Identification of molecular subphenotypes in two cohorts of paediatric ARDS.

BACKGROUND: Two subphenotypes of acute respiratory distress syndrome (ARDS), hypoinflammatory and hyperinflammatory, have been reported in adults and in a single paediatric cohort. The relevance of these subphenotypes in paediatrics requires further investigation. We aimed to identify subphenotypes in two large observational cohorts of paediatric ARDS and assess their congruence with prior descriptions. METHODS: We performed latent class analysis (LCA) separately on two cohorts using biomarkers as inputs. Subphenotypes were compared on clinical characteristics and outcomes. Finally, we assessed overlap with adult cohorts using parsimonious classifiers. FINDINGS: In two cohorts from the Children's Hospital of Philadelphia (n=333) and from a multicentre study based at the University of California San Francisco (n=293), LCA identified two subphenotypes defined by differential elevation of biomarkers reflecting inflammation and endotheliopathy. In both cohorts, hyperinflammatory subjects had greater illness severity, more sepsis and higher mortality (41% and 28% in hyperinflammatory vs 11% and 7% in hypoinflammatory). Both cohorts demonstrated overlap with adult subphenotypes when assessed using parsimonious classifiers. INTERPRETATION: We identified hypoinflammatory and hyperinflammatory subphenotypes of paediatric ARDS from two separate cohorts with utility for prognostic and potentially predictive, enrichment. Future paediatric ARDS trials should identify and leverage biomarker-defined subphenotypes in their analysis.

The association of immediate post cardiac arrest diastolic hypertension and survival following pediatric cardiac arrest.

AIM: In-hospital cardiac arrest occurs in >5000 children each year in the US and almost half will not survive to discharge. Animal data demonstrate that an immediate post-resuscitation burst of hypertension is associated with improved survival. We aimed to determine if systolic and diastolic invasive arterial blood pressures immediately (0-20 min) after return of spontaneous circulation (ROSC) are associated with survival and neurologic outcomes at hospital discharge. METHODS: This is a secondary analysis of the Pediatric Intensive Care Quality of CPR (PICqCPR) study of invasively measured blood pressures during intensive care unit CPR. Patients were eligible if they achieved ROSC and had at least one invasively measured blood pressure within the first 20 min following ROSC. Post-ROSC blood pressures were normalized for age, sex and height. "Immediate hypertension" was defined as at least one systolic or diastolic blood pressure >90th percentile. The primary outcome was survival to hospital discharge. RESULTS: Of 102 children, 70 (68.6%) had at least one episode of immediate post-CPR diastolic hypertension. After controlling for pre-existing hypotension, duration of CPR, calcium administration, and first documented rhythm, patients with immediate post-CPR diastolic hypertension were more likely to survive to hospital discharge (79.3% vs. 54.5%; adjusted OR = 2.93; 95%CI, 1.16-7.69). CONCLUSIONS: In this post hoc secondary analysis of the PICqCPR study, 68.6% of subjects had diastolic hypertension within 20 min of ROSC. Immediate post-ROSC hypertension was associated with increased odds of survival to discharge, even after adjusting for covariates of interest.

Beneficial effects of resveratrol and exercise training on cardiac and aortic function and structure in the 3xTg mouse model of Alzheimer's disease.

Background: Studies have indicated an association between Alzheimer's disease (AD) and increased risk of developing cardiovascular complications. Lifestyle modifiable factors, such as exercise and diet, are known to prevent cardio-cerebral disease. Recent studies demonstrate that hearts from early onset triple-transgenic AD mice exhibit pathologies, but it is not clear whether cardiovascular function is altered in this model. Methods: In this study, we measured in vivo cardiovascular function in 7-month-old male 3xTg mice and age-matched wild-type (WT) mice using high-frequency high-resolution ultrasound imaging. Results: Our findings indicated that aortic root measurements and interventricular septal dimensions were similar in 3xTg and wild-type mice. Systolic function, expressed as ejection fraction and fractional shortening, were decreased in 3xTg mice. Late (A) ventricular filling velocities, the early/atrial (E/A) ratio, and mitral valve deceleration time, all indices of diastolic function, were increased in 3xTg mice compared to WT mice. Treadmill exercise training and resveratrol supplementation in the diet for 5 months improved ejection fraction, fractional shortening, and restored diastolic deceleration times. Pulse wave velocity was ~33% higher in 3xTg, and accompanied by a significant increase in elastin fiber fragmentation within the aortic wall, which was associated with decrease in elastin content and fiber length. Aortic wall and adventitia thickness were increased in 3xTg mice compared to the WT group. Exercise training and resveratrol supplementation, or both, improved overall aortic morphology with no change in pulse wave velocity. Conclusion: Taken together, the results indicate that the aberrations in cardiac function and aortic elastin morphology observed in the 3xTg mouse model of AD can be prevented with exercise training and treatment with resveratrol. The benefits of regular exercise training and resveratrol supplementation of heart and aortic structure in the 3xTg mouse support the value of healthy lifestyle factors on cardiovascular health.

Exercise and resveratrol increase fracture resistance in the 3xTg-AD mouse model of Alzheimer's disease.

BACKGROUND: Alzheimer's disease (AD) and osteoporosis are progressive diseases that affect the elderly population. Both conditions are associated with fracture risk that is greater than twice that of the healthy population. Resveratrol and exercise are two treatments that have been linked with attenuation of age-related diseases, including the risk of bone fractures. In this study, we test the hypothesis that these treatments improve fracture resistance in a mouse model representative of the AD condition. METHODS: Three-month-old male 3xTg-AD mice were treated for 4 months with resveratrol or exercise or both combined, and compared with wild type mice. Exercise training was performed on a treadmill at 15 m/min for 45 min/day, 5 days/week. Resveratrol was given at 4 g/kg diet in the form of pellets. Three-point bending, cross-sectional geometric, and fluorescence analyses were conducted on tibias and compared by treatment group. RESULTS: Tibias of 3xTg mice exhibited signs of diminished bone quality and fracture under less force than age-matched wild type mice (P < 0.05). Treatment with both resveratrol and exercise improved indicators of fracture resistance and bone quality in AD mice to levels comparable to that of wild type mice (P < 0.05). CONCLUSIONS: The 3xTg mouse model of AD is at elevated risk for limb bone fracture compared to wild type controls. Treatment with resveratrol, exercise, or both in combination improves fracture resistance and cross-sectional geometric indicators of bone strength.

Positive Cumulative Fluid Balance Is Associated With Mortality in Pediatric Acute Respiratory Distress Syndrome in the Setting of Acute Kidney Injury.

OBJECTIVES: As acute kidney injury and elevated cumulative fluid balance commonly co-occur in pediatric acute respiratory distress syndrome, we aimed to identify risk factors for their development and evaluate their independent relationships with mortality. We hypothesized that acute kidney injury and elevated cumulative fluid balance would be associated with markers of inflammation and that children with elevated cumulative fluid balance and concomitant acute kidney injury would have worse outcomes than other children. DESIGN: Prospective observational study using the pediatric Risk, Injury, Failure, Loss, End-Stage acute kidney injury classification. SETTING: Five academic PICUs. PATIENTS: Two-hundred sixty patients 1 month to 18 years old meeting the Berlin definition of acute respiratory distress syndrome between 2008 and 2014. INTERVENTIONS: None. MEASUREMENTS AND RESULTS: PICU mortality was 13% (34/260). Relative to survivors, nonsurvivors had greater cumulative fluid balance on day 3 of acute respiratory distress syndrome (+90.1 mL/kg; interquartile range 26.6-161.7 vs +44.9 mL/kg; interquartile range 10.0-111.3; p = 0.008) and also had higher prevalence of acute kidney injury on day 3 of acute respiratory distress syndrome (50% vs 23%; p = 0.001). On stratified analysis, greater cumulative fluid balance on day 3 of acute respiratory distress syndrome was associated with mortality among patients with concomitant acute kidney injury (+111.5 mL/kg for nonsurvivors; interquartile range 82.6-236.8 vs +58.5 mL/kg for survivors; interquartile range 0.9-176.2; p = 0.041) but not among patients without acute kidney injury (p = 0.308). The presence of acute kidney injury on acute respiratory distress syndrome day 3 was associated with mortality among patients with positive cumulative fluid balance (29.1% vs 10.4% mortality; p = 0.001) but not among patients with even or negative cumulative fluid balance (p = 0.430). Day 1 plasma interleukin-6 levels were associated with the development of day 3 positive cumulative fluid balance, day 3 acute kidney injury, and PICU mortality and the association between elevated day 1 interleukin-6 and PICU mortality was partially mediated by the interval development of day 3 positive cumulative fluid balance and day 3 acute kidney injury (p < 0.001). CONCLUSIONS: In pediatric acute respiratory distress syndrome, elevated cumulative fluid balance on day 3 of acute respiratory distress syndrome is associated with mortality specifically in patients with concomitant acute kidney injury. Plasma interleukin-6 levels are associated with the development of positive cumulative fluid balance and acute kidney injury, suggesting a potential mechanism by which inflammation might predispose to mortality.

Early Plasma Matrix Metalloproteinase Profiles. A Novel Pathway in Pediatric Acute Respiratory Distress Syndrome.

RATIONALE: MMPs (Matrix metalloproteinases) and their endogenous tissue inhibitors may contribute to lung injury through extracellular matrix degradation and modulation of inflammation and fibrosis. OBJECTIVES: To test for an association between MMP pathway proteins and inflammation, endothelial dysfunction, and clinical outcomes. METHODS: We measured MMPs in plasma collected on acute respiratory distress syndrome (ARDS) Day 1 from 235 children at five hospitals between 2008 and 2017. We used latent class analysis to identify patients with distinct MMP profiles and then associated those profiles with markers of inflammation (IL-1RA, -6, -8, -10, and -18; macrophage inflammatory protein-1α and -1ß; tumor necrosis factor-α and -R2), endothelial injury (angiopoietin-2, von Willebrand factor, soluble thrombomodulin), impaired oxygenation (PaO2/FiO2 [P/F] ratio, oxygenation index), morbidity, and mortality. MEASUREMENTS AND MAIN RESULTS: In geographically distinct derivation and validation cohorts, approximately one-third of patients demonstrated an MMP profile characterized by elevated MMP-1, -2, -3, -7, and -8 and tissue inhibitor of metalloproteinase-1 and -2; and depressed active and total MMP-9. This MMP profile was associated with multiple markers of inflammation, endothelial injury, and impaired oxygenation on Day 1 of ARDS, and conferred fourfold increased odds of mortality or severe morbidity independent of the P/F ratio and other confounders (95% confidence interval, 2.1-7.6; P < 0.001). Logistic regression using both the P/F ratio and MMP profiles was superior to the P/F ratio alone in prognosticating mortality or severe morbidity (area under the receiver operating characteristic curve, 0.75; 95% confidence interval, 0.68-0.82 vs. area under the receiver operating characteristic curve, 0.66; 95% confidence interval, 0.58-0.73; P = 0.009). CONCLUSIONS: Pediatric patients with ARDS have specific plasma MMP profiles associated with inflammation, endothelial injury, morbidity, and mortality. MMPs may play a role in the pathobiology of children with ARDS.

Incorporating Inflammation into Mortality Risk in Pediatric Acute Respiratory Distress Syndrome.

OBJECTIVES: In pediatric acute respiratory distress syndrome, lung injury is mediated by immune activation and severe inflammation. Therefore, we hypothesized that patients with elevated pro- and anti-inflammatory cytokines would have higher mortality rates and that these biomarkers could improve risk stratification of poor outcomes. DESIGN: Multicenter prospective observational study. SETTING: We enrolled patients from five academic PICUs between 2008 and 2015. PATIENTS: Patients were 1 month to 18 years old, used noninvasive or invasive ventilation, and met the American European Consensus Conference definition of acute respiratory distress syndrome. INTERVENTIONS: Eight proinflammatory and anti-inflammatory cytokines were measured on acute respiratory distress syndrome day 1 and correlated with mortality, ICU morbidity as measured by survivor Pediatric Logistic Organ Dysfunction score, and biomarkers of endothelial injury, including angiopoietin-2, von Willebrand Factor, and soluble thrombomodulin. MEASUREMENTS AND MAIN RESULTS: We measured biomarker levels in 194 patients, including 38 acute respiratory distress syndrome nonsurvivors. Interleukin-6, interleukin-8, interleukin-10, interleukin-18, and tumor necrosis factor-R2 were each strongly associated with all-cause mortality, multiple markers of ICU morbidity, and endothelial injury. A multiple logistic regression model incorporating oxygenation index, interleukin-8, and tumor necrosis factor-R2 was superior to a model of oxygenation index alone in predicting the composite outcome of mortality or severe morbidity (area under the receiver operating characteristic, 0.77 [0.70-0.83] vs 0.70 [0.62-0.77]; p = 0.042). CONCLUSIONS: In pediatric acute respiratory distress syndrome, pro- and anti-inflammatory cytokines are strongly associated with mortality, ICU morbidity, and biochemical evidence of endothelial injury. These cytokines significantly improve the ability of the oxygenation index to discriminate risk of mortality or severe morbidity and may allow for identification and enrollment of high-risk subgroups for future studies.

A Simple and Robust Bedside Model for Mortality Risk in Pediatric Patients With Acute Respiratory Distress Syndrome.

OBJECTIVES: Despite declining mortality, acute respiratory distress syndrome is still involved in up to one third of pediatric intensive care deaths. The recently convened Pediatric Acute Lung Injury Consensus Conference has outlined research priorities for the field, which include the need for accurate bedside risk stratification of patients. We aimed to develop a simple yet robust model of mortality risk among pediatric patients with acute respiratory distress syndrome to facilitate the targeted application of high-risk investigational therapies and stratification for enrollment in clinical trials. DESIGN: Prospective, multicenter cohort. SETTING: Five academic PICUs. PATIENTS: Three hundred eight children greater than 1 month and less than or equal to 18 years old, admitted to the ICU, with bilateral infiltrates on chest radiograph and PaO2/FIO2 ratio less than 300 in the clinical absence of left atrial hypertension. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Twenty clinical variables were recorded in the following six categories: demographics, medical history, oxygenation, ventilation, radiographic imaging, and multiple organ dysfunction. Data were measured 0-24 and 48-72 hours after acute respiratory distress syndrome onset (day 1 and 3) and examined for associations with hospital mortality. Among 308 enrolled patients, mortality was 17%. Children with a history of cancer and/or hematopoietic stem cell transplant had higher mortality (47% vs 11%; p < 0.001). Oxygenation index, the PaO2/FIO2 ratio, extrapulmonary organ dysfunction, Pediatric Risk of Mortality-3, and positive cumulative fluid balance were each associated with mortality. Using two statistical approaches, we found that a parsimonious model of mortality risk using only oxygenation index and cancer/hematopoietic stem cell transplant history performed as well as other more complex models that required additional variables. CONCLUSIONS: In the PICU, oxygenation index and cancer/hematopoietic stem cell transplant history can be used on acute respiratory distress syndrome day 1 or day 3 to predict hospital mortality without the need for more complex models. These findings may simplify risk assessment for clinical trials, counseling families, and high-risk interventions such as extracorporeal life support.

Elevated soluble thrombomodulin is associated with organ failure and mortality in children with acute respiratory distress syndrome (ARDS): a prospective observational cohort study.

INTRODUCTION: The significance of endothelial injury in children with the acute respiratory distress syndrome (ARDS) has not been well studied. Plasma levels of soluble thrombomodulin (sTM), an endothelial surface protein involved in coagulation, have been associated with endothelial injury. We hypothesized that elevated plasma sTM would correlate with mortality and organ failure in children with ARDS. METHODS: We conducted a multicenter prospective observational study of pediatric patients with ARDS between 2008 and 2014. sTM was measured in plasma collected less than 24 hours from ARDS diagnosis. Outcomes were intensive care unit mortality and organ dysfunction by pediatric logistic organ dysfunction scores. Logistic regression was used to adjust for clinically relevant covariates. RESULTS: Plasma sTM was higher in patients with indirect lung injury compared to direct lung injury (100 ng/mL vs. 86 ng/mL, p = 0.02). Increased sTM levels were correlated with more organ dysfunction in the entire study population (Spearman's rho = 0.37, p < 0.01). Overall mortality was 16%. sTM levels were associated with increased mortality in patients with indirect lung injury (OR 2.7 per log(sTM), p = 0.02). These relationships were independent of age, oxygenation defect, or presence of acute kidney injury. CONCLUSION: Elevated plasma sTM levels are associated with organ dysfunction in children with ARDS and with higher mortality in children with indirect lung injury. These findings highlight the importance of endothelial injury in children with ARDS and may guide the development of future therapies targeted toward endothelial stabilization, repair, or functional replacement in this population.

Plasma soluble thrombomodulin levels are associated with mortality in the acute respiratory distress syndrome.

OBJECTIVE: Thombomodulin (TM) is an activator of protein C and a biomarker for endothelial injury. We hypothesized that (1) elevated plasma levels would be associated with clinical outcomes and (2) polymorphisms in the TM gene would be associated with plasma levels. PATIENTS: We studied 449 patients enrolled in the Fluid and Catheter Treatment Trial (FACTT) for whom both plasma and DNA were available. We used logistic regression and receiver operator curves (ROC) to test for associations between soluble TM (sTM) and mortality at 60 days. MEASUREMENTS AND RESULTS: Plasma sTM levels were higher in non-survivors than survivors at baseline [median 147 (IQR, 95-218) vs. 89 (56-129) ng/mL, p < 0.0001] and on day 3 after study enrollment [205 (146-302) vs. 127 (85-189), p < 0.0001]. The odds of death increased by 2.4 (95 % CI 1.5-3.8, p < 0.001), and by 2.8 (1.7-4.7, P < 0.001) for every log increase in baseline and day 3 sTM levels, respectively, after adjustment for age, race, gender, severity of illness, fluid management strategy, baseline creatinine, and non-pulmonary sepsis as the primary cause of ARDS. By ROC analysis, plasma sTM levels discriminated between non-survivors and survivors [AUC = 72 % (66-78 %) vs. AUC = 54 % for severity based on Berlin criteria). Addition of sTM improved discrimination based on APACHE III from 77 to 80 % (P < 0.03). sTM levels at baseline were not statistically different among subjects stratified by genotypes of tag SNPs in the TM gene. CONCLUSIONS: Higher plasma sTM levels are associated with increased mortality in ARDS. The lack of association between the sTM levels and genetic variants suggests that the increased levels of sTM may reflect severity of endothelial damage rather than genetic heterogeneity. These findings underscore the importance of endothelial injury in ARDS pathogenesis and suggest that, in combination with clinical markers, sTM could contribute to risk stratification.