Cyanosis in children

  DEFINITION-

Cyanosis is derived from the Greek word “cyanós (κυανός)” meaning dark blue¹. It refers to the bluish discoloration of the skin, nail beds or mucous membranes. While oxygenated hemoglobin is bright red, reduced hemoglobin is dark blue or purple in color and if in sufficient quantity it produces the dusky or blue color of the skin and mucous membranes. According to classical textbook teaching, concentrations of deoxyhemoglobin of about 5 g/dl are necessary before central cyanosis is clinically detectable. This figure has recently been questioned and thought to be a considerable overestimation. (6) Usually, it is associated with oxygen saturation below 85%.

Goss et al (6) have reported that central cyanosis can be detected when deoxyhemoglobin levels are 1 -1 g/dl or greater; at concentrations of 1 5 g/dl or more central cyanosis was recognised in all patients. The other factors on which the detection of cyanosis is dependant are  amount of Hb present in the patient, color of skin, amount of met-Hb present in body etc.  as shown in Fig 1.

 

 

 

 

 

 

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Type of Cyanosis- Depending on the mechanism and causes cyanosis may be central, peripheral, mixed or differential.

 

	Central cyanosis	Peripheral cyanosis (acrocyanosis)	Mixed cyanosis	Differential cyanosis
Site	mucosae (around the core, lips, and tongue)	Involves only extremities	mucosae and extremities	Two types : a)     hands are blue but feet are pink b)               the hands are pink, but the feet are blue
Cause	Cardiac as well as pulmonary pathology	generally physiological	It occurs due to decreased oxygenation and sluggish blood flow	Mostly cardiac causes. Seen when the pre-ductal O2 saturation is higher than the post-ductal saturation.
Temp of cyanosed area	Same in whole body	Temp of affected part usually low	Same in whole body	Same in whole body
Clubbing	Present	Absent	Present	Present
Oxygenation	Cyanosis decreases	No effect	Cyanosis decreases	Cyanosis decreases
CFT	<3 sec	.> 3 sec	>3 sec	<3 sec

 

ETIOLOGY

1. Central cyanosis- : Central cyanosis may result from the reduced arterial oxygen saturation caused by cardiac or pulmonary disease. It affects not only the skin and the lips but also the mucous membranes of the mouth. Cardiac causes include pulmonary edema (prevents adequate oxygenation of the blood) and congenital heart disease.

A. Cardiac

1. Cyanotic congenital heart disease-

(i) Decreased pulmonary blood flow –

Pulmonary atresia with intact ventricular septum, critical pulmonic stenosis with right-to-left shunt (R→L) at atrial level, Ebstein anomaly, isolated right ventricular hypoplasia.

 

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Unrestrictive ventricular communication: All conditions under VSD with pulmonic stenosis

 

(ii) Increased pulmonary blood flow -

Pre-tricuspid: Total anomalous pulmonary venous communication, Common atrium.

Post-tricuspid: All single ventricle physiology lesions without pulmonic stenosis, Persistent truncus arteriosus, Transposition of great vessels.

 

(iii) Pulmonary hypertension

(iv) Pulmonary vascular obstructive disease (Eisenmenger physiology).

 

(v) Miscellaneous- Pulmonary arteriovenous malformation, Anomalous drainage of systemic veins to left atrium

(vi) Congestive cardiac failure.

 

B. Pulmonary –

Impaired pulmonary function- Alveolar hypoventilation, ventilation-perfusion mismatch, impaired oxygen diffusion

1. Chronic obstructive lung disease.

2. Collapse and fibrosis of lung.

3. Marked pulmonary destruction due to any cause.

4. Pulmonary AV fistula.

5. Impaired oxygen diffusion- interstitial pneumonia

C. Abdominal-

      Hepato-pulmonary syndrome.

D. High altitude due to low partial pressure of oxygen.

E. Hemoglobin abnormalities- Methemoglobinemia, Carboxyhemoglobinemia.

 

2. Peripheral Cyanosis:   It arises due to slowing of blood flow in an area and greater extraction of oxygen from normally saturated arterial blood in that area.

A. Cold (local vasoconstriction)

B. Increased viscosity of blood

 

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C. Shock and heart failure, when reduced cardiac output produces reflex cutaneous vasoconstriction.

D. Reynaud's phenomenon

E. In mitral stenosis, cyanosis over the malar area produces the characteristic mitral facies or malar flush.

F. Peripheral vascular disease

G. In birth asphyxia, the blood flow to the vital organs such as brain and heart is maintained at the expense of kidney, skin etc. This results in decreased blood flow to the skin, leading to cyanosis. This is called diving reflex.

H. Arterial and venous obstruction: Any condition causing stagnation of blood flow will result in an increased amount of reduced hemoglobin.

 

3. Mixed Cyanosis-

A. Acute left ventricular failure

B. Mitral stenosis (left atrial failure and peripheral vasoconstriction).

C. Cardiogenic shock

D. Acute pulmonary edema

E. Congestive cardiac failure

F. Hypotension

4. Differential Cyanosis-

A. Only of lower limbs (the hands are pink, but the feet are blue) - Patent ductus arteriosus (PDA) with reversal of shunt. In PDA, the deoxygenated blood directly enters the systemic circulation and the part of the body distal to this shunt is cyanosed

B. Only of upper limbs (the hands are blue but feet are pink) - PDA with reversal of shunt in a transposition of great vessels.

C. Cyanosis of left upper limb and both lower limbs- PDA with reversal of shunt and pre ductal coarctation of aorta.

D. Persistent pulmonary hypertension of the newborn (PPHN)

E. Left ventricular outflow obstruction

F. Ductal opening proximal to the origin of left subclavian artery with reversal of shunt-cyanosis is seen in both lower limbs and left upper limb

 

 

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5. Reverse Differential Cyanosis-

It is the condition where only the upper part of the body is cyanosed and the lower part is normal.

It is seen in the following conditions:

PDA + TGV + severe pulmonary hypertension

PDA + TGV + pre-ductal coarctation of aorta

 

Conditions where Cyanosis does not occur-

1. In severe anemia where hemoglobin is less than 5 gm%, even if whole of the hemoglobin is reduced in the capillaries, it will be less than the critical level of 5 gm% and cyanosis does not occur.

2. In carbon monoxide poisoning where carboxy-hemoglobin prevents reduction of oxyhemoglobin and the former has a cherry red color. Hence there is no cyanosis.

 

PATHOPHYSIOLOGY-

Cyanosis typically occurs when the amount of oxygen bound to hemoglobin is very low. ^. Oxygen in the blood is carried in two forms. Approximately 2% is dissolved in plasma and the other 98% bound to haemoglobin.^2,3  The presence of cyanosis might be an indication of inadequate oxygen delivery to the peripheral tissues. It also could be related to an increased oxygen extraction by the peripheral tissues.

The presence of jaundice, color of skin, ambient temperature, or light exposure might affect the assessment of cyanosis^4. Anemia or polycythemia also plays a role in cyanosis. The level of hypoxia required to produce clinically evidenced cyanosis varies for a given level of hemoglobin⁵. Therefore, children with polycythemia may exhibit cyanosis at relatively high arterial saturations while it is more difficult to discern cyanosis in a severely anaemic infant unless the oxygen saturation is extremely low.

 

Differences between Cardiac and Respiratory Cyanosis

S.No.		Cardiac	Respiratory
1	Symptom	Tachypnoea	Dyspnoea
2	Onset	Early	Variable
3	Retractions	Less pronounced	More pronounced
4	Cyanosis on crying	Increase	Improve
5	Hyperoxia test	No significance increase pO2	Increase in pO2
6	pCO2	Normal or low	May be increased

 

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Hyperoxia test is done to distinguish cyanosis because of Cyanotic CHD’s or because of respiratory pathology –

 

 

DIFFERENTIAL DIAGNOSIS

Circumoral cyanosis:

Bluish discolouration around the lips (and not on the lips) may be seen in normal children and newborns due to the underlying veins. This is areas that are visible when the normal arterial supply is diminished. It may be seen in infants during feeding and resolves spontaneously following feeding.

It is also seen after the ingestion of certain drugs such as dapsone. This should not be confused with cyanosis as lips, tongue and other sites such as nail beds are pink.

 

Pseudocyanosis is a bluish tinge of the skin and mucosae, which is usually drug induced such as amiodarone and clomipramine.

Cyanosis in new-borns babies

Cyanosis is commonly observed in the area around a baby’s mouth. Sometimes even the palms, soles of the feet, head, or torso turn blue. This indictaes that the baby is not getting enough oxygen. Transient cyanosis clears in a few minutes after birth.  Pulse oximetry studies of healthy term and preterm infants who did not require resuscitation at birth demonstrated

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that preductal oxygen saturation (SpO₂) is ~60% at birth and takes 5–10 min to reach 85–90%. Current guidelines recommend starting resuscitation with 21% oxygen in term infants. Oxygen supplementation is then guided by preductal SpO₂ and adjusted to maintain SpO₂ values in the goal saturation range at the corresponding minute of postnatal life

DIAGNOSTIC EVALUATION-

Diagnosis approach of cyanosis in children is based on careful history, a thorough physical and systemic examination, and the use of investigations. As detailed below the history and physical examination are very important in determining the cause of cyanosis-

1.     Assess type of cyanosis : Central;/peripheral/other

2.     Age of onset : Early perinatal period : congenital cause

    Late onset:  Acquired causes

3.     Pulse oximetry: to see for level of oxygen saturation

4.     Co-oximeter blood gas analyzer: It can measures the pH and levels of carbon dioxide and oxygen along with Carbonmonoxy,  Methemoglobin and Sulfhemoglobin .

5.     Complete Blood Count: Haemoglobin levels are increased with the prevalence of chronic Cyanosis. The white cell count increases in conditions like pneumonia and pulmonary embolism.

6.     ECG: Taken to completely rule out the prevalence of cardiac abnormalities.

7.     Ventilation-perfusion scan or Pulmonary Angiography is taken to rule out pulmonary causes.

8.     Echocardiography/color doppler : To fix cardiac causes

9.     X Ray Chest : To look for pulmonary causes

10.  CT scan/MRI : To diagnose both cardio or pulmonary causes

11.  Hb electrophoresis : To see for Hb M

12.  Haemoglobin spectroscopy will look for methemoglobinemia, or sulfhemoglobinemia.

13.   Digital Subtraction Angiography: is done to completely rule out conditions like acute arterial occlusion

14.  A duplex Doppler or Venography can detect the prevalence of acute venous occlusion.

15.  Isoelectric focusing: Both sulfHb and metHb show an absorption peak at about 620 nm that is not present in deoxyHbA.  Thus Sulfhemoglobin has a similar peak to methemoglobin on a spectral absorption instrument. The sulfhemoglobin  spectral curve, however, does not shift when cyanide or dithionate is added, a feature that distinguishes it from methemoglobin.

Management of cyanosis-

Treatment of cyanosis depends upon underlying cause-

Cyanosis due to hypothermia	Warming
Cyanotic CHD	Corrective surgery
Methemoglobinemia	Vit “C”,  Methylene blue
Sulf hemoglobinemia	Remove offending agent
Drug induce cyanosis	Drug withdrawal
Respiratory conditions	Oxygen inhalation
New born	21% Room air resuscitation to start with

 

 

CONCLUSION

 

The presence of cyanosis has a lot of clinical significance and cyanosis is frequently encountered in clinical practice, and the differential diagnosis can be challenging as there are many conditions that can cause cyanosis. Early diagnosis depends on early recognition of the findings and a systematic approach to the children with cyanosis. The management of cyanosis can be very challenging, and at times requires a multidisciplinary approach.