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Treatment of hyponatremic encephalopathy with a 3% sodium chloride protocol: a case series.

BACKGROUND
3% sodium chloride solution is the accepted treatment for hyponatremic encephalopathy, but evidence-based guidelines for its use are lacking.


STUDY DESIGN
A case series.


SETTING & PARTICIPANTS
Adult patients presenting to the emergency department of a university hospital with hyponatremic encephalopathy, defined as serum sodium level < 130 mEq/L with neurologic symptoms of increased intracranial pressure without other apparent cause, and treated with a continuous infusion of 500mL of 3% sodium chloride solution over 6 hours through a peripheral vein.


PREDICTORS
Hyponatremic encephalopathy defined as serum sodium level < 130 mEq/L with neurologic symptoms of increased intracranial pressure without other apparent cause.


OUTCOMES
Change in serum sodium level within 48 hours, improvement in neurologic symptoms, and clinical evidence of cerebral demyelination, permanent neurologic injury, or death within 6 months' posttreatment follow-up.


RESULTS
There were 71 episodes of hyponatremic encephalopathy in 64 individuals. Comorbid conditions were present in 86% of individuals. Baseline mean serum sodium level was 114.1±0.8 (SEM) mEq/L and increased to 117.9±1.3, 121.2±1.2, 123.9±1.0, and 128.3±0.8 mEq/L at 3, 12, 24, and 48 hours following the initiation of 3% sodium chloride solution treatment, respectively. There was a marked improvement in central nervous system symptoms within hours of therapy in 69 of 71 (97%) episodes. There were 12 deaths, all of which occurred following the resolution of hyponatremic encephalopathy and were related to comorbid conditions, with 75% of deaths related to sepsis. No patient developed neurologic symptoms consistent with cerebral demyelination at any point during the 6-month follow-up period.


LIMITATIONS
Lack of a comparison group and follow-up neuroimaging studies. Number of cases is too small to provide definitive assessment of the safety of this protocol.


CONCLUSIONS
3% sodium chloride solution was effective in reversing the symptoms of hyponatremic encephalopathy in the emergency department without producing neurologic injury related to cerebral demyelination on long-term follow-up in this case series.