Risk Factors Associated With Acute Kidney Injury in Traumatic Brain Injury Patients Treated With Hypertonic Saline: A Retrospective Study

Background: Hypertonic saline (HTS) is essential pharmacologic treatment for traumatic brain injury (TBI). Previous studies associate HTS with acute kidney injury (AKI), however evidence in TBIs is limited. Objective: This study examines factors associated with AKI in patients requiring HTS for TBI. Methods: This retrospective study was performed at a Level-1 Trauma, Academic Medical Center. Inclusion criteria were TBI, age ≥12 years, ICU length of stay ≥72 hours, and administration of ≥24 hours of continuous HTS or 500 mL of HTS boluses. The primary outcome was identifying factors associated with AKI. Secondary outcomes included correlation between chloride load and level with development of AKI. Chloride load was calculated from HTS and non-HTS sources. Results: Of 129 patients included, 18 (14%) developed AKI. Maximum sodium level was higher in the AKI group (P < 0.0001). Hyperchloremia (Cl ≥ 115 mEq/L) was more common in the AKI group (100% vs 81%, P = 0.0428). Maximum and change in serum chloride were higher in the AKI group (median 128 vs 123 mEq/L, P = 0.0026 and +24 mEq/L vs +17 mEq/L, P = 0.0084, respectively). Logistic regression analysis indicated an OR 1.095 times higher [95% CI (1.022, 1.172)] for developing AKI for every one mEq/L increase in maximum chloride level and an OR 1.032 [95% CI (1.006, 1.058)] for developing AKI for every 1-year increase in age. There was no difference in total chloride load between groups (P = 0.2143). Non-HTS sources provided more than 40% of total chloride load in both groups. Conclusion: Chloride level, and age may be associated with AKI in TBI patients treated with HTS.