5 Ts of cyanosis in neonates

1. Truncus Arteriosus (1 trunk)
2. Transposition of the Great Arteries  (2 arteries) - CXR "egg on a string"
3. Tricuspid Atresia (tri=3)
4. Tetralogy of Fallot (tetra=4) - CXR boot shaped or egg on its side
5. TAPVR (5 letters) Total anomalous pulmonary venous return - CXR snow man appearance
6. and Hypoplastic Left Heart Syndrome

Clinical cyanosis:

• Need 5 g reduced Hb/100 ml blood (in cutaneous venules) to be clinically cyanotic
• we normally have 2 g of reduced Hb in veins, so we need 3 more grams
• normally we have about 15 g hb... 3/15 = 20%
• So, when we are 20% desaturated (or 80% arterial sat), we get cyanosis
• if polycythemic, ie 20 g Hb, 3/30 = 15%, therefore you can be cyanotic with higher sats (85%)
• vice versa with anemia

Causes of cyanosis:

1. decreased SaO2 (central cyanosis) i.e., R->L shunt or decreased alveolar ventilation (CNS, ventilatory drive, obstruction, lung structure, VQ mismatch, weak resp muscles
2. increased deoxygenation in capillaries (peripheral) i.e., circ shock, CHF, acrocyanosis in nbn
3. abnormal Hb i.e. methemoglobinemia, CO poisoning

Central cyanosis: due to desaturation of arterial blood
Peripheral cyanosis: normal arterial sats. Due to increased oxygen extraction from conditions of sluggish blood flow ie shock, hypovolemia, vasoconstriction from cold
Circumoral cyanosis: bluish color of skin around mouth; if isolated, of no concern. Worry if it is because of decreased cardiac output -> in this case sats will be normal. ~ reflects sluggish flow in a child w/ fair skin, or cold vasoconstriction.

Newborn: acrocyanosis is normal (plus some newborn polycythemia)
Cyanosis is better perceived in natural light
Chronic cyanosis can lead to clubbing

Crying and cyanosis:

• if cyanosis worsens: cyanotic heart defect
  if cyanosis improves, consider pulmonary or CNS causes