Fluid balance and outcome in critically ill patients with traumatic brain injury (CENTER-TBI and OzENTER-TBI)

Background Fluid therapy-the administration of fluids to maintain adequate organ tissue perfusion and oxygenation-is essential in patients admitted to the intensive care unit (ICU) with traumatic brain injury. We aimed to quantify the variability in fluid management policies in patients with traumatic brain injury and to study the effect of this variability on patients' outcomes.Methods We did a prospective, multicentre, comparative effectiveness study of two observational cohorts: CENTER-TBI in Europe and OzENTER-TBI in Australia. Patients from 55 hospitals in 18 countries, aged 16 years or older with traumatic brain injury requiring a head CT, and admitted to the ICU were included in this analysis. We extracted data on demographics, injury, and clinical and treatment characteristics, and calculated the mean daily fluid balance (difference between fluid input and loss) and mean daily fluid input during ICU stay per patient. We analysed the association of fluid balance and input with ICU mortality and functional outcome at 6 months, measured by the Glasgow Outcome Scale Extended (GOSE). Patient-level analyses relied on adjustment for key characteristics per patient, whereas centre-level analyses used the centre as the instrumental variable.Findings 2125 patients enrolled in CENTER-TBI and OzENTER-TBI between Dec 19, 2014, and Dec 17, 2017, were eligible for inclusion in this analysis. The median age was 50 years (IQR 31 to 66) and 1566 (74%) of patients were male. The median of the mean daily fluid input ranged from 1middot48 L (IQR 1middot12 to 2middot09) to 4middot23 L (3middot78 to 4middot94) across centres. The median of the mean daily fluid balance ranged from -0middot85 L (IQR -1middot51 to -0middot49) to 1middot13 L (0middot99 to 1middot37) across centres. In patient-level analyses, a mean positive daily fluid balance was associated with higher ICU mortality (odds ratio [OR] 1middot10 [95% CI 1middot07 to 1middot12] per 0middot1 L increase) and worse functional outcome (1middot04 [1middot02 to 1middot05] per 0middot1 L increase); higher mean daily fluid input was also associated with higher ICU mortality (1middot05 [1middot03 to 1middot06] per 0middot1 L increase) and worse functional outcome (1middot04 [1middot03 to 1middot04] per 1-point decrease of the GOSE per 0middot1 L increase). Centre-level analyses showed similar associations of higher fluid balance with ICU mortality (OR 1middot17 [95% CI 1middot05 to 1middot29]) and worse functional outcome (1middot07 [1middot02 to 1middot13]), but higher fluid input was not associated with ICU mortality (OR 0middot95 [0middot90 to 1middot00]) or worse functional outcome (1middot01 [0middot98 to 1middot03]).Interpretation In critically ill patients with traumatic brain injury, there is significant variability in fluid management, with more positive fluid balances being associated with worse outcomes. These results, when added to previous evidence, suggest that aiming for neutral fluid balances, indicating a state of normovolaemia, contributes to improved outcome. Copyright (C) 2021 Elsevier Ltd. All rights reserved.