Todd F. Glass

Identification of children at very low risk of clinically-important brain injuries after head trauma: a prospective cohort study

BACKGROUND CT imaging of head-injured children has risks of radiation-induced malignancy. Our aim was to identify children at very low risk of clinically-important traumatic brain injuries (ciTBI) for whom CT might be unnecessary. METHODS We enrolled patients younger than 18 years presenting within 24 h of head trauma with Glasgow Coma Scale scores of 14-15 in 25 North American emergency departments. We derived and validated age-specific prediction rules for ciTBI (death from traumatic brain injury, neurosurgery, intubation >24 h, or hospital admission >or=2 nights). FINDINGS We enrolled and analysed 42 412 children (derivation and validation populations: 8502 and 2216 younger than 2 years, and 25 283 and 6411 aged 2 years and older). We obtained CT scans on 14 969 (35.3%); ciTBIs occurred in 376 (0.9%), and 60 (0.1%) underwent neurosurgery. In the validation population, the prediction rule for children younger than 2 years (normal mental status, no scalp haematoma except frontal, no loss of consciousness or loss of consciousness for less than 5 s, non-severe injury mechanism, no palpable skull fracture, and acting normally according to the parents) had a negative predictive value for ciTBI of 1176/1176 (100.0%, 95% CI 99.7-100 0) and sensitivity of 25/25 (100%, 86.3-100.0). 167 (24.1%) of 694 CT-imaged patients younger than 2 years were in this low-risk group. The prediction rule for children aged 2 years and older (normal mental status, no loss of consciousness, no vomiting, non-severe injury mechanism, no signs of basilar skull fracture, and no severe headache) had a negative predictive value of 3798/3800 (99.95%, 99.81-99.99) and sensitivity of 61/63 (96.8%, 89.0-99.6). 446 (20.1%) of 2223 CT-imaged patients aged 2 years and older were in this low-risk group. Neither rule missed neurosurgery in validation populations. INTERPRETATION These validated prediction rules identified children at very low risk of ciTBIs for whom CT can routinely be obviated. FUNDING The Emergency Medical Services for Children Programme of the Maternal and Child Health Bureau, and the Maternal and Child Health Bureau Research Programme, Health Resources and Services Administration, US Department of Health and Human Services.

Hypoxic preconditioning protects against ischemic brain injury.

SummaryAnimals exposed to brief periods of moderate hypoxia (8% to 10% oxygen for 3 hours) are protected against cerebral and cardiac ischemia between 1 and 2 days later. This hypoxia preconditioning requires new RNA and protein synthesis. The mechanism of this hypoxia-induced tolerance correlates with the induction of the hypoxia-inducible factor (HIF), a transcription factor heterodimeric complex composed of inducible HIF-1α and constitutive HIF-1β proteins that bind to the hypoxia response elements in a number of HIF target genes. Our recent studies show that HIF-1α correlates with hypoxia induced tolerance in neonatal rat brain. HIF target genes, also induced following hypoxia-induced tolerance, include vascular endothelial growth factor, erythropoietin, glucose transporters, glycolytic enzymes, and many other genes. Some or all of these genes may contribute to hypoxia-induced protection against ischemia. HIF induction of the glycolytic enzymes accounts in part for the Pasteur effect in brain and other tissues. Hypoxia-induced tolerance is not likely to be equivalent to treatment with a single HIF target gene protein since other transcription factors including Egr-1 (NGFI-A) have been implicated in hypoxia regulation of gene expression. Understanding the mechanisms and genes involved in hypoxic tolerance may provide new therapeutic targets to treat ischemic injury and enhance recovery.

Isolated linear skull fractures in children with blunt head trauma

BACKGROUND AND OBJECTIVE: Children and adolescents with minor blunt head trauma and isolated skull fractures are often admitted to the hospital. The objective of this study was to describe the injury circumstances and frequency of clinically important neurologic complications among children with minor blunt head trauma and isolated linear skull fractures. METHODS: This study was a planned secondary analysis of a large prospective cohort study in children <18 years old with blunt head trauma. Data were collected in 25 emergency departments. We analyzed patients with Glasgow Coma Scale scores of 14 or 15 and isolated linear skull fractures. We ascertained acute neurologic outcomes through clinical information collected during admission or via telephone or mail at least 1 week after the emergency department visit. RESULTS: In the parent study, we enrolled 43 904 children (11 035 [25%] <2 years old). Of those with imaging studies, 350 had isolated linear skull fractures. Falls were the most common injury mechanism, accounting for 70% (81% for ages <2 years old). Of 201 hospitalized children, 42 had computed tomography or MRI repeated; 5 had new findings but none required neurosurgical intervention. Of 149 patients discharged from the hospital, 20 had repeated imaging, and none had new findings. CONCLUSIONS: Children with minor blunt head trauma and isolated linear skull fractures are at very low risk of evolving other traumatic findings noted in subsequent imaging studies or requiring neurosurgical intervention. Hospital admission for neurologically normal children with isolated linear skull fractures after minor blunt head trauma for monitoring is typically unnecessary.

Isolated Loss of Consciousness in Children With Minor Blunt Head Trauma

IMPORTANCE A history of loss of consciousness (LOC) is frequently a driving factor for computed tomography use in the emergency department evaluation of children with blunt head trauma. Computed tomography carries a nonnegligible risk for lethal radiation-induced malignancy. The Pediatric Emergency Care Applied Research Network (PECARN) derived 2 age-specific prediction rules with 6 variables for clinically important traumatic brain injury (ciTBI), which included LOC as one of the risk factors. OBJECTIVE To determine the risk for ciTBIs in children with isolated LOC. DESIGN, SETTING, AND PARTICIPANTS This was a planned secondary analysis of a large prospective multicenter cohort study. The study included 42 ,412 children aged 0 to 18 years with blunt head trauma and Glasgow Coma Scale scores of 14 and 15 evaluated in 25 emergency departments from 2004-2006. EXPOSURE A history of LOC after minor blunt head trauma. MAIN OUTCOMES AND MEASURES The main outcome measures were ciTBIs (resulting in death, neurosurgery, intubation for >24 hours, or hospitalization for ≥2 nights) and a comparison of the rates of ciTBIs in children with no LOC, any LOC, and isolated LOC (ie, with no other PECARN ciTBI predictors). RESULTS A total of 42 412 children were enrolled in the parent study, with 40 693 remaining in the current analysis after exclusions. Of these, LOC occurred in 15.4% (6286 children). The prevalence of ciTBI with any history of LOC was 2.5% and for no history of LOC was 0.5% (difference, 2.0%; 95% CI, 1.7-2.5). The ciTBI rate in children with isolated LOC, with no other PECARN predictors, was 0.5% (95% CI, 0.2-0.8; 13 of 2780). When comparing children who have isolated LOC with those who have LOC and other PECARN predictors, the risk ratio for ciTBI in children younger than 2 years was 0.13 (95% CI, 0.005-0.72) and for children 2 years or older was 0.10 (95% CI, 0.06-0.19). CONCLUSIONS AND RELEVANCE Children with minor blunt head trauma presenting to the emergency department with isolated LOC are at very low risk for ciTBI and do not routinely require computed tomographic evaluation.

The impact of hypercarbia on the evolution of brain injury in a porcine model of traumatic brain injury and systemic hemorrhage

Carbon dioxide is perhaps the most potent available modulator of cerebrovascular tone and thus cerebral blood flow (CBF). These experiments evaluate the impact of induced hypercarbia on the matching of blood flow and metabolism in the injured brain. We explore the hypothesis that hypercarbia will restore the relationship of CBF to metabolic demand, resulting in improved outcome following traumatic brain injury (TBI) and hemorrhage. A behavioral outcome score, hemodynamic, metabolic, and pathologic parameters were assessed in anesthetized and ventilated juvenile pigs. Animals were assigned to either normocarbia or hypercarbia and subdivided into TBI (via fluid percussion) with or without hemorrhage. The experimental groups were TBI; TBI + 40% hemorrhage (40%H); TBI + hypercarbia (CO2); and TBI + 40%H + CO2. Hemorrhaged animals were resuscitated with blood and crystalloid. Hypercarbia was induced immediately following TBI using 10% FiCO2. The normocarbic group demonstrated disturbance of the matching of CBF to metabolism evidenced by statistically significant increases in cerebral oxygen and glucose extraction. Hypercarbic animals showed falls in the same parameters, demonstrating improvement in the matching of CBF to metabolic demand. Parenchymal injury was significantly decreased in hypercarbic animals: 3/10 hypercarbic versus 6/8 normocarbic animals showed cerebral contusions at the gray/white interface (p = 0.05). The hypercarbic group had significantly better behavioral outcome scores, 10.5, versus 7.3 for the normocarbic groups (p = 0.005). The decreased incidence of cerebral contusion and improved behavioral outcome scores in our experiments appear to be mediated by better matching of cerebral metabolism and blood flow, suggesting that manipulations modulating the balance of blood flow and metabolism in injured brain may improve outcomes from TBI.

Building Cyclic Schedules for Emergency Department Physicians

Physicians at a branch of the emergency department at Cincinnati Childrens Hospital Medical Center complained that their schedules were too erratic because of the multitude of operating requirements, regulatory constraints, physician preferences, and holiday requests. We addressed this issue by using integer programming to build cyclic schedules that can be repeated throughout the year. These schedules are flexible enough to handle incorporating holidays, work assignments, and vacation requests ex post. After we rolled out the calendar-year-based cyclic schedule, we captured statistics to assess the viability and the quality of the yearly schedule generated. Surveys of the physicians and the scheduler after implementation showed that the new schedule provides predictability and well-balanced work patterns.

Traumatic brain injuries and computed tomography use in pediatric sports participants.

BACKGROUND Childhood sports-related head trauma is common, frequently leading to emergency department (ED) visits. We describe the spectrum of these injuries and trends in computed tomography (CT) use in the Pediatric Emergency Care Applied Research Network. METHODS This was a secondary analysis of a large prospective cohort of children with head trauma in 25 Pediatric Emergency Care Applied Research Network EDs between 2004 and 2006. We described and compared children 5 to 18 years old by CT rate, traumatic brain injury (TBI) on CT, and clinically important TBI (ciTBI). We used multi-variable logistic regression to compare CT rates, adjusting for clinical severity. Outcomes included frequency of CT, TBIs on CT, and ciTBIs (defined by [a] death, [b] neurosurgery, [c] intubation>24 hours, or [d] hospitalization for ≥2 nights). FINDINGS A total of 3289 (14%) of 23082 children had sports-related head trauma. Two percent had Glasgow Coma Scale scores less than 14. 53% received ED CTs, 4% had TBIs on CT, and 1% had ciTBIs. Equestrians had increased adjusted odds (1.8; 95% confidence interval [CI], 1.0-3.0]) of CTs; the rate of TBI on CT was 4% (95% CI, 3%-5%). Compared with team sports, snow (adjusted odds ratio, 4.1; 95% CI 1.5-11.4) and nonmotorized wheeled (adjusted odds ratio, 12.8; 95% CI, 5.5-32.4) sports had increased adjusted odds of ciTBIs. CONCLUSIONS Children with sports-related head trauma commonly undergo CT. Only 4% of those imaged had TBIs on CT. Clinically important TBIs occurred in 1%, with significant variation by sport. There is an opportunity for injury prevention efforts in high-risk sports and opportunities to reduce CT use in general by use of evidence-based prediction rules. What is known about this subject: Pediatric sports-related head injuries are a common and increasingly frequent ED presentation, as is the use of CT in their evaluation. Little is known about TBIs resulting from different types of sports activities in children. What this study adds to existing knowledge: This study broadens the understanding of the epidemiology of Pediatric TBIs resulting from different sports activities through a prospective assessment of frequency and severity of ciTBIs and ED CT use in a large cohort of head-injured children in a network of pediatric EDs.

The Impact of Hypercarbia on the Evolution of Brain Injury in the Setting of Traumatic Brain Injury and Systemic Hemorrhage

The Impact of Hypercarbia on the Evolution of Brain Injury in the Setting of Traumatic Brain Injury and Systemic Hemorrhage

Simulation-Based Design of ED Operations with Care Streams to Optimize Care Delivery and Reduce Length of Stay in the Emergency Department

Faced with the opportunity to significantly deviate from classic operations, a new emergency department (ED) and novel strategy for patient care delivery were simultaneously initiated with the aid of model-based simulation. To answer the design and implementation questions, a traditional strategy for construction of discrete-eventmodel simulation was employed to define ED operations for a newly constructed facility in terms of workflow, variables, resources, structure, process logic and associated assumptions. Benefits were achieved before, during and after implementation of an unprecedented operations strategy—i.e., the organization of the ED care delivery around four care streams: Critical, Diagnostic, Therapeutic and Fast Track. Prior to opening, it shed light on the range of context variables where benefits might be anticipated, and it facilitated staff understanding and judgements of performance. Two years after opening, the operations data is compared to the simulation with encouraging results that shed light on where to continue pursuit of improvement.