A BREATHLESS NEWBORN
History
You are called to the labour ward to see a full-term newborn baby boy because he has difficulty breathing. He was born 15 min ago to a 20-year-old first-time mother, who apparently had little antenatal care. The baby was born by Caesarean section because it was found to be in the breech position. The midwife said that the baby made a few cries immediately after birth, had good tone and a heart rate over 100 beats/min. She had placed him on the resuscitaire and then had to attend to the mother. When she next looked at the baby, he was breathing very fast and was making a grunting noise. The mother has mild learning difficulties but no history of any other significant medical problems or of drug use.
Examination
The baby looks an appropriate size for his gestational age, he is not dysmorphic, and he has been wrapped in a dry towel. His lips and tongue appear slightly blue. He is making an intermittent grunting expiratory sound, and his respiratory rate is 70/min. Air entry is reduced on the left side of his chest, with no increase in resonance on percussion. His heart rate is approximately 150 beats/min, his heart sounds are normal and his femoral pulses are palpable. His abdomen appears slightly concave. He is transferred urgently to the neonatal unit and a chest radiograph (Fig. 78.1) is taken shortly afterwards.
Questions
• What is the diagnosis?
• How should this newborn be managed?
• What other conditions can cause respiratory distress in a term newborn after an unremarkable delivery?
Medicine
The most common cause of respiratory distress in a term baby following a Caesarean section is transient tachypnoea of the newborn due to delayed clearance of lung fluid. However, this does not produce the clinical or radiographic features seen in this case. Here the diagnosis is congenital diaphragmatic hernia. Although many cases are picked up through antenatal screening, herniation of bowel through defects in the diaphragm can occur late in gestation or even after delivery. It usually presents with respiratory distress at, or shortly after, birth. The abdomen appears concave because some of its contents are within the thorax, the mediastinum and apex beat may be displaced and bowel sounds may be heard in the chest. The chest radiograph shows mediastinal shift with air-filled bowel loops occupying the left hemithorax. The baby has been intubated, a nasogastric tube is in place, and umbilical venous and arterial catheters have been inserted. It is important to intubate the baby early to prevent the swallowing of air, which can cause expansion of the bowel within the chest and further respiratory compromise. If the diagnosis is known before delivery, the use of bag-and-mask ventilation should be avoided for the same reason. A nasogastric tube should be placed to aspirate gastric fluid and air. Meticulous intensive care is needed to optimize the baby before surgery is performed because the lungs are usually hypoplastic (partly due to compression by bowel within the thorax) and pulmonary hypertension is a frequent complication. Mortality rates of 20 per cent are expected even with optimal care.
Causes of unexpected respiratory distress in the term newborn
• Transient tachypnoea of the newborn
• Pneumothorax
• Congenital pneumonia, sepsis
• Lung malformations, congenital diaphragmatic hernia
• Oesophageal atresia, tracheo-oesophageal fistula
• Choanal atresia, other upper airway malformations
• Congenital heart disease
• Anaemia, polycythaemia
• Cerebral haemorrhage
KEY POINTS
• Transient tachypnoea of the newborn is the most common cause of respiratory distress in a term baby, most often following Caesarean section.
• A newborn with congenital diaphragmatic hernia should be intubated promptly to prevent swallowed air distending the bowel within the thorax.
• Prognosis in congenital diaphragmatic hernia is mainly related to the degree of lung hypoplasia, and the mortality rate is approximately 20 per cent.
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