Researchers monitor ICP and PRx to characterize temporal evolution in severe TBI patients

Winner of the Best International Abstract Award, Hadie Adams, presented his research, Characterizing the Temporal Evolution of ICP and Cerebrovascular Reactivity after Severe Traumatic Brain Injury, during the 2016 American Association of Neurological Surgeons (AANS) Annual Scientific Meeting.

Large-cohort traumatic brain injury (TBI) studies have shown that intracranial pressure (ICP) and the pressure reactivity index (PRx) are independently associated with patient outcome. However, how these parameters evolve over the course of the intensive care stay and the question of whether this evolution has any prognostic importance has not been well studied.

ICP and PRx were monitored in 573 severe TBI patients in a regional neuro-critical care unit. Data were calculated in 12-hour epochs for the first 168 hours (seven days) referenced from the time of incident. Data were stratified by the presence of diffuse TBI (dTBI) or space occupying lesions (SOL) as well as fatal or non-fatal outcome at six months post-injury. Mixed linear modelling was used to assess change of ICP and PRx over time to detect differences in mortality.

Mean ICP peaked between 24 hours and 36 hours after injury, but only in those who died. The difference in mean ICP between those with fatal and non-fatal outcome was only significant for the first 120 hours after ictus. For PRx, those with a fatal outcome also had higher (more impaired) PRx throughout the whole first 168 hours after ictus. The separation of ICP and PRx was greatest in the first 72 hours after ictus. Also, mean differences of ICP and PRx between the outcomes groups were more pronounced in those with dTBI than those with SOL.

In this cohort of 573 TBI patients with high resolution physiologic data, both ICP and PRx display a distinctive temporal evolution. Importantly, early ICP and PRx allow for the clearest prognostic delineation. The optimal thresholds, prognostic significance and clinical correlations of ICP and PRx are likely to be time dependent. Prognostic and therapeutic applications of ICP and PRx should therefore account for their temporal evolution.