Automated Measurement of “Pressure Times Time Dose” of Intracranial Hypertension Best Predicts Outcome After Severe Traumatic Brain Injury

Kahraman, Sibel; Dutton, Richard P.; Hu, Peter; Xiao, Yan; Aarabi, Bizhan; Stein, Deborah M.; Scalea, Thomas M.

doi:10.1097/ta.0b013e3181c99853

Cited by 75 publications

(40 citation statements)

References 20 publications

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“…49 Sheth et al used automated "pressure times time dose" (PTD) to demonstrate that the total PTD for patients with an ICP of > 20 mm Hg and CPP of < 60 mm Hg had a high predictive power for functional outcome and in-hospital mortality. 23,46 These methods were also validated in a study in the pediatric population, in which the ICP AUC was correlated with mortality, and the cumulative pressure-time index for below-threshold CPP was correlated with outcome morbidity and mortality. 22,50 Therefore, the measurement of daily and cumulative ICP burdens is a meaningful outcome variable.…”

Section: Cumulative Icp Reductionmentioning

confidence: 99%

Hypertonic saline reduces cumulative and daily intracranial pressure burdens after severe traumatic brain injury

Mangat

Chiu²,

Gerber

et al. 2015

JNS

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ObJect Increased intracranial pressure (ICP) in patients with traumatic brain injury (TBI) is associated with a higher mortality rate and poor outcome. Mannitol and hypertonic saline (HTS) have both been used to treat high ICP, but it is unclear which one is more effective. Here, the authors compare the effect of mannitol versus HTS on lowering the cumulative and daily ICP burdens after severe TBI. MetHODS The Brain Trauma Foundation TBI-trac New York State database was used for this retrospective study. Patients with severe TBI and intracranial hypertension who received only 1 type of hyperosmotic agent, mannitol or HTS, were included. Patients in the 2 groups were individually matched for Glasgow Coma Scale score (GCS), pupillary reactivity, craniotomy, occurrence of hypotension on Day 1, and the day of ICP monitor insertion. Patients with missing or erroneous data were excluded. Cumulative and daily ICP burdens were used as primary outcome measures. The cumulative ICP burden was defined as the total number of days with an ICP of > 25 mm Hg, expressed as a percentage of the total number of days of ICP monitoring. The daily ICP burden was calculated as the mean daily duration of an ICP of > 25 mm Hg, expressed as the number of hours per day. The numbers of intensive care unit (ICU) days, numbers of days with ICP monitoring, and 2-week mortality rates were also compared between the groups. A 2-sample t-test or chisquare test was used to compare independent samples. The Wilcoxon signed-rank or Cochran-Mantel-Haenszel test was used for comparing matched samples. reSultS A total of 35 patients who received only HTS and 477 who received only mannitol after severe TBI were identified. Eight patients in the HTS group were excluded because of erroneous or missing data, and 2 other patients did not have matches in the mannitol group. The remaining 25 patients were matched 1:1. Twenty-four patients received 3% HTS, and 1 received 23.4% HTS as bolus therapy. All 25 patients in the mannitol group received 20% mannitol. The mean cumulative ICP burden (15.52% [HTS] vs 36.5% [mannitol]; p = 0.003) and the mean (± SD) daily ICP burden (0.3 ± 0.6 hours/day [HTS] vs 1.3 ± 1.3 hours/day [mannitol]; p = 0.001) were significantly lower in the HTS group. The mean (± SD) number of ICU days was significantly lower in the HTS group than in the mannitol group (8.5 ± 2.1 vs 9.8 ± 0.6, respectively; p = 0.004), whereas there was no difference in the numbers of days of ICP monitoring (p = 0.09). There were no significant differences between the cumulative median doses of HTS and mannitol (p = 0.19). The 2-week mortality rate was lower in the HTS group, but the difference was not statistically significant (p = 0.56). cONcluSiONS HTS given as bolus therapy was more effective than mannitol in lowering the cumulative and daily ICP burdens after severe TBI. Patients in the HTS group had significantly lower number of ICU days. The 2-week mortality rates were not statistically different between the 2 groups.http://thejns.org/doi/abs/10.3171/2014....

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Section: Cumulative Icp Reductionmentioning

confidence: 99%

Hypertonic saline reduces cumulative and daily intracranial pressure burdens after severe traumatic brain injury

Mangat

Chiu²,

Gerber

et al. 2015

JNS

View full text Add to dashboard Cite

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“…This approach may more accurately reflect the impact of secondary brain insults on outcome than did previous methods (for example, traditionally taking into account only the mean ICP or the time spent above a given threshold), because it accounts for both the degree and the duration of ICP elevation. 3,13,17,32 An additional advantage, as pointed out by Vik et al, 32 is that the predictive power of doses for different thresholds can be explored.…”

Section: Discussionmentioning

confidence: 99%

Patient-specific thresholds of intracranial pressure in severe traumatic brain injury

Lazaridis

DeSantis

Smielewski

et al. 2014

JNS

123

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Object Based on continuous monitoring of the pressure reactivity index (PRx), the authors defined individualized intracranial pressure (ICP) thresholds by graphing the relationship between ICP and PRx. These investigators hypothesized that an “ICP dose” based on individually assessed ICP thresholds would correlate more closely with the 6-month outcome when compared with ICP doses derived by the recommended universal thresholds of 20 and 25 mm Hg. Methods This study was a retrospective analysis of prospectively collected data from 327 patients with severe traumatic brain injury. Results Individualized thresholds were visually identified from graphs of PRx versus ICP; PRx > 0.2 was the cutoff. Intracranial pressure doses were then computed as the cumulative area under the curve above the defined thresholds in graphing ICP versus time. The term “Dose 20” (D20) was used to refer to an ICP threshold of 20 mm Hg; the markers D25 and DPRx were calculated similarly. Separate logistic regression models were fit with death as the outcome and each dose as the predictor, both alone and adjusted for covariates. The discriminative ability of each dose for mortality was assessed by receiver operating characteristic AUC analysis in which 5-fold cross-validation was used. A clearly identifiable PRx-based threshold was possible in 224 patients (68%). The DPRx (AUC 0.81, 95% CI 0.74–0.87) was found to have the highest area under the curve (AUC) over both D20 (0.75, 95% CI 0.68–0.81) and D25 (0.77, 95% CI 0.70–0.83); in the cross-validation model, DPRx remained the best discriminator of mortality (DPRx: AUC 0.77 [95% CI 0.68–0.89]; D20: 0.72 [95% CI 0.66–0.81]; and D25: 0.65 [95% CI 0.56–0.73]). Conclusions The authors explored the importance of different ICP thresholds for outcome by calculating patient-specific ICP doses based on the continuous monitoring of cerebrovascular pressure reactivity. They found that these individualized doses of intracranial hypertension were stronger predictors of death than doses derived from the universal thresholds of 20 and 25 mm Hg. The PRx could offer a method that can be directed toward individualizing the ICP threshold.

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“…Although these guidelines acknowledge a lack of level I evidence, the recommended treatment threshold for ICP-lowering therapies is 20 mmHg, based mainly on observational data [8][9][10][11][12]. An increased ICP is an independent risk factor for mortality [13,14], and the total burden of ICP derangements, calculated as the area under the ICP curve (measured over time) above 20 mmHg, is an independent predictor of worse outcome in adults [15,16] and children [17].…”

Section: Introductionmentioning

confidence: 99%

Visualizing the pressure and time burden of intracranial hypertension in adult and paediatric traumatic brain injury

et al. 2015

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Take-home message:In adult and paediatric patients suffering from severe traumatic brain injury, an approximately exponential curve describes the relationship between intensity and duration of episodes of increased intracranial pressure (ICP) and worse clinical outcomes. In children, compared to adults, this occurs at lower ICP thresholds of shorter duration. Electronic supplementary materialThe online version of this article (doi:10.1007/s00134-015-3806-1) contains supplementary material, which is available to authorized users. To assess the impact of the duration and intensity of episodes of increased intracranial pressure on 6-month neurological outcome in adult and paediatric traumatic brain injury. Methods:Analysis of prospectively collected minute-by-minute intracranial pressure and mean arterial blood pressure data of 261 adult and 99 paediatric traumatic brain injury patients from multiple European centres. The relationship of episodes of elevated intracranial pressure (defined as a pressure above a certain threshold during a certain time) with 6-month Glasgow Outcome Scale was visualized in a colour-coded plot. Results:The colour-coded plot illustrates the intuitive concept that episodes of higher intracranial pressure can only be tolerated for shorter durations: the curve that delineates the duration and intensity of those intracranial pressure episodes associated with worse outcome is an approximately exponential decay curve. In children, the curve resembles that of adults, but the delineation between episodes associated with worse outcome occurs at lower intracranial pressure thresholds. Intracranial pressures above 20 mmHg lasting longer than 37 minutes in adults, and longer than 8 minutes in children, are associated with worse outcomes. In a multivariate model, together with known baseline risk factors for outcome in severe traumatic brain injury, the cumulative intracranial pressure-time burden is independently associated with mortality. When cerebrovascular autoregulation, assessed with the low-frequency autoregulation index, is impaired, the ability to tolerate elevated intracranial pressures is reduced. When the cerebral perfusion pressure is below 50 mmHg, all intracranial pressure insults, regardless of duration are associated with worse outcome. Conclusions:The intracranial pressure-time burden associated with worse outcome is visualised in a colour-coded plot. In children, secondary injury occurs at lower intracranial pressure thresholds as compared to adults. Impaired cerebrovascular autoregulation reduces the ability to tolerate intracranial pressure insults. Thus, 50 mmHg might be the lower acceptable threshold for cerebral perfusion pressure.

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Automated Measurement of “Pressure Times Time Dose” of Intracranial Hypertension Best Predicts Outcome After Severe Traumatic Brain Injury

Abstract: PTD calculation of high resolution ICP and CPP recording is a reliable and feasible way of monitoring severe TBI patients.

Cited by 75 publications

References 20 publications

Hypertonic saline reduces cumulative and daily intracranial pressure burdens after severe traumatic brain injury

Hypertonic saline reduces cumulative and daily intracranial pressure burdens after severe traumatic brain injury

Patient-specific thresholds of intracranial pressure in severe traumatic brain injury

Visualizing the pressure and time burden of intracranial hypertension in adult and paediatric traumatic brain injury

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