Impact of continuous hypertonic (NaCl 20%) saline solution on renal outcomes after traumatic brain injury (TBI): A post-hoc analysis of the COBI trial

Background To evaluate if the increase of chloride intake during a continuous infusion of 20% hypertonic saline solution (HSS) is associated with an increase in the incidence of acute kidney injury (AKI) compared to standard of care in traumatic brain injury patients. Methods In this post-hoc analysis of COBI trial, 370 patients admitted for a moderate-to-severe TBI in the 9 participating ICUs were enrolled. The intervention consisted in a continuous infusion of HSS to maintain a blood sodium level ranging from 150 to 155 mmol/l for at least 48 hours. Patients enrolled in the control arm were treated as recommended by the last Brain Trauma foundation guidelines. The primary outcome was the occurrence of AKI defined by stages 2 or 3 according to KDIGO criteria from inclusion to Day 30. Results After exclusion of missing data, 322 patients were included in this post-hoc analysis. The patients randomized in the intervention arm received a significantly higher amount of chloride during the first 4 days. (intervention group: 97.3 ± 31.6 g vs. control group: 61.3 ± 38.1 g; p < 0.001) and had higher chloride blood levels at day 4 (117.9 ± 10.7 mmol/L vs. 111.6 ± 9 mmol/L respectively, p < 0.001). The rates of patients with AKI were not statistically different between the intervention and the control groups (24.5% vs. 28.9% respectively; p = 0.45). Conclusions Despite a significant increase in chloride intake, a continuous infusion of HSS was not associated with AKI in moderate-to-severe TBI patients. Our study does not confirm the potentially detrimental effect of chloride load on kidney function in ICU patients. Trial registration: Clinicaltrial.gov, NCT03143751. The COBI trial was registered on 8 May 2017.