Respiratory distress syndrome in newborns, and why CPAP comes first

Respiratory distress syndrome (RDS) is the most common breathing problem in babies born early. It happens because the lungs have not yet made enough surfactant, a natural coating that keeps the tiny air sacs open. Today we treat it with steroid injections before birth, CPAP, surfactant medicine and caffeine, and most babies recover well.

What is respiratory distress syndrome in a newborn?

RDS is breathing difficulty caused by a shortage of surfactant in the lungs. Without enough surfactant, the tiny air sacs collapse each time the baby breathes out.

The lungs contain millions of small air sacs. Each one is lined with a thin film of water, and water pulls inward, trying to close the sac. Surfactant is a mix of fats and proteins that lowers this pull. The lungs make more of it towards the end of pregnancy. A baby born early may not have enough, so every breath becomes hard work, like blowing up a new balloon again and again.

What are the signs of RDS in a baby?

Signs usually start within minutes to hours of birth: fast breathing, grunting, and the skin between the ribs sucking in with each breath.

• Breathing fast.
• A grunting sound on breathing out. The baby is partly closing the voice box to hold air in.
• Chest drawing in below or between the ribs.
• Nostrils flaring.
• Blue or grey colour, or a falling oxygen level on the monitor.

A chest X-ray showing hazy lungs helps confirm it.

Which babies get respiratory distress syndrome?

The earlier a baby is born, the more likely RDS is. The risk falls with each extra week the baby stays in the womb.

It can still occur in babies born a few weeks early, especially by planned caesarean before labour, and in babies of mothers with diabetes. Steroid injections given to the mother before birth lower the risk a great deal.¹

How do steroid injections before birth help the baby's lungs?

Steroid injections given to a mother at risk of early delivery speed up the baby's lung development. They reduce RDS, newborn deaths and probably brain bleeds.¹

Liggins and Howie reported a controlled trial of steroids before preterm birth back in 1972.² Since then, a Cochrane review of 27 trials has confirmed that one course lowers perinatal death, newborn death and RDS, in rich and poor countries alike.¹ European guidelines recommend steroids for all pregnancies at risk of birth before 34 weeks when the baby will receive active care.³ If you are pregnant and at risk of early delivery, ask whether you have had them, and make sure this is written in your transfer papers.

Do antenatal steroids work in India?

Yes, when the pregnancy is dated correctly and good newborn care is available. The WHO ACTION-I trial tested this in India and four other countries.⁴

The trial, published in the New England Journal of Medicine in 2020, gave dexamethasone or a dummy injection to 2852 women between 26 and 33 weeks of pregnancy in 29 hospitals in Bangladesh, India, Kenya, Nigeria and Pakistan. Newborn deaths fell from 23.5 percent to 19.6 percent, with no rise in infection in mothers.⁴ The trial was stopped early because the benefit was clear.

Should steroids be given after 34 weeks?

This is less clear, and practice varies. Steroids after 34 weeks reduce some breathing problems but cause more low blood sugar in babies.

In a large American trial of women at risk of delivery at 34 to 36 weeks, steroids lowered serious breathing problems in the first three days from 14.4 to 11.6 percent. But low blood sugar in the babies rose from 15 to 24 percent.⁵ European guidelines say steroids after 34 weeks in spontaneous preterm labour are not advisable because of concerns about later development.³ In India this is a decision for your obstetrician and neonatologist together.

What is CPAP and why is it used first?

CPAP (continuous positive airway pressure) blows gentle, steady air pressure through small nose prongs or a mask. It keeps the air sacs open while your baby does the breathing.

WHO strongly recommends CPAP for preterm babies with signs of RDS, and suggests bubble CPAP, a simple and affordable system widely used in India.⁶ European guidelines advise starting babies on breathing support without a tube from birth and avoiding a ventilator where possible.³

Is CPAP as good as a ventilator for premature babies?

For many babies it is, and it is gentler on the lungs. Trials show that starting with CPAP avoids a ventilator for a large share of very premature babies.

In the international COIN trial of babies born at 25 to 28 weeks, about half of those started on CPAP never needed a breathing tube in the first five days, and surfactant use was halved. Air leaks from the lung were more common with CPAP, 9 percent compared with 3 percent.⁷ In the American SUPPORT trial, babies started on CPAP needed fewer breathing tubes, fewer steroid medicines and fewer days on a ventilator.⁸

What is surfactant and when is it given?

Surfactant is a medicine made to replace what the baby's lungs are missing. It is dripped directly into the windpipe.

European guidelines suggest giving it early to babies whose RDS is getting worse, for example when they need more than 30 percent oxygen on CPAP at a pressure of at least 6 cm of water.³ Early treatment works better than late rescue.³ Surfactant is costly for many Indian families, which is one reason doctors use it carefully, but it should not be delayed when a baby needs it.

What is LISA, the gentle way to give surfactant?

LISA (less invasive surfactant administration) gives surfactant through a very thin, soft tube passed briefly into the windpipe while the baby keeps breathing on CPAP. The baby does not need to go on a ventilator.

A Cochrane review of 16 trials found that giving surfactant by thin tube, instead of through a full breathing tube, lowered the combined risk of death or chronic lung disease.⁹ European guidelines now call LISA the preferred method for babies breathing on CPAP.³ It needs a skilled team, and many Indian tertiary NICUs now use it.

When does a baby with RDS need a ventilator?

A ventilator is used when CPAP is not enough. Being ventilated is not a failure, and it does not mean your baby will do badly.

Common reasons are rising oxygen needs despite CPAP and surfactant, long or repeated breathing pauses, severe infection, an operation, or a baby who is simply too tired. Doctors aim to keep the time on a ventilator as short as possible, because long ventilation can injure immature lungs.³

Why does my baby need caffeine?

Caffeine helps premature babies breathe more regularly and come off breathing support sooner. It treats apnoea, the pauses in breathing that are common in babies born early.

In a trial of 2006 very small babies, those given caffeine were less likely to still need oxygen at 36 weeks, 36 percent compared with 47 percent.¹⁰ European guidelines describe caffeine as a well established part of newborn breathing care.³

What oxygen level is right for a baby with RDS?

Doctors usually aim for an oxygen saturation of 90 to 94 percent in premature babies on oxygen.³ A higher number is not better.

Too much oxygen harms the developing eyes and lungs. Too little is also risky. When five big trials were pooled, a lower target range led to more deaths, while a higher range led to more babies needing eye treatment.¹¹ The middle band balances both risks.

How long does RDS last, and what is chronic lung disease?

RDS usually gets worse over the first day or two, then improves as the baby starts making their own surfactant. Babies then move from CPAP to high flow and finally to room air.

Some very premature babies still need oxygen at 36 weeks postmenstrual age (weeks of pregnancy plus weeks since birth). This is called bronchopulmonary dysplasia (BPD), or chronic lung disease.¹⁰ Most of these babies improve steadily over the first year or two, though they get more wheezy chest infections. That is why vaccines for the whole family and keeping away from smoke matter so much later.

When should I worry about my baby's breathing at home?

Go to a doctor urgently if your baby shows any of these signs. In a large study of young infants, each of these signs, including fast breathing, predicted serious illness, and severe chest drawing in was one of the strongest.¹²

• Breathing 60 times a minute or more while calm.
• Chest drawing in deeply with each breath.
• Grunting.
• Blue or grey lips or tongue.
• Pauses in breathing.
• Too breathless to finish feeds.
• A temperature of 37.5 degrees C or more, or below 35.5 degrees C.