Simple test helps pick up dangerous baby heart defects

A simple new test could save babies’ lives, by picking up life-threatening heart defects before a newborn baby goes home from hospital. That’s the conclusion of a new study from Sweden.

What do we know already?

About 1 in every 100 babies born in the UK are born with a heart defect. There are lots of different types. The heart defect may mean that the blood doesn’t circulate properly. This can cause a problem called duct dependent circulation, where the baby’s blood flow depends on a hole in a heart artery, which should have closed up when the baby was born.

Duct dependent circulation is dangerous, because if the hole in the artery does close up naturally, it cuts off the baby’s blood supply. The baby may die suddenly. It’s really important that duct dependent circulation is spotted quickly, so it can be treated. Sometimes it can be picked up by scans before the baby is born. But that doesn’t always happen.

Currently, babies born in the UK are given a physical examination within 24 hours of birth, before they are discharged. The examination includes checking their pulses and listening to their hearts. But this examination doesn’t pick up all the potential problems. Also, nowadays babies often go home quite soon after being born, and this trend is increasing. Some doctors are worried that problems like duct dependent circulation are more likely to be missed, because the signs that the examination looks for might not have developed by the time the baby goes home.

One quick and easy test, called pulse oximetry, might help spot babies with heart defects. Pulse oximetry uses sensors held against the skin to check how much oxygen is in a baby’s blood. If a baby has duct dependent circulation, he or she might have less oxygen in the blood than normal, or different amounts of oxygen in the blood circulating through his or her hands and feet.

A new study set out to find out how good pulse oximetry was at spotting heart problems. Previous studies have been encouraging, but have been too small to be sure about the results.

What does the new study say?

Babies who had pulse oximetry as well as a physical examination before being sent home were much less likely to be sent home with undiagnosed duct dependent circulation. The study found:

* In centres using pulse oximetry, babies with duct dependent circulation had an 8 in 100 chance of being sent home undiagnosed
* In centres not using pulse oximetry, they had a 28 in 100 chance.

Babies who had abnormal pulse oximetry results were sent for an echocardiogram. An echocardiogram is a scan that looks at the heart, and can show heart defects.

Tell me more about the study’s findings.

Pulse oximetry worked best when combined with a physical examination. It picked up some problems that would have been missed by physical examination, but physical examinations also picked up some problems that would have been missed by pulse oximetry alone.

How reliable are the findings?

These results are quite convincing, because the difference in the chance of being diagnosed with or without pulse oximetry were so big. But because of the type of study, we can’t be completely sure that it was all down to the new test. That’s because the centres using pulse oximetry might have been better at diagnosing problems through physical examination as well. These doctors all knew they were taking part in a study, so they were probably extra-keen to be sure they didn’t miss any problems. The doctors at the other centres didn’t know they were taking part in a study. They just did what they normally did, and the researchers used the figures from these centres for comparison afterwards. This makes the findings a bit less reliable.

Where does the study come from?

The study was carried out at hospitals in West Götaland, Sweden. It was published in the British Medical Journal (BMJ).

What does this mean for me?

Pulse oximetry isn’t available routinely for new-born babies in the UK at the moment. A big study started last year in Birmingham, to see how well it works in UK hospitals. If the results are positive, pulse oximetry might become a routine test.