Refractory hypoxemia caused by hepatopulmonary syndrome: a case report

Introduction

Hepatopulmonary syndrome is a clinical syndrome that can affect patients of all ages with liver disease and is more common in children with biliary atresia. Contrast echocardiography is the test of choice to diagnose the presence of intrapulmonary vascular dilatation. The established treatment for hepatopulmonary syndrome is liver transplantation.

Case presentation

We present the case of an 8-month-old Caucasian baby boy with a history of biliary atresia, polysplenia, and interrupted inferior vena cava who presented with hypoxemia and cyanosis that progressed rapidly. A chest computed tomography angiogram revealed significant dilatation of the pulmonary vasculature, prompting further evaluation and diagnosis of hepatopulmonary syndrome with contrast echocardiography. He was maintained on a milrinone infusion while awaiting liver transplantation. His hypoxemia improved slowly following liver transplantation, requiring tracheostomy and prolonged ventilator dependence.

Conclusions

Hepatopulmonary syndrome should be included in the differential for progressive hypoxemia in children with liver disease, particularly those with biliary atresia. Imaging with chest computed tomography angiogram and contrast echocardiography should be considered in cases of unexplained refractory hypoxemia.

Differential expression of the nuclear-encoded mitochondrial transcriptome in pediatric septic shock

Introduction

Increasing evidence supports a role for mitochondrial dysfunction in organ injury and immune dysregulation in sepsis. Although differential expression of mitochondrial genes in blood cells has been reported for several diseases in which bioenergetic failure is a postulated mechanism, there are no data about the blood cell mitochondrial transcriptome in pediatric sepsis.

Methods

We conducted a focused analysis using a multicenter genome-wide expression database of 180 children ≤10 years of age with septic shock and 53 healthy controls. Using total RNA isolated from whole blood within 24 hours of PICU admission for septic shock, we evaluated 296 nuclear-encoded mitochondrial genes using a false discovery rate of 1%. A series of bioinformatic approaches were applied to compare differentially expressed genes across previously validated gene expression-based subclasses (groups A, B, and C) of pediatric septic shock.

Results

In total, 118 genes were differentially regulated in subjects with septic shock compared to healthy controls, including 48 genes that were upregulated and 70 that were downregulated. The top scoring canonical pathway was oxidative phosphorylation, with general downregulation of the 51 genes corresponding to the electron transport system (ETS). The top two gene networks were composed primarily of mitochondrial ribosomal proteins highly connected to ETS complex I, and genes encoding for ETS complexes I, II, and IV that were highly connected to the peroxisome proliferator activated receptor (PPAR) family. There were 162 mitochondrial genes differentially regulated between groups A, B, and C. Group A, which had the highest maximum number of organ failures and mortality, exhibited a greater downregulation of mitochondrial genes compared to groups B and C.

Conclusions

Based on a focused analysis of a pediatric septic shock transcriptomic database, nuclear-encoded mitochondrial genes were differentially regulated early in pediatric septic shock compared to healthy controls, as well as across genotypic and phenotypic distinct pediatric septic shock subclasses. The nuclear genome may be an important mechanism contributing to alterations in mitochondrial bioenergetic function and outcomes in pediatric sepsis.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-014-0623-9) contains supplementary material, which is available to authorized users.

Corticosteroids and pediatric septic shock outcomes: a risk stratified analysis

Background

The potential benefits of corticosteroids for septic shock may depend on initial mortality risk.

Objective

We determined associations between corticosteroids and outcomes in children with septic shock who were stratified by initial mortality risk.

Methods

We conducted a retrospective analysis of an ongoing, multi-center pediatric septic shock clinical and biological database. Using a validated biomarker-based stratification tool (PERSEVERE), 496 subjects were stratified into three initial mortality risk strata (low, intermediate, and high). Subjects receiving corticosteroids during the initial 7 days of admission (n = 252) were compared to subjects who did not receive corticosteroids (n = 244). Logistic regression was used to model the effects of corticosteroids on 28-day mortality and complicated course, defined as death within 28 days or persistence of two or more organ failures at 7 days.

Results

Subjects who received corticosteroids had greater organ failure burden, higher illness severity, higher mortality, and a greater requirement for vasoactive medications, compared to subjects who did not receive corticosteroids. PERSEVERE-based mortality risk did not differ between the two groups. For the entire cohort, corticosteroids were associated with increased risk of mortality (OR 2.3, 95% CI 1.3–4.0, p = 0.004) and a complicated course (OR 1.7, 95% CI 1.1–2.5, p = 0.012). Within each PERSEVERE-based stratum, corticosteroid administration was not associated with improved outcomes. Similarly, corticosteroid administration was not associated with improved outcomes among patients with no comorbidities, nor in groups of patients stratified by PRISM.

Conclusions

Risk stratified analysis failed to demonstrate any benefit from corticosteroids in this pediatric septic shock cohort.

Corticosteroids are associated with repression of adaptive immunity gene programs in pediatric septic shock

RATIONALE

Corticosteroids are prescribed commonly for patients with septic shock, but their use remains controversial and concerns remain regarding side effects.

OBJECTIVES

To determine the effect of adjunctive corticosteroids on the genomic response of pediatric septic shock.

METHODS

We retrospectively analyzed an existing transcriptomic database of pediatric septic shock. Subjects receiving any formulation of systemic corticosteroids at the time of blood draw for microarray analysis were classified in the septic shock corticosteroid group. We compared normal control subjects (n = 52), a septic shock no corticosteroid group (n = 110), and a septic shock corticosteroid group (n = 70) using analysis of variance. Genes differentially regulated between the no corticosteroid group and the corticosteroid group were analyzed using Ingenuity Pathway Analysis.

MEASUREMENTS AND MAIN RESULTS

The two study groups did not differ with respect to illness severity, organ failure burden, mortality, or mortality risk. There were 319 gene probes differentially regulated between the no corticosteroid group and the corticosteroid group. These genes corresponded predominately to adaptive immunity-related signaling pathways, and were down-regulated relative to control subjects. Notably, the degree of down-regulation was significantly greater in the corticosteroid group, compared with the no corticosteroid group. A similar pattern was observed for genes corresponding to the glucocorticoid receptor signaling pathway.

CONCLUSIONS

Administration of corticosteroids in pediatric septic shock is associated with additional repression of genes corresponding to adaptive immunity. These data should be taken into account when considering the benefit to risk ratio of adjunctive corticosteroids for septic shock.

Integrated nanoplasmonic sensing for cellular functional immunoanalysis using human blood

Localized surface plasmon resonance (LSPR) nanoplasmonic effects allow for label-free, real-time detection of biomolecule binding events on a nanostructured metallic surface with simple optics and sensing tunability. Despite numerous reports on LSPR bionanosensing in the past, no study thus far has applied the technique for a cytokine secretion assay using clinically relevant immune cells from human blood. Cytokine secretion assays, a technique to quantify intercellular-signaling proteins secreted by blood immune cells, allow determination of the functional response of the donor's immune cells, thus providing valuable information about the immune status of the donor. However, implementation of LSPR bionanosensing in cellular functional immunoanalysis based on a cytokine secretion assay poses major challenges primarily owing to its limited sensitivity and a lack of sufficient sample handling capability. In this paper, we have developed a label-free LSPR biosensing technique to detect cell-secreted tumor necrosis factor (TNF)-α cytokines in clinical blood samples. Our approach integrates LSPR bionanosensors in an optofluidic platform that permits trapping and stimulation of target immune cells in a microfluidic chamber with optical access for subsequent cytokine detection. The on-chip spatial confinement of the cells is the key to rapidly increasing a cytokine concentration high enough for detection by the LSPR setup, thereby allowing the assay time and sample volume to be significantly reduced. We have successfully applied this approach first to THP-1 cells and then later to CD45 cells isolated directly from human blood. Our LSPR optofluidics device allows for detection of TNF-α secreted from cells as few as 1000, which translates into a nearly 100 times decrease in sample volume than conventional cytokine secretion assay techniques require. We achieved cellular functional immunoanalysis with a minimal blood sample volume (3 μL) and a total assay time 3 times shorter than that of the conventional enzyme-linked immunosorbent assay (ELISA).

The temporal version of the pediatric sepsis biomarker risk model

Background

PERSEVERE is a risk model for estimating mortality probability in pediatric septic shock, using five biomarkers measured within 24 hours of clinical presentation.

Objective

Here, we derive and test a temporal version of PERSEVERE (tPERSEVERE) that considers biomarker values at the first and third day following presentation to estimate the probability of a “complicated course”, defined as persistence of ≥2 organ failures at seven days after meeting criteria for septic shock, or death within 28 days.

Methods

Biomarkers were measured in the derivation cohort (n = 225) using serum samples obtained during days 1 and 3 of septic shock. Classification and Regression Tree (CART) analysis was used to derive a model to estimate the risk of a complicated course. The derived model was validated in the test cohort (n = 74), and subsequently updated using the combined derivation and test cohorts.

Results

A complicated course occurred in 23% of the derivation cohort subjects. The derived model had a sensitivity for a complicated course of 90% (95% CI 78–96), specificity was 70% (62–77), positive predictive value was 47% (37–58), and negative predictive value was 96% (91–99). The area under the receiver operating characteristic curve was 0.85 (0.79–0.90). Similar test characteristics were observed in the test cohort. The updated model had a sensitivity of 91% (81–96), a specificity of 70% (64–76), a positive predictive value of 47% (39–56), and a negative predictive value of 96% (92–99).

Conclusions

tPERSEVERE reasonably estimates the probability of a complicated course in children with septic shock. tPERSEVERE could potentially serve as an adjunct to physiological assessments for monitoring how risk for poor outcomes changes during early interventions in pediatric septic shock.

Testing the prognostic accuracy of the updated pediatric sepsis biomarker risk model

BACKGROUND

We previously derived and validated a risk model to estimate mortality probability in children with septic shock (PERSEVERE; PEdiatRic SEpsis biomarkEr Risk modEl). PERSEVERE uses five biomarkers and age to estimate mortality probability. After the initial derivation and validation of PERSEVERE, we combined the derivation and validation cohorts (n = 355) and updated PERSEVERE. An important step in the development of updated risk models is to test their accuracy using an independent test cohort.

OBJECTIVE

To test the prognostic accuracy of the updated version PERSEVERE in an independent test cohort.

METHODS

Study subjects were recruited from multiple pediatric intensive care units in the United States. Biomarkers were measured in 182 pediatric subjects with septic shock using serum samples obtained during the first 24 hours of presentation. The accuracy of PERSEVERE 28-day mortality risk estimate was tested using diagnostic test statistics, and the net reclassification improvement (NRI) was used to test whether PERSEVERE adds information to a physiology-based scoring system.

RESULTS

Mortality in the test cohort was 13.2%. Using a risk cut-off of 2.5%, the sensitivity of PERSEVERE for mortality was 83% (95% CI 62-95), specificity was 75% (68-82), positive predictive value was 34% (22-47), and negative predictive value was 97% (91-99). The area under the receiver operating characteristic curve was 0.81 (0.70-0.92). The false positive subjects had a greater degree of organ failure burden and longer intensive care unit length of stay, compared to the true negative subjects. When adding PERSEVERE to a physiology-based scoring system, the net reclassification improvement was 0.91 (0.47-1.35; p<0.001).

CONCLUSIONS

The updated version of PERSEVERE estimates mortality probability reliably in a heterogeneous test cohort of children with septic shock and provides information over and above a physiology-based scoring system.

Biology of sepsis: its relevance to pediatric nephrology

Because of its multi-organ involvement, the syndrome of sepsis provides clinical challenges to a wide variety of health care providers. While multi-organ dysfunction triggered by sepsis requires general supportive critical care provided by intensivists, the impact of sepsis on renal function and the ability of renal replacement therapies to modulate its biologic consequences provide a significant opportunity for pediatric nephrologists and related care providers to impact outcomes. In this review, we aim to highlight newer areas of understanding of the pathobiology of sepsis with special emphasis on those aspects of particular interest to pediatric nephrology. As such, we aim to: (1) review the definition of sepsis and discuss advances in our mechanistic understanding of sepsis; (2) review current hypotheses regarding sepsis-induced acute kidney injury (AKI) and describe its epidemiology based on evolving definitions of AKI; (3) review the impact of renal failure on the immune system, highlighting the sepsis risk in this cohort and strategies that might minimize this risk; (4) review how renal replacement therapeutic strategies may impact sepsis-induced AKI outcomes. By focusing the review on these specific areas, we have omitted other important areas of the biology of sepsis and additional interactions with renal function from this discussion; however, we have aimed to provide a comprehensive list of references that provide contemporary reviews of these additional areas.

Surface-micromachined microfiltration membranes for efficient isolation and functional immunophenotyping of subpopulations of immune cells

An accurate measurement of the immune status in patients with immune system disorders is critical in evaluating the stage of diseases and tailoring drug treatments. The functional cellular immunity test is a promising method to establish the diagnosis of immune dysfunctions. The conventional functional cellular immunity test involves measurements of the capacity of peripheral blood mononuclear cells to produce pro-inflammatory cytokines when stimulated ex vivo. However, this "bulk" assay measures the overall reactivity of a population of lymphocytes and monocytes, making it difficult to pinpoint the phenotype or real identity of the reactive immune cells involved. In this research, we develop a large surface micromachined poly-dimethylsiloxane (PDMS) microfiltration membrane (PMM) with high porosity, which is integrated in a microfluidic microfiltration platform. Using the PMM with functionalized microbeads conjugated with antibodies against specific cell surface proteins, we demonstrated rapid, efficient and high-throughput on-chip isolation, enrichment, and stimulation of subpopulations of immune cells from blood specimens. Furthermore, the PMM-integrated microfiltration platform, coupled with a no-wash homogeneous chemiluminescence assay ("AlphaLISA"), enables us to demonstrate rapid and sensitive on-chip immunophenotyping assays for subpopulations of immune cells isolated directly from minute quantities of blood samples.

Dual role of interleukin-10 in the regulation of respiratory syncitial virus (RSV)-induced lung inflammation

RSV lower respiratory tract infections (LRTI) are among the most common diseases necessitating hospital admission in children. In addition to causing acute respiratory failure, RSV infections are associated with sequelae such as secondary bacterial infections and reactive airway disease. One characteristic host response observed in severe RSV-induced LRTI and/or subsequent development of asthma is increased expression of interleukin (IL)-10. However, contradictory results have been reported regarding whether IL-10 inhibits asthmatic responses or intensifies the disease. We aimed to reconcile these discordant observations by elucidating the role of IL-10 in regulating the host response to RSV LRTI. In this study, we used a lung-specific, inducible IL-10 over-expression (OE) transgenic mouse model to address this question. Our results showed that the presence of IL-10 at the time of RSV infection not only attenuated acute inflammatory process (i.e. 24 h post-infection), but also late inflammatory changes [characterized by T helper type 2 (Th2) cytokine and chemokine expression]. While this result appears contradictory to some clinical observations where elevated IL-10 levels are observed in asthmatic patients, we also found that delaying IL-10 OE until the late immune response to RSV infection, additive effects rather than inhibitory effects were observed. Importantly, in non-infected, IL-10 OE mice, IL-10 OE alone induced up-regulation of Th2 cytokine (IL-13 and IL-5) and Th2-related chemokine [monocyte chemoattractant protein 1 (MCP-1), chemokine (C-C motif) ligand 3 (CCL3) and regulated upon activation normal T cell expressed and secreted (RANTES)] expression. We identified a subset of CD11b(+)CD11c(+)CD49b(+)F4/80(-)Gr-1(-) myeloid cells as a prinicipal source of IL-10-induced IL-13 production. Therefore, the augmented pathological responses observed in our 'delayed' IL-10 over-expression model could be attributed to IL-10 OE alone. Taken together, our study indicated dual roles of IL-10 on RSV-induced lung inflammation which appear to depend upon the timing of when elevated IL-10 is expressed in the lung.

The use of extracorporeal membrane oxygenation in pediatric patients with sickle cell disease

Previous reports have described the use of extracorporeal membrane oxygenation (ECMO) for acute chest syndrome of sickle cell disease (SCD). However, there have been no reports of venoarterial (VA) ECMO for cardiac dysfunction in patients with SCD. We describe a patient with SCD and life-threatening cardiogenic shock who was successfully treated with VA ECMO. Furthermore, SCD patients have unique comorbidities that warrant particular consideration when utilizing ECMO. We discuss these considerations and review the documented experience with ECMO for pediatric SCD patients from the Extracorporeal Life Support Organization (ELSO) registry. From 1990 until 2012, 52% of the 65 pediatric patients with SCD placed on ECMO survived, with 85% of those receiving venovenous (VV) ECMO surviving and 43% of those receiving VA ECMO surviving. However, significant complications, such as bleeding, neurological injury and kidney injury, also occurred with both VV and VA ECMO. Ten percent of SCD patients receiving VA ECMO experienced either a cerebral infarct or hemorrhage; our patient suffered a cerebrovascular accident while on ECMO, though she survived with good neurologic outcome. To our knowledge, this is the first report of a pediatric patient with SCD and cardiogenic shock successfully managed with VA ECMO. In conjunction with the ELSO registry review, this case report suggests that, while VA ECMO can be successfully used in patients with SCD and severe cardiovascular dysfunction, clinicians should also be aware of the potential for serious complications in this high-risk population.

Tristetraprolin mediates radiation-induced TNF-α production in lung macrophages

The efficacy of radiation therapy for lung cancer is limited by radiation-induced lung toxicity (RILT). Although tumor necrosis factor-alpha (TNF-α) signaling plays a critical role in RILT, the molecular regulators of radiation-induced TNF-α production remain unknown. We investigated the role of a major TNF-α regulator, Tristetraprolin (TTP), in radiation-induced TNF-α production by macrophages. For in vitro studies we irradiated (4 Gy) either a mouse lung macrophage cell line, MH-S or macrophages isolated from TTP knockout mice, and studied the effects of radiation on TTP and TNF-α levels. To study the in vivo relevance, mouse lungs were irradiated with a single dose (15 Gy) and assessed at varying times for TTP alterations. Irradiation of MH-S cells caused TTP to undergo an inhibitory phosphorylation at Ser-178 and proteasome-mediated degradation, which resulted in increased TNF-α mRNA stabilization and secretion. Similarly, MH-S cells treated with TTP siRNA or macrophages isolated from ttp (−/−) mice had higher basal levels of TNF-α, which was increased minimally after irradiation. Conversely, cells overexpressing TTP mutants defective in undergoing phosphorylation released significantly lower levels of TNF-α. Inhibition of p38, a known kinase for TTP, by either siRNA or a small molecule inhibitor abrogated radiation-induced TNF-α release by MH-S cells. Lung irradiation induced TTP^Ser178 phosphorylation and protein degradation and a simultaneous increase in TNF-α production in C57BL/6 mice starting 24 h post-radiation. In conclusion, irradiation of lung macrophages causes TTP inactivation via p38-mediated phosphorylation and proteasome-mediated degradation, leading to TNF-α production. These findings suggest that agents capable of blocking TTP phosphorylation or stabilizing TTP after irradiation could decrease RILT.

Public participation in, and awareness about, medical research opportunities in the era of clinical and translational research

CONTEXT

In the United States, levels of public participation in medical research in the era of Clinical and Translational Science Awards (CTSAs) are unknown.

METHODS

In 2011, a household survey was administered to a sample of U.S. adults, asking whether they (and children <18 years old) had participated, or were aware of opportunities to participate, in medical research. Respondents living within 100 miles of CTSA sites were identified. Regression analyses of participation and awareness (PA) were performed, applying sampling weights to permit nationally representative inferences.

RESULTS

Overall, 2,150 individuals responded (completion rate = 60%); 65% of adults and 63% of families with children resided within 100 miles of ≥1 CTSA location. Research participation rates were 11% among adults and 5% among children. Among nonparticipants, awareness rates were 64% among adults and 12% among parents of children. PA among adults was associated with higher income and education, older age, presence of chronic conditions, and living within 100 miles of four specific CTSA locations. For children, PA was associated with higher household income and parents' chronic health conditions.

CONCLUSIONS

PA of medical research opportunities is substantially higher for adults than children. Higher PA levels near specific CTSAs merit investigation to identify their successful approaches.

Interleukin-27 is a novel candidate diagnostic biomarker for bacterial infection in critically ill children

Introduction

Differentiating between sterile inflammation and bacterial infection in critically ill patients with fever and other signs of the systemic inflammatory response syndrome (SIRS) remains a clinical challenge. The objective of our study was to mine an existing genome-wide expression database for the discovery of candidate diagnostic biomarkers to predict the presence of bacterial infection in critically ill children.

Methods

Genome-wide expression data were compared between patients with SIRS having negative bacterial cultures (n = 21) and patients with sepsis having positive bacterial cultures (n = 60). Differentially expressed genes were subjected to a leave-one-out cross-validation (LOOCV) procedure to predict SIRS or sepsis classes. Serum concentrations of interleukin-27 (IL-27) and procalcitonin (PCT) were compared between 101 patients with SIRS and 130 patients with sepsis. All data represent the first 24 hours of meeting criteria for either SIRS or sepsis.

Results

Two hundred twenty one gene probes were differentially regulated between patients with SIRS and patients with sepsis. The LOOCV procedure correctly predicted 86% of the SIRS and sepsis classes, and Epstein-Barr virus-induced gene 3 (EBI3) had the highest predictive strength. Computer-assisted image analyses of gene-expression mosaics were able to predict infection with a specificity of 90% and a positive predictive value of 94%. Because EBI3 is a subunit of the heterodimeric cytokine, IL-27, we tested the ability of serum IL-27 protein concentrations to predict infection. At a cut-point value of ≥5 ng/ml, serum IL-27 protein concentrations predicted infection with a specificity and a positive predictive value of >90%, and the overall performance of IL-27 was generally better than that of PCT. A decision tree combining IL-27 and PCT improved overall predictive capacity compared with that of either biomarker alone.

Conclusions

Genome-wide expression analysis has provided the foundation for the identification of IL-27 as a novel candidate diagnostic biomarker for predicting bacterial infection in critically ill children. Additional studies will be required to test further the diagnostic performance of IL-27.

The microarray data reported in this article have been deposited in the Gene Expression Omnibus under accession number GSE4607.

An integrated microfluidic platform for in situ cellular cytokine secretion immunophenotyping

Rapid, quantitative detection of cell-secreted biomarker proteins with a low sample volume holds great promise to advance cellular immunophenotyping techniques for personalized diagnosis and treatment of infectious diseases. Here we achieved such an assay with the THP-1 human acute moncytic leukemia cell line (a model for human monocyte) using a highly integrated microfluidic platform incorporating a no-wash bead-based chemiluminescence immunodetection scheme. Our microfluidic device allowed us to stimulate cells with lipopolysaccharide (LPS), which is an endotoxin causing septic shock due to severely pronounced immune response of the human body, under a well-controlled on-chip environment. Tumor necrosis factor-alpha (TNF-α) secreted from stimulated THP-1 cells was subsequently measured within the device with no flushing process required. Our study achieved high-sensitivity cellular immunophenotyping with 20-fold fewer cells than current cell-stimulation assay. The total assay time was also 7 times shorter than that of a conventional enzyme-linked immunosorbent assay (ELISA). Our strategy of monitoring immune cell functions in situ using a microfluidic platform could impact future medical treatments of acute infectious diseases and immune disorders by enabling a rapid, sample-efficient cellular immunophenotyping analysis.

The pediatric sepsis biomarker risk model

INTRODUCTION

The intrinsic heterogeneity of clinical septic shock is a major challenge. For clinical trials, individual patient management, and quality improvement efforts, it is unclear which patients are least likely to survive and thus benefit from alternative treatment approaches. A robust risk stratification tool would greatly aid decision-making. The objective of our study was to derive and test a multi-biomarker-based risk model to predict outcome in pediatric septic shock.

METHODS

Twelve candidate serum protein stratification biomarkers were identified from previous genome-wide expression profiling. To derive the risk stratification tool, biomarkers were measured in serum samples from 220 unselected children with septic shock, obtained during the first 24 hours of admission to the intensive care unit. Classification and Regression Tree (CART) analysis was used to generate a decision tree to predict 28-day all-cause mortality based on both biomarkers and clinical variables. The derived tree was subsequently tested in an independent cohort of 135 children with septic shock.

RESULTS

The derived decision tree included five biomarkers. In the derivation cohort, sensitivity for mortality was 91% (95% CI 70 - 98), specificity was 86% (80 - 90), positive predictive value was 43% (29 - 58), and negative predictive value was 99% (95 - 100). When applied to the test cohort, sensitivity was 89% (64 - 98) and specificity was 64% (55 - 73). In an updated model including all 355 subjects in the combined derivation and test cohorts, sensitivity for mortality was 93% (79 - 98), specificity was 74% (69 - 79), positive predictive value was 32% (24 - 41), and negative predictive value was 99% (96 - 100). False positive subjects in the updated model had greater illness severity compared to the true negative subjects, as measured by persistence of organ failure, length of stay, and intensive care unit free days.

CONCLUSIONS

The pediatric sepsis biomarker risk model (PERSEVERE; PEdiatRic SEpsis biomarkEr Risk modEl) reliably identifies children at risk of death and greater illness severity from pediatric septic shock. PERSEVERE has the potential to substantially enhance clinical decision making, to adjust for risk in clinical trials, and to serve as a septic shock-specific quality metric.

Fatal and near-fatal asthma in children: the critical care perspective

OBJECTIVE

To characterize the clinical course, therapies, and outcomes of children with fatal and near-fatal asthma admitted to pediatric intensive care units (PICUs).

STUDY DESIGN

This was a retrospective chart abstraction across the 8 tertiary care PICUs of the Collaborative Pediatric Critical Care Research Network (CPCCRN). Inclusion criteria were children (aged 1-18 years) admitted between 2005 and 2009 (inclusive) for asthma who received ventilation (near-fatal) or died (fatal). Data collected included medications, ventilator strategies, concomitant therapies, demographic information, and risk variables.

RESULTS

Of the 261 eligible children, 33 (13%) had no previous history of asthma, 218 (84%) survived with no known complications, and 32 (12%) had complications. Eleven (4%) died, 10 of whom had experienced cardiac arrest before admission. Patients intubated outside the PICU had a shorter duration of ventilation (median, 25 hours vs 84 hours; P < .001). African-Americans were disproportionately represented among the intubated children and had a shorter duration of intubation. Barotrauma occurred in 15 children (6%) before admission. Pharmacologic therapy was highly variable, with similar outcomes.

CONCLUSION

Of the children ventilated in the CPCCRN PICUs, 96% survived to hospital discharge. Most of the children who died experienced cardiac arrest before admission. Intubation outside the PICU was correlated with shorter duration of ventilation. Complications of barotrauma and neuromyopathy were uncommon. Practice patterns varied widely among the CPCCRN sites.

Mitogen-activated protein kinase phosphatase 2, MKP-2, regulates early inflammation in acute lung injury

Acute lung injury (ALI) is mediated by an early proinflammatory response resulting from either a direct or indirect insult to the lung mediating neutrophil infiltration and consequent disruption of the alveolar capillary membrane ultimately leading to refractory hypoxemia. The mitogen-activated protein kinase (MAPK) pathways are a key component of the molecular response activated by those insults triggering the proinflammatory response in ALI. The MAPK pathways are counterbalanced by a set of dual-specific phosphatases (DUSP) that deactivate the kinases by removing phosphate groups from tyrosine or threonine residues. We have previously shown that one DUSP, MKP-2, regulates the MAPK pathway in a model of sepsis-induced inflammation; however, the role of MKP-2 in modulating the inflammatory response in ALI has not been previously investigated. We utilized both MKP-2-null (MKP-2(-/-)) mice and MKP-2 knockdown in a murine macrophage cell line to elucidate the role of MKP-2 in regulating inflammation during ALI. Our data demonstrated attenuated proinflammatory cytokine production as well as decreased neutrophil infiltration in the lungs of MKP-2(-/-) mice following direct, intratracheal LPS. Importantly, when challenged with a viable pathogen, this decrease in neutrophil infiltration did not impact the ability of MKP-2(-/-) mice to clear either gram-positive or gram-negative bacteria. Furthermore, MKP-2 knockdown led to an attenuated proinflammatory response and was associated with an increase in phosphorylation of ERK and induction of a related DUSP, MKP-1. These data suggest that altering MKP-2 activity may have therapeutic potential to reduce lung inflammation in ALI without impacting pathogen clearance.

Critical care for pediatric asthma: wide care variability and challenges for study

OBJECTIVES

To describe pediatric severe asthma care, complications, and outcomes to plan for future prospective studies by the Collaborative Pediatric Critical Care Research Network.

DESIGN

Retrospective cohort study.

SETTING

: Pediatric intensive care units in the United States that submit administrative data to the Pediatric Health Information System.

PATIENTS

Children 1-18 yrs old treated in a Pediatric Health Information System pediatric intensive care unit for asthma during 2004-2008.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Thirteen-thousand five-hundred fifty-two children were studied; 2,812 (21%) were treated in a Collaborative Pediatric Critical Care Research Network and 10,740 (79%) were treated in a non-Collaborative Pediatric Critical Care Research Network pediatric intensive care unit. Medication use in individual Collaborative Pediatric Critical Care Research Network centers differed widely: ipratropium bromide (41%-84%), terbutaline (11%-74%), magnesium sulfate (23%-64%), and methylxanthines (0%-46%). Complications including pneumothorax (0%-0.6%), cardiac arrest (0.2%-2%), and aspiration (0.2%-2%) were rare. Overall use of medical therapies and complications at Collaborative Pediatric Critical Care Research Network centers were representative of pediatric asthma care at non-Collaborative Pediatric Critical Care Research Network pediatric intensive care units. Median length of pediatric intensive care unit stay at Collaborative Pediatric Critical Care Research Network centers was 1 to 2 days and death was rare (0.1%-3%). Ten percent of children treated at Collaborative Pediatric Critical Care Research Network centers received invasive mechanical ventilation compared to 12% at non-Collaborative Pediatric Critical Care Research Network centers. Overall 44% of patients who received invasive mechanical ventilation were intubated in the pediatric intensive care unit. Children intubated outside the pediatric intensive care unit had significantly shorter median ventilation days (1 vs. 3), pediatric intensive care unit days (2 vs. 4), and hospital days (4 vs. 7) compared to those intubated in the pediatric intensive care unit. Among children who received mechanical respiratory support, significantly more (41% vs. 25%) were treated with noninvasive ventilation and significantly fewer (41% vs. 58%) were intubated before pediatric intensive care unit care when treated in a Pediatric Health Information System hospital emergency department.

CONCLUSIONS

Marked variations in medication therapies and mechanical support exist. Death and other complications were rare. More than half of patients treated with mechanical ventilation were intubated before pediatric intensive care unit care. Site of respiratory mechanical support initiation was associated with length of stay.

Tracking the impact of the National Institutes of Health Clinical and Translational Science Awards on child health research: developing and evaluating a measurement strategy

Since 2006, the National Institutes of Health has provided institutional infrastructure grants, called Clinical and Translational Science Awards (CTSAs), to support adult and pediatric clinical and translational research in United States institutions. A CTSA Consortium Child Health Oversight Committee workgroup developed metrics to measure the impact of CTSAs on child health (CH) research. A cross-sectional survey to collect metric data was distributed to the 46 institutions that received CTSAs during 2006-09. Thirty-seven (80%) institutions responded to the survey. Data regarding 7 metrics were reported by >70% of responding institutions: the proportion of overall funding (median, interquartile range; 0.12, 0.06–0.19) and pilot grants (0.15, 0.11–0.21) supporting CH research; the proportion of active clinical research center studies involving children (0.23, 0.15–0.35); the proportion of IRB-approved (0.24, 0.16–0.30) and funded (0.22, 0.18–0.30) studies involving children; the proportion of mentored research training awards to CH investigators (0.18, 0.11–0.28); and, the proportion of CTSA leadership positions held by pediatricians (0.18, 0.12–0.28). CTSAs provide substantial support for CH research, although additional investment in CH research is needed to improve the health of children. These metrics provide an initial means to track the impact of CTSAs on CH research.

Identification of candidate serum biomarkers for severe septic shock-associated kidney injury via microarray

Introduction

Septic-shock-associated acute kidney injury (SSAKI) carries high morbidity in the pediatric population. Effective treatment strategies are lacking, in part due to poor detection and prediction. There is a need to identify novel candidate biomarkers of SSAKI. The objective of our study was to determine whether microarray data from children with septic shock could be used to derive a panel of candidate biomarkers for predicting SSAKI.

Methods

A retrospective cohort study compared microarray data representing the first 24 hours of admission for 179 children with septic shock with those of 53 age-matched normal controls. SSAKI was defined as a >200% increase of baseline serum creatinine, persistent to 7 days after admission.

Results

Patients with SSAKI (n = 31) and patients without SSAKI (n = 148) were clinically similar, but SSAKI carried a higher mortality (45% vs. 10%). Twenty-one unique gene probes were upregulated in SSAKI patients versus patients without SSAKI. Using leave-one-out cross-validation and class prediction modeling, these probes predicted SSAKI with a sensitivity of 98% (95% confidence interval (CI) = 81 to 100) and a specificity of 80% (95% CI = 72 to 86). Serum protein levels of two specific genes showed high sensitivity for predicting SSAKI: matrix metalloproteinase-8 (89%, 95% CI = 64 to 98) and elastase-2 (83%, 95% CI = 58 to 96). Both biomarkers carried a negative predictive value of 95%. When applied to a validation cohort, although both biomarkers carried low specificity (matrix metalloproteinase-8: 41%, 95% CI = 28 to 50; and elastase-2: 49%, 95% CI = 36 to 62), they carried high sensitivity (100%, 95% CI = 68 to 100 for both).

Conclusions

Gene probes upregulated in critically ill pediatric patients with septic shock may allow for the identification of novel candidate serum biomarkers for SSAKI prediction.

Clinical implications and molecular mechanisms of immunoparalysis after cardiopulmonary bypass

OBJECTIVE

We used a whole blood assay to characterize the immune system's response after cardiopulmonary bypass (CPB) in children to identify the risk for postoperative infections. We assessed the impact of CPB on histone methylation as a potential mechanism for altering gene expression necessary for the immune system's capacity to defend against infections.

METHODS

We prospectively enrolled patients less than 18 years old undergoing heart surgery requiring CPB at C.S. Mott Children's Hospital. Blood was obtained from patients before CPB, on CPB, and on postoperative days 1, 3, and 5. Ex vivo lipopolysaccharide-induced tumor necrosis factor-alpha production measured the capacity of the immune system. Serum cytokines were measured using a multiplex assay. Chromatin immunoprecipitation to detect histone modifications at the interleukin (IL) 10 promoter was performed on circulating mononuclear cells from a subgroup of patients.

RESULTS

We enrolled 92 patients, and postoperative day 1 samples identified a subpopulation of immunocompetent patients at low risk for infections with a specificity of 93% (confidence interval [CI], 83%-98%) and a negative predictive value of 88% (CI, 77%-95%; P = .006). Patients classified as immunoparalyzed had serum IL-10 levels 2.4-fold higher than the immunocompetent group (mean, 14.3 ± 18.3 pg/mL vs 6.0 ± 5.0 pg/mL; P = .01). In a subgroup of patients, we identified a greater percent of the "gene on" epigenetic signature, H3K4me3, associated with the IL-10 promoter after CPB.

CONCLUSIONS

Our data demonstrate that immunophenotyping patients after CPB can predict their risk for the development of postoperative infections. Novel mechanistic data suggest that CPB affects epigenetic alterations in IL-10 gene regulation.

Management and Treatment Guidelines for Sepsis in Pediatric Patients

Sepsis remains one of the leading causes of morbidity and mortality in children despite improved understanding of the pathophysiology leading to better clinical management and survival. Recent studies have identified several areas that must be addressed by the clinician in order to continue to impact the morbidity and mortality associated with sepsis. In this review, we discuss the evidence in several of these areas including initial resuscitation, pathogen eradication, maintenance of oxygen delivery, and directed modifiers of the inflammatory response. Our overall goal is to provide the bedside clinician with an updated systematic approach to treat sepsis in children.