Impact of duration and magnitude of raised intracranial pressure on outcome after severe traumatic brain injury: A CENTER-TBI high-resolution group study

Abstract

Magnitude of intracranial pressure (ICP) elevations and their duration have been associated with worse outcomes in patients with traumatic brain injuries (TBI), however published thresholds for injury vary and uncertainty about these levels has received relatively little attention. In this study, we have analyzed high-resolution ICP monitoring data in 227 adult patients in the CENTER-TBI dataset. Our aim was to identify thresholds of ICP intensity and duration associated with worse outcome, and to evaluate the uncertainty in any such thresholds. We present ICP intensity and duration plots to visualize the relationship between ICP events and outcome. We also introduced a novel bootstrap technique to evaluate uncertainty of the equipoise line. We found that an intensity threshold of 18 ± 4 mmHg (2 standard deviations) was associated with worse outcomes in this cohort. In contrast, the uncertainty in what duration is associated with harm was larger, and safe durations were found to be population dependent. The pressure and time dose (PTD) was also calculated as area under the curve above thresholds of ICP. A relationship between PTD and mortality could be established, as well as for unfavourable outcome. This relationship remained valid for mortality but not unfavourable outcome after adjusting for IMPACT core variables and maximum therapy intensity level. Importantly, during periods of impaired autoregulation (defined as pressure reactivity index (PRx)>0.3) ICP events were associated with worse outcomes for nearly all durations and ICP levels in this cohort and there was a stronger relationship between outcome and PTD. Whilst caution should be exercised in ascribing causation in observational analyses, these results suggest intracranial hypertension is poorly tolerated in the presence of impaired autoregulation. ICP level guidelines may need to be revised in the future taking into account cerebrovascular autoregulation status considered jointly with ICP levels.

Impact of Age and Biological Sex on Cerebrovascular Reactivity in Adult Moderate/Severe Traumatic Brain Injury: An Exploratory Analysis

“… 19 Although it must be acknowledged that ICP/CPP derangements in the historical cohort of these previous publications were much more prevalent than in our cohort, 19 potentially driving the PRx derangements seen. 27 , 46 , 52 , 53 …”

“…It can likely be attributed to brain volume loss at advanced ages, because brain atrophy does not allow for adequate swelling and generation of critical ICPs, which is a known driver of autoregulation failure in moderate/severe TBI. 27 , 46 , 52 , 53 …”

Targeting Autoregulation-Guided Cerebral Perfusion Pressure after Traumatic Brain Injury (COGiTATE): A Feasibility Randomized Controlled Clinical Trial

“…Other retrospective TBIicp analyses demonstrated that impaired CA reduces the tolerability for low CPP and high ICP. [18][19][20][21] On average, CPP targets <60 mm Hg were less common (10%; Fig. 2) compared to targets ‡70 mm Hg (55%; Fig.…”

External Lumbar Drainage for Refractory Intracranial Hypertension in Traumatic Brain Injury: A Systematic Review

“…A signi cant reduction in ICP was reported in four studies which included ventriculostomy drainage prior to lumbar drainage [21,28,34,37], suggesting that ELD offers both a bene t when used as the sole modality of CSF diversion, and additional bene t when used in combination with EVD. Functional outcomes were not considered as a marker of "e cacy", rather ICP control can be considered as a surrogate marker of potentially improving functional outcome due to the association of intracranial hypertension and poor outcome [4]. The numbers enrolled in these combined studies are by far insu ciently powered to assess for an effect on functional outcome.…”