Outcomes associated with brain tissue oxygen monitoring in patients with severe traumatic brain injury undergoing intracranial pressure monitoring

Brain tissue oxygen combined with intracranial pressure monitoring versus isolated intracranial pressure monitoring in patients with traumatic brain injury: an updated systematic review and meta-analysis

Monitoring intracranial pressure (ICP) is pivotal in the management of severe traumatic brain injury (TBI), but secondary brain injuries can arise despite normal ICP levels. Cerebral tissue oxygenation monitoring (PbtO2) may detect neuronal tissue infarction thresholds, enhancing neuroprotection. We performed a systematic review and meta-analysis to evaluate the effects of combined cerebral tissue oxygenation (PbtO2) and ICP compared to isolated ICP monitoring in patients with TBI. PubMed, Embase, Cochrane, and Web of Sciences databases were searched for trials published up to June 2023. A total of 16 studies comprising 37,820 patients were included. ICP monitoring was universal, with additional placement of PbtO2 in 2222 individuals (5.8%). The meta-analysis revealed a reduction in mortality (OR 0.57, 95% CI 0.37-0.89, p = 0.01), a greater likelihood of favorable outcomes (OR 2.28, 95% CI 1.66-3.14, p < 0.01), and a lower chance of poor outcomes (OR 0.51, 95% CI 0.34-0.79, p < 0.01) at 6 months for the PbtO2 plus ICP group. However, these patients experienced a longer length of hospital stay (MD 2.35, 95% CI 0.50-4.20, p = 0.01). No significant difference was found in hospital mortality rates (OR 0.81, 95% CI 0.61-1.08, p = 0.16) or intensive care unit length of stay (MD 2.46, 95% CI - 0.11-5.04, p = 0.06). The integration of PbtO2 to ICP monitoring improved mortality outcomes and functional recovery at 6 months in patients with TBI. PROSPERO (International Prospective Register of Systematic Reviews) CRD42022383937; https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=383937.

Letter to editor: Brain tissue oxygen partial pressure monitoring and prognosis of patients with traumatic brain injury: a meta-analysis of published cases

This critique evaluates a letter to the editor discussing the role of brain tissue oxygen partial pressure (PbtO2) monitoring in the prognosis of patients with traumatic brain injury (TBI). The meta-analysis aims to synthesize existing evidence, highlighting the potential of PbtO2 monitoring as an early indicator of cerebral hypoxia and its correlation with improved patient outcomes. Despite these promising findings, the analysis is constrained by significant methodological variability among the included studies, potential publication bias, and the practical challenges of implementing PbtO2 monitoring widely. The letter emphasizes the need for standardized protocols and further research to solidify the clinical utility of PbtO2 monitoring and integrate it with other monitoring strategies for comprehensive TBI management.

Brain tissue oxygen plus intracranial pressure monitoring versus isolated intracranial pressure monitoring in patients with traumatic brain injury: an updated meta-analysis of randomized controlled trials

BACKGROUND

Intracranial pressure (ICP) monitoring plays a key role in patients with traumatic brain injury (TBI), however, cerebral hypoxia can occur without intracranial hypertension. Aiming to improve neuroprotection in these patients, a possible alternative is the association of Brain Tissue Oxygen Pressure (PbtO2) monitoring, used to detect PbtO2 tension.

METHOD

We systematically searched PubMed, Embase and Cochrane Central for RCTs comparing combined PbtO2 + ICP monitoring with ICP monitoring alone in patients with severe or moderate TBI. The outcomes analyzed were mortality at 6 months, favorable outcome (GOS ≥ 4 or GOSE ≥ 5) at 6 months, pulmonary events, cardiovascular events and sepsis rate.

RESULTS

We included 4 RCTs in the analysis, totaling 505 patients. Combined PbtO2 + ICP monitoring was used in 241 (47.72%) patients. There was no significant difference between the groups in relation to favorable outcome at 6 months (RR 1.17; 95% CI 0.95-1.43; p = 0.134; I2 = 0%), mortality at 6 months (RR 0.82; 95% CI 0.57-1.18; p = 0.281; I2 = 34%), cardiovascular events (RR 1.75; 95% CI 0.86-3.52; p = 0.120; I2 = 0%) or sepsis (RR 0.75; 95% CI 0.25-2.22; p = 0.604; I2 = 0%). The risk of pulmonary events was significantly higher in the group with combined PbtO2 + ICP monitoring (RR 1.44; 95% CI 1.11-1.87; p = 0.006; I2 = 0%).

CONCLUSIONS

Our findings suggest that combined PbtO2 + ICP monitoring does not change outcomes such as mortality, functional recovery, cardiovascular events or sepsis. Furthermore, we found a higher risk of pulmonary events in patients undergoing combined monitoring.

Brain tissue oxygen partial pressure monitoring and prognosis of patients with traumatic brain injury: a meta-analysis

To assess whether monitoring brain tissue oxygen partial pressure (PbtO2) or employing intracranial pressure (ICP)/cerebral perfusion pressure (CCP)-guided management improves patient outcomes, including mortality, hospital length of stay (LOS), mean daily ICP and mean daily CCP during the intensive care unit(ICU)stay. We searched the Web of Science, EMBASE, PubMed, Cochrane Library, and MEDLINE databases until December 12, 2023. Prospective randomized controlled and cohort studies were included. A meta-analysis was performed for the primary outcome measure, mortality, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Eleven studies with a total of 37,492 patients were included. The mortality in the group with PbtO2 was 29.0% (odds ratio: 0.73;95% confidence interval [CI]:0.56-0.96; P = 0.03; I = 55%), demonstrating a significant benefit. The overall hospital LOS was longer in the PbtO2 group than that in the ICP/CPP group (mean difference:2.03; 95% CI:1.03-3.02; P<0.0001; I = 39%). The mean daily ICP in the PbtO2 monitoring group was lower than that in the ICP/CPP group (mean difference:-1.93; 95% CI: -3.61 to -0.24; P = 0.03; I = 41%). Moreover, PbtO2 monitoring did not improve the mean daily CPP (mean difference:2.43; 95%CI: -1.39 to 6.25;P = 0.21; I = 56%).Compared with ICP/CPP monitoring, PbtO2 monitoring reduced the mortality and the mean daily ICP in patients with severe traumatic brain injury; however, no significant effect was noted on the mean daily CPP. In contrast, ICP/CPP monitoring alone was associated with a short hospital stay.

Using EEG total energy as a noninvasively tracking of intracranial (and cerebral perfussion) pressure in an animal model: A pilot study

PURPOSE

This study aims to describe the total EEG energy during episodes of intracranial hypertension (IH) and evaluate its potential as a classification feature for IH.

NEW METHODS

We computed the sample correlation coefficient between intracranial pressure (ICP) and the total EEG energy. Additionally, a generalized additive model was employed to assess the relationship between arterial blood pressure (ABP), total EEG energy, and the odds of IH.

RESULTS

The median sample cross-correlation between total EEG energy and ICP was 0.7, and for cerebral perfusion pressure (CPP) was 0.55. Moreover, the proposed model exhibited an accuracy of 0.70, sensitivity of 0.53, specificity of 0.79, precision of 0.54, F1-score of 0.54, and an AUC of 0.7.

COMPARISON WITH EXISTING METHODS

The only existing comparable methods, up to our knowledge, use 13 variables as predictor of IH, our model uses only 3, our model, as it is an extension of the generalized model is interpretable and it achieves the same performance.

CONCLUSION

These findings hold promise for the advancement of multimodal monitoring systems in neurocritical care and the development of a non-invasive ICP monitoring tool, particularly in resource-constrained environments.

The impact of brain tissue oxygenation monitoring on the Glasgow Outcome Scale/Glasgow Outcome Scale Extended in patients with moderate to severe traumatic brain injury: A systematic review

BACKGROUND

Traumatic brain injuries (TBIs) are one of the leading causes of death or long-term disability around the world. As a result of improvements in supportive care, patients are surviving more severe insults with more pronounced dependency on their families, hospitals, and long-term care facilities. The introduction of brain tissue oxygenation (PbtO2) monitoring aims to recognize episodes of reduced cerebral perfusion with and without associated increased intracranial pressure (ICP).

AIM

The aim of this review is to determine the impact of PbtO2 on the Glasgow Outcome Scale/Glasgow Outcome Scale Extended (GOS/GOSE) in patients with moderate to severe TBI.

DESIGN

Systematic review with narrative and meta-analysis. All original research in which adult patients undergoing PbtO2 were compared with a control group of traditional ICP/cerebral perfusion pressure (CPP) monitoring. Both randomized controlled trials and observational studies were included in this review.

METHODS

Databases were searched in September 2022. The primary outcome of the review was the impact of PbtO2 monitoring on GOS/GOSE, while secondary outcomes were mortality and length of stay (LOS) in the intensive care unit (ICU).

RESULTS

Seven studies with a combined number of 770 patients were included in the review. These patients were adults ≥16 years of age. Only two of the studies included found a statistically significant association between PbtO2 monitoring and improved long-term neurological outcomes in patients with TBI (p = .01, p < .01). A meta-analysis of the secondary outcomes identified an associated reduction of mortality in favour of the group treated with PbtO2 monitoring (p < .0001). Results from studies examining LOS in ICU have demonstrated an associated increase of LOS in ICU in patients treated with PbtO2-guided therapy.

CONCLUSION

From the studies included in this review, only two found a statistically significant association between PbtO2 monitoring and long-term outcomes. It is unclear whether PbtO2 goal-directed therapy has a positive impact on the long-term neurological functions and mortality of patients suffering from TBI. A multicentre randomized controlled trial may provide further evidence, but not necessarily conclusive.

RELEVANCE TO CLINICAL PRACTICE

Further research is warranted to determine the efficacy of the introduction of this new monitoring system to guide local policy change.

Multi-Mechanistic Approaches to the Treatment of Traumatic Brain Injury: A Review

Traumatic brain injury (TBI) is a leading cause of death and disability worldwide. Despite extensive research efforts, the majority of trialed monotherapies to date have failed to demonstrate significant benefit. It has been suggested that this is due to the complex pathophysiology of TBI, which may possibly be addressed by a combination of therapeutic interventions. In this article, we have reviewed combinations of different pharmacologic treatments, combinations of non-pharmacologic interventions, and combined pharmacologic and non-pharmacologic interventions for TBI. Both preclinical and clinical studies have been included. While promising results have been found in animal models, clinical trials of combination therapies have not yet shown clear benefit. This may possibly be due to their application without consideration of the evolving pathophysiology of TBI. Improvements of this paradigm may come from novel interventions guided by multimodal neuromonitoring and multimodal imaging techniques, as well as the application of multi-targeted non-pharmacologic and endogenous therapies. There also needs to be a greater representation of female subjects in preclinical and clinical studies.

Invasive Neuromonitoring Modalities in the Pediatric Population

Invasive neuromonitoring has become an important part of pediatric neurocritical care, as neuromonitoring devices provide objective data that can guide patient management in real time. New modalities continue to emerge, allowing clinicians to integrate data that reflect different aspects of cerebral function to optimize patient management. Currently, available common invasive neuromonitoring devices that have been studied in the pediatric population include the intracranial pressure monitor, brain tissue oxygenation monitor, jugular venous oximetry, cerebral microdialysis, and thermal diffusion flowmetry. In this review, we describe these neuromonitoring technologies, including their mechanisms of function, indications for use, advantages and disadvantages, and efficacy, in pediatric neurocritical care settings with respect to patient outcomes.

Avoiding brain hypoxia in severe traumatic brain injury in settings with limited resources - A pathophysiological guide

Cerebral oxygenation represents the balance between oxygen delivery, consumption and utilization by the brain, and therefore reflects the adequacy of cerebral perfusion. Different factors can influence the amount of oxygen to the brain including arterial blood pressure, hemoglobin levels, systemic oxygenation, and transfer of oxygen from blood to the cerebral microcirculation. A mismatch between cerebral oxygen supply and demand results in cerebral hypoxia/ischemia, and is associated with secondary brain damage and worsened outcome after acute brain injury. Therefore, monitoring and prompt treatment of cerebral oxygenation compromise is warranted in both neuro and general intensive care unit populations. Several tools have been proposed for the assessment of cerebral oxygenation, including non-invasive/invasive or indirect/direct methods, including Jugular Venous Oxygen Saturation (SjO2), Partial Brain Tissue Oxygen Tension (PtiO2), Near infrared spectroscopy (NIRS), Transcranial Doppler, electroencephalography and Computed Tomography. In this manuscript, we aim to review the pathophysiology of cerebral oxygenation, describe monitoring technics, and generate recommendations for avoiding brain hypoxia in settings with low availability of resources for direct brain oxygen monitoring.

Intracranial-Pressure-Monitoring-Assisted Management Associated with Favorable Outcomes in Moderate Traumatic Brain Injury Patients with a GCS of 9-11

Objective: With a mortality rate of 10−30%, a moderate traumatic brain injury (mTBI) is one of the most variable traumas. The indications for intracranial pressure (ICP) monitoring in patients with mTBI and the effects of ICP on patients’ outcomes are uncertain. The purpose of this study was to examine the indications of ICP monitoring (ICPm) and its effects on the long-term functional outcomes of mTBI patients. Methods: Patients with Glasgow Coma Scale (GCS) scores of 9−11 at Tangdu hospital, between January 2015 and December 2021, were enrolled and treated in this retrospective cohort study. We assessed practice variations in ICP interventions using the therapy intensity level (TIL). Six-month mortality and a Glasgow Outcome Scale Extended (GOS-E) score were the main outcomes. The secondary outcome was neurological deterioration (ND) events. The indication and the estimated impact of ICPm on the functional outcome were investigated by using binary regression analyses. Results: Of the 350 patients, 145 underwent ICP monitoring-assisted management, and the other 205 patients received a standard control based on imaging or clinical examinations. A GCS ≤ 10 (OR 1.751 (95% CI 1.216−3.023), p = 0.003), midline shift (mm) ≥ 2.5 (OR 3.916 (95% CI 2.076−7.386) p < 0.001), and SDH (OR 1.772 (95% CI 1.065−2.949) p = 0.028) were predictors of ICP. Patients who had ICPm (14/145 (9.7%)) had a decreased 6-month mortality rate compared to those who were not monitored (40/205 (19.5%), p = 0.011). ICPm was linked to both improved neurological outcomes at 6 months (OR 0.815 (95% CI 0.712−0.933), p = 0.003) and a lower ND rate (2 = 11.375, p = 0.010). A higher mean ICP (17.32 ± 3.52, t = −6.047, p < 0.001) and a more significant number of ICP > 15 mmHg (27 (9−45.5), Z = −5.406, p < 0.001) or ICP > 20 mmHg (5 (0−23), Z = −4.635, p < 0.001) 72 h after injury were associated with unfavorable outcomes. The best unfavorable GOS-E cutoff value of different ICP characteristics showed that the mean ICP was >15.8 mmHg (AUC 0.698; 95% CI, 0.606−0.789, p < 0.001), the number of ICP > 15 mmHg was >25.5 (AUC 0.681; 95% CI, 0.587−0.774, p < 0.001), and the number of ICP > 20 mmHg was >6 (AUC 0.660; 95% CI, 0.561−0.759, p < 0.001). The total TIL score during the first 72 h post-injury in the non-ICP group (9 (8, 11)) was lower than that of the ICP group (13 (9, 17), Z = −8.388, p < 0.001), and was associated with unfavorable outcomes. Conclusion: ICPm-assisted management was associated with better clinical outcomes six months after discharge and lower incidences of ND for seven days post-injury. A mean ICP > 15.8 mmHg, the number of ICP > 15 mmHg > 25.5, or the number of ICP > 20 mmHg > 6 implicate an unfavorable long-term prognosis after 72 h of an mTBI.

Cerebral metabolic derangements following traumatic brain injury

PURPOSE OF REVIEW

Outcome following traumatic brain injury (TBI) remains variable, and derangements in cerebral metabolism are a common finding in patients with poor outcome. This review compares our understanding of cerebral metabolism in health with derangements seen following TBI.

RECENT FINDINGS

Ischemia is common within the first 24 h of injury and inconsistently detected by bedside monitoring. Metabolic derangements can also result from tissue hypoxia in the absence of ischemic reductions in blood flow due to microvascular ischemia and mitochondrial dysfunction. Glucose delivery across the injured brain is dependent on blood glucose and regional cerebral blood flow, and is an important contributor to derangements in glucose metabolism. Alternative energy substrates such as lactate, ketone bodies and succinate that may support mitochondrial function, and can be utilized when glucose availability is low, have been studied following TBI but require further investigation.

SUMMARY

Mitochondrial dysfunction and the use of alternative energy substrates are potential therapeutic targets, but improved understanding of the causes, impact and significance of metabolic derangements in clinical TBI are needed. Maintaining adequate oxygen and glucose delivery across the injured brain may accelerate the recovery of mitochondrial function and cerebral energy metabolism and remain important management targets.

The Impact of Invasive Brain Oxygen Pressure Guided Therapy on the Outcome of Patients with Traumatic Brain Injury: A Systematic Review and Meta-Analysis

Traumatic brain injury (TBI) is a major public health burden, causing death and disability worldwide. Intracranial hypertension and brain hypoxia are the main mechanisms of secondary brain injury. As such, management strategies guided by intracranial pressure (ICP) and brain oxygen (PbtO₂) monitoring could improve the prognosis of these patients. Our objective was to summarize the current evidence regarding the impact of PbtO₂-guided therapy on the outcome of patients with TBI. We performed a systematic search of PubMed, Scopus, and the Cochrane library databases, following the protocol registered in PROSPERO. Only studies comparing PbtO₂/ICP-guided therapy with ICP-guided therapy were selected. Primary outcome was neurological outcome at 3 and 6 months assessed by using the Glasgow Outcome Scale; secondary outcomes included hospital and long-term mortality, burden of intracranial hypertension, and brain tissue hypoxia. Out of 6254 retrieved studies, 15 studies (n = 37,245 patients, of who 2184 received PbtO₂-guided therapy) were included in the final analysis. When compared with ICP-guided therapy, the use of combined PbO₂/ICP-guided therapy was associated with a higher probability of favorable neurological outcome (odds ratio 2.21 [95% confidence interval 1.72-2.84]) and of hospital survival (odds ratio 1.15 [95% confidence interval 1.04-1.28]). The heterogeneity (I²) of the studies in each analysis was below 40%. However, the quality of evidence was overall low to moderate. In this meta-analysis, PbtO₂-guided therapy was associated with reduced mortality and more favorable neurological outcome in patients with TBI. The low-quality evidence underlines the need for the results from ongoing phase III randomized trials.

Initial neurocritical care of severe traumatic brain injury: New paradigms and old challenges

Background:

Early neurocritical care aims to ameliorate secondary traumatic brain injury (TBI) and improve neural salvage. Increased engagement of neurosurgeons in neurocritical care is warranted as daily briefings between the intensivist and the neurosurgeon are considered a quality indicator for TBI care. Hence, neurosurgeons should be aware of the latest evidence in the neurocritical care of severe TBI (sTBI).

Methods:

We conducted a narrative literature review of bibliographic databases (PubMed and Scopus) to examine recent research of sTBI.

Results:

This review has several take-away messages. The concept of critical neuroworsening and its possible causes is discussed. Static thresholds of intracranial pressure (ICP) and cerebral perfusion pressure may not be optimal for all patients. The use of dynamic cerebrovascular reactivity indices such as the pressure reactivity index can facilitate individualized treatment decisions. The use of ICP monitoring to tailor treatment of intracranial hypertension (IHT) is not routinely feasible. Different guidelines have been formulated for different scenarios. Accordingly, we propose an integrated algorithm for ICP management in sTBI patients in different resource settings. Although hyperosmolar therapy and decompressive craniectomy are standard treatments for IHT, there is a lack high-quality evidence on how to use them. A discussion of the advantages and disadvantages of invasive ICP monitoring is included in the study. Addition of beta-blocker, anti-seizure, and anticoagulant medications to standardized management protocols (SMPs) should be considered with careful patient selection.

Conclusion:

Despite consolidated research efforts in the refinement of SMPs, there are still many unanswered questions and novel research opportunities for sTBI care.

Invasive brain tissue oxygen and intracranial pressure (ICP) monitoring versus ICP-only monitoring in pediatric severe traumatic brain injury

OBJECTIVE

Severe traumatic brain injury (TBI) is a leading cause of disability and death in the pediatric population. While intracranial pressure (ICP) monitoring is the gold standard in acute neurocritical care following pediatric severe TBI, brain tissue oxygen tension (PbtO2) monitoring may also help limit secondary brain injury and improve outcomes. The authors hypothesized that pediatric patients with severe TBI and ICP + PbtO2 monitoring and treatment would have better outcomes than those who underwent ICP-only monitoring and treatment.

METHODS

Patients ≤ 18 years of age with severe TBI who received ICP ± PbtO2 monitoring at a quaternary children's hospital between 1998 and 2021 were retrospectively reviewed. The relationships between conventional measurements of TBI were evaluated, i.e., ICP, cerebral perfusion pressure (CPP), and PbtO2. Differences were analyzed between patients with ICP + PbtO2 versus ICP-only monitoring on hospital and pediatric intensive care unit (PICU) length of stay (LOS), length of intubation, Pediatric Intensity Level of Therapy scale score, and functional outcome using the Glasgow Outcome Score-Extended (GOS-E) scale at 6 months postinjury.

RESULTS

Forty-nine patients, including 19 with ICP + PbtO2 and 30 with ICP only, were analyzed. There was a weak negative association between ICP and PbtO2 (β = -0.04). Conversely, there was a strong positive correlation between CPP ≥ 40 mm Hg and PbtO2 ≥ 15 and ≥ 20 mm Hg (β = 0.30 and β = 0.29, p < 0.001, respectively). An increased number of events of cerebral PbtO2 < 15 mm Hg or < 20 mm Hg were associated with longer hospital (p = 0.01 and p = 0.022, respectively) and PICU (p = 0.015 and p = 0.007, respectively) LOS, increased duration of mechanical ventilation (p = 0.015 when PbtO2 < 15 mm Hg), and an unfavorable 6-month GOS-E score (p = 0.045 and p = 0.022, respectively). An increased number of intracranial hypertension episodes (ICP ≥ 20 mm Hg) were associated with longer hospital (p = 0.007) and PICU (p < 0.001) LOS and longer duration of mechanical ventilation (p < 0.001). Lower minimum hourly and average daily ICP values predicted favorable GOS-E scores (p < 0.001 for both). Patients with ICP + PbtO2 monitoring experienced longer PICU LOS (p = 0.018) compared to patients with ICP-only monitoring, with no significant GOS-E score difference between groups (p = 0.733).

CONCLUSIONS

An increased number of cerebral hypoxic episodes and an increased number of intracranial hypertension episodes resulted in longer hospital LOS and longer duration of mechanical ventilator support. An increased number of cerebral hypoxic episodes also correlated with less favorable functional outcomes. In contrast, lower minimum hourly and average daily ICP values, but not the number of intracranial hypertension episodes, were associated with more favorable functional outcomes. There was a weak correlation between ICP and PbtO2, supporting the importance of multimodal invasive neuromonitoring in pediatric severe TBI.