What is respiratory distress syndrome (RDS)?

Babies born without enough surfactant (a substance which helps the air sacs in the lung remain open), develop a condition called respiratory distress syndrome (RDS), also known as hyaline membrane disease.

Who is affected and what are the risk factors?

RDS occurs almost exclusively in preterm born infants due to the immaturity of their lungs and an inability to make sufficient surfactant. Babies born at the lowest gestations are at greatest risk: RDS affects approximately half of infants born at 26-28 weeks of gestation and a  third of babies born at 30-31 weeks of gestation. Given antenatal steroid medication to mothers in the days before delivery reduces the risk and severity of RDS and is an important preventive treatment.

What is the cause?

Surfactant is secreted by the lining cells in the lung in small quantities from mid-gestation – 23-25 weeks. Surfactant synthesis is switched on by the processes that lead to birth (and by antenatal steroids) but may not be established until several days after birth.

Surfactant works in the airsacs (called alveoli), and its presence makes the lungs easier to inflate and less likely to deflate at the end of a breathing cycle.  As babies work harder to open their lungs or in the presence of asphyxia or infection, more surfactant is used up, leading to the symptoms of RDS.

How is it diagnosed?

The healthcare team will look for symptoms such as rapid  breathing, apnoea, and a characteristic grunt just as the baby breathes out. Blood tests and X-rays of the chest are used to confirm the diagnosis and help the team know the treatment is working.

How is it managed?

If preterm birth is not completely unexpected, the mother may be given steroids which cross the placenta and help the baby to produce surfactant in the lung.

The healthcare teams now prefer to prevent RDS if they can and so they often help babies breathing, for example with CPAP, before they develop symptoms.  If it looks likely that the baby is developing RDS, the team can give artificial or natural surfactant, also called surfactant replacement therapy. There are several types of surfactant replacement therapy available. Some experts prefer to give surfactant replacement treatment into the lungs immediately after birth, while others give it when needed. The dose may need to be repeated.

Alongside surfactant, babies usually need extra help to stabilise breathing, e.g. by giving extra oxygen or some form of breathing support, such as CPAP or ventilation. Most affected preterm babies recover from RDS without severe complications over the course of the first week.

© 2018 EFCNI - European Foundation for the Care of Newborn Infants
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