Relationship between fluid management, changes in serum sodium and outcome in hypernatraemia associated with gastroenteritis.

OBJECTIVE: To describe the relationship between fluid management, serum sodium and outcome in critically ill children with hypernatraemic gastroenteritis. METHODS: A retrospective study of 57 children with hypernatraemic gastroenteritis admitted to a paediatric intensive care unit in Cape Town, South Africa. Data were collected on fluid management, serum electrolytes and adverse outcome (seizures, new neurological deficit and mortality) and analysed using univariate and multivariate statistics. RESULTS: Median admission sodium was 165 mmol/L (145-199). Median volume of intravenous rehydration fluid was 6 mL/kg/h (144 mL/kg/day), with sodium concentration of 61 mmol/L (0-154 mmol/L), resulting in a median fall in sodium of 0.6 mmol/L/h (14.4 mmol/L/day). Fourteen children (25%) had seizures during rehydration, four children (7%) died and five children (9%) developed neurological deficit. Median admission sodium in children with adverse outcome was 172 mmol/L, with rate of fall of 0.63 mmol/L/h, compared with median admission sodium of 163 mmol/L and rate of fall of 0.48 mmol/L/h, in children with good outcome (P=0.068 and P=0.08, respectively). Median sodium content of intravenous solution was 61 mmol/L in both groups (P=0.68). Multivariate analysis demonstrated that neither sodium content of intravenous solution (P=0.59), nor rate of fall of sodium (P=0.31), was independently associated with adverse outcome. CONCLUSIONS: Rehydration in hypernatraemic gastroenteritis using intravenous solutions containing 61 mmol/L sodium would be expected to correct serum sodium at a rate of approximately 0.6 mmol/L/h. Neither sodium content of the intravenous solution, nor rate of correction of sodium, was independently associated with adverse outcome.