Subcutaneous fat necrosis in neonates with hypoxic ischaemic encephalopathy registered in the Swiss National Asphyxia and Cooling Register

Background: Neonates with hypoxic ischaemic encephalopathy (HIE) are routinely treated with therapeutic hypothermia (TH) for 72 h in order to improve neurological outcome. Subcutaneous fat necrosis (SCFN) is an adverse event occurring in neonates with HIE. Methods: We analyzed risk factors for SCFN regarding demographic factors, cooling methods and deviation from target temperature range during hypothermia therapy. Data of all neonates registered in the National Asphyxia and Cooling Register in Switzerland between 2011 and 2013 were analyzed. Results: 2.8 % of all cooled neonates with HIE developed SCFN. Perinatal and neonatal characteristics did not differ between neonates with and without SCFN. Applied cooling methods did not correlate with the occurrence of SCFN. In neonates with SCFN 83.3 % of all noted temperatures were within the target temperature range versus 77.5 % in neonates without SCFN. Neonates with SCFN showed 3.6 % of all measured temperatures below target temperature range compared to 12.7 % in neonates without SCFN. Conclusion: Subcutaneous fat necrosis in the neonate with HIE undergoing TH is a potential adverse event that seems to occur independently from the whole-body cooling method applied and proportion of temperature measurements outside target temperature range. In this cohort, moderate overcooling associated with moderate hypothermia (33.0-34.0 degrees C) does not seem to be an independent risk factor for SCFN. There is no correlation between the severity of HIE and incidence of SCFN.