A Comparison of the Anticoagulation Efficacy and Safety of Epoprostenol to Heparin and Citrate in Children Receiving Continuous Renal Replacement Therapy.

INTRODUCTION: Anticoagulants are used in continuous renal replacement therapy (CRRT) to prolong filter life. There are no prior investigations directly comparing epoprostenol to more commonly used forms of anticoagulation in children. Therefore, the primary aim of this study was to assess the efficacy and safety of epoprostenol as compared to heparin and citrate anticoagulation in a pediatric cohort. METHODS: We performed a retrospective analysis of all patients <18 years of age admitted to an academic quaternary care children's hospital from 2017-2022 who received epoprostenol, heparin, or citrate exclusively for CRRT anticoagulation. Efficacy was evaluated by comparing the hours to the first unintended filter change and the ratio of filters used to CRRT days. Safety was assessed by evaluating changes in platelet count and vasoactive-ionotropic score (VIS). RESULTS: Of 101 patients, 44 received epoprostenol (43.6%), 38 received heparin (37.6%), and 19 received citrate (18.8%). The first filter change was more commonly planned in patients receiving anticoagulation with epoprostenol (43%) as compared to citrate (11%) or heparin (29%) (p = 0.034). Of those patients where the first filter change was unintended (n = 33), there were greater median hours until the filter was replaced in those receiving epoprostenol (29) when compared to citrate (21) (p = 0.002) or heparin (18) (p = 0.003). There was a smaller median ratio of filters used to days on therapy in the patients that received epoprostenol (0.53) when compared to citrate (1) (p = 0.003) or heparin (0.75) (p = 0.001). For those receiving epoprostenol, there was no significant decrease in platelet count when comparing values prior to CRRT initiation through 7 days of therapy. There was no significant difference in VIS when comparing values prior to CRRT initiation through the first 2 days of CRRT. CONCLUSIONS: Epoprostenol-based anticoagulation is effective when compared to other anticoagulation strategies used in pediatric CRRT with a favorable side effect profile.

Accuracy of the HemoCue® to measure cell-free plasma hemoglobin and detect clinically significant hemolysis.

INTRODUCTION: Monitoring cell-free plasma hemoglobin (PHb) during extracorporeal therapies allows early intervention of significant hemolysis, but timely measurements are often challenging. We thus present an analysis of a rapid benchtop device's ability to detect clinically significant hemolysis (PHb ≥50 mg/dL). METHODS: PHb was measured in 419 plasma samples from 88 pediatric patients undergoing cardiopulmonary bypass via both the benchtop device (HemoCue® Plasma/Low Hb system) and the clinical laboratory at the Children's Hospital of Pittsburgh (reference standards). Values of PHb ≥50 mg/dL as measured by the reference standard was defined as the binary outcome of clinically significant hemolysis. Analyses included Pearson correlations, logistic regression, receiver operating characteristic curves, and Bland-Altman. Because the manufacturer specifications identify the measurement range of the HemoCue® system as 30-3000 mg/dL, a secondary analysis was completed using PHb ≥30 mg/dL. RESULTS: Using reference measurements, 66/88 subjects had at least one PHb level that fell within the range of detection (≥30 mg/dL) of the benchtop device and 46/88 had significant hemolysis as defined by PHb ≥50 mg/dL. PHb levels ≥30 mg/dL largely correlated with measurements made with the benchtop device (r = 0.82, p < .001). The device was able to predict PHb values ≥30 mg/dL (AUROC 0.9582) and ≥50 mg/dL (AUROC 0.9637). The Bland-Altman demonstrated a mean difference of 7.0 mg/dL with <5% outside the 95% limits of agreement. CONCLUSIONS: The HemoCue® system is an effective surrogate for more robust laboratory testing to identify clinically significant hemolysis during cardiopulmonary bypass.

Association Between Hyperoxemia and Increased Cell-Free Plasma Hemoglobin During Cardiopulmonary Bypass in Infants and Children.

OBJECTIVES: To determine potential risk factors for severe hemolysis during pediatric cardiopulmonary bypass and examine whether supraphysiologic levels of oxygen and cardiopulmonary bypass duration are associated with hemolysis. DESIGN: Prospective observational study. SETTING: Cardiac ICU in a university-affiliated children's hospital. PATIENTS: Greater than 1 month to less than 18 years old patients undergoing cardiopulmonary bypass for cardiac surgery. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Plasma samples from 100 patients to assess cell-free plasma hemoglobin levels were obtained at start cardiopulmonary bypass, at the end of cardiopulmonary bypass, and 2 and 24 hours after reperfusion. Arterial blood gas samples were obtained before and every 30 minutes during cardiopulmonary bypass. Patient demographics and laboratory data were collected from the electronic medical record. Plasma hemoglobin levels peaked at the end of cardiopulmonary bypass and haptoglobin levels continued to fall throughout all time points. There were 44 patients with severe hemolysis (change in cell-free plasma hemoglobin > 50 mg/dL). Younger age (odds ratio/sd 0.45 [95% CI, 0.25-0.81]) and higher mean Pao2 × cardiopulmonary bypass duration (31.11 [1.46-664.64]) were identified as risk factors for severe hemolysis in multivariable analysis. Severe hemolysis was associated with longer hospital and ICU lengths of stay as well as acute kidney injury. CONCLUSIONS: We observed younger age and the exposure to both oxygen and duration of cardiopulmonary bypass as risk factors for hemolysis. Oxygen delivery through the cardiopulmonary bypass circuit is an easily modifiable risk factor. Its role in the production of reactive oxygen species that could alter the erythrocyte membrane deserves further examination in larger prospective studies.

Activation of AMP-activated protein kinase during sepsis/inflammation improves survival by preserving cellular metabolic fitness.

The purpose was to determine the role of AMPK activation in the renal metabolic response to sepsis, the development of sepsis-induced acute kidney injury (AKI) and on survival. In a prospective experimental study, 167 10- to 12-week-old C57BL/6 mice underwent cecal ligation and puncture (CLP) and human proximal tubule epithelial cells (TEC; HK2) were exposed to inflammatory mix (IM), a combination of lipopolysaccharide (LPS) and high mobility group box 1 (HMGB1). Renal/TEC metabolic fitness was assessed by monitoring the expression of drivers of oxidative phosphorylation (OXPHOS), the rates of utilization of OXPHOS/glycolysis in response to metabolic stress, and mitochondrial function by measuring O2 consumption rates (OCR) and the membrane potential (Δψm ). Sepsis/IM resulted in AKI, increased mortality, and in renal AMPK activation 6-24 hours after CLP/IM. Pharmacologic activation of AMPK with 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR) or metformin during sepsis improved the survival, while AMPK inhibition with Compound C increased mortality, impaired mitochondrial respiration, decreased OCR, and disrupted TEC metabolic fitness. AMPK-driven protection was associated with increased Sirt 3 expression and restoration of metabolic fitness. Renal AMPK activation in response to sepsis/IM is an adaptive mechanism that protects TEC, organs, and the host by preserving mitochondrial function and metabolic fitness likely through Sirt3 signaling.

Bioactive Oxylipins in Infants and Children With Congenital Heart Disease Undergoing Pediatric Cardiopulmonary Bypass.

OBJECTIVES: To determine the production of 9-hydroxyoctadecadienoic acid and 13-hydroxyoctadecadienoic acid during cardiopulmonary bypass in infants and children undergoing cardiac surgery, evaluate their relationship with increase in cell-free plasma hemoglobin, provide evidence of bioactivity through markers of inflammation and vasoactivity (WBC count, milrinone use, vasoactive-inotropic score), and examine their association with overall clinical burden (ICU/hospital length of stay and mechanical ventilation duration). DESIGN: Prospective observational study. SETTING: Twelve-bed cardiac ICU in a university-affiliated children's hospital. PATIENTS: Children were prospectively enrolled during their preoperative clinic appointments with the following criteria: greater than 1 month to less than 18 years old, procedures requiring cardiopulmonary bypass INTERVENTIONS:: None. MEASUREMENTS AND MAIN RESULTS: Plasma was collected at the start and end of cardiopulmonary bypass in 34 patients. 9-hydroxyoctadecadienoic acid, 13-hydroxyoctadecadienoic acid, plasma hemoglobin, and WBC increased. 9:13-hydroxyoctadecadienoic acid at the start of cardiopulmonary bypass was associated with vasoactive-inotropic score at 2-24 hours postcardiopulmonary bypass (R = 0.25; p < 0.01), milrinone use (R = 0.17; p < 0.05), and WBC (R = 0.12; p < 0.05). 9:13-hydroxyoctadecadienoic acid at the end of cardiopulmonary bypass was associated with vasoactive-inotropic score at 2-24 hours (R = 0.17; p < 0.05), 24-48 hours postcardiopulmonary bypass (R = 0.12; p < 0.05), and milrinone use (R = 0.19; p < 0.05). 9:13-hydroxyoctadecadienoic acid at the start and end of cardiopulmonary bypass were associated with the changes in plasma hemoglobin (R = 0.21 and R = 0.23; p < 0.01). The changes in plasma hemoglobin was associated with milrinone use (R = 0.36; p < 0.001) and vasoactive-inotropic score less than 2 hours (R = 0.22; p < 0.01), 2-24 hours (R = 0.24; p < 0.01), and 24-48 hours (R = 0.48; p < 0.001) postcardiopulmonary bypass. Cardiopulmonary bypass duration, 9:13-hydroxyoctadecadienoic acid at start of cardiopulmonary bypass, and plasma hemoglobin may be risk factors for high vasoactive-inotropic score. Cardiopulmonary bypass duration, changes in plasma hemoglobin, 9:13-hydroxyoctadecadienoic acid, and vasoactive-inotropic score correlate with ICU and hospital length of stay and/mechanical ventilation days. CONCLUSIONS: In low-risk pediatric patients undergoing cardiopulmonary bypass, 9:13-hydroxyoctadecadienoic acid was associated with changes in plasma hemoglobin, vasoactive-inotropic score, and WBC count, and may be a risk factor for high vasoactive-inotropic score, indicating possible inflammatory and vasoactive effects. Further studies are warranted to delineate the role of hydroxyoctadecadienoic acids and plasma hemoglobin in cardiopulmonary bypass-related dysfunction and to explore hydroxyoctadecadienoic acid production as a potential therapeutic target.

Cell-Free Plasma Hemoglobin and Male Gender Are Risk Factors for Acute Kidney Injury in Low Risk Children Undergoing Cardiopulmonary Bypass.

OBJECTIVES: To determine the relationship between the production of cell-free plasma hemoglobin and acute kidney injury in infants and children undergoing cardiopulmonary bypass for cardiac surgery. DESIGN: Prospective observational study. SETTING: Twelve-bed cardiac ICU in a university-affiliated children's hospital. PATIENTS: Children were prospectively enrolled during their preoperative outpatient appointment with the following criteria: greater than 1 month to less than 18 years old, procedures requiring cardiopulmonary bypass, no preexisting renal dysfunction. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Plasma and urine were collected at baseline (in a subset), the beginning and end of cardiopulmonary bypass, and 2 hours and 24 hours after cardiopulmonary bypass in 60 subjects. Levels of plasma hemoglobin increased during cardiopulmonary bypass and were associated (p < 0.01) with cardiopulmonary bypass duration (R = 0.22), depletion of haptoglobin at end and 24 hours after cardiopulmonary bypass (R = 0.12 and 0.15, respectively), lactate dehydrogenase levels at end cardiopulmonary bypass (R = 0.27), and change in creatinine (R = 0.12). Forty-three percent of patients developed acute kidney injury. There was an association between plasma hemoglobin level and change in creatinine that varied by age (overall [R = 0.12; p < 0.01]; in age > 2 yr [R = 0.22; p < 0.01]; and in < 2 yr [R = 0.03; p = 0.42]). Change in plasma hemoglobin and male gender were found to be risk factors for acute kidney injury (odds ratio, 1.02 and 3.78, respectively; p < 0.05). CONCLUSIONS: Generation of plasma hemoglobin during cardiopulmonary bypass and male gender are associated with subsequent renal dysfunction in low-risk pediatric patients, especially in those older than 2 years. Further studies are needed to determine whether specific subgroups of pediatric patients undergoing cardiopulmonary bypass would benefit from potential treatments for hemolysis and plasma hemoglobin-associated renal dysfunction.

Oxidative lipidomics: applications in critical care.

PURPOSE OF REVIEW: Lipid peroxidation has long been established as a key player in the pathophysiology of critical illness. Recent developments in oxidative lipidomics have aided in deciphering the molecular mechanisms of lipid oxidation in health and disease. This review discusses recent achievements and recent developments in oxidative lipidomics and its contribution to the understanding of critical illness. RECENT FINDINGS: Most studies involving acute injury focus on identifying the end products of lipid peroxidation. This misses the early events and targets of peroxidation mechanisms. Recent developments in liquid chromatography tandem mass spectrometry-based oxidative lipidomics have enabled the identification of a wide variety of enzymatically generated lipid oxidation products. Such lipid mediators have been found to play an important role in injury, inflammation, and recovery in disease states such as sepsis or head trauma. SUMMARY: Multiple lipid oxidation products are formed either through enzymatic pathways or through random chemical reactions. These products are often biologically active and can contribute to the regulation of cellular signaling. Oxidative lipidomics has contributed to the identification and quantification of lipid peroxidation products, the mechanism and time course of their production after injury, and synergistic functioning with other regulatory processes in the body. These advances in knowledge will help guide the future development of interventions in critical illness.

Therapeutic Plasma Exchange Is Associated With Improved Major Adverse Kidney Events in Children and Young Adults With Thrombocytopenia at the Time of Continuous Kidney Replacement Therapy Initiation.

Therapeutic plasma exchange (TPE) has been shown to improve organ dysfunction and survival in patients with thrombotic microangiopathy and thrombocytopenia associated with multiple organ failure. There are no known therapies for the prevention of major adverse kidney events after continuous kidney replacement therapy (CKRT). The primary objective of this study was to evaluate the effect of TPE on the rate of adverse kidney events in children and young adults with thrombocytopenia at the time of CKRT initiation. DESIGN: Retrospective cohort. SETTING: Two large quaternary care pediatric hospitals. PATIENTS: All patients less than or equal to 26 years old who received CKRT between 2014 and 2020. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: We defined thrombocytopenia as a platelet count less than or equal to 100,000 (cell/mm3) at the time of CKRT initiation. We ascertained major adverse kidney events at 90 days (MAKE90) after CKRT initiation as the composite of death, need for kidney replacement therapy, or a greater than or equal to 25% decline in estimated glomerular filtration rate from baseline. We performed multivariable logistic regression and propensity score weighting to analyze the relationship between the use of TPE and MAKE90. After excluding patients with a diagnosis of thrombotic thrombocytopenia purpura and atypical hemolytic uremic syndrome (n = 6) and with thrombocytopenia due to a chronic illness (n = 2), 284 of 413 total patients (68.8%) had thrombocytopenia at CKRT initiation (51% female). Of the patients with thrombocytopenia, the median (interquartile range) age was 69 months (13-128 mo). MAKE90 occurred in 69.0% and 41.5% received TPE. The use of TPE was independently associated with reduced MAKE90 by multivariable analysis (odds ratio [OR], 0.35; 95% CI, 0.20-0.60) and by propensity score weighting (adjusted OR, 0.31; 95% CI, 0.16-0.59). CONCLUSIONS: Thrombocytopenia is common in children and young adults at CKRT initiation and is associated with increased MAKE90. In this subset of patients, our data show benefit of TPE in reducing the rate of MAKE90.