Feasibility and Safety of Targeting Neutral vs Liberal Fluid Balance in Traumatic Brain Injured Patients: a Phase II Randomized Controlled Trial - LIMIT-TBI Trial

Severe traumatic brain injury (TBI) is a major cause of mortality and long-term disability worldwide and frequently requires intensive care management. In these patients, preventing secondary brain injury is essential and involves optimizing cerebral perfusion pressure (CPP), systemic hemodynamics, and organ function. Fluid therapy plays a central role in achieving these goals.

However, the optimal fluid management strategy in TBI remains unclear. Excessive fluid administration may lead to complications such as pulmonary edema and worsening cerebral edema, while restrictive strategies may increase the risk of hypovolemia and impaired cerebral perfusion. Current guidelines provide limited or no specific recommendations due to the lack of high-quality randomized evidence. Observational data suggest that a more positive fluid balance is associated with worse outcomes, but causality has not been established.

The LIMIT-TBI trial is a pragmatic, international, multicenter, randomized, unblinded, parallel-group phase II study designed to address this evidence gap. Adult patients with TBI admitted to the ICU will be randomized within 48 hours in a 1:1 ratio to either:

A neutral fluid balance strategy, targeting a daily balance of 0 mL (±500 mL) and cumulative neutrality over the first 5 days, using a protocolized approach combining fluid restriction, vasopressors, and diuretics when needed; A standard of care strategy, in which fluid administration is guided by local practice and clinician judgment.

In the intervention group, all fluid inputs (intravenous fluids, medications, and enteral nutrition) and outputs are strictly monitored. Maintenance fluids are minimized, and adjustments are made daily to achieve neutrality while maintaining adequate mean arterial pressure and cerebral perfusion pressure targets.