Brain Tissue Oxygenation in Children Diagnosed With Brain Death

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.

Pediatric brain death certification: a narrative review

In the five decades since its inception, brain death has become an accepted medical and legal concept throughout most of the world. There was initial reluctance to apply brain death criteria to children as they are believed more likely to regain neurologic function following injury. In spite of early trepidation, criteria for pediatric brain death certification were first proposed in 1987 by a multidisciplinary committee comprised of experts in the medical and legal communities. Protocols have since been developed to standardize brain death determination, but there remains substantial variability in practice throughout the world. In addition, brain death remains a topic of considerable ethical, philosophical, and legal controversy, and is often misrepresented in the media. In the present article, we discuss the history of brain death and the guidelines for its determination. We provide an overview of past and present challenges to its concept and diagnosis from biophilosophical, ethical and legal perspectives, and highlight differences between adult and pediatric brain death determination. We conclude by anticipating future directions for brain death as related to the emergence of new technologies. It is our position that providers should endorse the criteria for brain death diagnosis in children as proposed by the Society of Critical Care Medicine (SCCM), American Academy of Pediatrics (AAP), and Child Neurology Society (CNS), in order to prevent controversy and subjectivity surrounding what constitutes life versus death.

Anatomical and Physiological Differences between Children and Adults Relevant to Traumatic Brain Injury and the Implications for Clinical Assessment and Care

General and central nervous system anatomy and physiology in children is different to that of adults and this is relevant to traumatic brain injury (TBI) and spinal cord injury. The controversies and uncertainties in adult neurotrauma are magnified by these differences, the lack of normative data for children, the scarcity of pediatric studies, and inappropriate generalization from adult studies. Cerebral metabolism develops rapidly in the early years, driven by cortical development, synaptogenesis, and rapid myelination, followed by equally dramatic changes in baseline and stimulated cerebral blood flow. Therefore, adult values for cerebral hemodynamics do not apply to children, and children cannot be easily approached as a homogenous group, especially given the marked changes between birth and age 8. Their cranial and spinal anatomy undergoes many changes, from the presence and disappearance of the fontanels, the presence and closure of cranial sutures, the thickness and pliability of the cranium, anatomy of the vertebra, and the maturity of the cervical ligaments and muscles. Moreover, their systemic anatomy changes over time. The head is relatively large in young children, the airway is easily compromised, the chest is poorly protected, the abdominal organs are large. Physiology changes—blood volume is small by comparison, hypothermia develops easily, intracranial pressure (ICP) is lower, and blood pressure normograms are considerably different at different ages, with potentially important implications for cerebral perfusion pressure (CPP) thresholds. Mechanisms and pathologies also differ—diffuse injuries are common in accidental injury, and growing fractures, non-accidental injury and spinal cord injury without radiographic abnormality are unique to the pediatric population. Despite these clear differences and the vulnerability of children, the amount of pediatric-specific data in TBI is surprisingly weak. There are no robust guidelines for even basics aspects of care in children, such as ICP and CPP management. This is particularly alarming given that TBI is a leading cause of death in children. To address this, there is an urgent need for pediatric-specific clinical research. If this goal is to be achieved, any clinician or researcher interested in pediatric neurotrauma must be familiar with its unique pathophysiological characteristics.

Targeted treatment in severe traumatic brain injury in the age of precision medicine

In recent years, much progress has been made in our understanding of traumatic brain injury (TBI). Clinical outcomes have progressively improved, but evidence-based guidelines for how we manage patients remain surprisingly weak. The problem is that the many interventions and strategies that have been investigated in randomized controlled trials have all disappointed. These include many concepts that had become standard care in TBI. And that is just for adult TBI; in children, the situation is even worse. Not only is pediatric care more difficult than adult care because physiological norms change with age, but also there is less evidence for clinical practice. In this article, we discuss the heterogeneity inherent in TBI and why so many clinical trials have failed. We submit that a key goal for the future is to appreciate important clinical differences between patients in their pathophysiology and their responses to treatment. The challenge that faces us is how to rationally apply therapies based on the specific needs of an individual patient. In doing so, we may be able to apply the principles of precision medicine approaches to the patients we treat.

Pathophysiology and Treatment of Severe Traumatic Brain Injuries in Children

Traumatic brain injuries (TBIs) in children are a major cause of morbidity and mortality worldwide. Severe TBIs account for 15,000 admissions annually and a mortality rate of 24% in children in the United States. The purpose of this article is to explore pathophysiologic events, examine monitoring techniques, and explain current treatment modalities and nursing care related to caring for children with severe TBI. The primary injury of a TBI is because of direct trauma from an external force, a penetrating object, blast waves, or a jolt to the head. Secondary injury occurs because of alterations in cerebral blood flow, and the development of cerebral edema leads to necrotic and apoptotic cellular death after TBI. Monitoring focuses on intracranial pressure, cerebral oxygenation, cerebral edema, and cerebrovascular injuries. If abnormalities are identified, treatments are available to manage the negative effects caused to the cerebral tissue. The mainstay treatments are hyperosmolar therapy; temperature control; cerebrospinal fluid drainage; barbiturate therapy; decompressive craniectomy; analgesia, sedation, and neuromuscular blockade; and antiseizure prophylaxis.

Intracranial pressure and cerebral perfusion pressure in patients developing brain death

PURPOSE

We investigated whether a critical rise of intracranial pressure (ICP) leading to a loss of cerebral perfusion pressure (CPP) could serve as a surrogate marker of brain death (BD).

MATERIALS AND METHODS

We retrospectively analyzed ICP and CPP of patients in whom BD was diagnosed (n = 32, 16-79 years). Intracranial pressure and CPP were recorded using parenchymal (n = 27) and ventricular probes (n = 5). Data were analyzed from admission until BD was diagnosed.

RESULTS

Intracranial pressure was severely elevated (mean ± SD, 95.5 ± 9.8 mm Hg) in all patients when BD was diagnosed. In 28 patients, CPP was negative at the time of diagnosis (-8.2 ± 6.5 mm Hg). In 4 patients (12.5%), CPP was reduced but not negative. In these patients, minimal CPP was 4 to 18 mm Hg. In 1 patient, loss of CPP occurred 4 hours before apnea completed the BD syndrome.

CONCLUSIONS

Brain death was universally preceded by a severe reduction of CPP, supporting loss of cerebral perfusion as a critical step in BD development. Our data show that a negative CPP is neither sufficient nor a prerequisite to diagnose BD. In BD cases with positive CPP, we speculate that arterial blood pressure dropped below a critical closing pressure, thereby causing cessation of cerebral blood flow.

Multimodality monitoring consensus statement: monitoring in emerging economies

The burden of disease and so the need for care is often greater at hospitals in emerging economies. This is compounded by frequent restrictions in the delivery of good quality clinical care due to resource limitations. However, there is substantial heterogeneity in this economically defined group, such that advanced brain monitoring is routinely practiced at certain centers that have an interest in neurocritical care. It also must be recognized that significant heterogeneity in the delivery of neurocritical care exists even within individual high-income countries (HICs), determined by costs and level of interest. Direct comparisons of data between HICs and the group of low- and middle-income countries (LAMICs) are made difficult by differences in patient demographics, selection for ICU admission, therapies administered, and outcome assessment. Evidence suggests that potential benefits of multimodality monitoring depend on an appropriate environment and clinical expertise. There is no evidence to suggest that patients in LAMICs where such resources exist should be treated any differently to patients from HICs. The potential for outcome benefits in LAMICs is arguably greater in absolute terms because of the large burden of disease; however, the relative cost/benefit ratio of such monitoring in this setting must be viewed in context of the overall priorities in delivering health care at individual institutions.

Cerebral oximetry with cerebral blood volume index in detecting pediatric stroke in a pediatric ED

BACKGROUND

Despite pediatric stroke awareness and pediatric stroke activation systems, recognition and imaging delays along with activation inconsistency still occur. Reliable objective pediatric stroke detection tools are needed to improve detection and activations. Regional cerebral oxygen saturation (rcso2) with cerebral blood volume index (CBVI) can detect abnormal cerebral physiology.

OBJECTIVE

To determine cerebral oximetry in detecting strokes in stroke alert and overall stroke patients.

METHOD

Left rcso2, right rcso2, and rcso2 side differences for stroke, location, and types were analyzed.

RESULTS

Compared with stroke alert (n = 25) and overall strokes (n = 52), rcso2 and CBVI were less than those in nonstrokes (n = 133; P < .0001). Rcso2 side differences in stroke alert and overall strokes were greater than in nonstrokes (P < .0001). Lower rcso2 and CBVI correlated with both groups' stroke location, left (P < .0001) and right rcso2 (P = .004). Rcso2 differences greater than 10 had a 100% positive predictive value for stroke. Both groups' rcso2 and CBVI side differences were consistent for stroke location and type (P < .0001). For both groups, left rcso2 and CBVI were greater than those of the right (P < .0001). Hemorrhagic strokes had lower bilateral rcso2 and CBVI than did ischemic strokes (P < .001).

CONCLUSIONS

Cerebral oximetry and CBVI detected abnormal cerebral physiology, stroke location, and type (hemorrhagic or ischemic). Rcso2 side differences greater than 10 or rcso2 readings less than 50% had a 100% positive predictive value for stroke. Cerebral oximetry has shown potential as a detection tool for stroke location and type in a pediatric stroke alert and nonalert stroke patients. Using cerebral oximetry by the nonneurologist, we found that the patient's rcso2 side difference greater than 10 or one or both sides having less than 50% rcso2 readings suggests abnormal hemispheric pathology and expedites the patient's diagnosis, neuroresuscitation, and radiologic imaging.

Advances in neurocritical care

The neurologically injured child, whether from trauma or other causes, is a common admission into any Pediatric critical care unit. Whatever the cause, the risk for death and life long disability remains very high. Unlike the adult population, neurological diseases in children are diverse and arise from a variety of factors that vary greatly in age and presentation. Nervous system dysfunction is often a complication of critical illness and interventions. While neurointensive care units may be ideal for the at-risk child, in mixed units, 40 % of admissions may be neurological or have neurological complications. Improved quality of care and the application of protocols and bundles, appear to have contributed significantly to improved outcomes. Since we are constantly facing an uphill task of dealing with deterioration while trying to preserve function, detection of early shifts of any nature would be deemed helpful. The intensivist must focus not only on saving life but also on preventing disability with full awareness that responsibility does not end with discharge from the pediatric intensive care unit (PICU). Outcome audits should include not only deaths and discharge from PICU but also one year mortality and even degree of disability at the end of one year from discharge.

Special considerations in infants and children

Head injury in children is one of the most common causes of death and disability in the US and, increasingly, worldwide. This chapter reviews the causes, patterns, pathophysiology, and treatment of head injury in children across the age spectrum, and compares pediatric head injury to that in adults. Classification of head injury in children can be organized according to severity, pathoanatomic type, or mechanism. Response to injury and repair mechanisms appear to vary at different ages, and these may influence optimal treatment; however, much work is still needed before investigation leads to clearly effective clinical interventions. This is true both for the more severe injuries as well as those at the milder end of the injury spectrum, the latter of which have received increasing attention. In this chapter, neuroassessment tools for each age, newer imaging modalities including magnetic resonance imaging (MRI), and specific pediatric management issues, including intracranial pressure (ICP) monitoring and seizure prophylaxis, are reviewed. Finally, specific head injury patterns and functional outcomes relevant to pediatric patients are discussed. While head injury is common, the number of head-injured children is significantly smaller than the corresponding adult head-injured population. When divided further by specific ages, injury types, and other sources of heterogeneity, properly powered clinical research is likely to require large data sets that will allow for stratification across variables, including age. While much has been learned in the past several decades, further study will be required to determine the best management practices for optimizing recovery in individual pediatric patients. This approach is likely to depend on collaborative international head injury databases that will allow researchers to better understand the nuanced evolution of different types of head injury in patients at each age, and the pathophysiologic, treatment-related, and genetic factors that influence recovery.

Cerebral oximetry with blood volume index in asystolic pediatric cerebrospinal fluid malfunctioning shunt patients

Pediatric cerebrospinal fluid shunt malfunctions can present with varying complaints. The primary cause is elevated intracranial pressure (ICP). Malfunctioning sites are the proximal or distal sites[1-4]. A rare presenting complaint is cardiac arrest. Immediate ICP reduction is the only reversible option for this type of cardiac arrest.

Cerebral oximetry and cerebral blood flow monitoring in 2 pediatric survivors with out-of-hospital cardiac arrest

In pediatric out-of-hospital cardiac arrest (POHCA), cardiovascular monitoring tools have improved resuscitative endeavors and cardiovascular outcomes but with still poor neurologic outcomes. Regarding cardiac arrest in patients with congenital heart disease during surgery, the application of cerebral oximetry with blood volume index (BVI) during the resuscitation has shown significant results and prognostic significance. We present 2 POHCA patients who had cerebral oximetry with BVI monitoring during their arrest and postarrest phase in the emergency department and its potential prognostic aspect.Basic procedures include left and right cerebral oximetry with BVI monitoring at every 5-second interval during cardiac arrest, resuscitation, and postarrest in 2 POHCA patients in the pediatric emergency department.Regional cerebral tissue oxygen saturation (rSo2) with BVI readings in these 2 POHCA survivors demonstrated interesting cerebral physiology, blood flow, and potential prognostic outcome. In 1 patient, the reference range of cerebral rSo2 with positive blood flow during arrest and postarrest phases consistently occurred. This neurologic monitoring had its significance when the resuscitation effectiveness was used and end-tidal CO2 changes were lost. The other patient's cerebral rSo2 with simultaneous BVI readings and trending showed the effectiveness of the emergency medical services (EMS) resuscitation.Cerebral oximetry with cerebral blood flow index monitoring in these POHCA survivors demonstrates compelling periarrest and postarrest cerebral physiology information and prognostication. Cerebral oximetry with cerebral BVI monitoring during these arrest phases has potential as a neurologic monitor for the resuscitative intervention's effectiveness and its possible neurologic prognostic application in the pediatric OCHA patients.

S100B protein may detect brain death development after severe traumatic brain injury

Despite improvements in the process of organ donation and transplants, the number of organ donors is progressively declining in developed countries. Therefore, the early detection of patients at risk for brain death (BD) is a priority for transplant teams seeking more efficient identification of potential donors. In the extensive literature on S100B as a biomarker for traumatic brain injury (TBI), no evidence appears to exist on its prognostic capacity as a predictor of BD after severe TBI. The objective of this study is to assess the value of including acute S100B levels in standard clinical data as an early screening tool for BD after severe TBI. This prospective study included patients with severe TBI (Glasgow Coma Scale score [GCS] ≤ 8) admitted to our Neurocritical Care Unit over a 30 month period. We collected the following clinical variables: age, gender, GCS score, pupillary alterations at admission, hypotension and pre-hospital desaturation, CT scan results, isolated TBI or other related injuries, Injury Severity Score (ISS), serum S100B levels at admission and 24 h post-admission, and a final diagnosis regarding BD. Of the 140 patients studied, 11.4% developed BD and showed significantly higher S100B concentrations (p<0.001). Multivariate analysis showed that bilateral unresponsive mydriasis at admission and serum S100B at 24 h post-admission had odds ratios (ORs) of 21.35 (p=0.005) and 4.9 (p=0.010), respectively. The same analysis on patients with photomotor reflex in one pupil at admission left only the 24 h S100B sample in the model (OR=15.5; p=0.009). Receiver operating characteristics (ROC) curve analysis on this group showed the highest area under the curve (AUC) (0.86; p=0.001) for 24 h S100B determinations. The cut off was set at 0.372 μg/L (85.7% sensitivity, 79.3% specificity, positive predictive value [PPV]=18.7% and negative predictive value [NPV]=98.9%). This study shows that pupillary responsiveness at admission, as well as 24 h serum S100B levels, could serve as screening tools for the early detection of patients at risk for BD after severe TBI.

Clinical variables and neuromonitoring information (intracranial pressure and brain tissue oxygenation) as predictors of brain-death development after severe traumatic brain injury

BACKGROUND AND PURPOSE

The aim of this study was to ascertain the role of clinical variables and neuromonitoring data as predictors of brain death (BD) after severe traumatic brain injury (TBI).

PATIENTS AND METHODS

This prospective observational study involved severe TBI patients admitted to the intensive care unit between October 2009 and May 2011. The following variables were recorded: gender, age, reference Glasgow Coma Scale after resuscitation, pupillary reactivity, prehospital hypotension and desaturation, injury severity score, computed tomography (CT) findings, intracranial hypertension, and low brain tissue oxygenation (Pti02) levels (<16 mm Hg), as well as the final result of BD.

RESULTS

Among 61 patients (86.9% males) who met the inclusion criteria, the average age was 37.69 ± 16.44 years. Traffic accidents were the main cause of TBI (62.3%). The patients at risk of progressing to BD (14.8% of the entire cohort) were those with a mass lesion on CT (odds ratio [OR] 33.6; 95% confidence interval [CI]: 3.75-300.30; P = .002), altered pupillary reaction at admission (OR 25.5; 95% CI: 2.27-285.65; P = .009), as well low Pti02 levels on admission (OR 20.41; 95% CI: 3.52-118.33; P < .001) and during the first 24 hours of neuromonitoring (OR 20; 95% CI: 2.90-137.83; P < .001). Multivariate logistic regression showed that a low Pti02 level on admission was the best independent predictor for BD (OR 20.41; 95% CI: 3.53-118.33; P = .001).

CONCLUSIONS

Clinical variables and neuromonitoring information may identify TBI patients at risk of deterioration to BD.

Advanced neuromonitoring and imaging in pediatric traumatic brain injury

While the cornerstone of monitoring following severe pediatric traumatic brain injury is serial neurologic examinations, vital signs, and intracranial pressure monitoring, additional techniques may provide useful insight into early detection of evolving brain injury. This paper provides an overview of recent advances in neuromonitoring, neuroimaging, and biomarker analysis of pediatric patients following traumatic brain injury.