Severe Hyponatremia in the Emergency Department Incidence of Cerebral Edema and Risk of Osmotic Demyelination Syndrome.

STUDY OBJECTIVE: Treatment strategies in severe hyponatremia aim at rapid sodium correction to prevent or treat cerebral edema but limit sodium rise to prevent osmotic demyelination syndrome (ODS). The true risk of edema or ODS in ED patients is unknown. METHODS: We performed a retrospective study of patients admitted to the ED of a tertiary hospital from January 2013 to December 2018 with plasma sodium ≤ 125 mmol/L. The rate of cerebral edema at presentation and the rate of ODS that developed during the stay were determined based on imaging studies and clinical evaluation. Secondary analyses looked at the association between overly rapid sodium correction (> 8 mmol/L) at 24 h, ODS risk, mortality, and length of stay. RESULTS: The primary analysis group comprised 852 patients; 318 (37%) of these presented with severe symptoms. Four patients (0.5%) with cerebral edema and 11 patients (1.3%) with ODS were detected. Alcoholism, liver disease, and malnutrition were identified as risk factors for ODS. While overly rapid correction showed no association with ODS in the primary analysis group, it became the predominant risk factor in a reduced dataset with a more accurate estimate of 24-h sodium correction. Correction rate had no impact on mortality or length of stay. CONCLUSIONS: Given the low rate of cerebral edema even in severely symptomatic patients, aggressive treatment may not be necessary in most cases. The risk to develop ODS seems to be higher than the risk of brain edema. Since we found no beneficial impact of a liberal correction strategy, current treatment limits should stay in place.