normal saline (0.9% sodium chloride) administered intravenously

balanced crystalloid intravenous fluid therapy

For the primary purpose of fluid therapy or resuscitation in the emergency room and during hospitalization. The interventions will be administered intravenously whenever isotonic intravenous fluid administration is ordered by the treating provider for fluid resuscitation and/or maintenance in the emergency room and during inpatient hospitalization. Assignment to the intervention arm will be adhered to from enrollment to discharge. The total volume, rate, initiation, cessation, and co-interventions will be left to the discretion of the treating provider. Adherence will be ensured by dual interventions at the level of pharmacy IV fluid supply and physician order. The fluids will be physically administered according to the standard intravenous procedures and those outlined in the manufacturer's instructions.

Glasgow Outcome Scale-Extended (GOSE) 8-point scale. Glasgow Outcome Scale has been widely accepted as the standard assessment scale of global outcomes after severe brain injury because it captures well how the injury affects functioning in major areas of life. Using the manual for the GOSE interview, we will conduct our primary efficacy assessment at 6 months after ICU admission in person or over the phone. Outcomes on the GOSE scale do not change past the 6-month mark in moderate and severe TBI patients.

The 8-point ordinal GOSE scale for the primary efficacy assessment will be dichotomized into favorable (GOSE score 4-8) and unfavorable (GOSE 1-3) outcomes. The primary analysis model will be a logistic regression model where the outcome of interest is the dichotomized GOS-E evaluated at 6 months to reflect favorable and unfavorable outcomes. The covariate of interest is a randomization assignment.

We will assess the inpatient mortality of the participants. We will note the time from admission to death or discharge.

The secondary outcome (inpatient mortality) will be analyzed using two approaches. The primary analysis model will be a logistic regression model where the outcome of interest is the vitality status (alive or dead) at discharge. The covariate of interest is a randomization assignment. The secondary analysis will be a time-to-death analysis comparing the survival curves between the two randomized groups using a log-rank test.

Surgical or medical ICP-related therapeutic interventions. Events of acute kidney injury, cerebral edema, and in-patient mortality, will be captured.