The impact of COVID-19 on incidence and outcomes from out-of-hospital cardiac arrest (OHCA) in Texas.

INTRODUCTION: Emerging research demonstrates lower rates of bystander cardiopulmonary resuscitation (BCPR), public AED (PAD), worse outcomes, and higher incidence of OHCA during the COVID-19 pandemic. We aim to characterize the incidence of OHCA during the early pandemic period and the subsequent long-term period while describing changes in OHCA outcomes and survival. METHODS: We analyzed adult OHCAs in Texas from the Cardiac Arrest Registry to Enhance Survival (CARES) during March 11-December 31 of 2019 and 2020. We stratified cases into pre-COVID-19 and COVID-19 periods. Our prehospital outcomes were bystander cardiopulmonary resuscitation (BCPR), public AED use (PAD), sustained ROSC, and prehospital termination of resuscitation (TOR). Our hospital survival outcomes were survival to hospital admission, survival to hospital discharge, good neurological outcomes (CPC Score of 1 or 2) and Utstein bystander survival. We created a mixed effects logistic regression model analyzing the association between the pandemic on outcomes, using EMS agency as the random intercept. RESULTS: There were 3619 OHCAs (45.0% of overall study population) in 2019 compared to 4418 (55.0% of overall study population) in 2020. Rates of BCPR (46.2% in 2019 to 42.2% in 2020, P < 0.01) and PAD (13.0% to 7.3%, p < 0.01) decreased. Patient survival to hospital admission decreased from 27.2% in 2019 to 21.0% in 2020 (p < 0.01) and survival to hospital discharge decreased from 10.0% in 2019 to 7.4% in 2020 (p < 0.01). OHCA patients were less likely to receive PAD (aOR = 0.5, 95% CI [0.4, 0.8]) and the odds of field termination increased (aOR = 1.5, 95% CI [1.4, 1.7]). CONCLUSIONS: Our study adds state-wide evidence to the national phenomenon of long-term increased OHCA incidence during COVID-19, worsening rates of BCPR, PAD use and survival outcomes.

SARS-CoV-2 and RSV bronchiolitis outcomes.

BACKGROUND: Severe acute respiratory syndrome related coronavirus (SARS-CoV-2) bronchiolitis has arisen with the SARS-CoV-2 pandemic. There is a paucity of literature on SARS-CoV-2 bronchiolitis. OBJECTIVE: The purpose of our paper was to review and compare outcomes in bronchiolitis due to severe acute respiratory syndrome related coronavirus 2 (SARS- CoV-2) and Respiratory Syncytial Virus (RSV). We also performed a subgroup analysis of two disrupted RSV seasons during the pandemic. METHODS: This was a retrospective study from a US TriNetX database from March 1, 2020-January 1, 2023. Propensity matching was utilized for confounders. RESULTS: There was a total of 3,592 patients (1,796 in each group) after propensity matching. There was an increased risk of oxygen saturation ≤95 % (RR=1.50 95 % CI 1.58-1.94, p = 0.002) and ICU admission (RR=1.44 95 % CI 1.06-1.94, p = 0.02) in those with SARS- CoV-2 but not for oxygen saturation ≤90 % (RR=1.03 95 %CI 0.75-1.42, p = 0.85) or intubation (RR=0.73 95 % CI 0.35-1.47, p = 0.37). There was a decreased risk of a patient with SARS- CoV-2 bronchiolitis being hospitalized (RR=0.65 95 % CI 0.57-0.74, p < 0.0001), respiratory rate ≥60 (RR=0.64 95 % CI 0.48-0.88, p < 0.001) or ≥70 (RR=0.64 95 % CI 0.43-0.96, p = 0.03) when compared to RSV bronchiolitis. Specifically examining SARS- CoV-2 versus RSV bronchiolitis during the delayed RSV seasons, during the first season both infections were not severe, but during the second RSV bronchiolitis season, patients infected with RSV had less risk of ICU admission compared to those infected with SARS- CoV-2. CONCLUSION: SARS- CoV-2 bronchiolitis patients appeared to have more severe outcomes since the risk of ICU admission was higher for these patients. Also, during the second delayed RSV season, SARS- CoV-2 bronchiolitis was more severe than RSV bronchiolitis.

Social interaction in young children with inflicted and accidental traumatic brain injury: relations with family resources and social outcomes.

Core social interaction behaviors were examined in young children 0-36 months of age who were hospitalized for accidental (n = 61) or inflicted (n = 64) traumatic brain injury (TBI) in comparison to typically developing children (n = 60). Responding to and initiating gaze and joint attention (JA) were evaluated during a semi-structured sequence of social interactions between the child and an examiner at 2 and 12 months after injury. The accidental TBI group established gaze less often and had an initial deficit initiating JA that resolved by the follow-up. Contrary to expectation, children with inflicted TBI did not have lower rates of social engagement than other groups. Responding to JA was more strongly related than initiating JA to measures of injury severity and to later cognitive and social outcomes. Compared to complicated-mild/moderate TBI, severe TBI in young children was associated with less responsiveness in social interactions and less favorable caregiver ratings of communication and social behavior. JA response, family resources, and group interacted to predict outcomes. Children with inflicted TBI who were less socially responsive and had lower levels of family resources had the least favorable outcomes. Low social responsiveness after TBI may be an early marker for later cognitive and adaptive behavior difficulties.

At the intersection of toxicology, psychiatry, and genetics: a diagnosis of ornithine transcarbamylase deficiency.

Ornithine transcarbamylase (OTC) deficiency is a genetic disorder involving a mutation of the ornithine transcarbamylase gene, located on the short arm of the X chromosome (Xp21.1). This makes the expression of the gene most common in homozygous males, but heterozygous females can also be affected and may be more likely to suffer from serious morbidity. Most males present early in the neonatal period with more devastating outcomes than their female counterparts. Up to 34% will present in the first 30 days of life (J Pediatr 2001;138:S30). Females often have partially functioning mitochondria due to uneven distribution of the mutant gene secondary to lyonization ("X-chromosome Inactivation". Genetics Home Reference, 2012). Occasionally, symptomatic females may not even present until they are placed under metabolic stress such as a severe illness, fasting, pregnancy, or new medication (Roth KS, Steiner RD. "Ornithine Transcarbamylase Deficiency". EMedicine, 2012). The urea cycle is the body's primary tool for the disposal of excess nitrogen, which is generated by the routine metabolism of proteins and amino acids. Mitochondrial dysfunction impairs urea production and result in hyperammonemia (Semin Neonatol 2002;7:27). The sine qua non among all degrees of OTC deficiency at presentation is hyperammonemia. As in adults, children will have similar symptoms of encephalopathy, but this may be expressed differently depending on the child's developmental level. We present an unusual case of OTC deficiency in an older child with undifferentiated symptoms of an anticholinergic toxidrome, liver failure, iron overdose, and mushroom poisoning.

Outcomes of croup in children: COVID-19 versus non-COVID-19 cases.

Objectives: The emergence of COVID-19 has revealed its association with croup. The objective of this study was to compare outcomes of COVID-19 related croup to non-COVID-19 related croup during the COVID-19 pandemic. Methods: This retrospective propensity matched study used data from 2020-2023 in the United States Cohort of the TriNetX database that includes 56 major health care organizations. The analysis compared the outcomes of 2 cohorts of patients between 2 months and 7 years of age: Cohort A had croup and a positive test for COVID-19 and Cohort B had croup without a positive COVID-19 test, both within 1 week before or after presentation with croup. Outcomes were death, admission to the hospital, intensive care unit (ICU) admission, respiratory rate >60, and oxygen saturation <90 within 7 days after the diagnosis of croup. Results: There were 2590 patients with COVID-19 related croup and 103,439 patients with non-COVID-19 croup. The final propensity matched cohort included 5180 patients evenly divided between groups. When both groups were compared based on outcomes after matching, there was twice the risk of the patient being admitted to the hospital with COVID-19 croup (risk ratio [RR] = 2.12; 95% confidence interval [CI] 1.59-2.84; P < 0.001). Those with COVID-19 related croup had significantly increased risk of being admitted to the ICU (RR = 4.90; 95% CI 3.11-7.73; P < 0.001). The patients with COVID-19 related croup were more likely to have a respiratory rate ≥60 (RR = 2.00; 95% CI 1.18-3.37; P = 0.008) and oxygen saturation ≤90% (RR = 2.12; 95% CI 1.21-3.70; P = 0.007). There were no deaths in the final cohorts. There were no worse outcomes in the Omicron COVID-19 related croup group. Conclusions: The patients with COVID-19 related croup exhibited more severe disease manifestations. These children were more likely to be admitted to the hospital/ICU and had more significant respiratory distress.

The diagnostic accuracy of an abdominal radiograph with signs and symptoms of intussusception.

OBJECTIVE: The objective of this study was to compare the diagnostic accuracy of an abdominal ultrasound to that of a highly suggestive abdominal radiograph combined with signs and symptoms of intussusception. DESIGN: This was a retrospective cross-sectional study of children 3 years or younger with signs and symptoms of intussusceptions who presented to a pediatric emergency department (ED). Univariate analysis, multivariate analysis, and diagnostic accuracy of clinical characteristics and radiographic findings were derived. RESULTS: A highly suggestive abdominal radiograph (14.80; 5.85-37.45), right upper quadrant mass (8.90; 1.14-69.47), vomiting (2.54; 1.36-4.76), and abdominal pain (2.45; 1.36-4.40) were found to be significantly associated with intussusception by univariate analysis. Vomiting (2.80; 1.34-5.85), abdominal pain (2.75; 1.33-5.69), and bloody stools (2.70; 1.07-6.81) were independently associated with intussusceptions by multivariate analysis. Bloody stools were time dependent. Bloody stools occurred in those patients with intussusception at a median time of 24 hours, from the time the patient started with signs and symptoms to the time of presentation to the ED, vs those without bloody stools presenting at a median time of 11 hours. The combination of a highly suggestive abdominal radiograph, abdominal pain, lethargy, and vomiting was highly specific (95%) for intussusception, comparable to that of an ultrasound (93%). In patients with this combination, all were found to have intussusception by enema or surgery. CONCLUSIONS: Ultrasound is not needed before an enema for the diagnosis of intussusception for those with a highly suggestive abdominal radiograph, abdominal pain, lethargy, and vomiting.

Computed Tomography of the Chest in Younger Pediatric Patients with Thoracic Blunt Trauma Rarely Changes Surgical Management.

INTRODUCTION: Thoracic trauma is the second leading cause of death after traumatic brain injury in children presenting with blunt chest trauma, which represents 80% of thoracic trauma in children. We hypothesized that older children undergo more clinical and surgical changes in management than younger children screened for intrathoracic injury at a single, urban, pediatric Level I trauma center. METHODS: In this retrospective observational study, we determined the frequencies and types of lesions diagnosed only by chest computed tomography (CCT) and resulting changes of clinical and surgical management among different age groups in a pediatric cohort examined for blunt trauma with chest radiograph and CCT. We used logistic regression to quantify variations in CCT diagnoses and changes in clinical and surgical management across age groups. For each age category, we determined the odds ratio for diagnosis made only on CCT and subsequent changes in all clinical management and, specifically, surgical management. We performed the test of trend to determine the relationship across age with changes in management resulting from additional diagnoses made by CCT. RESULTS: We analyzed data on 1,235 patients screened for intrathoracic injury. We found the following overall clinical management and surgical management changes, respectively, per age group: 0-2 years, 5/128 (3.9) and 0/128 (0.0); 3-6 years, 11/212 (5.2) and 1/212 (0.5); 7-10 years, 16/175 (9.1) and 2/175 (1.1); 11-13 years, 17/188 (9.0) and 3/188 (1.6); 14-17 years, 58/532 (10.9) and 25/532 (4.7). There were no observed surgical management changes in the 0-2 age group and, thus, no estimated odds ratio could be calculated. The adjusted odds ratios for the occurrence of surgical change in management (14-17 age group as reference) was 0.1 (0.0-0.9) for 3-6 years, 0.3 (0.1-1.3) for 7-10 years, and 0.3 (0.1-1.1) for 11-13 years. The trend of odds ratios across ages showed that with every subsequent year of life there was a 10% increase in management change and a 30% increase in surgical management change. CONCLUSION: Chest computed tomography plays a limited role in younger children and seldom significantly changes management albeit making additional diagnoses.

Chest x-ray vs. computed tomography of the chest in pediatric blunt trauma.

INTRODUCTION: Chest x-ray (CXR) has been shown to be an effective detection tool for clinically significant trauma. We evaluated differences in findings between CXR and computed tomography of the chest (CCT), their impact on clinical management and the performance of the CXR. METHODS: This retrospective study examined children (less than 18 years) who received a CXR and CCT between 2009 and 2015. We compared characteristics of children by conducting univariate analysis, reporting the proportion of additional diagnoses captured by CCT, and using it to evaluate the sensitivity and specificity of the CXR. Outcome variables were diagnoses made by CCT as well as the ensuing changes in the clinical management attributable to the diagnoses reported by the CCT and not observed by the CXR. RESULTS: In 1235 children, CCT was associated with diagnosing higher proportions of contusion or atelectasis (60% vs 31%; p < .0001), pneumothorax (23% vs 9%; p < .0001), rib fracture (18% vs 7%; p < .0001), other fracture (20% vs 10%; p < .0001), diaphragm rupture (0.2% vs 0.1%; p = .002), and incidental findings (7% vs 2%; p < .0001) as compared to CXR. CCT findings changed the management of 107 children (8.7%) with 32 (2.6%) of the changes being surgical procedures. The overall sensitivity and specificity of the CXR were 57.9% (95% CI: 54.5-61.2) and 90.2% (95% CI: 86.8-93.1), respectively. The positive predictive value and negative predictive value were 93.1% and 48.6%, respectively. CONCLUSION: CXR is a useful initial screening tool to evaluate pediatric trauma patients along with clinical presentation in the Emergency Department in children. LEVEL OF EVIDENCE: Level III, diagnostic test.

The Effect of Simulation Wars on EM Residents' Global Rating Scales and In-Training Examination Scores.

PURPOSE: The Accreditation Council for Graduate Medical Education (ACGME) restricted the duty hours for residents training in 2004. With less time to learn medicine, residents may not develop the clinical reasoning skills needed. Simulation can provide a remedy for this lack of time by allowing residents to practice skills and develop clinical reasoning in a simulated environment. Simulation Wars (SimWars), a clinical reasoning simulation has been shown to improve clinical reasoning skills. The purpose of the study was to investigate the effect of Simulation Wars on In-Training Examination (ITE) Scores and Global Rating Scale (GRS) Scores in Emergency Medicine (EM) residents. METHODS: The Quasi-Experimental design was used in this retrospective study. The main comparison was between historical controls, the residents who did not participate in the Simulation Wars, and the intervention group comprised of residents who participated in the SimWars. RESULTS: A total of 127 residents were participants in this study including 70 from the intervention and 57 from the historical control group. There were no significant differences found in GRS scores between both groups except for Communication and Professionalism (p<0.001). No overall improvement in ITE scores for the control group and for the intervention group was found. Furthermore, within the intervention group, while comparing those residents who participated in certain subcategories of SimWars and those who did not, there was a significant improvement in ITE scores in the subcategories of Thoracic Disorders, Abdominal/Gastrointestinal, Trauma Disorders and OBGyn. CONCLUSION: SimWars in the subcategories of Abdominal/Gastrointestinal, Thoracic, OBGyn and Trauma were found to be associated with improved ITE scores in those subcategories. Since Emergency Medicine utilizes extensive clinical reasoning skills, SimWars may provide better educational opportunities for EM residents.

Late intellectual and academic outcomes following traumatic brain injury sustained during early childhood.

OBJECT: Although long-term neurological outcomes after traumatic brain injury (TBI) sustained early in life are generally unfavorable, the effect of TBI on the development of academic competencies is unknown. The present study characterizes intelligence quotient (IQ) and academic outcomes an average of 5.7 years after injury in children who sustained moderate to severe TBI prior to 6 years of age. METHODS: Twenty-three children who suffered inflicted or noninflicted TBI between the ages of 4 and 71 months were enrolled in a prospective, longitudinal cohort study. Their mean age at injury was 21 months; their mean age at assessment was 89 months. The authors used general linear modeling approaches to compare IQ and standardized academic achievement test scores from the TBI group and a community comparison group (21 children). Children who sustained early TBI scored significantly lower than children in the comparison group on intelligence tests and in the reading, mathematical, and language domains of achievement tests. Forty-eight percent of the TBI group had IQs below the 10th percentile. During the approximately 5-year follow-up period, longitudinal IQ testing revealed continuing deficits and no recovery of function. Both IQ and academic achievement test scores were significantly related to the number of intracranial lesions and the lowest postresuscitation Glasgow Coma Scale score but not to age at the time of injury. Nearly 50% of the TBI group failed a school grade and/or required placement in self-contained special education classrooms; the odds of unfavorable academic performance were 18 times higher for the TBI group than the comparison group. CONCLUSIONS: Traumatic brain injury sustained early in life has significant and persistent consequences for the development of intellectual and academic functions and deleterious effects on academic performance.

Prevalence and Predictors of Poor Recovery from Mild Traumatic Brain Injury.

Although most patients with mild traumatic brain injury (mTBI) recover within 3 months, a subgroup of patients experience persistent symptoms. Yet, the prevalence and predictors of persistent dysfunction in patients with mTBI remain poorly understood. In a longitudinal study, we evaluated predictors of symptomatic and cognitive dysfunction in adolescents and young adults with mTBI, compared with two control groups-patients with orthopedic injuries and healthy uninjured individuals. Outcomes were assessed at 3 months post-injury. Poor symptomatic outcome was defined as exhibiting a symptom score higher than 90% of the orthopedic control (OC) group, and poor cognitive outcome was defined as exhibiting cognitive performance poorer than 90% of the OC group. At 3 months post-injury, more than half of the patients with mTBI (52%) exhibited persistently elevated symptoms, and more than a third (36.4%) exhibited poor cognitive outcome. The rate of high symptom report in mTBI was markedly greater than that of typically developing (13%) and OC (17%) groups; the proportion of those with poor cognitive performance in the mTBI group exceeded that of typically developing controls (15.8%), but was similar to that of the OC group (34.9%). Older age at injury, female sex, and acute symptom report were predictors of poor symptomatic outcome at 3 months. Socioeconomic status was the only significant predictor of poor cognitive outcome at 3 months.

Prospective pilot derivation of a decision tool for children at low risk for testicular torsion.

OBJECTIVE: The purpose of this study was to derive a pilot clinical decision tool with 100% negative predictive value for testicular torsion based on prospectively collected data in children with acute scrotal pain. METHODS: This was a prospective cohort study of a convenience sample of newborn to 21-year-old males evaluated for acute (72 hours or less) scrotal pain at an urban children's hospital emergency department (ED). A pediatric emergency medicine fellow or attending physician documented history and examination findings on a standardized data collection form. The study investigators used ultrasound (US), operative reports, or clinical follow-up to identify patients who had testicular torsion. Pearson's chi-square test and odds ratios (OR) were used to identify factors associated with the diagnosis of testicular torsion. The authors also used a recursive partitioning model to create a low-risk decision tool for testicular torsion. RESULTS: Of the 450 eligible patients, 228 (51%) were enrolled, with a mean (± SD) age of 9.9 (± 4.1) years, including 21 (9.2%, 95% confidence interval [CI] = 5.8% to 13.7%) with testicular torsion. The derived clinical decision tool consisted of three variables: horizontal or inguinal testicular lie (OR = 18.17, 95% CI = 6.2 to 53.2), nausea or vomiting (OR = 5.63, 95% CI = 2.08 to 15.22), and age 11 to 21 years (OR = 3.9, 95% CI = 1.27 to 11.97). These variables had a sensitivity of 100% (95% CI = 98% to 100%) and negative predictive value of 100% (95% CI = 98% to 100%) for the diagnosis of testicular torsion. CONCLUSIONS: Based on a decision tool derived with recursive partitioning, study patients with all of the following characteristics had no risk of testicular torsion: normal testicular lie, lack of nausea or vomiting, and age 0 to 10 years. Future research should focus on externally validating this tool to optimize emergent evaluation when testicular torsion is likely, while minimizing routine sonographic evaluation when patients are unlikely to have a serious condition requiring immediate management.

Updating memory after mild traumatic brain injury and orthopedic injuries.

Few studies have examined the trajectory of recovery of executive function (EF) after mild TBI (mTBI). Therefore, consensus has not been reached on the incidence and extent of EF impairment after mTBI. The present study investigated trajectory of change in executive memory over 3 months after mTBI on 59 right-handed participants with mTBI, as defined by Centers for Disease Control criteria, ages 14-30 years, recruited within 96 hours post-injury and tested <1 week (baseline), 1 month, and 3 months after injury. Also included were 58 participants with orthopedic injury (OI) and 27 typically developing (TD) non-injured participants with similar age, socioeconomic status, sex, and ethnicity. MRI data were acquired at baseline and 3 months. Although criteria included a normal CT scan, lesions were detected by MRI in 19 mTBI patients. Participants completed the KeepTrack task, a verbal recall task placing demands on goal maintenance, semantic memory, and memory updating. Scores reflected items recalled and semantic categories maintained. The mTBI group was divided into two groups: high (score ≥12) or low (score <12) symptoms based on the Rivermead Post-Concussion Symptoms Questionnaire (RPQ). Mixed model analyses revealed the trajectory of change in mTBI patients (high and low RPQ), OI patients, and TD subjects were similar over time (although the TD group differed from other groups at baseline), suggesting no recovery from mTBI up to 90 days. For categories maintained, differences in trajectory of recovery were discovered, with the OI comparison group surprisingly performing similar to those in the mTBI group with high RPQ symptoms, and different from low RPQ and the TD groups, bringing up questions about utility of OIs as a comparison group for mTBI. Patients with frontal lesions (on MRI) were also found to perform worse than those without lesions, a pattern that became more pronounced with time.

Social communication in young children with traumatic brain injury: relations with corpus callosum morphometry.

The purpose of the present investigation was to characterize the relations of specific social communication behaviors, including joint attention, gestures, and verbalization, with surface area of midsagittal corpus callosum (CC) subregions in children who sustained traumatic brain injury (TBI) before 7 years of age. Participants sustained mild (n=10) or moderate-severe (n=26) noninflicted TBI. The mean age at injury was 33.6 months; mean age at MRI was 44.4 months. The CC was divided into seven subregions. Relative to young children with mild TBI, those with moderate-severe TBI had smaller surface area of the isthmus. A semi-structured sequence of social interactions between the child and an examiner was videotaped and coded for specific social initiation and response behaviors. Social responses were similar across severity groups. Even though the complexity of their language was similar, children with moderate-severe TBI used more gestures than those with mild TBI to initiate social overtures; this may indicate a developmental lag or deficit as the use of gestural communication typically diminishes after age 2. After controlling for age at scan and for total brain volume, the correlation of social interaction response and initiation scores with the midsagittal surface area of the CC regions was examined. For the total group, responding to a social overture using joint attention was significantly and positively correlated with surface area of all regions, except the rostrum. Initiating joint attention was specifically and negatively correlated with surface area of the anterior midbody. Use of gestures to initiate a social interaction correlated significantly and positively with surface area of the anterior and posterior midbody. Social response and initiation behaviors were selectively related to regional callosal surface areas in young children with TBI. Specific brainbehavior relations indicate early regional specialization of anterior and posterior CC for social communication.

Total and ionized plasma magnesium concentrations in children after traumatic brain injury.

This study examined 1) whether plasma total Mg (TMg) and ionized Mg (IMg) concentrations in children are reduced by traumatic brain injury (TBI) and 2) whether the extent of reduction correlates with severity of trauma assessed by the Glasgow Coma Scale (GSC) score. This was a prospective cohort study of 98 pediatric patients who had TBI and were admitted through the emergency department. A GCS score was assigned and blood was obtained upon presentation and 24 h later. Plasma was analyzed for TMg and IMg. Patients were grouped into three categories-GCS scores 13-15, 8-12, and <8-to designate mild (n=21), moderate (n=37), and severe (n=40) TBI, respectively. Blood was obtained from 50 healthy children before elective surgery as controls. Control subjects had a TMg and an IMg of 0.94 +/- 0.08 and 0.550 +/- 0.06 mM. TBI patients had an initial TMg and IMg of 0.83 +/- 0.09 and 0.520 +/- 0.05 mM, respectively. Initial TMg for mild, moderate, and severe TBI subgroups (0.87 +/- 0.16, 0.81 +/- 0.15, and 0.83 +/- 0.14 mM, respectively) was reduced from control subjects (p <0.01). IMg was reduced only in the severe TBI subgroup (0.516 +/- 0.07 mM; p=0.016). Twenty-four hours later, TMg remained lower than in control subjects for all subgroups of TBI; however, IMg normalized. TBI in children is associated with a reduction in TMg, whereas IMg decreased only with severe TBI. IMg returned to control values by 24 h despite a continued lower TMg, suggesting mechanisms to maintain IMg. Changes in plasma IMg may serve as a marker for TBI but only over a limited time interval.

Laser Doppler flow and brain tissue PO2 after cortical impact injury complicated by secondary ischemia in rats treated with arginine.

BACKGROUND: Traumatic brain injury (TBI) makes the brain susceptible to secondary insults such as ischemia. This study tested the hypothesis that L-arginine would increase regional CBF (rCBF) and brain tissue PO2 (PbtO2) at the injury site. METHODS: A secondary insult model was employed in rodents. rCBF was measured with laser doppler flowmetry (LDF) and PbtO2 with a PO2 catheter at the impact site. Animals were randomized to receive L-arginine, D-arginine or saline intravenously, 5 minutes after impact. RESULTS: In animals who received L-arginine, the percentage rCBF from baseline (%CBF) was higher at the impact site after impact (p < 0.001), during bilateral carotid occulation (BCO) (p = 0.001) and during reperfusion (p = 0.032). In contrast, PbtO2 was not significantly increased throughout the experiment for the L-arginine group. CONCLUSIONS: Administration of L-arginine increased rCBF in the injured brain tissue, and resulted in better preservation of CBF during BCO than D-arginine and saline.

Oxidative DNA lesions in a rodent model of traumatic brain injury.

BACKGROUND: Oxidative DNA lesions have not been well studied in traumatic brain injury (TBI). METHODS: TBI was induced with a controlled cortical impact injury in rats. Brain tissue was examined for 8-hydroxy-2'-deoxyguanosine (oh8dG) using mono-clonal antibodies at different time frames; 15 minutes (n = 4), 30 minutes (n = 7), 60 minutes (n = 6), and 240 minutes (n = 5). The control group consisted of sham-operated animals undergoing the same surgery without the controlled cortical impact injury (n = 5). RESULTS: An elevation of oh8dG was detected in the nuclear and perinuclear (mitochondrial) regions of the ipsilateral cortex, but seldom in those of the contralateral cortex. The amount of oh8dG in those animals with TBI was significant in all time frames when compared with sham-operated controls (p < 0.001). The oh8dG levels were more prominent at 15 minutes (p < 0.0001) when compared with controls. CONCLUSION: Oxidative DNA lesions occurred in this model of TBI maximally early after TBI. This suggests that oh8dGs may affect genetic material of the brain and that oh8dGs may adversely affect gene expression that occurs early after head injury.