Does hemofiltration protect the brain after head trauma? An experimental study in rabbits

Background Traumatic brain injury (TBI) is one of the most frequent and severe neurological diseases. In the last few decades, significant advances have been made in TBI pathophysiology and monitoring, however new treatments have not emerged. Although the central nervous system (CNS) has been historically defined as an immunologically privileged organ, recent studies show the increasingly predominant role of inflammatory and apoptotic phenomena in the pathogenesis of TBI. Inflammatory response mediators can be eliminated with continuous renal replacement therapies (CRRT). Our aim was to investigate whether hemofiltration protects the brain after head trauma in an experimental study in animals. Methods and results A model of TBI and CVVH was performed in anesthetized New Zealand white rabbits without acute renal failure. The experimental group TBI ( +)-CVVH ( +) was compared with a TBI ( +)-CVVH (-) and a TBI (-)-CVVH ( +) control groups. Rabbits were assessed immediately (NES1) and 24 h hours after (NES2) TBI and/or CVVH using a functional Neurological Evaluation Score (NES) and histology of the brains after sacrifice. There was evidence to support a difference of NES1 comparing with the TBI (-)-CVVH ( +), but not with TBI ( +)-CVVH (-) with only 15% of the rabbits treated with CVVH and TBI showing a favorable neurological course. The final neurological outcome (mortality at 24 h) was 0%, 22% and 53% in the TBI(-) + CVVH( +), TBI( +)-CVVH(-) and TBI( +)-CVVH( +) groups respectively. The use of hemofiltration before or after TBI did not make a difference in regards the outcome of the rabbits. There was evidence in the histology to support an increase of mild ischemia, hemorrhage and edema in the experimental group compared with the other two groups. Conclusions CVVH in rabbits without renal failure used with the intention to protect the brain may worsen the prognosis in TBI.