Dysnatremia in critically ill burn patients: incidence, timing and association with kidney outcomes

Dysnatremia is common in critically ill patients and has been linked to poor outcomes and renal prognosis. Burn patients are particularly vulnerable, but the prognostic significance of dysnatremia in this population remains unclear.

We conducted a single-center retrospective cohort study of 1,758 burn patients admitted to a French burn center between 2011 and 2023. Dysnatremia was defined as at least one episode of hyponatremia (<135 mmol/L) or hypernatremia (>145 mmol/L) during intensive care unit (ICU) stay. The primary endpoint was the incidence of dysnatremia; secondary endpoints included major adverse kidney events (MAKE) at ICU discharge and acute kidney injury (AKI) occurrence and severity.

Dysnatremia occurred in 56.3% of patients (n = 990), with hyponatremia in 50.5% (n = 888) and hypernatremia in 23.8% (n = 418). MAKE at ICU discharge did not differ between hyponatremic and normonatremic patients (12.6% vs. 10.9%, p = 0.304) but was sixfold higher with hypernatremia (32.3% vs. 5.4%, p < 0.001). After adjustment for age and burned total body surface area, hypernatremia was independently associated with MAKE at ICU discharge (adjusted hazard ratio [aHR] 4.03; 95% confidence interval [CI]: 2.92-5.56; p < 0.001), whereas hyponatremia was not (aHR 1.15; 95% CI: 0.85-1.55; p = 0.377). Clustering analysis identified three phenotypes: Cluster B (severe burns, worst outcomes), Cluster A (older patients, mostly hyponatremic, intermediate outcomes), and Cluster C (younger patients, mild burns, best outcomes).

Dysnatremia affects over half of burn patients. Sodium disturbances should be viewed as markers of systemic severity, warranting close monitoring and preventive strategies.