ICP threshold in CPP management of severe head injury patients

Intracranial Pressure Monitoring and Treatment Thresholds in Acute Neural Injury: A Narrative Review of the Historical Achievements, Current State, and Future Perspectives

Since its introduction in the 1960s, intracranial pressure (ICP) monitoring has become an indispensable tool in neurocritical care practice and a key component of the management of moderate/severe traumatic brain injury (TBI). The primary utility of ICP monitoring is to guide therapeutic interventions aimed at maintaining physiological ICP and preventing intracranial hypertension. The rationale for such ICP maintenance is to prevent secondary brain injury arising from brain herniation and inadequate cerebral blood flow. There exists a large body of evidence indicating that elevated ICP is associated with mortality and that aggressive ICP control protocols improve outcomes in severe TBI patients. Therefore, current management guidelines recommend a cerebral perfusion pressure (CPP) target range of 60-70 mm Hg and an ICP threshold of >20 or >22 mm Hg, beyond which therapeutic intervention should be initiated. Though our ability to achieve these thresholds has drastically improved over the past decades, there has been little to no change in the mortality and morbidity associated with moderate-severe TBI. This is a result of the "one treatment fits all" dogma of current guideline-based care that fails to take individual phenotype into account. The way forward in moderate-severe TBI care is through the development of continuously derived individualized ICP thresholds. This narrative review covers the topic of ICP monitoring in TBI care, including historical context/achievements, current monitoring technologies and indications, treatment methods, associations with patient outcome and multi-modal cerebral physiology, present controversies surrounding treatment thresholds, and future perspectives on personalized approaches to ICP-directed therapy.

How to Clear Polytrauma Patients for Fracture Fixation: Results of a systematic review of the literature

INTRODUCTION

Early patient assessment is relevant for surgical decision making in severely injured patients and early definitive surgery is known to be beneficial in stable patients. The aim of this systematic review is to extract parameters indicative of risk factors for adverse outcome. Moreover, we aim to improve decision making and separate patients who would benefit from early versus staged definitive surgical fixation.

METHODS

Following the PRISMA guidelines, a systematic review of peer-reviewed articles in English or German language published between (2000 and 2022) was performed. The primary outcome was the pathophysiological response to polytrauma including coagulopathy, shock/haemorrhage, hypothermia and soft tissue injury (trauma, brain injury, thoracic and abdominal trauma, and musculoskeletal injury) to determine the treatment strategy associated with the least amount of complications. Articles that had used quantitative parameters to distinguish between stable and unstable patients were summarized. Two authors screened articles and discrepancies were resolved by consensus. Quantitative values for relevant parameters indicative of an unstable polytrauma patient were obtained.

RESULTS

The initial systematic search using MeSH criteria yielded 1550 publications deemed relevant to the following topics (coagulopathy (n = 37), haemorrhage/shock (n = 7), hypothermia (n = 11), soft tissue injury (n = 24)). Thresholds for stable, borderline, unstable and in extremis conditions were defined according to the existing literature as follows: Coagulopathy; International Normalized Ratio (INR) and viscoelastic methods (VEM)/Blood/shock; lactate, systolic blood pressure and haemoglobin, hypothermia; thresholds in degrees Celsius/Soft tissue trauma: traumatic brain injury, thoracic and abdominal trauma and musculoskeletal trauma.

CONCLUSION

In this systematic literature review, we summarize publications by focusing on different pathways that stimulate pathophysiological cascades and remote organ damage. We propose that these parameters can be used for clinical decision making within the concept of safe definitive surgery (SDS) in the treatment of severely injured patients.

Failure of an effective physiologic threshold compliance tool to demonstrate benefit in a clinical trial of traumatic brain injury patients

BACKGROUND

Better physiologic threshold compliance holds promise for improving outcomes in neurocritical care patients.

METHODS

Our group developed a threshold compliance tool. This software computes and displays the proportion of values out of range in real time. We captured intracranial pressure (ICP) measures in our patients before and after implementation of this technology. Ten months after the threshold compliance tool was introduced we initiated a randomized controlled trial involving acute traumatic brain injury (TBI) patients to assess whether the tool was effective at reducing out-of-range ICP values.

RESULTS

A total of 54 patients with ICP monitors were included in our analysis, 42 of whom sustained a TBI. Implementation of the threshold compliance tool was associated with an 85.3% reduction in ICP values exceeding 22 mmHg in neurocritical care patients (p = 0.004) and a 76.8% reduction in patients with TBI (p = 0.043). Out-of-range values in an area-under-the-curve analysis were reduced by 78.8% in all patients (p = 0.009) and in TBI patients by 77.9% (p = 0.051). Out-of-range values were not further reduced during our randomized controlled trial examining the threshold compliance tool, and a difference between treatment groups was not suggested.

CONCLUSIONS

Implementation of a threshold compliance tool was associated with a marked and significant reduction in out-of-range ICP values. Benefit was, however, not evident in a randomized controlled trial. Our analysis provides a unique perspective on our failure to detect an apparent true difference and may provide insights into other neurotrauma trial failures.

Intracranial pressure monitoring: fundamental considerations and rationale for monitoring

Traumatic brain injury (TBI) is a major cause of death and disability worldwide. In large part critical care for TBI is focused on the identification and management of secondary brain injury. This requires effective neuromonitoring that traditionally has centered on intracranial pressure (ICP). The purpose of this paper is to review the fundamental literature relative to the clinical application of ICP monitoring in TBI critical care and to provide recommendations on how the technique maybe applied to help patient management and enhance outcome. A PubMed search between 1980 and September 2013 identified 2,253 articles; 244 of which were reviewed in detail to prepare this report and the evidentiary tables. Several important concepts emerge from this review. ICP monitoring is safe and is best performed using a parenchymal monitor or ventricular catheter. While the indications for ICP monitoring are well established, there remains great variability in its use. Increased ICP, particularly the pattern of the increase and ICP refractory to treatment is associated with increased mortality. Class I evidence is lacking on how monitoring and management of ICP influences outcome. However, a large body of observational data suggests that ICP management has the potential to influence outcome, particularly when care is targeted and individualized and supplemented with data from other monitors including the clinical examination and imaging.

Decompressive craniectomy reduces white matter injury after controlled cortical impact in mice

Reduction and avoidance of increases in intracranial pressure (ICP) after severe traumatic brain injury (TBI) continue to be the mainstays of treatment. Traumatic axonal injury is a major contributor to morbidity after TBI, but it remains unclear whether elevations in ICP influence axonal injury. Here we tested the hypothesis that reduction in elevations in ICP after experimental TBI would result in decreased axonal injury and white matter atrophy in mice. Six-week-old male mice (C57BL/6J) underwent either moderate controlled cortical impact (CCI) (n=48) or Sham surgery (Sham, n=12). Immediately after CCI, injured animals were randomized to a loose fitting plastic cap (Open) or replacement of the previously removed bone flap (Closed). Elevated ICP was observed in Closed animals compared with Open and Sham at 15 min (21.4±4.2 vs. 12.3±2.9 and 8.8±1.8 mm Hg, p<0.0001) and 1 day (17.8±3.7 vs. 10.6±2.0 and 8.9±1.9 mm Hg, p<0.0001) after injury. Beta amyloid precursor protein staining in the corpus callosum and ipsilateral external capsule revealed reduced axonal swellings and bulbs in Open compared with Closed animals (32% decrease, p<0.01 and 40% decrease, p<0.001 at 1 and 7 days post-injury, respectively). Open animals were also found to have decreased neurofilament-200 stained axonal swellings at 7 days post-injury compared with Open animals (32% decrease, p<0.001). At 4 weeks post-injury, Open animals had an 18% reduction in white matter volume compared with 34% in Closed animals (p<0.01). Thus, our results indicate that CCI with decompressive craniectomy was associated with reductions in ICP and reduced pericontusional axonal injury and white matter atrophy. If similar in humans, therapeutic interventions that ameliorate intracranial hypertension may positively influence white matter injury severity.

What is wrong with the tenets underpinning current management of severe traumatic brain injury?

The results of a recent randomized controlled trial comparing intracranial pressure (ICP) monitor-based treatment of severe traumatic brain injury (sTBI) to management without ICP monitoring prompt this skeptical reconsideration of the scientific foundation underlying current sTBI management. Much of current practice arises from research performed under conditions that are no longer relevant today. The definition of an episode of intracranial hypertension is incomplete, and the application of a fixed, universal ICP treatment threshold is poorly founded. Although intracranial hypertension is a valid indicator of disease severity, it remains to be demonstrated that lowering ICP improves outcome. Furthermore, sTBI has not been categorized on the basis of underlying pathophysiology despite the current capability to do so. Similar concerns also apply to manipulation of cerebral perfusion with respect to maintaining universal thresholds for contrived variables rather than tailoring treatment to monitored processes. As such, there is a failure to either optimize management approaches or minimize associated treatment risks for individual sTBI patients. The clinical and research TBI communities need to reassess many of the sTBI management concepts that are currently considered well established.

Prognostic significance of blood-brain barrier disruption in patients with severe nonpenetrating traumatic brain injury requiring decompressive craniectomy

OBJECT

The authors assessed the risk factors and outcomes associated with blood-brain barrier (BBB) disruption in patients with severe, nonpenetrating, traumatic brain injury (TBI) requiring decompressive craniectomy.

METHODS

At 2 major neurotrauma centers in Western Australia, a retrospective cohort study was conducted among 97 adult neurotrauma patients who required an external ventricular drain (EVD) and decompressive craniectomy during 2004-2012. Glasgow Outcome Scale scores were used to assess neurological outcomes. Logistic regression was used to identify factors associated with BBB disruption, defined by a ratio of total CSF protein concentrations to total plasma protein concentration > 0.007 in the earliest CSF specimen collected after TBI.

RESULTS

Of the 252 patients who required decompressive craniectomy, 97 (39%) required an EVD to control intracranial pressure, and biochemical evidence of BBB disruption was observed in 43 (44%). Presence of disruption was associated with more severe TBI (median predicted risk for unfavorable outcome 75% vs 63%, respectively; p = 0.001) and with worse outcomes at 6, 12, and 18 months than was absence of BBB disruption (72% vs 37% unfavorable outcomes, respectively; p = 0.015). The only risk factor significantly associated with increased risk for BBB disruption was presence of nonevacuated intracerebral hematoma (> 1 cm diameter) (OR 3.03, 95% CI 1.23-7.50; p = 0.016). Although BBB disruption was associated with more severe TBI and worse long-term outcomes, when combined with the prognostic information contained in the Corticosteroid Randomization after Significant Head Injury (CRASH) prognostic model, it did not seem to add significant prognostic value (area under the receiver operating characteristic curve 0.855 vs 0.864, respectively; p = 0.453).

CONCLUSIONS

Biochemical evidence of BBB disruption after severe nonpenetrating TBI was common, especially among patients with large intracerebral hematomas. Disruption of the BBB was associated with more severe TBI and worse long-term outcomes, but when combined with the prognostic information contained in the CRASH prognostic model, this information did not add significant prognostic value.

The impacts and outcomes of implementing head injury guidelines: clinical experience in Thailand

OBJECTIVE

To describe the impact of implementing clinical practice guidelines (CPG) for head injury in a trauma referral system in Songkla province, Thailand.

METHODS

The CPG was developed by a local multidisciplinary team and implemented using multi-faceted methods. The outcome of patients with head injury from three community hospitals and a university hospital (Songklanagarind Hospital) was reported in terms of "talk and deteriorate" patients and a "poor" outcome for patients with severe head injury. Changes to clinical practice were observed where the guidelines were implemented.

RESULTS

1000 patients with head injury were enrolled from 1st August 2005 to 15th January 2006. The incidence of "talk and deteriorate" patients was 10.5% and a poor outcome was noted in 35.5% of patients with severe head injury, similar to the results of a previous study in Songklanagarind Hospital (p>0.05). Following implementation of the guidelines, 19.8% of patients underwent CT scanning with similar outcomes for alert patients with and without basal skull fracture (p>0.05). The clinician-nurse relationship also improved and there was closer collaboration between hospitals. Short observation in community hospitals for repeat neurological examination may be an appropriate strategy for management of some patients with minor head injury.

CONCLUSIONS

Local ownership, an appropriate implementation strategy and working as a multidisciplinary team are key factors for success in implementing the CPG. Basal skull fracture may not be an absolute criterion for CT imaging of the head. Further initiatives will be developed in response to the incidence of "talk and deteriorate" patients.