Enteral feeding of children on noninvasive respiratory support : a four-centre European study

Objective: To explore enteral feeding practices and the achievement of energy targets in children on Non-invasive respiratory support (NRS), in four European Pediatric Intensive Care Units (PICUs). Design: A four centre retrospective cohort study Setting: Four PICUs: Bristol UK, Lyon France, Madrid Spain, Rotterdam the Netherlands. Patients: Children in PICU who required acute NRS in the first 7 days. The primary outcome was achievement of standardised kcal/goal. Interventions: Nil Measurements and Main Results: 325 children were included (Bristol 104; Lyon 99; Madrid 72; Rotterdam 50). The median (IQR) age and weight were 3 months (1-16) and 5 Kg (4-10) respectively, with 66% admitted with respiratory failure. There were large between-centre variations in practices. Overall, 190/325 (58.5%) received NRS in order to prevent intubation and 41.5% after extubation. The main modes of NRS used were high-flow nasal cannula 43.6%, bilevel positive airway pressure 33.2% and continuous positive airway pressure 21.2% Most children (77.8%) were fed gastrically (48.4% continuously) and the median time to first feed after NRS initiation was 4 hours (IQR 1-9). The median percentage of time a child was nil per oral whilst on NRS was 4 hours (2-13). Overall, children received a median of 56% (25%-82%) of their energy goals compared to a standardised target of 0.85 of the recommended dietary allowance. Patients receiving step-up NRS (p=<0.001), those on BLPAP or CPAP (compared to HFNC) (p =<0.001) and those on continuous feeds (p =<0.001) achieved significantly more of their kcal goal. GI complications varied from 4.8 – 20%, with the most common reported being vomiting in 54/325 (16.6%), other complications occurred in 40/325 (12.3%) children, but pulmonary aspiration was rare 5/325 (1.5%). Conclusions: Children on NRS tolerated feeding well, with relatively few complications, but prospective trials are now required to determine the optimal timing and feeding method for these children

Lower respiratory tract infections in children requiring mechanical ventilation: a multicentre prospective surveillance study incorporating airway metagenomics

BackgroundLower respiratory tract infections (LRTI) are a leading cause of critical illness and mortality in mechanically ventilated children; however, the pathogenic microbes frequently remain unknown. We combined traditional diagnostics with metagenomic next generation sequencing (mNGS) to evaluate the cause of LRTI in critically ill children.MethodsWe conducted a prospective, multicentre cohort study of critically ill children aged 31 days to 17 years with respiratory failure requiring mechanical ventilation (&gt;72 h) in the USA. By combining bacterial culture and upper respiratory viral PCR testing with mNGS of tracheal aspirate collected from all patients within 24 h of intubation, we determined the prevalence, age distribution, and seasonal variation of viral and bacterial respiratory pathogens detected by either method in children with or without LRTI.FindingsBetween Feb 26, 2015, and Dec 31, 2017, of the 514 enrolled patients, 397 were eligible and included in the study (276 children with LRTI and 121 with no evidence of LRTI). A presumptive microbiological cause was identified in 255 (92%) children with LRTI, with respiratory syncytial virus (127 [46%]), Haemophilus influenzae (70 [25%]), and Moraxella catarrhalis (65 [24%]) being most prevalent. mNGS identified uncommon pathogens including Ureaplasma parvum and Bocavirus. Co-detection of viral and bacterial pathogens occurred in 144 (52%) patients. Incidental carriage of potentially pathogenic microbes occurred in 82 (68%) children without LRTI, with rhinovirus (30 [25%]) being most prevalent. Respiratory syncytial virus (p&lt;0·0001), H influenzae (p=0·0006), and M catarrhalis (p=0·0002) were most common in children younger than 5 years. Viral and bacterial LRTI occurred predominantly during winter months.InterpretationThese findings demonstrate that respiratory syncytial virus, H influenzae, and M catarrhalis contribute disproportionately to severe paediatric LRTI, co-infections are common, and incidental carriage of potentially pathogenic microbes occurs frequently. Further, we provide a framework for future epidemiological and emerging pathogen surveillance studies, highlighting the potential for metagenomics to enhance clinical diagnosis.FundingUS National Institutes of Health and CZ Biohub

Alteration in Indole Metabolites After Cardiopulmonary Bypass Surgery in Neonates and Infants

IMPORTANCE:. Cardiopulmonary bypass (CPB) surgery is associated with changes in the intestinal microbiome. Metabolism of tryptophan into the indole pathway is entirely facilitated by the intestinal microbiome, and indole metabolites play a critical role in intestinal epithelial integrity, intestinal and systemic vascular tone, and intestinal and systemic immune response. OBJECTIVES:. To evaluate the impact of CPB on microbial-derived indole metabolites and their association with clinical outcomes. DESIGN, SETTING, AND PARTICIPANTS:. Prospective cohort study of neonates and infants younger than 6 months of age undergoing CPB at a quaternary children’s hospital. MAIN OUTCOMES AND MEASURES:. Serum samples underwent quantitative pathway mapping via mass spectroscopy. Clinical outcomes of interest included cardiac ICU (CICU) length of stay and Vasoactive-Inotropic Score (VIS) at 48 hours. RESULTS:. Ninety patients between 2 and 169 days old were enrolled. Patients showed significant postoperative changes in seven of eight indole metabolites. A two-fold increase in preoperative levels of indole-3-carboxylic acid was associated with 0.63 odds of requiring vasoactive medications at 48 hours (p = 0.023) and among those subjects still requiring vasoactives at 48 hours, they had an average 7.1% decrease in VIS at 48 hours (p = 0.005), and a 12.25% reduction in CICU length of stay (p = 0.001). Higher levels of indole-3-carboxylic acid preoperatively and at 24 and 48 hours postoperatively were also significantly associated with decreased CICU length of stay. Conversely, increased levels of several metabolites, including indole-3-lactic acid, indole-3-carbaldhyde, indole-3-propionic acid, tryptamine, and tryptophol, in the preoperative and postoperative period were associated with higher VIS at 48 hours and increased CICU length of stay. CONCLUSIONS AND RELEVANCE:. CPB was associated with significant changes in indole metabolite levels postoperatively. Indole-3-carboxylic acid, which suppresses T-regulatory (Treg) differentiation, is associated with improved patient outcomes, whereas other metabolites, that promote Treg differentiation, were associated with worse outcomes

Proteomic profiling of the local and systemic immune response to pediatric respiratory viral infections

ABSTRACT Viral lower respiratory tract infection (vLRTI) is a leading cause of hospitalization and death in children worldwide. Despite this, no studies have employed proteomics to characterize host immune responses to severe pediatric vLRTI in both the lower airway and systemic circulation. To address this gap, gain insights into vLRTI pathophysiology, and test a novel diagnostic approach, we assayed 1,305 proteins in tracheal aspirate (TA) and plasma from 62 critically ill children using SomaScan. We performed differential expression (DE) and pathway analyses comparing vLRTI (n = 40) to controls with non-infectious acute respiratory failure (n = 22), developed a diagnostic classifier using LASSO regression, and analyzed matched TA and plasma samples. We further investigated the impact of viral load and bacterial coinfection on the proteome. The TA signature of vLRTI was characterized by 200 DE proteins (Padj <0.05) with upregulation of interferons and T cell responses and downregulation of inflammation-modulating proteins including FABP and MIP-5. A nine-protein TA classifier achieved an area under the receiver operator curve (AUC) of 0.96 (95% CI: 0.90–1.00) for identifying vLRTI. In plasma, the host response to vLRTI was more muted with 56 DE proteins. Correlation between TA and plasma was limited, although ISG15 was elevated in both compartments. In bacterial coinfection, we observed increases in the TNF-stimulated protein TSG-6, as well as CRP, and interferon-related proteins. Viral load correlated positively with interferon signaling and negatively with neutrophil-activation pathways. Taken together, our study provides fresh insights into the lower airway and systemic proteome of severe pediatric vLRTI and identifies novel protein biomarkers with diagnostic potential.IMPORTANCEWe describe the first proteomic profiling of the lower airway and blood in critically ill children with severe viral lower respiratory tract infection (vLRTI). From tracheal aspirate (TA), we defined a proteomic signature of vLRTI characterized by increased expression of interferon signaling proteins and decreased expression of proteins involved in immune modulation including FABP and MIP-5. Using machine learning, we developed a parsimonious diagnostic classifier that distinguished vLRTI from non-infectious respiratory failure with high accuracy. Comparative analysis of paired TA and plasma specimens demonstrated limited concordance, although the interferon-stimulated protein ISG15 was significantly upregulated with vLRTI in both compartments. We further identified TSG-6 and CRP as airway biomarkers of bacterial-viral coinfection, and viral load analyses demonstrated a positive correlation with interferon-related protein expression and a negative correlation with the expression of neutrophil activation proteins. Taken together, our study provides new insights into the lower airway and systemic proteome of severe pediatric vLRTI

Integrated host/microbe metagenomics enables accurate lower respiratory tract infection diagnosis in critically ill children.

BACKGROUNDLower respiratory tract infection (LRTI) is a leading cause of death in children worldwide. LRTI diagnosis is challenging because noninfectious respiratory illnesses appear clinically similar and because existing microbiologic tests are often falsely negative or detect incidentally carried microbes, resulting in antimicrobial overuse and adverse outcomes. Lower airway metagenomics has the potential to detect host and microbial signatures of LRTI. Whether it can be applied at scale and in a pediatric population to enable improved diagnosis and treatment remains unclear.METHODSWe used tracheal aspirate RNA-Seq to profile host gene expression and respiratory microbiota in 261 children with acute respiratory failure. We developed a gene expression classifier for LRTI by training on patients with an established diagnosis of LRTI (n = 117) or of noninfectious respiratory failure (n = 50). We then developed a classifier that integrates the host LRTI probability, abundance of respiratory viruses, and dominance in the lung microbiome of bacteria/fungi considered pathogenic by a rules-based algorithm.RESULTSThe host classifier achieved a median AUC of 0.967 by cross-validation, driven by activation markers of T cells, alveolar macrophages, and the interferon response. The integrated classifier achieved a median AUC of 0.986 and increased the confidence of patient classifications. When applied to patients with an uncertain diagnosis (n = 94), the integrated classifier indicated LRTI in 52% of cases and nominated likely causal pathogens in 98% of those.CONCLUSIONLower airway metagenomics enables accurate LRTI diagnosis and pathogen identification in a heterogeneous cohort of critically ill children through integration of host, pathogen, and microbiome features.FUNDINGSupport for this study was provided by the Eunice Kennedy Shriver National Institute of Child Health and Human Development and the National Heart, Lung, and Blood Institute (UG1HD083171, 1R01HL124103, UG1HD049983, UG01HD049934, UG1HD083170, UG1HD050096, UG1HD63108, UG1HD083116, UG1HD083166, UG1HD049981, K23HL138461, and 5R01HL155418) as well as by the Chan Zuckerberg Biohub