Saving thousands of newborns by cooling them down

1 June 2012

Giving birth is an exciting event for most but there can be complications for some and where babies experience a lack of oxygen at birth it can lead to devastating effects for parents and their babies. Known as birth asphyxia, this condition can happen in a number of situations such as when the umbilical cord compresses the baby’s airway, during a difficult delivery or when anaesthetic used during labour also sedates the baby.

Around one in 1,000 full-term babies in the UK suffer a lack of oxygen during labour and delivery severe enough to injure their brains. In the past, 70 per cent either died, or survived with cerebral palsy and learning disability. Worldwide, birth ashpyxia accounts for 23 per cent of newborn deaths.

In 1998, Thoresen and Whitelaw introduced the cooling treatment known as therapeutic hypothermia at Bristol’s Southmead and St Michael’s Hospitals in a bid to reduce some of the devastating after effects of birth asphyxia. The novel treatment built on Thoresen’s experimental research in Norway in the 1990s where she was the first investigator to show in the laboratory that mild cooling reduces injury in the newborn brain after oxygen deprivation.

The treatment induces hypothermia within the first six hours of life by lowering the baby’s core body temperature to 33.5 degrees C for 72 hours, before gradually rewarming the baby in intensive care. This revolutionary idea flew in the face of the accepted practice of keeping sick babies warm which had been current in neonatal nursing care for over a century.

Led by Thoresen and Whitelaw from Bristol’s School of Clinical Sciences, further successful clinical trials were co-ordinated between Bristol University, Imperial College, London and Oxford University with funding of £1 million from the Medical Research Council alongside colleagues from Leeds University and Belfast University.  Forty-two hospitals in the UK, Hungary, Sweden, Israel and Finland took part in the trials.

Now practised in neonatal intensive care units throughout the UK, therapeutic hypothermia is recommended by the National Institute for Health and Clinical Excellence (NICE) and the International Liaison Committee on Resuscitation (ILCOR) and is being adopted throughout the world.

Thoresen is now collaborating with Dr John Dingley of Swansea University to investigate how combining xenon gas with the cooling technique will improve the success of the treatment.  As Thoresen explains, “Xenon is a very rare and chemically inert anaesthetic gas found in tiny quantities in the air that we breathe.  In 2002, John Dingley and I realised the potential xenon and cooling might have in combination to further reduce disability.”

Dr Dingley has since invented a machine to successfully deliver the gas to newborns and, in a world first, Riley Joyce was the first baby to receive the treatment at Bristol’s St Michael’s Hospital in April 2010. A successful feasibility study has paved the way for further large scale clinical trials supported by funding from the children’s medical charity Sparks.

Key facts

• Babies’ body temperature is lowered to 33.5°C for 72 hours inducing total body hypothermia then gradually re-warmed in intensive care
• 1,200 severely asphyxiated infants were recruited to five international randomised clinical trials between 1999 and 2006.
• 44 % survived in clinical trial without any neurological abnormality
• Introduced as standard care in Bristol’s two neonatal intensive care units in December 2006 with 60% babies now surviving without significant injury compared to 30% previously.
• Recommended by the National Institute for Health and Clinical Excellence (NICE) and International Liaison Committee on Resuscitation (ILCOR) in 2010
• Now saves 1,500 babies from death and disability every year in the developed world.
• Discovery that addition of Xenon gas adds to the protective effects of cooling

Further information

• Marianne Thoresen is Professor of Neonatal Neuroscience at the School of Clinical Sciences in the Faculty of Medicine and Dentistry. Listen to Professor Thoresen talk about her research in this short film.
• Andrew Whitelaw is Emeritus Professor at the School of Clinical Sciences in the Faculty of Medicine and Dentistry
• St Michael’s Hospital is part of University Hospitals Bristol NHS Foundation Trust.  Southmead Hospital is part of North Bristol NHS Trust
• The Medical Research Council (MRC) supports and funds research with the aim of maintaining and improving human health.
• SPARKS is a medical children’s charity fundraising for research on medical conditions affecting babies, children and mothers-to-be.
• The National Institute for Health and Clinical Excellence (NICE) is the UK organisation responsible for providing national guidance on promoting good health and preventing and treating ill health.
• The International Liaison Committee on Resuscitation (ILCOR) provides a forum for liaison between principal resuscitation organisations worldwide.

Please contact Alison Leach for further information.