TableĀ 5

Pulmonary causes of central cyanosis

ProblemMechanismPresentation and investigations
Parenchymal disease:
Respiratory Distress Syndrome (RDS)/Surfactant deficiency
Transient tachypnoea of the newborn
Meconium aspiration
Congenital abnormality leading to pulmonary hypoplasia: diaphragmatic hernia, congenital cystic adenomatoid malformation (CCAM)
Pulmonary disease leads to impaired alveolar gas exchange resulting in decreased arterial oxygen saturationsHistory: risk factors for sepsis, meconium, oligohydramnios, prematurity, abnormal antenatal scans.
Examination: tachypnoea, intercostal recession, use of accessory muscles, crackles, wheeze. Cyanosis may improve on crying.
CXR: cardiac shadow normal, lung fields will most likely be abnormal.
Gas: raised pCO2 and respiratory acidosis.
Saturations: no difference in preductal and postductal readings, oxygen saturations will usually normalise in 100% oxygen.
Normal ECG and echocardiogram
Alveolar ventilation:
Neuromuscular hypoventilation: Spinal muscular atrophy, congenital myopathy, congenital myotonic dystrophy
Central hypoventilation syndrome
Progressive hypoventilation will ultimately lead to hypoxiaHistory: may be family history of neurological disorder, respiratory distress since birth, unable to wean from ventilator.
Examination: neurological signs: hypotonia, reduced reflexes, poor suck, abdominal breathing