Optimising the Duration of Cooling in Mild Encephalopathy

Although therapeutic hypothermia for 72 hours reduces brain injury and improves long term neurodevelopmental outcomes after moderate or severe neonatal encephalopathy, the benefits and optimal duration of cooling therapy in mild encephalopathy is not known. Adverse neurodevelopmental outcomes at 2 years occur in 16% of babies with un-treated mild neonatal encephalopathy. In the phase I of the COMET trial, we have shown that it is feasible to identify and randomise babies with mild encephalopathy, and to obtain the primary outcome (proton MR spectroscopy levels of Thalamic N-acetyl Aspartate) accurately. The phase II of the COMET trial will examine the benefits and optimal duration of cooling therapy in babies with mild encephalopathy. Research questions 1. Does whole body cooling initiated within 6 hours of birth and continued for 72 hours increase thalamic MR spectroscopy N-acetyl aspartate levels in babies with mild encephalopathy, when compared with those who are not cooled? (Cohort 1) 2. In babies with mild encephalopathy undergoing cooling therapy as clinical care, does rewarming at 48 hours as opposed to 72 hours result in similar thalamic N-acetyl aspartate levels? (Cohort 2) Study Population Cohort 1: A total of 60 babies with mild encephalopathy (\>36 weeks; \>2Kg) aged less than 6 hours will be recruited from several tertiary neonatal units in the UK, Europe, USA and Canada, over a 2 year period. The babies will be randomised to usual care (no cooling) or cooling therapy (core temperature 33 to 34 C) for 72 hours within six hours of birth. MR imaging and spectroscopy will be performed between 4 to 14 days after birth. Cohort 2: A total of 80 babies will mild encephalopathy (\>36 weeks; \>2Kg) aged 24 to 48 hours and undergoing cooling therapy as a part of standard clinical care will be recruited from several UK cooling centres, over a 2 year period. The babies will be randomised to rewarming after 48 hours or 72 hours of cooling therapy. MR imaging and spectroscopy will be performed between 4 to 14 days after birth. The babies recruited to cohort 1 will not be eligible for recruitment to cohort 2. Primary outcome (both cohorts) • Proton MR spectroscopy Thalamic N-acetyl aspartate levels between 4 to 14 days of age. Benefits of the trial These data will inform the national and international guidelines on management of babies with mild neonatal encephalopathy. If a shorter duration of cooling is as good or better than 3 days of cooling, this will reduce the intensive care stays, opioid use and separation from parents.