2010

“Approximately 5 g/dL of unoxygenated hemoglobin in the capillaries generates the dark blue color appreciated clinically as cyanosis. For this reason, patients who are anemic maybe hypoxemic without showing any cyanosis”


Q. 2

Cyanosis in trauma is interpreted as:

 A

Early sign of hypoxia

 B

Late sign of Hypoxia

 C

Absence of cyanosis means adequate tissue ventilation

 D

Absence of cyanosis means adequate tissue oxygenation

Q. 2

Cyanosis in trauma is interpreted as:

 A

Early sign of hypoxia

 B

Late sign of Hypoxia

 C

Absence of cyanosis means adequate tissue ventilation

 D

Absence of cyanosis means adequate tissue oxygenation

Ans. B

Explanation:

late sign of Hypoxia [Ref: Ganong 23/e p612; Guyton 11/e p531; http://prehospitaltraining.orgIvitalspdf; http://02(19395.netsolhost.com/mainke/chesechesttrauma.htm%5D

Cyanosis is a late sign of hypoxia. In a trauma patient one should not wait for cyanosis to identify hypoxia and other signs of hypoxia should be looked for. If cyanosis is seen it means that hypoxia is profound.

Reason- Cyanosis is seen when more than 5 g of hemoglobin per 100 mL of blood are desaturated. For a person with a normal hemoglobin concentration of 15 g/100 mL, cyanosis appears only when one-third of the blood is desaturated. Thus cyanosis appears late.

Cyanosis may appear even later in a person with anemia. He may have a significant portion of the hemoglobin desaturated without displaying cyanosis. This individual will not appear cyanotic but may be profoundly hypoxic. (e.g. if an anemic person has haemoglobin conc. of 8 gm/100 mL, he will develop cyanosis only when more than 60% of his blood is desaturated.)

Conversely, a polycythemic person may develop cyanosis early, sometimes even under otherwise normal condition, as there is great excess of haemoglobin. (For e.g. if his Hb conc. is 20 gm/mL, he needs only 20% of desaturated blood to produce cyanosis.)


Q. 3

In CO poisoning all of the following clinical features are seen, EXCEPT:

 A

Cyanosis

 B

Cerebral edema

 C

Convulsions

 D

Bradycardia

Q. 3

In CO poisoning all of the following clinical features are seen, EXCEPT:

 A

Cyanosis

 B

Cerebral edema

 C

Convulsions

 D

Bradycardia

Ans. A

Explanation:

Carbon monoxide (CO) is a colourless, odorless, tasteless, and non irritating gas produced by the incomplete combustion of any carbon-containing material.

CO binds to hemoglobin with an affinity 250 times that of oxygen, resulting in reduced oxyhemoglobin saturation and decreased blood oxygen-carrying capacity.

CO may also directly inhibit cytochrome oxidase, further disrupting cellular function, and it is known to bind to myoglobin, possibly contributing to impaired myocardial contractility.

Symptoms of intoxication are predominantly in organs with high oxygen consumption, such as the brain and heart.

The majority of patients describe headache, dizziness, and nausea.
Patients with coronary disease may experience angina or myocardial infarction.
With more severe exposures, impaired thinking, syncope, coma, convulsions, cardiac arrhythmias, hypotension, and death may occur.
 
Cerebral edema (swelling of the brain) is also a common result of severe carbon monoxide poisoning.
Survivors of serious poisoning may experience numerous overt neurologic sequelae consistent with a hypoxic-ischemic insult, ranging from gross deficits such as parkinsonism and a persistent vegetative state to subtler personality and memory disorders.
Cyanosis is not seen in CO poisoning.
Ref: Olson K.R. (2012). Chapter 44. Carbon Monoxide. In K.R. Olson (Ed), Poisoning & Drug Overdose, 6e.

Q. 4

A patient brought to the emergency room after a road traffic accident shows cyanosis. Which of the following is TRUE regarding in this patient?

 A

Cyanosis is a early s/o hypoxia

 B

Cyanosis is a late s/o hypoxia

 C

Absence of cyanosis indicates adequate airway

 D

Absence of cyanosis indicates adequate tissue perfusion

Q. 4

A patient brought to the emergency room after a road traffic accident shows cyanosis. Which of the following is TRUE regarding in this patient?

 A

Cyanosis is a early s/o hypoxia

 B

Cyanosis is a late s/o hypoxia

 C

Absence of cyanosis indicates adequate airway

 D

Absence of cyanosis indicates adequate tissue perfusion

Ans. B

Explanation:

  • Cyanosis becomes apparent when the concentration of reduced hemoglobin in capillary blood exceeds 40 g/L (4 g/dL).
  • Cyanosis is an extremely late sign of hypoxemia and may not occur at all if there has been extensive blood loss. 
  • Indeed, a patient has to have 5 grams of deoxygenated hemoglobin per 100 cc of blood for cyanosis to occur
 
Ref: Loscalzo J. (2012). Chapter 35. Hypoxia and Cyanosis. In D.L. Longo, A.S. Fauci, D.L. Kasper, S.L. Hauser, J.L. Jameson, J. Loscalzo (Eds), Harrison’s Principles of Internal Medicine, 18e.

 


Q. 5

Which among the following is not a cause for cyanosis?

 A

Methemoglobin

 B

Sulfhemoglobin

 C

Cirrhosis

 D

Carboxyhemoglobin

Q. 5

Which among the following is not a cause for cyanosis?

 A

Methemoglobin

 B

Sulfhemoglobin

 C

Cirrhosis

 D

Carboxyhemoglobin

Ans. D

Explanation:

Cyanosis is caused by reduced hemoglobin. CO poisoning doesn’t cause cyanosis. Approximately 5 g/dL of unoxygenated hemoglobin in the capillaries generates the dark blue color appreciated clinically as cyanosis.

Causes:

Central Nervous System: Intracranial hemorrhage, Cerebral anoxia

Respiratory System: Pulmonary Hypertension, Pulmonary embolism, Hypoventilation, COPD

Cardiac Disorders: Congenital heart disease, Heart failure, Heart valve disease

Blood: Methemoglobinemia, Polycythaemia

Others: High altitude, Hypothermia, Congenital cyanosis (HbM Boston), Obstructive sleep apnea


Q. 6

Why cyanosis does not occur in severe anemia?

 A

Hypoxia stimulates erythropoetin production

 B

Oxygen Hemoglobin curve shifted to the right

 C

Oxygen carrying capacity of available hemoglobin is increased

 D

Critical concentration of hemoglobin required to produce cyanosis is reduced

Q. 6

Why cyanosis does not occur in severe anemia?

 A

Hypoxia stimulates erythropoetin production

 B

Oxygen Hemoglobin curve shifted to the right

 C

Oxygen carrying capacity of available hemoglobin is increased

 D

Critical concentration of hemoglobin required to produce cyanosis is reduced

Ans. D

Explanation:

Cyanosis refers to bluish color of the skin and mucous membranes which occur when the concentration of reduced hemoglobin is more than 5gm per cent. Patients suffering from severe anemia with hemoglobin content less than 5gram per cent may not show cyanosis as the total hemoglobin is less than 5 gram per cent.

Ref: Textbook of Practical Physiology By G.K. and Pal, 2nd Edition, Page 127; Harrison’s Principles of Internal Medicine, 16th Edition, Page 210; Fundamentals of Medical Physiology By Joel Michael, Page 50


Q. 7

A patient in emergency department showed hypoxia without cyanosis. What is the most likely cause?

 A

Stagnant hypoxia

 B

Hypoxic hypoxia

 C

Anemic hypoxia

 D

Histotoxic hypoxia

Q. 7

A patient in emergency department showed hypoxia without cyanosis. What is the most likely cause?

 A

Stagnant hypoxia

 B

Hypoxic hypoxia

 C

Anemic hypoxia

 D

Histotoxic hypoxia

Ans. C

Explanation:

The presence of cyanosis is influenced by several factors, including site of observation, pH, temperature, and concentrations of adult and fetal hemoglobins. Cyanosis appears when the absolute concentration of reduced hemoglobin in arterial blood is greater than 4-5 g/dL. Because this amount of reduced arterial hemoglobin is necessary to produce cyanosis, a low hemoglobin concentration requires an arterial saturation of 60% to produce approximately 4 g/dL of deoxyhemoglobin and cyanosis.

Ref: Ganong’s physiology 22nd edition, chapter 37, Fundamentals of Human Physiology by Lauralee Sherwood, Page 371; Pediatric Hospital Medicine: Textbook of Inpatient Management By Ronald M. Perkin, Dale A. Newton, M.D., James D. Swift, M.D., 2007, Page 80


Q. 8

Which of the following conditions leads to tissue hypoxia without alteration of oxygen content of blood?

 A

CO poisoning

 B

Met Hb

 C

Cyanide poisoning

 D

Respiratory acidosis

Q. 8

Which of the following conditions leads to tissue hypoxia without alteration of oxygen content of blood?

 A

CO poisoning

 B

Met Hb

 C

Cyanide poisoning

 D

Respiratory acidosis

Ans. C

Explanation:

C i.e. Cyanide poisoning


Q. 9

Condition where severe hypoxaemia occurs without cyanosis

 A

CO poisoning

 B

High altitude

 C

Anaemia

 D

A & C

Q. 9

Condition where severe hypoxaemia occurs without cyanosis

 A

CO poisoning

 B

High altitude

 C

Anaemia

 D

A & C

Ans. D

Explanation:

A i.e. CO poisoning C i.e Anemia


Q. 10

Cyanosis does not occur in severe anemia because:

 A

Hypoxia stimulates erythropoietin production

 B

Oxygen carrying capacity of available Hb is increased

 C

Critica concentration of Hb required to produce cyanosis is reduced

 D

Oxygen Hemoglobin curve shift to the right

Q. 10

Cyanosis does not occur in severe anemia because:

 A

Hypoxia stimulates erythropoietin production

 B

Oxygen carrying capacity of available Hb is increased

 C

Critica concentration of Hb required to produce cyanosis is reduced

 D

Oxygen Hemoglobin curve shift to the right

Ans. C

Explanation:

C i.e. Critica concentration of H required to produce cyanosis is reduced


Q. 11

Central cyanosis is seen if:

 A

Methemoglobin 0.5 gm/dl

 B

O2 saturation < 85%

 C

O2 saturation < 94%

 D

O2 saturation < 94%

Q. 11

Central cyanosis is seen if:

 A

Methemoglobin 0.5 gm/dl

 B

O2 saturation < 85%

 C

O2 saturation < 94%

 D

O2 saturation < 94%

Ans. B

Explanation:

B i.e. O2 saturation < 85%


Q. 12

Central cyanosis not occurs when total Hb and reduced Hb level is respectively (in gm°/o):

 A

10.9 & 4.1

 B

10.9 & 5.110.9 & 6.1

 C

8.9 & 4.1

 D

All

Q. 12

Central cyanosis not occurs when total Hb and reduced Hb level is respectively (in gm°/o):

 A

10.9 & 4.1

 B

10.9 & 5.110.9 & 6.1

 C

8.9 & 4.1

 D

All

Ans. A

Explanation:

A i.e. 10.9 & 4.1


Q. 13

Cyanosis in trauma is interpreted as:

 A

Early sign of hypoxia

 B

Late sign of Hypoxia

 C

Absence of cyanosis indicates adequate airway / ventilation

 D

Absence of cyanosis indicates good tissue oxygenation

Q. 13

Cyanosis in trauma is interpreted as:

 A

Early sign of hypoxia

 B

Late sign of Hypoxia

 C

Absence of cyanosis indicates adequate airway / ventilation

 D

Absence of cyanosis indicates good tissue oxygenation

Ans. B

Explanation:

B i.e. Late sign of Hypoxia

– The critical concentration of reduced hemoglobin required to produce cynosis is 4 (Harrison) / 5 (wintrobe) gram/ dl. In severe anemia, the total concentration of hemoglobin may be < 4-5gin/ dl and so cynosis will not be manifested because the critical concentration can not be reachedQ.

Cyanosis is a late sign of hypoxiaQ; so it is never advisible to wait for cyanosis to appear to diagnose hypoxia. Cyanosis occurs when concentration of reduced hemoglobin is > 4-5 gin % in capillary blood. Whereas when concentration of reduced Hb is less than 4/5 gm % (like 4.1) cyanosis would not occur.

Cyanosis

–  It is bluish discolouration of skin & mucous membranes resulting from an increased quantity of reduced (deoxygenated) hemoglobin. The deoxygenated hemoglobin has an intense dark blue purple color that is transmitted through the skin.

–  In general cynosis becomes apparent when the mean capillary concentration of reduced Hb exceeds 4gm/dL (40gm/L)Q Harrison /5gm per dl (Ganong & Guyton). It is absolute rather than relative quantity of reduced hemoglobin that is important in producing cyanosis. Thus in a patient with severe anemia the relative amount of reduced Hb may be very high. However since the total conc. of Hb is reduced, the absolute quantity of reduced Hb may still be small, and therefore patients with severe anemia and even marked arterial desaturation may not display cyanosisQ Definite cyanosis appears whenever the arteria blood contains >5gms of deoxygenated Hb in each 100 milliliters of blood. So a patient with anemia almost never becomes cyanotic because there is not enough hemoglobin for 5 grams to be deoxygenated in 100 ml of arterial blood. Conversly in patients with polycythemia vera (excess RBCs) the great excess of available Hb that can become deoxygenated leads frequently to cyanosis , even otherwise normal conditions.

Cyanosis is not a reliable sign of mild desturation (i.e. early hypoxia) because its recognizition depends on so many variables, such as lighting conditions and skin pigmentation. Cyanosis is a late sign of hypoxia and indicates the condition is marked (profound). So it is never advisible to wait for cyanosis to appear to diagnose hypoxia. Similarly absence of cyanosis does not always indicate adequate airway and absence of hypoxiaQ, because if the percentage saturation is high or in cases of anemia, cyanosis does not appear.


Q. 14

Concentration of methemoglobin to appears cyanosis

 A

5 gm/ dl

 B

2 gm/di

 C

1.5 gm/ dl

 D

12 gm/dl

Q. 14

Concentration of methemoglobin to appears cyanosis

 A

5 gm/ dl

 B

2 gm/di

 C

1.5 gm/ dl

 D

12 gm/dl

Ans. C

Explanation:

C i.e. 1.5 01


Q. 15

Features supporting strangulation are:

 A

Blood outside vessels in microscopy from skin of ligature site

 B

Dribbling of saliva from angle of mouth

 C

Marked cyanosis of face

 D

a and c

Q. 15

Features supporting strangulation are:

 A

Blood outside vessels in microscopy from skin of ligature site

 B

Dribbling of saliva from angle of mouth

 C

Marked cyanosis of face

 D

a and c

Ans. D

Explanation:

A i.e. Blood outside vessels in microscopy from skin of ligature site; C i.e. Marked cyanosis of face


Q. 16

Postmortem finding in carbon monoxide poisoning is:

 A

Cherry red blood

 B

Intense cyanosis

 C

Excessive salivation

 D

Pin point pupil

Q. 16

Postmortem finding in carbon monoxide poisoning is:

 A

Cherry red blood

 B

Intense cyanosis

 C

Excessive salivation

 D

Pin point pupil

Ans. A

Explanation:

A i.e. Cherry red cyanosis


Q. 17

Normal finding in a newborn ‑

 A

Length 30 cm

 B

Peripheral cyanosis

 C

Central cyanosis

 D

Extension of body

Q. 17

Normal finding in a newborn ‑

 A

Length 30 cm

 B

Peripheral cyanosis

 C

Central cyanosis

 D

Extension of body

Ans. C

Explanation:

Ans. is ‘c’ i.e., Central cyanosis

o There is peripheral cyanosis (not central cyanosis).

o Length is approximately 50 cm and the attitude of body is in flexion (not extension).


Q. 18

A patient with blood pressure of 90/60 mm Hg presents with pronounced cyanosis. Blood drawn from peripheral veins is observed to be chocolate brown in colour. The most likely diagnosis is:

 A

Methaemoglobinemia

 B

Hypovolemic shock

 C

Cardiogenic shock

 D

Hemorrhagic shock

Q. 18

A patient with blood pressure of 90/60 mm Hg presents with pronounced cyanosis. Blood drawn from peripheral veins is observed to be chocolate brown in colour. The most likely diagnosis is:

 A

Methaemoglobinemia

 B

Hypovolemic shock

 C

Cardiogenic shock

 D

Hemorrhagic shock

Ans. A

Explanation:

Answer is A (Methaemoglobinemia)

Pronounced cyanosis together with chocolate brown colour of ‘freshly drawn blood suggests a diagnosis of methaemoglobinemia

Methaemoglobinemia

Methaemoglobinemia is an uncommon but distinct cause of central cyanosis in the absence of hypoxemia or cardio

vascular compromise

Methaemoglobinemia occurs when a significant concentration of hemoglobin (Hb) is oxidized to methaemoglobin

(Met Hb)

When the haem moety (iron atoms) of’ Hb molecule encounter a strong oxidizing agent iron loses an electron and

switches from the Ferrous (2+) to Ferric (3+) state turning Hb to ‘Met Hb’

Methaemoglobin has such high oxygen affinity that virtually no oxygen is delivered

Presentation

Methaemoglobinemia most commonly presents as cyanosis unresponsive to supplemental oxygen

The most notable physical examination finding is generalized cyanosis which can manifest as muddy brown dark

mucus membranes before proceding to global skin discolaration

‘The charachteristic muddy appearance (chocolate brown) of freshly drawn blood can be a critical clue’-*Blood appears dark brown, brownish, muddy or chocolate in colour immediately after withdrawal. In contrast to normal venous

blood, the color does not change with addition of oxygen or agitation in the air’- Diffirential diagnosis in Internal Medicine

Methaemoglobinemia > 15% cause symptoms of cerebral ischaemia

Methaemoglobinemia > 60% is usually lethal

 

Diagnosis

•     The hest  Methaemoglobinomia isMethaemoglohin Assay’

Treatment

The most effective emergency management for methaemaglobinemia is administration of Methylene bluee which

serves as an antidote (intravenous)

Methylene blue is not effective in patients with methaemoglobinemia due to Hemoglobinopathy MQ (Haemoglobin M)

Methylene blue is contraindicated in patients with G6 PD deficiencyQ since it can cause severe hemolysis due to

its potential for oxidation

Outline of The Four Main Pathways to MetHb Production

1. Congenitally abnormal hemoglobin: Hemoglobin M

  • Hemoglobin M is passed as an autosomal dominant trait affecting either the alpha or beta chain of hemoglobin; homozygous Hb M affecting both alpha and beta chains is incompatible with life.
  • Amino acid substitution (often a tyrosine for histidine) near the heme iron facilitates iron oxidation.

2. Inherited enzyme deficiencies: NADH-dependent cytochrome b5 -reductase and cytochrome bc deficiency.

  • Deficiency of either cytochrome b5 or its reducing enzyme, cytochrome b5-reductase, decreases reduction of MetHb back to Hb

3. Nitrite (NO2), other oxidants and oxygen-reducing compounds

  • Nitrites are a common oxidizing source of MetHb production.
  • Reducing agents paradoxically produce methemoglobinemia by reducing oxygen to a free radical or water to 1-1,O2, which then oxidizes hemoglobin.

4. “Sensitive” hemoglobin: Blue baby syndrome

  • Bacteria in the immature gastrointestinal tracts of infants convert nitrate (NO3) to the powerful oxidant nitrite (NO,).
  • Infants have a relative NADH-dependent reductase deficiency (only 50% of adult levels) and are more susceptible to oxidative injury.

Q. 19

All of the following statements about central cyanosis are true Except:

 A

Central cyanosis becomes evident when reduced haemoglobin < 5gldl

 B

Chronic Asthma may cause central cyanosis

 C

Alveolar Hypoventilation causes central cyanosis

 D

Methemoglobinemia causes central cyanosis

Q. 19

All of the following statements about central cyanosis are true Except:

 A

Central cyanosis becomes evident when reduced haemoglobin < 5gldl

 B

Chronic Asthma may cause central cyanosis

 C

Alveolar Hypoventilation causes central cyanosis

 D

Methemoglobinemia causes central cyanosis

Ans. A

Explanation:

Answer is A (Central cyanosis becomes evident when reduced Hb < 5g/dl):

Cyanosis (both central and peripheral) become evident when the amount of reduced Hb exceeds 5g/dl (becomes >5gm/dI) and not when reduced Hb is less than 5g/d1.

Cyanosis becomes evident when Reduced Hb exceeds

‘Cyanosis becomes evident when reduced Hb exceeds 

`Cyanosis becomes evident when reduced Hh exceeds

Pulmonary diseases such as chronic Asthma, Alveolar hypoventilation and Hemoglobin disorders like  methemoglobinemia all cause central cyanosis

Central cyanosis

  • Central cyanosis is caused by in adequate oxygenation of systemic arterial blood due to decreased arterial oxygen saturation or Hemoglobin abnormalities
  • It results from cardiac shunting, pulmonary diseases or hematological disorders (Hb abnormalities)
  • Central cyanosis is charachterized by cyanosis affective both mucous membranes and skin

Causes

Decreased arterial oxygen saturation

  • Decreased atmospheric pressure – high altitude
  • Impaired pulmonary function

Alveolar hyoventilation

– Uneven relationships between pulmonary ventilation and perfusion (perfusion of hypoventilated alveoli)

– Impaired oxygen diffusion

  • Anatomic shunts

– Certain types of congenital heart disease – Pulmonary arteriovenous fistulas

– Multiple small intrapulmonary shunts

  • Hemoglobin with low affinity for oxygen

 Hemoglobin abnormalities

  • ·Methemoglobinemia – hereditary, acquired
  • Sulfhemoglobinema – acquired
  • Carboxyhemoglobinemia (not true cyanosis)

Peripheral cyanosis

  • Peripheral cyanosis is caused by slowing of blood flow and increased extraction of oxygen from normally saturated blood
  • It results from vasoconstriction or decreased peripheral blood flow, reduced cardiac output or vascular occlusion
  • Peripheral cyanosis is characterized by cyanosis of
    skin alone and sparing of mucous membranes

Causes

  • Vascular occlusion – Arterial obstruction – Venous obstruction
  • Reduced cardiac output
  • Cold exposure
  • Redistribution of blood flow from extremities



Q. 20

Cause of central cyanosis include all of the following, Except

 A

Chronic Asthma

 B

Congenital Pulmonary stenosis

 C

Congestive heart failure

 D

Alveolar hypoventilation

Q. 20

Cause of central cyanosis include all of the following, Except

 A

Chronic Asthma

 B

Congenital Pulmonary stenosis

 C

Congestive heart failure

 D

Alveolar hypoventilation

Ans. C

Explanation:

Answer is C (Congestive heart failure):

Congestive Heart Failure is a cause for Peripheral cyanosis and not central cyanosis

Cyanosis when present in Asthma, pulmonic stenosis and alveolar hypoventilation is of the central type.


Q. 21

Cyanosis may seen in:  

March 2013

 A

Histotoxic hypoxia

 B

Anemic hypoxia

 C

Stagnant hypoxia

 D

All of the above

Q. 21

Cyanosis may seen in:  

March 2013

 A

Histotoxic hypoxia

 B

Anemic hypoxia

 C

Stagnant hypoxia

 D

All of the above

Ans. C

Explanation:

Ans. C i.e. Stagnant hypoxia

Central cyanosis

  • Often due to a circulatory or ventilatory problem that leads to poor blood oxygenatio in the lungs.

It develops when arterial saturation drops to 85% or 75% (in dark-skinned individuals).

Central cyanosis may be due to the following causes

Central Nervous System (impairing normal ventilation):

  • Intracranial hemorrhage,
  • Drug overdose (Heroin)

–           Respiratory System:

  • Pneumonia,
  • Bronchilitis,
  • Pulmonary hypertension

–           Cardiac Disorders:

  • Congenital heart disease: TOF, Right to left shunts

Blood:

  • Methemoglobinemia,
  • Polycythemia

Others: High altitude

Peripheral cyanosis

  • Peripheral cyanosis is the blue tint in fingers or extremities, due to inadequate circulation.
  • The blood reaching the extremities is not oxygen rich and when viewed through the skin a combination of factors can lead to the appearance of a blue colour.

All factors contributing to central cyanosis can also cause peripheral symptoms to appear, however peripheral cyanosis can be observed without there being heart or lung failures.

Peripheral cyanosis may be due to the following causes:

–  All common causes of central cyanosis

Reduced cardiac output (e.g. heart failure, hypovolemia)

– Cold exposure

– Arterial obstruction (e.g. peripheral vascular disease, Raynaud phenomenon)

– Venous obstruction (e.g. DVT)

Differential cyanosis

  • Differential cyanosis is the bluish coloration of the lower but not the upper extremity and the head.
  • This is seen in patients with a patent ductus arteriosus .
  • Patients with a large ductus develop progressive pulmonary vascular disease, and pressure overload of the right ventricle occurs.
  • As soon as pulmonary pressure exceeds aortic pressure, shunt reversal (right-to-left shunt) occurs.
  • The upper extremity remains pink because the brachiocephalic trunk, left common carotid trunk and the left subclavian trunk is given off proximal to the PDA.


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