Is hyponatremia in neonates with hypoxic ischaemic encephalopaty who underwent therapeutic hypothermia associated with poor neuro-developmental outcome at 12 months of ages?
Thesis (MMed)--Stellenbosch University, 2016.
ENGLISH SUMMARY: Introduction Perinatal asphyxia occurs at an incidence of 1-2% per live births in developed countries, and much higher in developing countries. The main consequence of significant perinatal asphyxia is neonatal encephalopathy which, if severe enough, may result in death or long term neurological disability. Therapeutic hypothermia (TH) has emerged as a promising therapy in reducing its mortality and morbidity. Electrolyte abnormalities, including hyponatremia, are a common occurrence in neonates with HIE. Possible causes of hyponatremia are renal impairment secondary to acute kidney injury and the syndrome of inappropriate anti-diuretic hormone (SIADH). Therapeutic hypothermia itself has an impact on fluid and electrolyte balance. Serum sodium concentration is closely linked to serum osmolality and neuroprotective strategies following brain injuries usually include maintaining serum sodium within normal limits to minimize further damage. Studies done on adults have shown adverse effects of dysnatremia on neurologic outcome following brain injuries. These studies however looked at disease entities more common in the adult population. There are very few studies assessing dysnatremia in the neonatal population, hence the interest in carrying out this analysis. Methods This retrospective descriptive study is a sub-analysis of a previous prospective study for infants who met therapeutic hypothermia criteria after sustaining hypoxic ischemic encephalopathy. The infants were treated in the neonatal intensive care unit of the Department of Paediatrics and Child Health at the Tygerberg Children’s Hospital between 2008 and 2011. According to the cooling protocol, each infant had serum sodium levels measured on three consecutive days during cooling. After discharge the neurodevelopmental functional status was assessed during follow-up visits. The primary aim of the study was to determine if there is an association between hyponatraemia in neonates with HIE who underwent therapeutic hypothermia and neurodevelopmental outcome at 12 months of age, as assessed by Bayley Screening tool (BSID - III) Results The patient records search yielded 100 patients from 2008 to 2011. After excluding those who did not meet the inclusion criteria, fifty patients were studied. Twenty-one (21/50; 42%) patients had hyponatremic episodes. The remainder (29/50; 58%) were normonatremic. None were hypernatremic. Thirty-five (35/50; 70%) were assessed as normal at twelve-month follow up, nine (9/50; 18%) as mildly abnormal and 6 (6/50; 12%) as abnormal. There was no association between neurodevelopmental functional status at 12 months and frequency of hyponatremic episodes in the first week of life (p = 0.444). There was a significant association between number of hyponatremic episodes and HIE grade. We found no association between HIE grade and neurodevelopmental functional status at 12 months. Conclusion There was no significant association between hyponatremia after hypoxic-ischemic encephalopathy and neurodevelopmental outcome at 12 months. There was a positive correlation between HIE grade and frequency of hyponatremic episodes.
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