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During a physical examination, an infant appears blue. Cyanosis can be caused by a rise in deoxygenated hemoglobin (more common) or an abnormal hemoglobin disorder.


  1. Does the infant have respiratory distress? If the infant has increased respiratory effort with increased rate, retractions, and nasal flaring, respiratory disease should be high on the list of differential diagnoses. Cyanotic heart disease usually presents without respiratory symptoms (“happy blue baby”) but can have effortless tachypnea (rapid respiratory rate without retractions). Blood disorders usually present without respiratory or cardiac symptoms.

  2. Does the infant have a murmur? A murmur usually implies heart disease, but in infants with congenital heart malformations, <50% have a murmur in the newborn period. Transposition of the great vessels can present without a murmur (∽60%). Muffled heart sounds can indicate pericardial effusions or pneumopericardium.

  3. Was the infant cyanotic at birth? Infants with transposition of the great vessels and tricuspid atresia can present almost immediately at birth with cyanosis. In the perinatal period, infants with truncus arteriosus, total anomalous pulmonary venous return, and tetralogy of Fallot can present with cyanosis.

  4. Is the cyanosis continuous, intermittent, cyclical, sudden in onset, or occurring only with feeding or crying? Intermittent cyanosis is more common with neurologic disorders; these infants may have apneic spells alternating with periods of normal breathing. Cyclical cyanosis can occur with nasal obstruction. Continuous cyanosis is more commonly associated with intrinsic lung disease or heart disease. Cyanosis with feeding can occur with esophageal atresia and severe gastroesophageal reflux. Sudden onset of cyanosis may occur with an air leak, such as pneumothorax. Cyanosis that disappears with crying may mean choanal atresia. Cyanosis only with crying can occur in infants with tetralogy of Fallot. Cyanotic spells with no or minimal coughing can occur with pertussis. Crying may improve cyanosis in respiratory disease and worsen it in cardiac disease.

  5. Is the pulse oximeter normal and the infant blue? The pulse oximeter measures oxygen saturation of hemoglobin that is available to bind oxygen. If there is abnormal hemoglobin, it will not be measured. If you see a normal pulse oximeter in a cyanotic infant, think methemoglobinemia.

  6. Has the baby had the recommended pulse oximetry screening for congenital heart disease? This has been recommended by the American Academy of Pediatrics (AAP) in all newborns (see Newborn Physical Examination) as a useful method for screening for critical congenital cyanotic heart disease.

  7. Is there differential cyanosis (DC)? Differential cyanosis is when there is cyanosis of the upper or lower part of the body only, and it usually signifies serious heart disease. The prerequisite for this to happen is the presence of a right-to-left shunt through the patent ductus arteriosus (PDA). To diagnose this, oxygen saturation should be measured in the preductal (right hand is preferred since it accurately reflects preductal value) and postductal (foot). There are 2 different types of differential cyanosis.

    1. Pink upper half of the ...

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