The plasma proteome differentiates the multisystem inflammatory syndrome in children (MIS-C) from children with SARS-CoV-2 negative sepsis.

BACKGROUND: The Multi-System Inflammatory Syndrome in Children (MIS-C) can develop several weeks after SARS-CoV-2 infection and requires a distinct treatment protocol. Distinguishing MIS-C from SARS-CoV-2 negative sepsis (SCNS) patients is important to quickly institute the correct therapies. We performed targeted proteomics and machine learning analysis to identify novel plasma proteins of MIS-C for early disease recognition. METHODS: A case-control study comparing the expression of 2,870 unique blood proteins in MIS-C versus SCNS patients, measured using proximity extension assays. The 2,870 proteins were reduced in number with either feature selection alone or with a prior COMBAT-Seq batch effect adjustment. The leading proteins were correlated with demographic and clinical variables. Organ system and cell type expression patterns were analyzed with Natural Language Processing (NLP). RESULTS: The cohorts were well-balanced for age and sex. Of the 2,870 unique blood proteins, 58 proteins were identified with feature selection (FDR-adjusted P < 0.005, P < 0.0001; accuracy = 0.96, AUC = 1.00, F1 = 0.95), and 15 proteins were identified with a COMBAT-Seq batch effect adjusted feature selection (FDR-adjusted P < 0.05, P < 0.0001; accuracy = 0.92, AUC = 1.00, F1 = 0.89). All of the latter 15 proteins were present in the former 58-protein model. Several proteins were correlated with illness severity scores, length of stay, and interventions (LTA4H, PTN, PPBP, and EGF; P < 0.001). NLP analysis highlighted the multi-system nature of MIS-C, with the 58-protein set expressed in all organ systems; the highest levels of expression were found in the digestive system. The cell types most involved included leukocytes not yet determined, lymphocytes, macrophages, and platelets. CONCLUSIONS: The plasma proteome of MIS-C patients was distinct from that of SCNS. The key proteins demonstrated expression in all organ systems and most cell types. The unique proteomic signature identified in MIS-C patients could aid future diagnostic and therapeutic advancements, as well as predict hospital length of stays, interventions, and mortality risks.

A reduced proteomic signature in critically ill Covid-19 patients determined with plasma antibody micro-array and machine learning.

BACKGROUND: COVID-19 is a complex, multi-system disease with varying severity and symptoms. Identifying changes in critically ill COVID-19 patients' proteomes enables a better understanding of markers associated with susceptibility, symptoms, and treatment. We performed plasma antibody microarray and machine learning analyses to identify novel proteins of COVID-19. METHODS: A case-control study comparing the concentration of 2000 plasma proteins in age- and sex-matched COVID-19 inpatients, non-COVID-19 sepsis controls, and healthy control subjects. Machine learning was used to identify a unique proteome signature in COVID-19 patients. Protein expression was correlated with clinically relevant variables and analyzed for temporal changes over hospitalization days 1, 3, 7, and 10. Expert-curated protein expression information was analyzed with Natural language processing (NLP) to determine organ- and cell-specific expression. RESULTS: Machine learning identified a 28-protein model that accurately differentiated COVID-19 patients from ICU non-COVID-19 patients (accuracy = 0.89, AUC = 1.00, F1 = 0.89) and healthy controls (accuracy = 0.89, AUC = 1.00, F1 = 0.88). An optimal nine-protein model (PF4V1, NUCB1, CrkL, SerpinD1, Fen1, GATA-4, ProSAAS, PARK7, and NET1) maintained high classification ability. Specific proteins correlated with hemoglobin, coagulation factors, hypertension, and high-flow nasal cannula intervention (P < 0.01). Time-course analysis of the 28 leading proteins demonstrated no significant temporal changes within the COVID-19 cohort. NLP analysis identified multi-system expression of the key proteins, with the digestive and nervous systems being the leading systems. CONCLUSIONS: The plasma proteome of critically ill COVID-19 patients was distinguishable from that of non-COVID-19 sepsis controls and healthy control subjects. The leading 28 proteins and their subset of 9 proteins yielded accurate classification models and are expressed in multiple organ systems. The identified COVID-19 proteomic signature helps elucidate COVID-19 pathophysiology and may guide future COVID-19 treatment development.

Kinome and phosphoproteome reprogramming underlies the aberrant immune responses in critically ill COVID-19 patients.

SARS-CoV-2 infection triggers extensive host immune reactions, leading to severe diseases in certain individuals. However, the molecular basis underlying the excessive yet non-productive immune responses in severe COVID-19 remains incompletely understood. In this study, we conducted a comprehensive analysis of the peripheral blood mononuclear cell (PBMC) proteome and phosphoproteome in sepsis patients positive or negative for SARS-CoV-2 infection, as well as healthy subjects, using quantitative mass spectrometry. Our findings demonstrate dynamic changes in the COVID-19 PBMC proteome and phosphoproteome during disease progression, with distinctive protein or phosphoprotein signatures capable of distinguishing longitudinal disease states. Furthermore, SARS-CoV-2 infection induces a global reprogramming of the kinome and phosphoproteome, resulting in defective adaptive immune response mediated by the B and T lymphocytes, compromised innate immune responses involving the SIGLEC and SLAM family of immunoreceptors, and excessive cytokine-JAK-STAT signaling. In addition to uncovering host proteome and phosphoproteome aberrations caused by SARS-CoV-2, our work recapitulates several reported therapeutic targets for COVID-19 and identified numerous new candidates, including the kinases PKG1, CK2, ROCK1/2, GRK2, SYK, JAK2/3, TYK2, DNA-PK, PKCδ, and the cytokine IL-12.

Post-Intensive Care Sequelae in Pediatrics-Results of an Early Rehabilitation Implementation Study.

OBJECTIVES: To compare post-PICU discharge functioning, health-related quality of life (HRQL), and parental stress before and after the implementation of an early rehabilitation bundle. DESIGN AND SETTING: Prospective cohort substudy within an early rehabilitation implementation program, conducted at the PICUs at McMaster Children's Hospital and London Health Sciences, London, Ontario, Canada. INTERVENTIONS: A bundle consisting of: 1) analgesia-first sedation; 2) delirium monitoring and prevention; and 3) early mobilization. Patients with an anticipated 48-hour PICU length of stay were approached for consent to participate. PATIENTS: Critically ill children with an anticipated 48-hour PICU length of stay were approached for consent to participate. MEASUREMENTS AND MAIN RESULTS: Patient-/proxy-reported outcome measures were assessed at baseline, PICU discharge, and 1 and 3 months post-PICU discharge using: 1) Pediatric Evaluation of Disability Inventory Computer Adaptive Test to assess physical, social, cognitive, and responsibility/caregiver domains of functioning; 2) KIDSCREEN to assess HRQL; and 3) the Pediatric Inventory for Parents to assess caregiver stress. A total of 117 participants were enrolled. Patient demographic characteristics were similar in the pre- and post-intervention groups. Following bundle implementation, 30 of 47 respondents (63.8%) experienced functional decline and 18 of 45 (40%) experienced low HRQL at PICU discharge. Eighteen of 36 (50%) at 1 month and 14 of 38 (36.8%) at 3 months experienced either persistent functional decline and/or low HRQL; 2.8% and 2.6% at 1- and 3-month follow-up, respectively, experienced both persistent functional decline and low HRQL. There were no significant differences in the rates of persistent functional decline, low HRQL, or caregiver stress scores post-bundle compared with pre-rehabilitation bundle implementation. CONCLUSIONS: We were unable to adequately determine the efficacy of a rehabilitation bundle on patient-centered outcomes as this substudy was not powered for these outcomes. Our results did reveal that persistent low functioning is common in PICU survivors, more common than low HRQL, while experiencing both functional decline and low HRQL was uncommon.

Early Rehabilitation in Critically ill Children: A Two Center Implementation Study.

OBJECTIVES: To implement an early rehabilitation bundle in two Canadian PICUs. DESIGN AND SETTING: Implementation study in the PICUs at McMaster Children's Hospital (site 1) and London Health Sciences (site 2). PATIENTS: All children under 18 years old admitted to the PICU were eligible for the intervention. INTERVENTIONS: A bundle consisting of: 1) analgesia-first sedation; 2) delirium monitoring and prevention; and 3) early mobilization. MEASUREMENTS AND MAIN RESULTS: Primary outcomes were the duration of implementation, bundle compliance, process of care, safety, and the factors influencing implementation. Secondary endpoints were the impact of the bundle on clinical outcomes such as pain, delirium, iatrogenic withdrawal, ventilator-free days, length of stay, and mortality. Implementation occurred over 26 months (August 2018 to October 2020). Data were collected on 1,036 patients representing 4,065 patient days. Bundle compliance was optimized within 6 months of roll-out. Goal setting for mobilization and level of arousal improved significantly (p < 0.01). Benzodiazepine, opioid, and dexmedetomidine use decreased in site 1 by 23.2% (95% CI, 30.8-15.5%), 26.1% (95% CI, 34.8-17.4%), and 9.2% (95% CI, 18.2-0.2%) patient exposure days, respectively, while at site 2, only dexmedetomidine exposure decreased significantly by 10.5% patient days (95% CI, 19.8-1.1%). Patient comfort, safety, and nursing workload were not adversely affected. There was no significant impact of the bundle on the rate of delirium, ventilator-free days, length of PICU stay, or mortality. Key facilitators to implementation included institutional support, unit-wide practice guidelines, dedicated PICU educators, easily accessible resources, and family engagement. CONCLUSIONS: A rehabilitation bundle can improve processes of care and reduce patient sedative exposure without increasing patient discomfort, nursing workload, or harm. We did not observe an impact on short-term clinical outcomes. The efficacy of a PICU-rehabilitation bundle requires ongoing study. Lessons learned in this study provide evidence to inform rehabilitation implementation in the PICU setting.

COVID-19 plasma proteome reveals novel temporal and cell-specific signatures for disease severity and high-precision disease management.

Coronavirus disease 2019 (COVID-19) is a systemic inflammatory condition with high mortality that may benefit from personalized medicine and high-precision approaches. COVID-19 patient plasma was analysed with targeted proteomics of 1161 proteins. Patients were monitored from Days 1 to 10 of their intensive care unit (ICU) stay. Age- and gender-matched COVID-19-negative sepsis ICU patients and healthy subjects were examined as controls. Proteomic data were resolved using both cell-specific annotation and deep-analysis for functional enrichment. COVID-19 caused extensive remodelling of the plasma microenvironment associated with a relative immunosuppressive milieu between ICU Days 3-7, and characterized by extensive organ damage. COVID-19 resulted in (1) reduced antigen presentation and B/T-cell function, (2) increased repurposed neutrophils and M1-type macrophages, (3) relatively immature or disrupted endothelia and fibroblasts with a defined secretome, and (4) reactive myeloid lines. Extracellular matrix changes identified in COVID-19 plasma could represent impaired immune cell homing and programmed cell death. The major functional modules disrupted in COVID-19 were exaggerated in patients with fatal outcome. Taken together, these findings provide systems-level insight into the mechanisms of COVID-19 inflammation and identify potential prognostic biomarkers. Therapeutic strategies could be tailored to the immune response of severely ill patients.

Organ and cell-specific biomarkers of Long-COVID identified with targeted proteomics and machine learning.

BACKGROUND: Survivors of acute COVID-19 often suffer prolonged, diffuse symptoms post-infection, referred to as "Long-COVID". A lack of Long-COVID biomarkers and pathophysiological mechanisms limits effective diagnosis, treatment and disease surveillance. We performed targeted proteomics and machine learning analyses to identify novel blood biomarkers of Long-COVID. METHODS: A case-control study comparing the expression of 2925 unique blood proteins in Long-COVID outpatients versus COVID-19 inpatients and healthy control subjects. Targeted proteomics was accomplished with proximity extension assays, and machine learning was used to identify the most important proteins for identifying Long-COVID patients. Organ system and cell type expression patterns were identified with Natural Language Processing (NLP) of the UniProt Knowledgebase. RESULTS: Machine learning analysis identified 119 relevant proteins for differentiating Long-COVID outpatients (Bonferonni corrected P < 0.01). Protein combinations were narrowed down to two optimal models, with nine and five proteins each, and with both having excellent sensitivity and specificity for Long-COVID status (AUC = 1.00, F1 = 1.00). NLP expression analysis highlighted the diffuse organ system involvement in Long-COVID, as well as the involved cell types, including leukocytes and platelets, as key components associated with Long-COVID. CONCLUSIONS: Proteomic analysis of plasma from Long-COVID patients identified 119 highly relevant proteins and two optimal models with nine and five proteins, respectively. The identified proteins reflected widespread organ and cell type expression. Optimal protein models, as well as individual proteins, hold the potential for accurate diagnosis of Long-COVID and targeted therapeutics.

Plasma proteome of Long-COVID patients indicates HIF-mediated vasculo-proliferative disease with impact on brain and heart function.

AIMS: Long-COVID occurs after SARS-CoV-2 infection and results in diverse, prolonged symptoms. The present study aimed to unveil potential mechanisms, and to inform prognosis and treatment. METHODS: Plasma proteome from Long-COVID outpatients was analyzed in comparison to matched acutely ill COVID-19 (mild and severe) inpatients and healthy control subjects. The expression of 3072 protein biomarkers was determined with proximity extension assays and then deconvoluted with multiple bioinformatics tools into both cell types and signaling mechanisms, as well as organ specificity. RESULTS: Compared to age- and sex-matched acutely ill COVID-19 inpatients and healthy control subjects, Long-COVID outpatients showed natural killer cell redistribution with a dominant resting phenotype, as opposed to active, and neutrophils that formed extracellular traps. This potential resetting of cell phenotypes was reflected in prospective vascular events mediated by both angiopoietin-1 (ANGPT1) and vascular-endothelial growth factor-A (VEGFA). Several markers (ANGPT1, VEGFA, CCR7, CD56, citrullinated histone 3, elastase) were validated by serological methods in additional patient cohorts. Signaling of transforming growth factor-ß1 with probable connections to elevated EP/p300 suggested vascular inflammation and tumor necrosis factor-α driven pathways. In addition, a vascular proliferative state associated with hypoxia inducible factor 1 pathway suggested progression from acute COVID-19 to Long-COVID. The vasculo-proliferative process predicted in Long-COVID might contribute to changes in the organ-specific proteome reflective of neurologic and cardiometabolic dysfunction. CONCLUSIONS: Taken together, our findings point to a vasculo-proliferative process in Long-COVID that is likely initiated either prior hypoxia (localized or systemic) and/or stimulatory factors (i.e., cytokines, chemokines, growth factors, angiotensin, etc). Analyses of the plasma proteome, used as a surrogate for cellular signaling, unveiled potential organ-specific prognostic biomarkers and therapeutic targets.

The utility of syndecan-1 circulating levels as a biomarker in patients with previous or active COVID-19: a systematic review and meta-analysis.

BACKGROUND: With the emergence of coronavirus disease of 2019 (COVID-19), several blood biomarkers have been identified, including the endothelial biomarker syndecan-1, a surface proteoglycan. In the current systematic review and meta-analysis, we aimed to assess the diagnostic and prognostic role of syndecan-1 in COVID-19. METHODS: PubMed, Embase, Scopus, and Web of Science, as international databases, were searched for relevant studies measuring blood syndecan-1 levels in COVID-19 patients, COVID-19 convalescents, and healthy control subjects, in patients with different COVID-19 severities and/or in COVID-19 patients with poor outcomes. Random-effect meta-analysis was performed using STATA to calculate the standardized mean difference (SMD) and 95% confidence interval (CI) for the comparison between COVID-19 patients and healthy control subjects or COVID-19 convalescents and controls. RESULTS: After screening by title/abstract and full text, 17 studies were included in the final review. Meta-analysis of syndecan-1 levels in COVID-19 compared with healthy control subjects revealed that patients with COVID-19 had significantly higher syndecan-1 levels (SMD 1.53, 95% CI 0.66 to 2.41, P < 0.01). In contrast, COVID-19 convalescent patients did not show significant difference with non-convalescents (SMD 0.08, 95% CI -0.63 to 0.78, P = 0.83). Regarding disease severity, two studies reported that more severe forms of the disease were associated with increased syndecan-1 levels. Moreover, patients who died from COVID-19 had higher syndecan-1 levels compared with survivors (SMD 1.22, 95% CI 0.10 to 2.33, P = 0.03). CONCLUSION: Circulating syndecan-1 level can be used as a biomarker of endothelial dysfunction in COVID-19, as it was increased in COVID-19 patients and was higher in more severe instances of the disease. Further larger studies are needed to confirm these findings and further enlighten the role of syndecan-1 in clinical settings.

Elevated vascular transformation blood biomarkers in Long-COVID indicate angiogenesis as a key pathophysiological mechanism.

BACKGROUND: Long-COVID is characterized by prolonged, diffuse symptoms months after acute COVID-19. Accurate diagnosis and targeted therapies for Long-COVID are lacking. We investigated vascular transformation biomarkers in Long-COVID patients. METHODS: A case-control study utilizing Long-COVID patients, one to six months (median 98.5 days) post-infection, with multiplex immunoassay measurement of sixteen blood biomarkers of vascular transformation, including ANG-1, P-SEL, MMP-1, VE-Cad, Syn-1, Endoglin, PECAM-1, VEGF-A, ICAM-1, VLA-4, E-SEL, thrombomodulin, VEGF-R2, VEGF-R3, VCAM-1 and VEGF-D. RESULTS: Fourteen vasculature transformation blood biomarkers were significantly elevated in Long-COVID outpatients, versus acutely ill COVID-19 inpatients and healthy controls subjects (P < 0.05). A unique two biomarker profile consisting of ANG-1/P-SEL was developed with machine learning, providing a classification accuracy for Long-COVID status of 96%. Individually, ANG-1 and P-SEL had excellent sensitivity and specificity for Long-COVID status (AUC = 1.00, P < 0.0001; validated in a secondary cohort). Specific to Long-COVID, ANG-1 levels were associated with female sex and a lack of disease interventions at follow-up (P < 0.05). CONCLUSIONS: Long-COVID patients suffer prolonged, diffuse symptoms and poorer health. Vascular transformation blood biomarkers were significantly elevated in Long-COVID, with angiogenesis markers (ANG-1/P-SEL) providing classification accuracy of 96%. Vascular transformation blood biomarkers hold potential for diagnostics, and modulators of angiogenesis may have therapeutic efficacy.

Novel plasma protein biomarkers from critically ill sepsis patients.

BACKGROUND: Despite the high morbidity and mortality associated with sepsis, the relationship between the plasma proteome and clinical outcome is poorly understood. In this study, we used targeted plasma proteomics to identify novel biomarkers of sepsis in critically ill patients. METHODS: Blood was obtained from 15 critically ill patients with suspected/confirmed sepsis (Sepsis-3.0 criteria) on intensive care unit (ICU) Day-1 and Day-3, as well as age- and sex-matched 15 healthy control subjects. A total of 1161 plasma proteins were measured with proximal extension assays. Promising sepsis biomarkers were narrowed with machine learning and then correlated with relevant clinical and laboratory variables. RESULTS: The median age for critically ill sepsis patients was 56 (IQR 51-61) years. The median MODS and SOFA values were 7 (IQR 5.0-8.0) and 7 (IQR 5.0-9.0) on ICU Day-1, and 4 (IQR 3.5-7.0) and 6 (IQR 3.5-7.0) on ICU Day-3, respectively. Targeted proteomics, together with feature selection, identified the leading proteins that distinguished sepsis patients from healthy control subjects with ≥ 90% classification accuracy; 25 proteins on ICU Day-1 and 26 proteins on ICU Day-3 (6 proteins overlapped both ICU days; PRTN3, UPAR, GDF8, NTRK3, WFDC2 and CXCL13). Only 7 of the leading proteins changed significantly between ICU Day-1 and Day-3 (IL10, CCL23, TGFα1, ST2, VSIG4, CNTN5, and ITGAV; P < 0.01). Significant correlations were observed between a variety of patient clinical/laboratory variables and the expression of 15 proteins on ICU Day-1 and 14 proteins on ICU Day-3 (P < 0.05). CONCLUSIONS: Targeted proteomics with feature selection identified proteins altered in critically ill sepsis patients relative to healthy control subjects. Correlations between protein expression and clinical/laboratory variables were identified, each providing pathophysiological insight. Our exploratory data provide a rationale for further hypothesis-driven sepsis research.

Patients with severe COVID-19 do not have elevated autoantibodies against common diagnostic autoantigens.

OBJECTIVES: Infection by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the causative pathogen of coronavirus disease 2019 (COVID-19) presents occasionally with an aberrant autoinflammatory response, including the presence of elevated circulating autoantibodies in some individuals. Whether the development of autoantibodies against self-antigens affects COVID-19 outcomes remains unclear. To better understand the prognostic role of autoantibodies in COVID-19, we quantified autoantibodies against 23 markers that are used for diagnosis of autoimmune disease. To this end, we used serum samples from patients with severe [intensive care unit (ICU)] and moderate (ward) COVID-19, across two to six consecutive time points, and compared autoantibody levels to uninfected healthy and ICU controls. METHODS: Acute and post-acute serum (from 1 to 26 ICU days) was collected from 18 ICU COVID-19-positive patients at three to six time points; 18 ICU COVID-19-negative patients (sampled on ICU day 1 and 3); 21 ward COVID-19-positive patients (sampled on hospital day 1 and 3); and from 59 healthy uninfected controls deriving from two cohorts. Levels of IgG autoantibodies against 23 autoantigens, commonly used for autoimmune disease diagnosis, were measured in serum samples using MSD® U-PLEX electrochemiluminescence technology (MSD division Meso Scale Discovery®), and results were compared between groups. RESULTS: There were no significant elevations of autoantibodies for any of the markers tested in patients with severe COVID-19. CONCLUSIONS: Sample collections at longer time points should be considered in future studies, for assessing the possible development of autoantibody responses following infection with SARS-CoV-2.

Novel severe traumatic brain injury blood outcome biomarkers identified with proximity extension assay.

OBJECTIVES: Severe traumatic brain injury (sTBI) patients suffer high mortality. Accurate prognostic biomarkers have not been identified. In this exploratory study, we performed targeted proteomics on plasma obtained from sTBI patients to identify potential outcome biomarkers. METHODS: Blood sample was collected from patients admitted to the ICU suffering a sTBI, using standardized clinical and computerized tomography (CT) imaging criteria. Age- and sex-matched healthy control subjects and sTBI patients were enrolled. Targeted proteomics was performed on plasma with proximity extension assays (1,161 proteins). RESULTS: Cohorts were well-balanced for age and sex. The majority of sTBI patients were injured in motor vehicle collisions and the most frequent head CT finding was subarachnoid hemorrhage. Mortality rate for sTBI patients was 40%. Feature selection identified the top performing 15 proteins for identifying sTBI patients from healthy control subjects with a classification accuracy of 100%. The sTBI proteome was dominated by markers of vascular pathology, immunity/inflammation, cell survival and macrophage/microglia activation. Receiver operating characteristic (ROC) curve analyses demonstrated areas-under-the-curves (AUC) for identifying sTBI that ranged from 0.870-1.000 (p≤0.005). When mortality was used as outcome, ROC curve analyses identified the top 3 proteins as Willebrand factor (vWF), Wnt inhibitory factor-1 (WIF-1), and colony stimulating factor-1 (CSF-1). Combining vWF with either WIF-1 or CSF-1 resulted in excellent mortality prediction with AUC of 1.000 for both combinations (p=0.011). CONCLUSIONS: Targeted proteomics with feature classification and selection distinguished sTBI patients from matched healthy control subjects. Two protein combinations were identified that accurately predicted sTBI patient mortality. Our exploratory findings require confirmation in larger sTBI patient populations.

Autonomic Dysregulation in Adolescent Concussion Is Sex- and Posture-Dependent.

OBJECTIVE: To study autonomic responses to postural changes in concussed adolescents. The influence of sex was also studied. DESIGN: Longitudinal cohort observational study. PARTICIPANTS: Concussed adolescents (CONC; n = 65; 26 male adolescents; age 15 ± 1 years, range = 12-18 years) and a control (CTRL) group of nonconcussed adolescents of similar age and sport (CTRL; n = 54; 29 male adolescents; age 14 ± 1 years, range = 12-18 years). INTERVENTIONS: Concussed participants were monitored through 6 weekly visits throughout usual physician care. Control participants underwent 2 visits separated by at least 1 week to account for intrapersonal variation in testing measures. MAIN OUTCOME MEASURES: Heart rate variability as the root mean square of successive differences in R-R intervals (RMSSD), heart rate (HR), and blood pressure [mean arterial pressure (MAP) and diastolic blood pressure (DBP)] were measured in supine, sitting, and standing postures. RESULTS: A mixed analysis of variance revealed a group × sex × posture interaction (P = 0.04) where seated values of RMSSD were less in concussed female participants versus control female participants (42 ± 4 vs 61 ± 7 ms; P = 0.01; Mann-Whitney rank test). Compared with CTRL, CONC exhibited increased pretesting seated DBP (69 ± 1 vs 74 ± 1 mm Hg; P < 0.01), MAP (83 ± 1 vs 86 ± 1 mm Hg; P = 0.02), and baseline seated HR (72 ± 1 vs 77 ± 2 bpm; P = 0.03). Values of DBP (P = 0.03) and MAP (P < 0.01) improved at clinical discharge, whereas the RMSSD in female participants did not (P > 0.5). Data are mean ± SEM. CONCLUSIONS: A modest reduction in female cardiac autonomic regulation was observed during seated postures. Alterations in seated concussed DBP and MAP, but not RMSSD, resolved at clinical discharge (median = 37 days). The results indicate that, in adolescents, concussion may impair cardiovagal function in a sex- and posture-dependent manner. The findings also suggest that BP metrics, but not RMSSD, are associated with clinical concussion recovery.

Proceedings From the Ice Hockey Summit III: Action on Concussion.

OBJECTIVES: The Ice Hockey Summit III provided updated scientific evidence on concussions in hockey to inform these 5 objectives: (1) describe sport related concussion (SRC) epidemiology; (2) classify prevention strategies; (3) define objective, diagnostic tests; (4) identify treatment; and (5) integrate science and clinical care into prioritized action plans and policy. METHODS: Our action plan evolved from 40 scientific presentations. The 155 attendees (physicians, athletic trainers, physical therapists, nurses, neuropsychologists, scientists, engineers, coaches, and officials) voted to prioritize these action items in the final Summit session. RESULTS: To (1) establish a national and international hockey database for SRCs at all levels; (2) eliminate body checking in Bantam youth hockey games; (3) expand a behavior modification program (Fair Play) to all youth hockey levels; (4) enforce game ejection penalties for fighting in Junior A and professional hockey leagues; (5) establish objective tests to diagnose concussion at point of care; and (6) mandate baseline testing to improve concussion diagnosis for all age groups. CONCLUSIONS: Expedient implementation of the Summit III prioritized action items is necessary to reduce the risk, severity, and consequences of concussion in the sport of ice hockey.

Total Daily Production and Periodicity of Melatonin Metabolite in Critically Ill Children.

OBJECTIVES: To determine whether total daily 6-sulfatoxymelatonin excretion and diurnal variation of melatonin secretion was maintained during the early phase of PICU admission through examination of the melatonin urinary metabolite, 6-sulfatoxymelatonin. DESIGN: Exploratory prospective, observational study. SETTING: Twelve-bed medical-surgical PICU of a Children's Hospital. PATIENTS: Fifty children 3 months to 18 years old enrolled within 24 hours of PICU admission with access for urinary sampling. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Urine samples were collected at 4-hour intervals for 24 hours and stored at -80C. 6-sulfatoxymelatonin was determined in duplicate by direct enzyme-linked immunosorbent assay. Patients were heterogeneous for diagnosis, had a mean age of 8.1 years (SD = 6.1 yr), and median (interquartile range) Pediatric Risk of Mortality III of 10 (4-13). Mean (SD) total daily 6-sulfatoxymelatonin production was 30.0 µg (25.6 µg) for the first 24 hours, which did not differ significantly from the means on days 2 (p = 0.56) or 3 (p = 0.29), and was similar to literature controls. Mean 6-sulfatoxymelatonin production for the population fit a periodic function well, with a reliable amplitude of 326 ng/hr and peak excretion from 04:00 to 08:00 (F = 4.4, p = 0.01), even when 6-sulfatoxymelatonin was corrected for body weight (F = 3.4, p = 0.03) and when sedation was included in the model (F = 3.95, p = 0.004). There was no significant correlation between lighting and 6-sulfatoxymelatonin excretion at any time period (R values: 0.11-0.25, p = 0.10-0.94). Mean 6-sulfatoxymelatonin excretion did not fit the model for a periodic function well for the subpopulations studied (sepsis [n = 18, F = 1.1, p = 0.32], respiratory failure requiring deep sedation [n = 10, F = 0.4, p = 0.66], and neurologic injury [n = 7, F = 0.6, p = 0.55]). CONCLUSIONS: Total daily and diurnal variation of 6-sulfatoxymelatonin excretion is heterogeneously maintained early in pediatric critical illness. However, this may not hold true for specific diagnostic categories.

Concussion Symptoms Predictive of Adolescent Sport-Related Concussion Injury.

OBJECTIVE: To assess the predictive capability of the postconcussion symptom scale (PCSS) of the sport concussion assessment tool (SCAT) III to differentiate concussed and nonconcussed adolescents. DESIGN: Retrospective. SETTING: Tertiary. PARTICIPANTS: Sixty-nine concussed (15.2 ± 1.6 years old) and 55 control (14.4 ± 1.7 years old) adolescents. INDEPENDENT VARIABLES: Postconcussion symptom scale. MAIN OUTCOME MEASURE: Two-proportion z-test determined differences in symptom endorsement between groups. To assess the predictive power of the PCSS, we trained an ensemble classifier composed of a forest of 1000 decision trees to classify subjects as concussed, or not concussed, based on PCSS responses. The initial classifier was trained on all 22-concussion symptoms addressed in the PCSS, whereas the second classifier removed concussion symptoms that were not statistically significant between groups. RESULTS: Concussion symptoms common between groups were trouble falling asleep, more emotional, irritability, sadness, and anxious. After removal, analysis of the second classifier indicated that the 5 leading feature rankings of symptoms were headache, head pressure, light sensitivity, noise sensitivity, and "don't feel right," which accounted for 52% of the variance between groups. CONCLUSIONS: Collectively, self-reported symptoms through the PCSS can differentiate concussed and nonconcussed adolescents. However, predictability for adolescent patients may be improved by removing emotional and sleep domain symptoms.

Concussion in Adolescents Impairs Heart Rate Response to Brief Handgrip Exercise.

OBJECTIVE: Test the hypotheses that (1) concussion in adolescents impairs autonomic neural control of heart rate (HR), and (2) HR reactivity improves with symptom resolution. DESIGN: Observational, case-control. PARTICIPANTS: Nineteen concussed adolescents (8 female adolescents; age 15 ± 2 years) and 16 healthy controls (6 female adolescents, age 15 ± 2 years). INTERVENTION: All participants performed an isometric handgrip (IHG) at 30% maximum voluntary contraction lasting 30 seconds. Heart rate (electrocardiogram) and hemodynamic responses (photoplethysmographic Finometer) were recorded from 30 seconds of baseline and the last 10 seconds of handgrip. MAIN OUTCOME MEASURES: The HR response (ΔHR) at the onset of moderate-intensity IHG using a mixed 1-way analysis of variance. RESULTS: A group × time interaction (P < 0.005) indicated that handgrip evoked a greater ΔHR among control participants (13 ± 10 beats/min) compared with concussed (6.4 ± 6.3 beats/min; group P = 0.63; time P < 0.001; d = 0.77). CONCLUSION: These preliminary results suggest that a concussion impairs the ability to elevate HR at the exercise onset and, given the nature of the task, this could be interpreted to reflect reduced ability to withdraw cardiovagal control. Therefore, the data support the hypothesis of neural cardiac dysregulation in adolescents diagnosed with concussion. CLINICAL RELEVANCE: The IHG test could aid concussion diagnosis and support return-to-play decisions.

Paroxysmal Sympathetic Hyperactivity After Severe Traumatic Brain Injury in Children: Prevalence, Risk Factors, and Outcome.

OBJECTIVE: To describe paroxysmal sympathetic hyperactivity in pediatric patients with severe traumatic brain injury using the new consensus definition, the risk factors associated with developing paroxysmal sympathetic hyperactivity, and the outcomes associated with paroxysmal sympathetic hyperactivity. DESIGN: Retrospective cohort study. SETTING: Academic children's hospital PICU. PATIENTS: All pediatric patients more than 1 month and less than 18 years old with severe traumatic brain injury between 2000 and 2016. We excluded patients if they had a history of five possible confounders for paroxysmal sympathetic hyperactivity diagnosis or if they died within 24 hours of admission for traumatic brain injury. MEASUREMENTS AND MAIN RESULTS: Our primary outcome was PICU mortality. One hundred seventy-nine patients met inclusion criteria. Thirty-six patients (20%) had at least eight criteria and therefore met classification of "likelihood of paroxysmal sympathetic hyperactivity." Older age was the only factor independently associated with developing paroxysmal sympathetic hyperactivity (odds ratio, 1.08; 95% CI, 1.00-1.16). PICU mortality was significantly lower for those with paroxysmal sympathetic hyperactivity compared with those without paroxysmal sympathetic hyperactivity (odds ratio, 0.08; 95% CI, 0.01-0.52), but PICU length of stay was greater in those with paroxysmal sympathetic hyperactivity (odds ratio, 4.36; 95% CI, 2.94-5.78), and discharge to an acute care or rehabilitation setting versus home was higher in those with paroxysmal sympathetic hyperactivity (odds ratio, 5.59; 95% CI, 1.26-24.84; odds ratio, 5.39; 95% CI, 1.87-15.57, respectively). When paroxysmal sympathetic hyperactivity was diagnosed in the first week of admission, it was not associated with discharge disposition. CONCLUSIONS: Our study suggests that the rate of paroxysmal sympathetic hyperactivity in patients with severe traumatic brain injury is higher than previously reported. Older age was associated with an increased risk for developing paroxysmal sympathetic hyperactivity, but severity of the trauma and the brain injury were not. For survivors of severe traumatic brain injury beyond 24 hours who developed paroxysmal sympathetic hyperactivity, there was a lower PICU mortality but also greater PICU length of stay and a lower likelihood of discharge home from the admitting hospital, suggesting that functional outcome in survivors with paroxysmal sympathetic hyperactivity is worse than survivors without paroxysmal sympathetic hyperactivity.