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Cold comfort for baby

Jonathan Wood

A new study published last week in the New England Journal of Medicine has shown that a simple cooling treatment for babies that suffer a lack of oxygen at birth could avoid brain damage in over 100 babies a year.

The TOBY (Total Body Hypothermia for Neonatal Encephalopathy) trial was led jointly by Oxford University and Imperial College London and was funded by the Medical Research Council.

I talked to TOBY Study Co-ordinator, Brenda Strohm RGN of the National Perinatal Epidemiology Unit [NPEU] at Oxford University.

OxSciBlog: What is birth asphyxia and how can it harm babies?
Brenda Strohm: Birth asphyxia occurs when a baby experiences lack of oxygen during labour and delivery, which can result in damage to the brain and other organs. This can occur if the umbilical cord is tight around the baby or the placenta separates from the womb too early, for example. Asphyxia can occur in both preterm and full term births; the TOBY Study was concerned only with full term babies. It is estimated that about 2 in 1000 full term births are affected, which is about 1400 cases a year in the UK.

OSB: What are the problems in detecting or treating birth asphyxia?
BS: In some cases there is warning that the baby is at risk, with signs of distress in the baby during labour or if there is a haemorrhage for example. But there may be no warning at all; only when the baby is born needing resuscitation does the condition become apparent.

OSB: What did the TOBY trial set out to investigate?
BS: The aim of TOBY was to find out whether whole body cooling (or hypothermia) as a treatment for birth asphyxia improves the outcomes for these babies and is a safe treatment.

The treatment is simple to use: the baby is nursed on a mattress which is cooled by circulating fluid within it. Typically the mattress temperature is set at around 28°C to maintain the baby’s temperature at 33–34°C, instead of the normal 37°C. The cooling lasts for 72 hours and then the baby is slowly re-warmed.

Brain injury from lack of oxygen occurs in two phases: immediately, when the brain is starved of oxygen and then later when the blood supply is restored. There is a chemical cascade when the machinery of the cells breaks down when it is possible to intervene to prevent long-term damage. It is during this ‘therapeutic window’ that cooling treatment is used as the intervention.

OSB: What were the findings of the study?
BS: 325 babies were recruited immediately after birth and were randomly allocated cooling treatment with intensive care or standard intensive care. While there was no difference in the deaths that occurred in the two groups, there was a significant improvement in the rate of survival without neurological abnormality in the cooled group. The cooled group showed improved outcomes in a range of other developmental measures at 18 months of age.

The study is important because birth asphyxia is associated with high morbidity in survivors that is a major burden for the child and family and on health and educational resources as the child matures. Up to now there has not been an effective treatment to offer these babies. Any treatment or intervention that can reduce this burden not only improves quality of life but reduces the costs of providing ongoing care.

OSB: What should pregnant women take from this study?
BS: Fortunately the vast majority of pregnant women will never need to know about cooling for their baby. For those whose baby is affected by birth asphyxia, there is now the knowledge that there is a simple treatment that could make a real difference to their baby’s future, although not every baby is bound to benefit from it.

OSB: What would you like to see happen next based on these findings?
BS: Cooling is not currently considered to be a standard treatment, but clinicians are increasingly using it. In the TOBY Study there were 34 UK neonatal units equipped to offer cooling, now there are nearly 50 with others obtaining the equipment and undergoing preparatory training. Many babies are transferred to units that can provide cooling treatment.

The National Institute for Health and Clinical Excellence (NICE) will be reviewing cooling as a treatment for birth asphyxia in full term babies now that TOBY has published its results. If NICE do recommend cooling, then it will become a standard treatment in the UK.