Respiratory disease in a neonate: Transient Tachypnoea of the Newborn

Question 1

Define transient tachypnoea of the newborn.

Answer 1

Acute, self-limiting tachypnoea in the absence of other causes metabolic acidosis, RDS or infection.

Question 2

Explain the aetiology/risk factors for transient tachypnoea of the newborn.

Answer 2

Secondary to delayed resorption of fetal lung fluid causing decreased pulmonary compliance and decreased tidal volume with increased dead space.

Association/Related: Elective caesarean section and precipitate deliveries (neonate has not experienced all stages of labour), maternal asthma.

Question 3

What is the pathophysiology of transient tachypnoea of the newborn?

Answer 3

In utero lung epithelium secretes Cl- and fluid but doesn’t have the ability to actively reabsorb Na+ (occurs late gestation). Postdelivery witch to Na+ resorption secondary to circulating catecholamines.

Changes in O2 tension, also increased Na+ resorption ability and increased amount of epithelial Na+ channels (increased gene expression). With a shorter delivery/lack of some stages of labour (caesarean section) then Na+ resorption doesn’t occur, leading to TTN.

Question 4

Summarise the epidemiology of transient tachypnoea of the newborn.

Answer 4

Most common cause of respiratory distress in full-term infants. 1–2% of neonates have respiratory distress; of these, 33–50% have TTN. M¼F. Nil ethnic variation. Term neonates.

Question 5

What are the symptoms of transient tachypnoea of the newborn?

Answer 5

Usually occurs in the first 1-3 hours following an uneventful normal preterm, term vaginal or elective caesarean section delivery. Most cases resolve < 72 hours.

Question 6

What are the signs of transient tachypnoea of the newborn?

Answer 6

Early onset of tachypnoea in the neonate +/- signs of respiratory distress; recession (intercostal/subcostal/sternal), expiratory grunting, nasal flaring and cyanosis (severe cases).

Question 7

What are appropriate investigations for transient tachypnoea of the newborn?

Answer 7

CXR: Prominent perihilar streaking (distended pulmonary veins and lymphatics), patchy infiltrates, fluid in the horizontal fissure, flat diaphragms and occasional pleural fluid.

ABG: Degree of decreased pO2 depends on the amount of fluid on the lungs.

Blood cultures: To exclude infectious causes of respiratory distress.

Question 8

What is the management for transient tachypnoea of the newborn?

Answer 8

• Exclusion of other causes of neonatal respiratory distress; pneumonia (e.g. group B haemolytic streptococcus), meconium aspiration, pulmonary haemorrhage or cerebral hyperventilation that follows birth asphyxia.
• Ventilatory support as required including supplemental oxygen and occasionally continuous positive airways pressure (CPAP).
• Maintenance hydration and intravenous fluids.
• NBM until respiratory rate <60/min to decrease aspiration incidence.
• Prophylactic antibiotics, discontinued once exclusion of infectious causes (-ve BC).
• Diuretics (frusemide) do not improve outcome.

Question 9

What are complications associated with transient tachypnoea of the newborn?

Answer 9

Usually no complications if managed with good supportive measures.

Question 10

What is the prognosis of transient tachypnoea of the newborn?

Answer 10

Excellent as self-limiting disorder. Possible link with development of wheezing syndromes in childhood.