Critical thresholds for intracranial pressure vary over time in non-craniectomised traumatic brain injury patients

Nourallah, Basil; Zeiler, Frederick A.; Calviello, Leanne; Smielewski, Peter; Czosnyka, Marek; Menon, David

doi:10.1007/s00701-018-3555-3

Cited by 19 publications

(14 citation statements)

References 25 publications

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“…This is in contrast to the ICP variables (i.e., % time with ICP > 20 mmHg and % time with ICP > 22 mmHg), where the percentage of time above ICP threshold appears to only be significantly different (i.e., higher) in those patients whom died, without any statistically significant differences for these ICP variables noted between favorable and unfavorable dichotomized outcome groups. This highlights the known strong relationship between elevated ICP and death in TBI, with a weaker relation between ICP and long-term functional outcome [ 5 , 17 , 18 ]. The results from this study suggest that ICP-derived indices of cerebrovascular reactivity may be better predictors of functional outcome in adult TBI, compared to ICP values alone, emphasizing the potential importance of cerebrovascular reactivity monitoring in prognostication.…”

Section: Discussionmentioning

confidence: 94%

Univariate comparison of performance of different cerebrovascular reactivity indices for outcome association in adult TBI: a CENTER-TBI study

et al. 2019

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Background Monitoring cerebrovascular reactivity in adult traumatic brain injury (TBI) has been linked to global patient outcome. Three intra-cranial pressure (ICP)-derived indices have been described. It is unknown which index is superior for outcome association in TBI outside previous single-center evaluations. The goal of this study is to evaluate indices for 6- to 12-month outcome association using uniform data harvested in multiple centers. Methods Using the prospectively collected data from the Collaborative European NeuroTrauma Effectiveness Research in TBI (CENTER-TBI) study, the following indices of cerebrovascular reactivity were derived: PRx (correlation between ICP and mean arterial pressure (MAP)), PAx (correlation between pulse amplitude of ICP (AMP) and MAP), and RAC (correlation between AMP and cerebral perfusion pressure (CPP)). Univariate logistic regression models were created to assess the association between vascular reactivity indices with global dichotomized outcome at 6 to 12 months, as assessed by Glasgow Outcome Score–Extended (GOSE). Models were compared via area under the receiver operating curve (AUC) and Delong’s test. Results Two separate patient groups from this cohort were assessed: the total population with available data ( n = 204) and only those without decompressive craniectomy ( n = 159), with identical results. PRx, PAx, and RAC perform similar in outcome association for both dichotomized outcomes, alive/dead and favorable/unfavorable, with RAC trending towards higher AUC values. There were statistically higher mean values for the index, % time above threshold, and hourly dose above threshold for each of PRx, PAx, and RAC in those patients with poor outcomes. Conclusions PRx, PAx, and RAC appear similar in their associations with 6- to 12-month outcome in moderate/severe adult TBI, with RAC showing tendency to achieve stronger associations. Further work is required to determine the role for each of these cerebrovascular indices in monitoring of TBI patients. Electronic supplementary material The online version of this article (10.1007/s00701-019-03844-1) contains supplementary material, which is available to authorized users.

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Section: Discussionmentioning

confidence: 94%

Univariate comparison of performance of different cerebrovascular reactivity indices for outcome association in adult TBI: a CENTER-TBI study

et al. 2019

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“…Finally, this work utilized the entire recording period, and average ICP, for determination of epidemiologic thresholds. Recent evidence supports the notion that such population-based thresholds may vary over time [12].…”

Section: Brain Trauma Foundation Guidelines: Fixed Population-level Tmentioning

confidence: 63%

Intracranial Pressure Threshold Heuristics in Traumatic Brain Injury: One, None, Many!

et al. 2020

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Critical care of the patient with severe traumatic brain injury (TBI) revolves around strategies to address intracranial hypertension (IHT), and optimizing cerebral perfusion. Strong evidence associates IHT (especially refractory IHT) with mortality, and unfavorable clinical outcomes. However, this association may merely indicate that IHT is a surrogate for severity of injury and not necessarily a modifiable, outcome-altering, treatment target, i.e., some patients die with IHT, not from IHT. Another reason for intracranial pressure (ICP), and derived cerebral perfusion pressure (CPP), to be central tenets of bedside management is the fact that are relatively easily monitored as opposed to other secondary brain injury (SBI) mechanisms such as metabolic and energy crisis, cortical spreading ischemia, diffusion microvascular hypoxia, and mitochondrial failure. Consequently, we may be misled targeting what we can measure, not necessarily what matters. A further concern is that by solely focusing on one pathophysiological aspect we may ignore complex multidimensional cascades leading to SBI, and our treatment interventions run the risk of being counterproductive and harmful. Despite limitations, it is unlikely that ICP-guided management should or will entirely go away in the near future. One telling indication is the concerns, and responses, generated by the Benchmark Evidence from South American Trials: Treatment of Intracranial Pressure (BEST TRIP) trial [1]. This is the only level-1 evidence-producing randomized clinical trial (RCT) on the topic, finding no primary outcome

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“…Normal ICP in adults can range from 5 to 15 mmHg, depending on factors such as age and pre-existing medical conditions 18 , 26 – 28 . Hence, five initial ICP values, given by 5, 10, 15, 20 and 25 mmHg, were investigated in the present study.…”

Section: Methodsmentioning

confidence: 99%

Pneumocephalus and air travel: an experimental investigation on the effects of aircraft cabin pressure on intracranial pressure

Lim

Lan

Ooi

et al. 2020

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This study investigates the effects of aircraft cabin pressure on intracranial pressure (ICP) elevation of a pneumocephalus patient. We propose an experimental setup that simulates the intracranial hydrodynamics of a pneumocephalus patient during flight. It consists of an acrylic box (skull), air-filled balloon [intracranial air (ICA)], water-filled balloon (cerebrospinal fluid and blood) and agarose gel (brain). The cabin was replicated using a custom-made pressure chamber. The setup can measure the rise in ICP during depressurization to levels similar to that inside the cabin at cruising altitude. ΔICP, i.e. the difference between mean cruising ICP and initial ICP, was found to increase with ICA volume and ROC. However, ΔICP was independent of the initial ICP. The largest ΔICP was 5 mmHg; obtained when ICA volume and ROC were 20 ml and 1,600 ft/min, respectively. The postulated ICA expansion and the subsequent increase in ICP in pneumocephalus patients during flight were successfully quantified in a laboratory setting. Based on the quantitative and qualitative analyses of the results, an ICA volume of 20 ml and initial ICP of 15 mmHg were recommended as conservative thresholds that are required for safe air travel among pneumocephalus patients. This study provides laboratory data that may be used by doctors to advise post-neurosurgical patients if they can safely fly. Craniotomy refers to the surgical removal of a portion of the skull to gain access to the contents of the intracranial cavity. The procedure usually involves exposing the brain after opening its membranous coverings 1 , which inevitably expose the human brain to surrounding air. Varying amounts of air within the intracranial cavity (ICA) (known as pneumocephalus) remain after craniotomy 2. In most cases, pneumocephalus is not life-threatening as the ICA is normally absorbed into the systemic circulation over a period of several weeks 3-5. Safety concerns arise when patients with pneumocephalus engage in air travel before the ICA is fully absorbed. Air safety regulations require cabins of commercial aircraft to be pressurized to a standardized minimum of 75 kPa, which is approximately 75% that of atmospheric pressure at sea level (101.3 kPa), at cruising altitude 6,7. Consequently, during air travel, the ambient pressure may be as much as 25 kPa lower than the initial pressure of the ICA, which is at 101.3 kPa. According to Boyle's law, the difference in pressure between the aircraft cabin and the ICA would result in an increase in the ICA volume, as the ICA expands to equilibrate with the cabin pressure. The expansion, which takes place inside the rigid cranium, may cause cerebral compression that can lead to elevations in the intracranial pressure (ICP). A mild increase in ICP is tolerable. However, if the increase in ICP is too large, cerebral herniation may occur, which severely endangers the life of the pneumocephalus patient. In spite of the potential life-threatening event, pneumocephalus and air travel safety remains a controversial topic 8...

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Critical thresholds for intracranial pressure vary over time in non-craniectomised traumatic brain injury patients

Cited by 19 publications

References 25 publications

Univariate comparison of performance of different cerebrovascular reactivity indices for outcome association in adult TBI: a CENTER-TBI study

Univariate comparison of performance of different cerebrovascular reactivity indices for outcome association in adult TBI: a CENTER-TBI study

Intracranial Pressure Threshold Heuristics in Traumatic Brain Injury: One, None, Many!

Pneumocephalus and air travel: an experimental investigation on the effects of aircraft cabin pressure on intracranial pressure

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