Enteral free water vs. parenteral dextrose 5% in water for the treatment of hypernatremia in the intensive care unit: a retrospective cohort study from a mixed ICU.

PURPOSE: Effective treatment options for patients with hypernatremia are limited. Free water administration (parenterally or enterally) is the mainstay of treatment but the impact of each strategy on lowering serum sodium (Na) is not known. The purpose of the study was thus to assess the effectiveness of enteral free water vs. parenteral dextrose 5% in water (D5W) in treating ICU-acquired hypernatremia. METHODS: An electronic medical record-based, retrospective cohort study was conducted in a 30-bed mixed medical-surgical intensive care unit (ICU) in Japan. All adult patients admitted to the ICU from August 2017 to July 2021 were reviewed. After a 2-step exclusion, patients who stayed in the ICU ≥ 24 h and received either or both treatments for ICU-acquired hypernatremia (Na ≥ 145 mEq/L) constituted the study cohort. The primary outcome was a change in serum Na during the 24 h before treatment each day (ΔNa); the secondary outcomes were gastrointestinal complications, serum glucose levels, ICU/hospital mortality, ICU/hospital length of stay, and the duration of mechanical ventilation. Repeated measurements on each patient were addressed using a generalized estimated equation (GEE) for multiple linear regression analysis. Analysis was conducted with R version 4.0.3. RESULTS: In total, 256/6596 (131: D5W, 125: enteral free water) patients were analyzed. Median treatment lasted 6 days [3-17] for the D5W group vs 7 days [3-14] for the enteral free water group with a total median daily treatment volume of 799 [IQR 299-1221] mL vs. 400 [IQR 262-573] mL. GEE multiple linear regression analysis showed an estimated mean ΔNa per liter of treatment fluid of - 2.25 [95% CI - 2.76 to - 1.74] mEq/L per liter of parenteral D5W vs. - 1.91 mEq decrease [95% CI - 2.75 to - 1.07] per liter of enteral free water. Hydrochlorothiazide was the only medication associated with a statistically significant negative ΔNa by- 0.89 [- 1.57 to - 0.21] mEq/L. There were no significant inter-group differences for secondary outcomes. CONCLUSIONS: These results suggest that both enteral free water and parenteral D5W are effective for treating ICU-acquired hypernatremia. Parenteral D5W was slightly more effective than enteral free water to lower serum Na levels in patients with ICU-acquired hypernatremia. TRIAL REGISTRATION: Not applicable.