The effects of cerebral pressure autoregulation status and CPP levels on cerebral metabolism in pediatric traumatic brain injury.

BACKGROUND: Cerebral perfusion pressure (CPP) management in the developing child with traumatic brain injury (TBI) is challenging. The pressure reactivity index (PRx) may serve as marker of cerebral pressure autoregulation (CPA) and optimal CPP (CPPopt) may be assessed by identifying the CPP level with best (lowest) PRx. To evaluate the potential of CPPopt guided management in children with severe TBI, cerebral microdialysis (CMD) monitoring levels of lactate and the lactate/pyruvate ratio (LPR) (indicators of ischemia) were related to actual CPP levels, autoregulatory state (PRx) and deviations from CPPopt (ΔCPPopt). METHODS: Retrospective study of 21 children ≤ 17 years with severe TBI who had both ICP and CMD monitoring were included. CPP, PRx, CPPopt and ΔCPPopt where calculated, dichotomized and compared with CMD lactate and lactate-pyruvate ratio. RESULTS: Median age was 16 years (range 8-17) and median Glasgow coma scale motor score 5 (range 2-5). Both lactate (p = 0.010) and LPR (p = < 0.001) were higher when CPP ≥ 70 mmHg than when CPP < 70. When PRx ≥ 0.1 both lactate and LPR were higher than when PRx < 0.1 (p = < 0.001). LPR was lower (p = 0.012) when CPPopt ≥ 70 mmHg than when CPPopt < 70, but there were no differences in lactate levels. When ΔCPPopt > 10 both lactate (p = 0.026) and LPR (p = 0.002) were higher than when ΔCPPopt < -10. CONCLUSIONS: Increased levels of CMD lactate and LPR in children with severe TBI appears to be related to disturbed CPA (PRx). Increased lactate and LPR also seems to be associated with actual CPP levels ≥ 70 mmHg. However, higher lactate and LPR values were also seen when actual CPP was above CPPopt. Higher CPP appears harmful when CPP is above the upper limit of pressure autoregulation. The findings indicate that CPPopt guided CPP management may have potential in pediatric TBI.

Decompressive craniectomy as a second/third-tier intervention in traumatic brain injury: A multicenter observational study.

OBJECTIVES: RESCUEicp studied decompressive craniectomy (DC) applied as third-tier option in severe traumatic brain injury (TBI) patients in a randomized controlled setting and demonstrated a decrease in mortality with similar rates of favorable outcome in the DC group compared to the medical management group. In many centers, DC is being used in combination with other second/third-tier therapies. The aim of the present study is to investigate outcomes from DC in a prospective non-RCT context. METHODS: This is a prospective observational study of 2 patient cohorts: one from the University Hospitals Leuven (2008-2016) and one from the Brain-IT study, a European multicenter database (2003-2005). In thirty-seven patients with refractory elevated intracranial pressure who underwent DC as a second/third-tier intervention, patient, injury and management variables including physiological monitoring data and administration of thiopental were analysed, as well as Extended Glasgow Outcome score (GOSE) at 6 months. RESULTS: In the current cohorts, patients were older than in the surgical RESCUEicp cohort (mean 39.6 vs. 32.3; p < 0.001), had higher Glasgow Motor Score on admission (GMS < 3 in 24.3% vs. 53.0%; p = 0.003) and 37.8% received thiopental (vs. 9.4%; p < 0.001). Other variables were not significantly different. GOSE distribution was: death 24.3%; vegetative 2.7%; lower severe disability 10.8%; upper severe disability 13.5%; lower moderate disability 5.4%; upper moderate disability 2.7%, lower good recovery 35.1%; and upper good recovery 5.4%. The outcome was unfavorable in 51.4% and favorable in 48.6%, as opposed to 72.6% and 27.4% respectively in RESCUEicp (p = 0.02). CONCLUSION: Outcomes in DC patients from two prospective cohorts reflecting everyday practice were better than in RESCUEicp surgical patients. Mortality was similar, but fewer patients remained vegetative or severely disabled and more patients had a good recovery. Although patients were older and injury severity was lower, a potential partial explanation may be in the pragmatic use of DC in combination with other second/third-tier therapies in real-life cohorts. The findings underscore that DC maintains an important role in managing severe TBI.

Capturing of intracranial pressure treatment during neurointensive care in patients with acute brain injury using a novel tablet-based method.

Critical care is complex and stressful. It is difficult to register in real time data not recorded by automatic systems. Time-specific knowledge of manual measures is important for understanding pathophysiology and for analyzing treatment and quality of care. Therefore, a novel iPad-based method for registration of manual measures was developed, which many can build themselves. Using a configuration for intracranial pressure (ICP) management, the methodology was validated, ICP treatment captured, and the quality of ICP management evaluated. Twenty-two patients with acute brain injuries were studied. The iPad-system was totally used for 2538 h. Thirteen-hundred-five manual measures were entered. Thirty-nine episodes of predefined ICP insults were identified. During 16/39 episodes, ICP treatments were registered. For 4/39 episodes treatments were registered within 90 s before or after the episode. For 3/39 episodes it was registered that treatment was intentionally refrained. In 15/16 episodes without registered treatment, the insult was mild or reasonable explanations were found when medical records and the Patient data management system were reviewed. In one situation without particular circumstances, morphine and clonidine were given to decrease ICP but not registered. No episodes of downtime or loss of data occurred. The developed methodology appears to be stable and robust as well as feasible and user-friendly. It was possible to capture the treatment of ICP insults with high temporal resolution, and to evaluate the quality of ICP management. An own developed novel tablet-based system like our system may be a promising potential tool useful in various future intensive care applications.

Forewarning of hypotensive events using a Bayesian artificial neural network in neurocritical care.

Traumatically brain injured (TBI) patients are at risk from secondary insults. Arterial hypotension, critically low blood pressure, is one of the most dangerous secondary insults and is related to poor outcome in patients. The overall aim of this study was to get proof of the concept that advanced statistical techniques (machine learning) are methods that are able to provide early warning of impending hypotensive events before they occur during neuro-critical care. A Bayesian artificial neural network (BANN) model predicting episodes of hypotension was developed using data from 104 patients selected from the BrainIT multi-center database. Arterial hypotension events were recorded and defined using the Edinburgh University Secondary Insult Grades (EUSIG) physiological adverse event scoring system. The BANN was trained on a random selection of 50% of the available patients (n = 52) and validated on the remaining cohort. A multi-center prospective pilot study (Phase 1, n = 30) was then conducted with the system running live in the clinical environment, followed by a second validation pilot study (Phase 2, n = 49). From these prospectively collected data, a final evaluation study was done on 69 of these patients with 10 patients excluded from the Phase 2 study because of insufficient or invalid data. Each data collection phase was a prospective non-interventional observational study conducted in a live clinical setting to test the data collection systems and the model performance. No prediction information was available to the clinical teams during a patient's stay in the ICU. The final cohort (n = 69), using a decision threshold of 0.4, and including false positive checks, gave a sensitivity of 39.3% (95% CI 32.9-46.1) and a specificity of 91.5% (95% CI 89.0-93.7). Using a decision threshold of 0.3, and false positive correction, gave a sensitivity of 46.6% (95% CI 40.1-53.2) and specificity of 85.6% (95% CI 82.3-88.8). With a decision threshold of 0.3, > 15 min warning of patient instability can be achieved. We have shown, using advanced machine learning techniques running in a live neuro-critical care environment, that it would be possible to give neurointensive teams early warning of potential hypotensive events before they emerge, allowing closer monitoring and earlier clinical assessment in an attempt to prevent the onset of hypotension. The multi-centre clinical infrastructure developed to support the clinical studies provides a solid base for further collaborative research on data quality, false positive correction and the display of early warning data in a clinical setting.

Intracranial pressure elevations in diffuse axonal injury: association with nonhemorrhagic MR lesions in central mesencephalic structures.

OBJECTIVE: Increased intracranial pressure (ICP) in patients with severe traumatic brain injury (TBI) with diffuse axonal injury (DAI) is not well defined. This study investigated the occurrence of increased ICP and whether clinical factors and lesion localization on MRI were associated with increased ICP in patients with DAI. METHODS: Fifty-two patients with severe TBI (median age 24 years, range 9-61 years), who had undergone ICP monitoring and had DAI on MRI, as determined using T2*-weighted gradient echo, susceptibility-weighted imaging, and diffusion-weighted imaging (DWI) sequences, were enrolled. The proportion of good monitoring time (GMT) with ICP > 20 mm Hg during the first 120 hours postinjury was calculated and associations with clinical and MRI-related factors were evaluated using linear regression. RESULTS: All patients had episodes of ICP > 20 mm Hg. The mean proportion of GMT with ICP > 20 mm Hg was 5%, and 27% of the patients (14/52) spent more than 5% of GMT with ICP > 20 mm Hg. The Glasgow Coma Scale motor score at admission (p = 0.04) and lesions on DWI sequences in the substantia nigra and mesencephalic tegmentum (SN-T, p = 0.001) were associated with the proportion of GMT with ICP > 20 mm Hg. In multivariable linear regression, lesions on DWI sequences in SN-T (8% of GMT with ICP > 20 mm Hg, 95% CI 3%-13%, p = 0.004) and young age (-0.2% of GMT with ICP > 20 mm Hg, 95% CI -0.07% to -0.3%, p = 0.002) were associated with increased ICP. CONCLUSIONS: Increased ICP occurs in approximately one-third of patients with severe TBI who have DAI. Age and lesions on DWI sequences in the central mesencephalon (i.e., SN-T) are associated with elevated ICP. These findings suggest that MR lesion localization may aid prediction of increased ICP in patients with DAI.

Optimal Cerebral Perfusion Pressure in Centers With Different Treatment Protocols.

OBJECTIVES: The three centers in this study have different policies regarding cerebral perfusion pressure targets and use of vasopressors in traumatic brain injury patients. The aim was to determine if the different policies affected the estimation of cerebral perfusion pressure which optimizes the strength of cerebral autoregulation, termed "optimal cerebral perfusion pressure." DESIGN: Retrospective analysis of prospectively collected data. SETTING: Three neurocritical care units at university hospitals in Cambridge, United Kingdom, Groningen, the Netherlands, and Uppsala, Sweden. PATIENTS: A total of 104 traumatic brain injury patients were included: 35 each from Cambridge and Groningen, and 34 from Uppsala. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: In Groningen, the cerebral perfusion pressure target was greater than or equal to 50 and less than 70 mm Hg, in Uppsala greater than or equal to 60, and in Cambridge greater than or equal to 60 or preferably greater than or equal to 70. Despite protocol differences, median cerebral perfusion pressure for each center was above 70 mm Hg. Optimal cerebral perfusion pressure was calculated as previously published and implemented in the Intensive Care Monitoring+ software by the Cambridge group, now replicated in the Odin software in Uppsala. Periods with cerebral perfusion pressure above and below optimal cerebral perfusion pressure were analyzed, as were absolute difference between cerebral perfusion pressure and optimal cerebral perfusion pressure and percentage of monitoring time with a valid optimal cerebral perfusion pressure. Uppsala had the highest cerebral perfusion pressure/optimal cerebral perfusion pressure difference. Uppsala patients were older than the other centers, and age is positively correlated with cerebral perfusion pressure/optimal cerebral perfusion pressure difference. Optimal cerebral perfusion pressure was significantly lower in Groningen than in Cambridge. There were no significant differences in percentage of monitoring time with valid optimal cerebral perfusion pressure. Summary optimal cerebral perfusion pressure curves were generated for the combined patient data for each center. These summary curves could be generated for Groningen and Cambridge, but not Uppsala. The older age of the Uppsala patient cohort may explain the absence of a summary curve. CONCLUSIONS: Differences in optimal cerebral perfusion pressure calculation were found between centers due to demographics (age) and treatment (cerebral perfusion pressure targets). These factors should be considered in the design of trials to determine the efficacy of autoregulation-guided treatment.

Hemodynamic Disturbances in the Early Phase After Subarachnoid Hemorrhage: Regional Cerebral Blood Flow Studied by Bedside Xenon-enhanced CT.

BACKGROUND: The mechanisms leading to neurological deterioration and the devastating course of delayed cerebral ischemia (DCI) after subarachnoid hemorrhage (SAH) are still not well understood. Bedside xenon-enhanced computerized tomography (XeCT) enables measurements of regional cerebral blood flow (rCBF) during neurosurgical intensive care. In the present study, CBF characteristics in the early phase after severe SAH were explored and related to clinical characteristics and early clinical course outcome. MATERIALS AND METHODS: Patients diagnosed with SAH and requiring mechanical ventilation were prospectively enrolled in the study. Bedside XeCT was performed within day 0 to 3. RESULTS: Data from 64 patients were obtained. Median global CBF was 34.9 mL/100 g/min (interquartile range [IQR], 26.7 to 41.6). There was a difference in CBF related to age with higher global CBF in the younger patients (30 to 49 y). CBF was also related to the severity of SAH with lower CBF in Fisher grade 4 compared with grade 3. rCBF disturbances and hypoperfusion were common; in 43 of the 64 patients rCBF<20 mL/100 g/min was detected in more than 10% of the region-of-interest (ROI) area and in 17 patients such low-flow area exceeded 30%. rCBF was not related to the localization of the aneurysm; there was no difference in rCBF of ipsilateral compared with contralateral vascular territories. In patients who initially were in Hunt & Hess grade I to III, median global CBF day 0 to 3 was significantly lower for patients who were in poor neurological state at discharge compared with patients in good neurological state, 25.5 mL/100 g/min (IQR, 21.3 to 28.3) versus 37.8 mL/100 g/min (IQR, 30.5 to 47.6). CONCLUSIONS: CBF disturbances are common in the early phase after SAH. In many patients, CBF was heterogenic and substantial areas with low rCBF were detected. Age and CT Fisher grade were factors influencing global cortical CBF. Bedside XeCT may be a tool to identify patients at risk of deteriorating so they can receive intensified management, but this needs further exploration.

Decompressive craniectomy in traumatic brain injury: usage and clinical outcome in a single centre.

BACKGROUND: Two randomised controlled trials (RCTs) of decompressive craniectomy (DC) in traumatic brain injury (TBI) have shown poor outcome, but there are considerations of how these protocols relate to real practice. The aims of this study were to evaluate usage and outcome of DC and thiopental in a single centre. METHOD: The study included all TBI patients treated at the neurointensive care unit, Akademiska sjukhuset, Uppsala, Sweden, between 2008 and 2014. Of 609 patients aged 16 years or older, 35 treated with DC and 23 treated with thiopental only were studied in particular. Background variables, intracranial pressure (ICP) measures and global outcome were analysed. RESULTS: Of 35 DC patients, 9 were treated stepwise with thiopental before DC, 9 were treated stepwise with no thiopental before DC and 17 were treated primarily with DC. Six patients received thiopental after DC. For 23 patients, no DC was needed after thiopental. Eighty-eight percent of our DC patients would have qualified for the DECRA study and 38% for the Rescue-ICP trial. Favourable outcome was 44% in patients treated with thiopental before DC, 56% in patients treated with DC without prior thiopental, 29% in patients treated primarily with DC and 52% in patients treated with thiopental with no DC. CONCLUSIONS: The place for DC in TBI management must be evaluated better, and we believe it is important that future RCTs should have clearer and less permissive ICP criteria regarding when thiopental should be followed by DC and DC followed by thiopental.

The influence of hyperthermia on intracranial pressure, cerebral oximetry and cerebral metabolism in traumatic brain injury.

BACKGROUND: Hyperthermia is a common secondary insult in traumatic brain injury (TBI). The aim was to evaluate the relationship between hyperthermia and intracranial pressure (ICP), and if intracranial compliance and cerebral blood flow (CBF) pressure autoregulation affected that relationship. The relationships between hyperthermia and cerebral oximetry (BtipO2) and cerebral metabolism were also studied. METHODS: A computerized multimodality monitoring system was used for data collection at the neurointensive care unit. Demographic and monitoring data (temperature, ICP, blood pressure, microdialysis, BtipO2) were analyzed from 87 consecutive TBI patients. ICP amplitude was used as measure of compliance, and CBF pressure autoregulation status was calculated using collected blood pressure and ICP values. Mixed models and comparison between groups were used. RESULTS: The influence of hyperthermia on intracranial dynamics (ICP, brain energy metabolism, and BtipO2) was small, but individual differences were seen. Linear mixed models showed that hyperthermia raises ICP slightly more when temperature increases in the groups with low compliance and impaired CBF pressure autoregulation. There was also a tendency (not statistically significant) for increased BtipO2, and for increased pyruvate and lactate, with higher temperature, while the lactate/pyruvate ratio and glucose were stable. CONCLUSIONS: The major finding was that the effects of hyperthermia on intracranial dynamics (ICP, brain energy metabolism, and BtipO2) were not extensive in general, but there were exceptional cases. Hyperthermia treatment has many side effects, so it is desirable to identify cases in which hyperthermia is dangerous. Information from multimodality monitoring may be used to guide treatment in individual patients.

Increased risk of critical CBF levels in SAH patients with actual CPP below calculated optimal CPP.

BACKGROUND: Cerebral pressure autoregulation can be quantified with the pressure reactivity index (PRx), based on the correlation between blood pressure and intracranial pressure. Using PRx optimal cerebral perfusion pressure (CPPopt) can be calculated, i.e., the level of CPP where autoregulation functions best. The relation between cerebral blood flow (CBF) and CPPopt has not been examined. The objective was to assess to which extent CPPopt can be calculated in SAH patients and to investigate CPPopt in relation to CBF. METHODS: Retrospective study of prospectively collected data. CBF was measured bedside with Xenon-enhanced CT (Xe-CT). The difference between actual CPP and CPPopt was calculated (CPP∆). Correlations between CPP∆ and CBF parameters were calculated with Spearman's rank order correlation coefficient (rho). Separate calculations were done using all patients (day 0-14 after onset) as well as in two subgroups (day 0-3 and day 4-14). RESULTS: Eighty-two patients with 145 Xe-CT scans were studied. Automated calculation of CPPopt was possible in adjunct to 60% of the Xe-CT scans. Actual CPP < CPPopt was associated with higher numbers of low-flow regions (CBF <10 ml/100 g/min) in both the early phase (day 0-3, n = 39, Spearman's rho = -0.38, p = 0.02) and late acute phase of the disease (day 4-14, n = 35, Spearman's rho = -0.39, p = 0.02). CPP level per se was not associated with CBF. CONCLUSIONS: Calculation of CPPopt is possible in a majority of patients with severe SAH. Actual CPP below CPPopt is associated with low CBF.

Predictive Factors That May Contribute to Secondary Insults With Nursing Interventions in Adults With Traumatic Brain Injury.

BACKGROUND: Nursing interventions pose risks and benefits to patients with traumatic brain injury at a neurointensive care unit. OBJECTIVES: The aim of this study was to investigate the risk of inducing high intracranial pressure (ICP) related to interventions and whether intracranial compliance, baseline ICP, or autoregulation could be used as predictors. METHODS: The study had a quantitative, prospective, observational design. Twenty-eight patients with TBI were included, and 67 interventions were observed. The definition of a secondary ICP insult was ICP of 20 mm Hg or greater for 5 minutes or more within a continuous 10-minute period. RESULTS: Secondary ICP insults related to nursing interventions occurred in 6 patients (21%) and 8 occasions (12%). Patients with baseline ICP of 15 mm Hg or greater had 4.7 times higher risk of developing an insult. The predictor with the best combination of sensitivity and specificity was baseline ICP. CONCLUSIONS: Baseline ICP of 15 mm Hg or greater was the most important factor to determine the risk of secondary ICP insult related to nursing intervention.

The effects of ventricular drainage on the intracranial pressure signal and the pressure reactivity index.

In subarachnoid hemorrhage (SAH) patients intracranial pressure (ICP) is usually monitored via an extraventricular drain (EVD), which can produce false readings when the drain is open. It is established that both the ICP cardiac pulse frequency and long term trends over several hours are often seriously corrupted. The aim of this study was to establish whether or not the intermediate frequency bands [respiratory, Mayer wave and very low frequency (VLF)] were also corrupted. The VLF range is of special interest because it is important in cerebral autoregulation studies. Using a pattern recognition algorithm we retrospectively identified 718 cases of EVD opening in 80 SAH patients. An analysis of differences between closed and open-drain periods showed that ICP amplitude decreased significantly in all of the three lower frequency bands when the EVD was open. A similar analysis of systemic arterial pressure signal revealed similar changes in the same frequency bands that were positively correlated with the ICP changes. Therefore we concluded that the changes in the ICP signal represented real, physiological changes and not artifact. Pressure reactivity index (PRx) values were also computed during closed and open-drain periods. We found a small but statistically significant decrease during open-drain periods. Based on analysis of the change in the PRx distribution during open drainage we concluded that this decrease also represented physiological changes rather than artifact. In summary the ICP respiratory, Mayer wave, and VLF frequency bands are not corrupted when the EVD is open, and it safe to use these for autoregulation studies.

Extended Anatomical Grading in Diffuse Axonal Injury Using MRI: Hemorrhagic Lesions in the Substantia Nigra and Mesencephalic Tegmentum Indicate Poor Long-Term Outcome.

Clinical outcome after traumatic diffuse axonal injury (DAI) is difficult to predict. In this study, three magnetic resonance imaging (MRI) sequences were used to quantify the anatomical distribution of lesions, to grade DAI according to the Adams grading system, and to evaluate the value of lesion localization in combination with clinical prognostic factors to improve outcome prediction. Thirty patients (mean 31.2 years ±14.3 standard deviation) with severe DAI (Glasgow Motor Score [GMS] <6) examined with MRI within 1 week post-injury were included. Diffusion-weighted (DW), T2*-weighted gradient echo and susceptibility-weighted (SWI) sequences were used. Extended Glasgow outcome score was assessed after 6 months. Number of DW lesions in the thalamus, basal ganglia, and internal capsule and number of SWI lesions in the mesencephalon correlated significantly with outcome in univariate analysis. Age, GMS at admission, GMS at discharge, and low proportion of good monitoring time with cerebral perfusion pressure <60 mm Hg correlated significantly with outcome in univariate analysis. Multivariate analysis revealed an independent relation with poor outcome for age (p = 0.005) and lesions in the mesencephalic region corresponding to substantia nigra and tegmentum on SWI (p = 0.008). We conclude that higher age and lesions in substantia nigra and mesencephalic tegmentum indicate poor long-term outcome in DAI. We propose an extended MRI classification system based on four stages (stage I-hemispheric lesions, stage II-corpus callosum lesions, stage III-brainstem lesions, and stage IV-substantia nigra or mesencephalic tegmentum lesions); all are subdivided by age (≥/<30 years).

Bedside Xenon-CT Shows Lower CBF in SAH Patients with Impaired CBF Pressure Autoregulation as Defined by Pressure Reactivity Index (PRx).

BACKGROUND: Subarachnoid hemorrhage (SAH) is a disease with a high rate of unfavorable outcome, often related to delayed cerebral ischemia (DCI), i.e., ischemic injury that develops days-weeks after onset, with a multifactorial etiology. Disturbances in cerebral pressure autoregulation, the ability to maintain a steady cerebral blood flow (CBF), despite fluctuations in systemic blood pressure, have been suggested to play a role in the development of DCI. Pressure reactivity index (PRx) is a well-established measure of cerebral pressure autoregulation that has been used to study traumatic brain injury, but not extensively in SAH. OBJECTIVE: To study the relation between PRx and CBF in SAH patients, and to examine if PRx can be used to predict DCI. METHODS: Retrospective analysis of prospectively collected data. PRx was calculated as the correlation coefficient between mean arterial blood pressure (MABP) and intracranial pressure (ICP) in a 5 min moving window. CBF was measured using bedside Xenon-CT (Xe-CT). DCI was diagnosed clinically. RESULTS: 47 poor-grade mechanically ventilated patients were studied. Patients with disturbed pressure autoregulation (high PRx values) had lower CBF, as measured by bedside Xe-CT; both in the early (day 0-3) and late (day 4-14) acute phase of the disease. PRx did not differ significantly between patients who developed DCI or not. CONCLUSION: In mechanically ventilated and sedated SAH patients, high PRx (more disturbed CBF pressure autoregulation) is associated with low CBF, both day 0-3 and day 4-14 after onset. The role of PRx as a monitoring tool in SAH patients needs further studying.

An optimal frequency range for assessing the pressure reactivity index in patients with traumatic brain injury.

The objective of this study was to identify the optimal frequency range for computing the pressure reactivity index (PRx). PRx is a clinical method for assessing cerebral pressure autoregulation based on the correlation of spontaneous variations of arterial blood pressure (ABP) and intracranial pressure (ICP). Our hypothesis was that optimizing the methodology for computing PRx in this way could produce a more stable, reliable and clinically useful index of autoregulation status. The patients studied were a series of 131 traumatic brain injury patients. Pressure reactivity indices were computed in various frequency bands during the first 4 days following injury using bandpass filtering of the input ABP and ICP signals. Patient outcome was assessed using the extended Glasgow Outcome Scale (GOSe). The optimization criterion was the strength of the correlation with GOSe of the mean index value over the first 4 days following injury. Stability of the indices was measured as the mean absolute deviation of the minute by minute index value from 30-min moving averages. The optimal index frequency range for prediction of outcome was identified as 0.018-0.067 Hz (oscillations with periods from 55 to 15 s). The index based on this frequency range correlated with GOSe with ρ=-0.46 compared to -0.41 for standard PRx, and reduced the 30-min variation by 23%.

Brain tissue oxygenation and cerebral metabolic patterns in focal and diffuse traumatic brain injury.

INTRODUCTION: Neurointensive care of traumatic brain injury (TBI) patients is currently based on intracranial pressure (ICP) and cerebral perfusion pressure (CPP) targeted protocols. There are reasons to believe that knowledge of brain tissue oxygenation (BtipO2) would add information with the potential of improving patient outcome. The aim of this study was to examine BtipO2 and cerebral metabolism using the Neurovent-PTO probe and cerebral microdialysis (MD) in TBI patients. METHODS: Twenty-three severe TBI patients with monitoring of physiological parameters, ICP, CPP, BtipO2, and MD for biomarkers of energy metabolism (glucose, lactate, and pyruvate) and cellular distress (glutamate, glycerol) were included. Patients were grouped according to injury type (focal/diffuse) and placement of the Neurovent-PTO probe and MD catheter (injured/non-injured hemisphere). RESULTS: We observed different patterns in BtipO2 and MD biomarkers in diffuse and focal injury where placement of the probe also influenced the results (ipsilateral/contralateral). In all groups, despite fairly normal levels of ICP and CPP, increased MD levels of glutamate, glycerol, or the L/P ratio were observed at BtipO2 <5 mmHg, indicating increased vulnerability of the brain at this level. CONCLUSION: Monitoring of BtipO2 adds important information in addition to traditional ICP and CPP surveillance. Because of the different metabolic responses to very low BtipO2 in the individual patient groups we submit that brain tissue oximetry is a complementary tool rather than an alternative to MD monitoring.

Should the neurointensive care management of traumatic brain injury patients be individualized according to autoregulation status and injury subtype?

INTRODUCTION: The status of autoregulation is an important prognostic factor in traumatic brain injury (TBI), and is important to consider in the management of TBI patients. Pressure reactivity index (PRx) is a measure of autoregulation that has been thoroughly studied, but little is known about its variation in different subtypes of TBI. In this study, we examined the impact of PRx and cerebral perfusion pressure (CPP) on outcome in different TBI subtypes. METHODS: 107 patients were retrospectively studied. Data on PRx, CPP, and outcome were collected from our database. The first CT scan was classified according to the Marshall classification system. Patients were assigned to "diffuse" (Marshall class: diffuse-1, diffuse-2, and diffuse-3) or "focal" (Marshall class: diffuse-4, evacuated mass lesion, and non-evacuated mass lesion) groups. 2 × 2 tables were constructed calculating the proportions of favorable/unfavorable outcome at different combinations of PRx and CPP. RESULTS: Low PRx was significantly associated with favorable outcome in the combined group (p = 0.002) and the diffuse group (p = 0.04), but not in the focal group (p = 0.06). In the focal group higher CPP values were associated with worse outcome (p = 0.02). In diffuse injury patients with disturbed autoregulation (PRx >0.1), CPP >70 mmHg was associated with better outcome (p = 0.03). CONCLUSION: TBI patients with diffuse injury may differ from those with mass lesions. In the latter higher levels of CPP may be harmful, possibly due to BBB disruption. In TBI patients with diffuse injury and disturbed autoregulation higher levels of CPP may be beneficial.

Introduction of the Uppsala Traumatic Brain Injury register for regular surveillance of patient characteristics and neurointensive care management including secondary insult quantification and clinical outcome.

BACKGROUND: To improve neurointensive care (NIC) and outcome for traumatic brain injury (TBI) patients it is crucial to define and monitor indexes of the quality of patient care. With this purpose we established the web-based Uppsala TBI register in 2008. In this study we will describe and analyze the data collected during the first three years of this project. METHODS: Data from the medical charts were organized in three columns containing: 1) Admission data; 2) Data from the NIC period including neurosurgery, type of monitoring, treatment, complications, neurological condition at discharge, and the amount of secondary insults; 3) Outcome six months after injury. Indexes of the quality of care implemented include: 1) Index of improvement; 2) Index of change; 3) The percentages of 'Talk and die' and 'Talk and deteriorate' patients. RESULTS: Altogether 314 patients were included 2008-2010: 66 women and 248 men aged 0-86 years. Automatic reports showed that the proportion of patients improving during NIC varied between 80% and 60%. The percentage of deteriorated patients was less than 10%. The percentage of Talk and die/Talk and deteriorate cases was <1%. The mean Glasgow Coma Score (Motor) improved from 5.04 to 5.68 during the NIC unit stay. The occurrences of secondary insults were less than 5% of good monitoring time for intracranial pressure (ICP) >25 mmHg, cerebral perfusion pressure (CPP) <50 mmHg, and systolic blood pressure <100 mmHg. Favorable outcome was achieved by 64% of adults. CONCLUSION: The Uppsala TBI register enables the routine monitoring of NIC quality indexes.

The use of nurse checklists in a bedside computer-based information system to focus on avoiding secondary insults in neurointensive care.

The feasibility and accuracy of using checklists after every working shift in a bedside computer-based information system for documentation of secondary insults in the neurointensive care unit were evaluated. The ultimate goal was to get maximal attention to avoid secondary insults. Feasibility was investigated by assessing if the checklists were filled in as prescribed. Accuracy was evaluated by comparing the checklists with recorded minute-by-minute monitoring data for intracranial pressure-ICP, cerebral perfusion pressure CPP, systolic blood pressure SBP, and temperature. The total number of checklist assessments was 2,184. In 85% of the shifts, the checklists were filled in. There was significantly longer duration of monitoring time at insult level when Yes was filled in regarding ICP (mean 134 versus 30 min), CPP (mean 125 versus 26 min) and temperature (mean 315 versus 120 min). When a secondary insult was defined as >5% of monitoring time spent at insult level, the sensitivity/specificity for the checklist assessments was 31%/100% for ICP, 38%/99% for CPP, and 66%/88% for temperature. Checklists were feasible and appeared relatively accurate. Checklists may elevate the alertness for avoiding secondary insults and help in the evaluation of the patients. This concept may be the next step towards tomorrow critical care.

An evaluation of three measures of intracranial compliance in traumatic brain injury patients.

PURPOSE: To compare intracranial pressure (ICP) amplitude, ICP slope, and the correlation of ICP amplitude and ICP mean (RAP index) as measures of compliance in a cohort of traumatic brain injury (TBI) patients. METHODS: Mean values of the three measures were calculated in the 2-h periods before and after surgery (craniectomies and evacuations), and in the 12-h periods preceding and following thiopental treatment, and during periods of thiopental coma. The changes in the metrics were evaluated using the Wilcoxon test. The correlations of 10-day mean values for the three metrics with age, admission Glasgow Motor Score (GMS), and Extended Glasgow Outcome Score (GOSe) were evaluated. Patients under and over 60 years old were also compared using the Student t test. The correlation of ICP amplitude with systemic pulse amplitude was analyzed. RESULTS: ICP amplitude was significantly correlated with GMS, and also with age for patients 35 years old and older. The correlations of ICP slope and the RAP index with GMS and with age were not significant. All three metrics indicated significant improvements in compliance following surgery and during thiopental coma. None of the metrics were significantly correlated with outcome, possibly due to confounding effects of treatment factors. The correlation of systemic pulse amplitude with ICP amplitude was low (R = 0.18), only explaining 3 % of the variance. CONCLUSIONS: This study provides further validation for all three of these features of the ICP waveform as measures of compliance. ICP amplitude had the best performance in these tests.