New clinical criteria for septic shock: serum lactate level as new emerging vital sign

Plasma-derived extracellular vesicles (EVs) as biomarkers of sepsis in burn patients via label-free Raman spectroscopy

Sepsis following burn trauma is a global complication with high mortality, with ∼60% of burn patient deaths resulting from infectious complications. Diagnosing sepsis is complicated by confounding clinical manifestations of the burn injury, and current biomarkers lack the sensitivity and specificity required for prompt treatment. There is a strong rationale to assess circulating extracellular vesicles (EVs) from patient liquid biopsy as sepsis biomarkers due to their release by pathogens from bacterial biofilms and roles in the subsequent immune response. This study applies Raman spectroscopy to patient plasma-derived EVs for rapid, sensitive, and specific detection of sepsis in burn patients, achieving 97.5% sensitivity and 90.0% specificity. Furthermore, spectral differences between septic and non-septic burn patient EVs could be traced to specific glycoconjugates of bacterial strains associated with sepsis morbidity. This work illustrates the potential application of EVs as biomarkers in clinical burn trauma care and establishes Raman analysis as a fast, label-free method to specifically identify features of bacterial EVs relevant to infection amongst the host background.

Lactate Monitoring in Intensive Care: A Comprehensive Review of Its Utility and Interpretation

Lactate monitoring is critical in managing critically ill patients in intensive care settings. Elevated lactate levels often signify underlying metabolic disturbances such as tissue hypoxia, anaerobic metabolism, or impaired lactate clearance, which are prevalent in conditions like sepsis, shock, and trauma. Understanding the physiological basis of lactate production and its significance in clinical practice is essential for interpreting its diagnostic and prognostic value. This comprehensive review aims to explore the utility of lactate monitoring across various critical care scenarios. It provides an overview of lactate's metabolic pathways, methods of measurement, and the clinical implications of interpreting lactate levels in different contexts. Additionally, the review discusses current evidence on lactate-guided therapeutic interventions and highlights challenges and limitations to their application. By synthesizing the existing literature and clinical insights, this review aims to enhance the understanding of the role of lactate monitoring in assessing disease severity, guiding treatment strategies, and predicting outcomes in critically ill patients. Ultimately, this review underscores the importance of integrating lactate monitoring into routine clinical practice to optimize patient care and improve clinical outcomes in intensive care settings.

Intradermal Lactate Monitoring Based on a Microneedle Sensor Patch for Enhanced In Vivo Accuracy

Lactate is an important diagnostic and prognostic biomarker of several human pathological conditions, such as sepsis, malaria, and dengue fever. Unfortunately, due to the lack of reliable analytical decentralized platforms, the determination of lactate yet relies on discrete blood-based assays, which are invasive and inefficient and may cause tension and pain in the patient. Herein, we demonstrate the potential of a fully integrated microneedle (MN) sensing system for the minimally invasive transdermal detection of lactate in an interstitial fluid (ISF). The originality of this analytical technology relies on: (i) a strategy to provide a uniform coating of a doped polymer-based membrane as a diffusion-limiting layer on the MN structure, optimized to perform full-range lactate detection in the ISF (linear range of response: 0.25-35 mM, 30 s assay time, 8 h operation), (ii) double validation of ex vivo and in vivo results based on ISF and blood measurements in rats, (iii) monitoring of lactate level fluctuations under the administration of anesthesia to mimic bedside clinical scenarios, and (iv) in-house design and fabrication of a fully integrated and portable sensing device in the form of a wearable patch including a custom application and user-friendly interface in a smartphone for the rapid, routine, continuous, and real-time lactate monitoring. The main analytical merits of the lactate MN sensor include appropriate selectivity, reversibility, stability, and durability by using a two-electrode amperometric readout. The ex-vivo testing of the MN patch of preconditioned rat skin pieces and euthanized rats successfully demonstrated the accuracy in measuring lactate levels. The in vivo measurements suggested the existence of a positive correlation between ISF and blood lactate when a lag time of 10 min is considered (Pearson's coefficient = 0.85, mean difference = 0.08 mM). The developed MN-based platform offers distinct advantages over noncontinuous blood sampling in a wide range of contexts, especially where access to laboratory services is limited or blood sampling is not suitable. Implementation of the wearable patch in healthcare could envision personalized medicine in a variety of clinical settings.

Plasma-derived Extracellular Vesicles (EVs) as Biomarkers of Sepsis in Burn Patients via Label-free Raman Spectroscopy

Sepsis following burn trauma is a global complication with high mortality, with ~60% of burn patient deaths resulting from infectious complications. Sepsis diagnosis is complicated by confounding clinical manifestations of the burn injury, and current biomarkers markers lack the sensitivity and specificity required for prompt treatment. Circulating extracellular vesicles (EVs) from patient liquid biopsy as biomarkers of sepsis due to their release by pathogens from bacterial biofilms and roles in subsequent immune response. This study applies Raman spectroscopy to patient plasma derived EVs for rapid, sensitive, and specific detection of sepsis in burn patients, achieving 97.5% sensitivity and 90.0% specificity. Furthermore, spectral differences between septic and non-septic burn patient EVs could be traced to specific glycoconjugates of bacterial strains associated with sepsis morbidity. This work illustrates the potential application of EVs as biomarkers in clinical burn trauma care, and establishes Raman analysis as a fast, label-free method to specifically identify features of bacterial EVs relevant to infection amongst the host background.

Lactate metabolism promotes in vivo fitness during Acinetobacter baumannii infection

Acinetobacter baumannii is one of the most prevalent causes of nosocomial infections worldwide. However, a paucity of information exists regarding the connection between metabolic capacity and in vivo bacterial fitness. Elevated lactate is a key marker of severe sepsis. We have previously shown that the putative A. baumannii lactate permease gene, lldP, is upregulated during in vivo infection. Here, we confirm that lldP expression is upregulated in three A. baumannii strains during a mammalian systemic infection. Utilising a transposon mutant disrupted for lldP in the contemporary clinical strain AB5075-UW, and a complemented strain, we confirmed its role in the in vitro utilisation of l-(+)-lactate. Furthermore, disruption of the lactate metabolism pathway resulted in reduced bacterial fitness during an in vivo systemic murine competition assay. The disruption of lldP had no impact on the susceptibility of this strain to complement mediated killing by healthy human serum. However, growth in biologically relevant concentrations of lactate observed during severe sepsis, led to bacterial tolerance to killing by healthy human blood, a phenotype that was abolished in the lldP mutant. This study highlights the importance of the lactate metabolism pathway for survival and growth of A. baumannii during infection.

Serum lactate and mean arterial pressure thresholds in patients with cirrhosis and septic shock

BACKGROUND

The Sepsis-3 guidelines have incorporated serum lactate levels of >2 mmol/L in septic shock definition to account for higher observed mortality. Further evidence is needed to support this threshold in cirrhosis, as well as target mean arterial pressure (MAP) during resuscitation.

METHODS

This observational cohort study investigated the association between initial serum lactate and resuscitation MAP levels on in-hospital mortality in patients with and without cirrhosis. Patients admitted to the intensive care unit for the treatment of septic shock between 2006 and 2021 in a quaternary academic center were included. Patients with cirrhosis documented on imaging and International Classification of Disease codes (n=595) were compared to patients without cirrhosis (n=575). The association of intensive care unit admission lactate levels and median 2-hour MAP with in-hospital mortality and the need for continuous renal replacement therapy was assessed. The association between median 24-hour MAP and in-hospital mortality was analyzed post hoc.

RESULTS

Within the cirrhosis group, admission lactate levels of 2-4 and >4 mmol/L were associated with increased in-hospital mortality compared to lactate <2 mmol/L [adjusted odds ratio (aOR): 1.69, CI: 1.03-2.81, aOR: 4.02, CI: 2.53-6.52]. Median 24-hour MAP 60-65 and <60 mm Hg were also associated with increased in-hospital mortality compared with MAP >65 mm Hg (aOR: 2.84, CI: 1.64-4.92 and aOR: 7.34, CI: 3.17-18.76). In the noncirrhosis group, associations with in-hospital mortality were weaker for lactate 2-4 and >4 mmol/L (aOR: 1.32, CI: 0.77-2.27 and aOR: 2.25, CI: 1.40-3.67) and median 24-hour MAP 60-65 and <60 mm Hg (aOR: 1.70, CI: 0.65-4.14 and aOR: 4.41, CI: 0.79-29.38).

CONCLUSIONS

These findings support utilizing lactate >2 mmol/L in the definition of septic shock, as well as a target MAP of >65 mm Hg during resuscitation in patients with cirrhosis.

Author Response

How to cite this article: Rajbanshi LK, Arjyal B. Author Response. Indian J Crit Care Med 2024;28(1):90-91.

Gallic Acid Protects from Sepsis-Induced Acute Lung Injury

Sepsis, a leading global cause of morbidity and mortality, involves multiple organ dysfunction syndromes driven by free radical-mediated processes. Uncontrolled inflammation in early sepsis stages can lead to acute lung injury (ALI). Activated leukocytes generate reactive oxygen species, contributing to sepsis development. Gallic acid, a phenolic compound, is known for its antimicrobial properties. This study aims to observe gallic acid's protective and restorative effect on the lungs in an experimental sepsis model. Male Wistar albino rats were subjected to a feces intraperitoneal injection procedure (FIP) to induce sepsis. Four groups were formed: normal control, FIP alone, FIP with saline, and FIP with gallic acid. Gallic acid was administered intraperitoneally at 20 mg/kg/day. Blood samples were collected for biochemical analysis, and computed tomography assessed lung tissue histopathologically and radiologically. Gallic acid significantly decreased malondialdehyde, IL-6, IL-1β, TNF-α, CRP levels, oxidative stress, and inflammation indicators. Lactic acid levels decreased, suggesting improved tissue oxygenation. Histopathological examinations revealed reduced lung damage in the gallic-acid-treated group. Computed tomography confirmed lower lung density, indicating less severe inflammation. Arterial blood gas analysis demonstrated improved oxygenation in gallic-acid-treated rats. Gallic acid exhibited anti-inflammatory and antioxidant effects, reducing markers of systemic inflammation and oxidative stress. The findings support its potential to protect against ALI during sepsis. Comparable studies underline gallic acid's anti-inflammatory properties in different tissues. Early administration of gallic acid in sepsis models demonstrated protective effects against ALI, emphasizing its potential as an adjunct therapy to mitigate adverse outcomes. The study proposes gallic acid to reduce mortality rates and decrease the need for mechanical ventilation during sepsis-induced ALI.

Metabolic fingerprint of patients showing responsiveness to treatment of septic shock in intensive care unit

OBJECTIVE

An early metabolic signature associated with the responsiveness to treatment can be useful in the better management of septic shock patients. This would help clinicians in designing personalized treatment protocols for patients showing non-responsiveness to treatment.

METHODS

We analyzed the serum on Day 1 (n = 60), Day 3 (n = 47), and Day 5 (n = 26) of patients with septic shock under treatment using NMR-based metabolomics. Partial least square discriminant analysis (PLS-DA) was performed to generate the list of metabolites that can be identified as potential disease biomarkers having statistical significance (that is, metabolites that had a VIP score > 1, and p value < 0.05, False discovery rate (FDR) < 0.05).

RESULTS

Common significant metabolites amongst the three time points were obtained that distinguished the patients being responsive (R) and non-responsive (NR) to treatments, namely 3 hydroxybutyrate, lactate, and phenylalanine which were lower, whereas glutamate and choline higher in patients showing responsiveness.

DISCUSSION

The study gave these metabolic signatures identifying patients' responsiveness to treatment. The results of the study will aid in the development of targeted therapy for ICU patients.

Evidence for Use of Validated Sepsis Screening Tools in the Prehospital Population: A Scoping Review

INTRODUCTION

Early detection and treatment of sepsis improves chances of survival; however, sepsis is often difficult to diagnose initially. This is especially true in the prehospital setting, where resources are scarce, yet time is of great significance. Early warning scores (EWS) based on vital signs were originally developed to guide medical practitioners in determining the degree of illness of a patient in the in-patient setting. These EWS were adapted for use in the prehospital setting to predict critical illness and sepsis. We performed a scoping review to evaluate the existing evidence for use of validated EWS to identify prehospital sepsis.

METHODS

We performed a systematic search using the CINAHL, Embase, Ovid-MEDLINE, and PubMed databases on September 1, 2022. Articles that examined the use of EWS to identify prehospital sepsis were included and assessed.

RESULTS

Twenty-three studies were included in this review: one validation study, two prospective studies, two systematic reviews, and 18 retrospective studies. Study characteristics, classification statistics, and primary conclusions of each article were extracted and tabulated. Classification statistics varied markedly for prehospital sepsis identification across all included EWS: sensitivities ranged from 0.02-1.00, specificities from 0.07-1.00, and PPV and NPV from 0.19-0.98 and 0.32-1.00, respectively.

CONCLUSIONS

All studies demonstrated inconsistency for the identification of prehospital sepsis. The variety of available EWS and study design heterogeneity suggest it is unlikely that new research can identify a single gold standard score. Based on our findings in this scoping review, we recommend future efforts focus on combining standardized prehospital care with clinical judgment to provide timely interventions for unstable patients where infection is considered a likely etiology, in addition to improving sepsis education for prehospital clinicians. At most, EWS can be used as an adjunct to these efforts, but they should not be relied on alone for prehospital sepsis identification.

Evaluation of the Recommended 30 cc/kg Fluid Dose for Patients With Septic Shock and Hypoperfusion With Lactate Greater Than 4 mmol/L

The Surviving Sepsis Campaign Guidelines recommend fluid administration of 30 cc/kg ideal body weight (IBW) for patients with sepsis and lactate greater than 4 mmol/L within 3 hours of identification. In this study, we explore the impact of fluid dose on lactate normalization, treatment cost, length of stay, and mortality in patients with lactate greater than 4.

DESIGN

Multicenter retrospective observational study.

SETTING

Eight-hospital urban healthcare system in Northeastern United States.

PATIENTS

Patients with sepsis, initial lactate value greater than 4 mmol/L, and received appropriate antibiotics within 3 hours.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We stratified patients into five groups based on the dose of fluid administered within 3 hours after sepsis identification. The groupings were less than 15 cc/kg IBW, 15.1-25 cc/kg IBW, 25.1-35 cc/kg IBW, 35.1-50 cc/kg IBW, and greater than 50 cc/kg IBW. We used the group that received a fluid dose of 25.1-35 cc/kg IBW, as a reference group. The mean age was 66 years, and 56% were male. Three hundred seventy-one (25%) received less than 15 cc/kg of IBW of crystalloid fluid, 278 (17%) received 15-25 cc/kg of IBW, 316 (21%) received 25.1-35 cc/kg of IBW, 319 (21%) received 35.1-50 cc/kg of IBW, and 207 (14%) received greater than 50 cc/kg of IBW. After multilinear regression, there was no significant difference in lactate normalization between the reference group and any of the other fluid groups. We also found no statistically significant difference in the observed/expected cost, or observed/expected length of stay, between the reference group and any of the other fluid groups. Mortality was higher among patients who received greater than 50 cc/kg IBW when compared to the recommended dose.

CONCLUSIONS

In patients with sepsis and lactate value greater than 4 mmol/L, high or low fluid doses were not associated with better lactate clearance or patient outcomes. Greater than 50 cc/kg IBW dose of fluids within 3 hours is associated with higher mortality.

Continuous Measurement of Lactate Concentration in Human Subjects through Direct Electron Transfer from Enzymes to Microneedle Electrodes

Microneedle lactate sensors may be used to continuously measure lactate concentration in the interstitial fluid in a minimally invasive and pain-free manner. First- and second-generation enzymatic sensors produce a redox-active product that is electrochemically sensed at the electrode surface. Direct electron transfer enzymes produce electrons directly as the product of enzymatic action; in this study, a direct electron transfer enzyme specific to lactate has been immobilized onto a microneedle surface to create lactate-sensing devices that function at low applied voltages (0.2 V). These devices have been validated in a small study of human volunteers; lactate concentrations were raised and lowered through physical exercise and subsequent rest. Lactazyme microneedle devices show good agreement with concurrently obtained and analyzed serum lactate levels.

Fabrication of a Lactate-Specific Molecularly Imprinted Polymer toward Disease Detection

The development of sensitive and selective robust sensor materials for targeted biomarker detection aims to contribute to self-health monitoring and management. Molecularly imprinted polymeric (MIP) materials can perform as biomimetic recognition elements via tailored routes of synthesis for specific target analyte extraction and/or detection. In this work, a sensitive- and selective-lactate MIP has been developed utilizing methacrylic acid and ethylene glycol dimethacrylate as the functional monomer and cross-linker, respectively. The sensitivity of the as-synthesized imprinted species was evaluated by determining the target analyte retention, imprinting factor, and selectivity adsorption of up to 63.5%, 6.86, and 0.82, respectively. MIP selectivity elucidated the imprinting mechanism between the functional monomers and target analyte lactate, further experimentally evidenced by using structurally competitive analytes malic acid and sodium 2-hydroxybutyrate, where retentions of 22.6 and 25.2%, respectively, were observed. Understanding the specific intermolecular mechanisms of both the template analyte and structural interferents with the MIP enables experimentalists to make informed decisions regarding monomer-target and porogen selections and possible sites of interaction for improved molecular imprinting. This imprinting system highlights the potential to be further developed into artificial receptor sensor materials for the detection of disease.

Prediction of the Postoperative Outcome in Liver Resection Using Perioperative Serum Lactate Levels

Background: The aim of our study was to analyze perioperative lactate levels and their predictive value for postoperative mortality and morbidity after liver resection. Methods: The clinicopathological characteristics and outcomes of 152 patients who underwent liver resection for benign and malign diagnoses were analyzed retrospectively. Lactate concentrations at three different time points, (1) before liver resection (LAC-PRE), (2) after liver resection on day 0 (LAC-POST), and (3) on day one after the operation (LAC-POD1) were assessed regarding the prognostic value in predicting postoperative complications and mortality according to the Clavien–Dindo (CD) classification. Results: The rates of postoperative complications (CD ≥ IIIb) and mortality rates were 19.7% (N = 30) and 4.6% (N = 7), respectively. The LAC-PRE levels showed no correlation with the postoperative outcome. The ROC curve analysis showed that LCT-POST and LCT-POD1 values were moderately strong in predicting postoperative morbidity (0.681 and 0.768, respectively) and had strong predictive accuracies regarding postoperative mortality (0.800 and 0.838, respectively). The multivariate analysis revealed LAC-POST as a significant predictor of postoperative complications (CD ≥ IIIb: OR 9.28; 95% CI: 2.88–29.9; p < 0.001) and mortality (OR 11.69; 95% CI: 1.76–77.7; p = 0.011). Conclusion: Early postoperative lactate levels are a useful and easily practicable predictor of postoperative morbidity and mortality in patients after liver resection.

INVESTIGATING BLOOD LACTATE CONCENTRATION AS A PROGNOSTIC INDICATOR FOR BIRDS PRESENTING WITH BREVETOXICOSIS: 2020-2021

Large blooms of the dinoflagellate Karenia brevis cause annual harmful algal bloom events, or "red tides" on Florida's Gulf Coast. Each year, the Clinic for the Rehabilitation of Wildlife (CROW) is presented with hundreds of cases of aquatic birds that exhibit neurologic clinical signs due to brevetoxicosis. Double-crested cormorants (Phalacrocorax auratus) are the most common species seen, and typically present with a combination of ataxia, head tremors, knuckling, and/or lagophthalmos. Blood lactate levels are known to increase in mammals for a variety of reasons, including stress, hypoxia, sepsis, and trauma, but there is limited literature on blood lactate values in avian species. The objective of this study was to determine the prognostic value of blood lactate concentration on successful rehabilitation and release of birds presenting with clinical signs consistent with brevetoxicosis. Blood lactate levels were collected on intake, the morning after presentation and initial therapy, and prior to disposition (release or euthanasia) from 194 birds (including 98 cormorants) representing 17 species during the 2020-2021 red tide season. Overall, mean blood lactate at intake, the morning after intake, and predisposition was 2.9, 2.8, and 3.2 mmol/L, respectively, for released birds across all species (2.9, 2.9, and 3.2 mmol/L for released cormorants); 3.4, 3.4, and 6.5 mmol/L for birds that died (4.0, 3.5, and 7.9 mmol/L for cormorants that died); and 3.1, 3.5, and 4.7 mmol/L for birds that were euthanized (3.5, 4.7, and 4.9 mmol/L for cormorants that were euthanized). On average, birds that died or were euthanized had an elevated lactate at all time points as compared to those that were released, but these results were not statistically significant (P = 0.13). These results indicate that blood lactate levels do not appear to be useful as a prognostic indicator for successful release of birds, including double-crested cormorants, affected by brevetoxicosis.

Cirrhosis Management in the Intensive Care Unit

Patients with cirrhosis frequently require admission to the intensive care unit as complications arise in the course of their disease. These admissions are associated with high short- and long-term morbidity and mortality. Thus, understanding and characterizing complications and unique needs of patients with cirrhosis and acute-on-chronic liver failure helps providers identify appropriate level of care and evidence-based treatments. While there is no widely accepted critical care admission criteria for patients with cirrhosis, the presence of organ failure and primary or nosocomial infections are associated with particularly high in-hospital mortality. Optimal management of patients with cirrhosis in the critical care setting requires a system-based approach that acknowledges deviations from canonical pathophysiology. In this review, we discuss appropriate considerations and evidence-based practices for the general care of patients with cirrhosis and critical illness.

Critical Illness-Related Corticosteroid Insufficiency (CIRCI) Among Patients with COVID-19 at a Tertiary Hospital: Clinical Characteristics and Outcomes

OBJECTIVES

Among critically ill patients, there is usually impairment of the hypothalamic-pituitary-adrenal axis, leading to a condition known as critical illness-related corticosteroid insufficiency (CIRCI). This investigation aims to determine the incidence of and characterize CIRCI among patients with COVID-19 as well as to analyze the outcomes of these critically ill patients.

METHODOLOGY

This is a single-center, retrospective cohort study that investigated the occurrence of CIRCI among critically ill patients infected with COVID-19.

RESULTS

In this cohort, there were 145 COVID-19-positive patients with refractory shock, which reflects that 22.94% of the COVID-19 admissions have probable CIRCI.Patients who were given corticosteroids were found to have statistically significant longer median days on a ventilator (p=0.001). However, those on the corticosteroid arm were at higher risk of morbidity and mortality and a greater proportion had organ dysfunction. Multivariable logistic regression analysis revealed that SOFA score was a significant predictor of mortality in CIRCI (p=0.013).

CONCLUSION

CIRCI has a unique presentation among patients with COVID-19 because of the presence of a high level of inflammation in this life-threatening infection. It is possibly a harbinger of a markedly increased risk of mortality in these patients.

Inhaled platelet vesicle-decoyed biomimetic nanoparticles attenuate inflammatory lung injury

Acute lung injury (ALI) is an inflammatory response which causes serious damages to alveolar epithelia and vasculature, and it still remains high lethality and mortality with no effective treatment. Based on the inflammatory homing of platelets and cell membrane cloaking nanotechnology, in this study we developed a biomimetic anti-inflammation nanoparticle delivery system for ALI treatment. PM@Cur-RV NPs were designed by combining the poly (lactic-co-glycolic acid) nanoparticles (NPs) coated with platelet membrane vesicles (PM) for the purpose of highly targeting delivery of curcumin (Cur) and resveratrol (RV) to inflammatory lungs. PM@Cur-RV NPs showed good biocompatibility and biosafety both in vitro and in vivo. Accumulation of NPs into lung tract was observed after inhaled NPs. Remarkably, the inhalation of PM@Cur-RV NPs effectively inhibited lung vascular injury evidenced by the decreased lung vascular permeability, and the reduced proinflammatory cytokine burden in an ALI mouse model. The analysis of infiltrated macrophages in the lungs showed that the Cur-RV-modulated macrophage polarized towards M2 phenotype and the decreased histone lactylation might contribute to their anti-inflammation effects. Together, this work highlights the potential of inhalation of biomimetic nanoparticle delivery of curcumin and resveratrol for the treatment of pulmonary diseases.

A novel animal model to study delayed resuscitation following traumatic hemorrhage

A focus of combat casualty care research is to develop treatments for when full resuscitation after hemorrhage is delayed. However, few animal models exist to investigate such treatments. Given the kidney's susceptibility to ischemia, we determined how delayed resuscitation affects renal function in a model of traumatic shock. Rats were randomized into three groups: resuscitation after 1 h (ETH-1) or 2 h (ETH-2) of extremity trauma and hemorrhagic shock, and sham control. ETH was induced in anesthetized rats with muscle injury and fibula fracture, followed by pressure-controlled hemorrhage [mean arterial pressure (MAP) = 55 mmHg] for 1 or 2 h. Rats were then resuscitated with whole blood until MAP stabilized between 90 and 100 mmHg for 30 min. MAP, glomerular filtration rate (GFR), creatinine, blood gases, and fractional excretion of sodium (nFENa+) were measured for 3 days. Compared with control, ETH-1 and ETH-2 exhibited decreases in GFR and nFENa+, and increases in circulating lactate, creatinine, and blood urea nitrogen (BUN) before and within 30 min after resuscitation. The increases in creatinine, BUN, and potassium were greater in ETH-2 than in ETH-1, whereas lactate levels were similar between ETH-1 and ETH-2 before and after resuscitation. All measurements were normalized in ETH-1 within 2 days after resuscitation, with 22% mortality. However, ETH-2 exhibited a prolonged impairment of GFR, increased nFENa+, and a 66% mortality. Resuscitation 1 h after injury therefore preserves renal function, whereas further delay of resuscitation irreversibly impairs renal function and increases mortality. This animal model can be used to explore treatments for prolonged prehospital care following traumatic hemorrhage.NEW & NOTEWORTHY A focus of combat casualty care research is to develop treatment where full resuscitation after hemorrhage is delayed. However, animal models of combat-related hemorrhagic shock in which to determine physiological outcomes of such delays and explore potential treatment for golden hour extension are lacking. In this study, we filled this knowledge gap by establishing a traumatic shock model with reproducible development of AKI and shock-related complications determined by the time of resuscitation.

The Variation in Outcomes of Septic Patients: A Dual-Centre Comparative Study

Introduction Despite significant advances in the field of medicine, sepsis is constantly growing as a major public health concern. The global epidemic of sepsis imposes a significant economic burden on healthcare systems world-over. Furthermore, its high prevalence in society is inevitably paralleled by an excessive mortality rate, with approximately six million deaths reported every year. The primary aim of this study was to evaluate and compare, the management of acutely septic patients against outcomes in a tertiary teaching institution in Pakistan versus a similar one in the United Kingdom. Methods This study was a dual-centred, retrospective comparative analysis comparing all patients admitted through the emergency department at the respective tertiary centres. Patient details were collected and compared across the two sites to evaluate the effect of individual characteristics on prognosis. The outcomes of these presentations were analysed by comparing rates of in-hospital mortality, admission to the ICU or discharge. Results The total number of patients identified as having sepsis was 60 in the Pakistan cohort, and 92 in the Aberdeen cohort. No significant difference was found when comparing genders, and the results of basic observations were largely similar at presentation. Twenty-five per cent (25%) (n=38) of the total study population were deemed to have a poor outcome at 3 days, but 50% of the Pakistan cohort was deemed to have a poor outcome. Conclusion Managing sepsis has developed significantly in recent years, but most of this development was implemented in high-income countries. There was a significant delay in time to resuscitate septic patients in Pakistan, with significantly raised three-day morbidity and mortality. There is a need for further comparative studies of the management of sepsis in Pakistan and other low-income countries to identify the problems and tackle obstacles on every level of the healthcare system.

Lactate-induced lactylation in skeletal muscle is associated with insulin resistance in humans

Elevated circulating lactate has been associated with obesity and insulin resistance. The aim of the current study was to determine if lactate-induced lysine lactylation (kla), a post-translational modification, was present in human skeletal muscle and related to insulin resistance. Fifteen lean (Body Mass Index: 22.1 ± 0.5 kg/m2) and fourteen obese (40.6 ± 1.4 kg/m2) adults underwent a muscle biopsy and 2-h oral glucose tolerance test. Skeletal muscle lactylation was increased in obese compared to lean females (19%, p < 0.05) and associated with insulin resistance (r = 0.37, p < 0.05) in the whole group. Skeletal muscle lactylation levels were significantly associated with markers of anaerobic metabolism (plasma lactate and skeletal muscle lactate dehydrogenase [LDH], p < 0.05) and negatively associated with markers of oxidative metabolism (skeletal muscle cytochrome c oxidase subunit 4 and Complex I [pyruvate] OXPHOS capacity, p < 0.05). Treatment of primary human skeletal muscle cells (HSkMC) with sodium lactate for 24 h increased protein lactylation and IRS-1 serine 636 phosphorylation in a similar dose-dependent manner (p < 0.05). Inhibition of glycolysis (with 2-deoxy-d-glucose) or LDH-A (with sodium oxamate or LDH-A siRNA) for 24 h reduced HSkMC lactylation which paralleled reductions in culture media lactate accumulation. This study identified the existence of a lactate-derived post-translational modification in human skeletal muscle and suggests skeletal muscle lactylation could provide additional insight into the regulation of skeletal muscle metabolism, including insulin resistance.

Prognostic Role of Serum Adrenomedullin in Patients with Ventilator Associated Pneumonia

Objective: Ventilator associated pneumonia is a common type of sepsis that occurs to about 9–27% of all mechanically ventilated patients and 20–50% of them develop septic shock. Several clinical, laboratory, and radiological methods have been used for diagnosing VAP. Adrenomedullin (ADM) has been found to be elevated in the plasma of septic patients. The study aim was to explore the prognostic role of ADM in the VAP patients. Design: A prospective observational study. Setting: Intensive Care Department of Alexandria University Hospitals. Patients: A total of 140 patients with proven VAP after medical ICU admission were consecutively enrolled. Methods: APACHE II score, SOFA score, CRP, lactate, and serum ADM were measured at day 0 of VAP diagnosis and 5 days later. The results were correlated with the outcomes of patients. Results: APACHE II, lactate, and serum ADM on day 0 could predict an unfavorable outcome. ADM prediction power was significantly higher than APACHE II and lactate. Day 5 readings of all tested parameters could predict occurrence of the unfavorable outcome. ADM on day 0 showed the highest sensitivity (96.25%). Conclusions: Serum adrenomedullin when measured at days 0 and 5 of VAP diagnosis may serve as an early predictor of unfavorable outcome.

Luteolin alleviates vascular dysfunctions in CLP-induced polymicrobial sepsis in mice

BACKGROUND

Luteolin, a naturally occurring flavonoid, is thought to have health-promoting properties as a part of human diet and has been reported to possess a wide range of pharmacological activities. Therefore, the present study was undertaken to evaluate the effect of luteolin pre-treatment on vascular dysfunctions in sepsis induced by caecal ligation and puncture (CLP) in the mouse model.

METHODS

Mice were divided into four groups: sham, luteolin plus sham, CLP, and luteolin plus CLP. Luteolin was administered (0.2 mg/kg body weight) intraperitoneally one hour (h) before CLP surgery in mice. 20 ± 2 h post CLP surgery, the isolated thoracic aorta of mice was assessed for its vascular reactivity to noradrenaline (NA) and acetylcholine (ACh). To explore the underlying mechanism, aortic mRNA expressions of α_1D adrenoceptors, eNOS and iNOS were investigated.

RESULTS

In mice with CLP-induced sepsis luteolin pre-treatment markedly increased the survival time and attenuated serum lactate level. The CLP group manifested the reduced vascular reactivity to NA and this deficit was restored by luteolin pre-treatment. However, luteolin pre-treatment did not improve α_1D adrenoceptors down-regulation observed in septic mice aorta. In the presence of 1400 W, the NA contractile response was significantly restored in CLP mice aortic tissue in comparison with the respective control of septic mice and further enhanced in the presence of luteolin. Luteolin reduced the iNOS mRNA expression and iNOS-derived nitrite production. Pre-treatment with luteolin restored the endothelial dysfunction in septic mice aorta by improving eNOS mRNA expression and enhanced eNOS-derived nitric oxide (NO) production in septic mice aorta and aortic iNOS gene expression and inducible NO production.

CONCLUSION

The present study suggests that the vasoplegic state to NA in aorta was restored through the iNOS pathway and endothelial dysfunction was reversed via eNOS and NO production pathway.

The Role of Circadian Clock Genes in Critical Illness: The Potential Role of Translational Clock Gene Therapies for Targeting Inflammation, Mitochondrial Function, and Muscle Mass in Intensive Care

The Earth's 24-h planetary rotation, with predictable light and heat cycles, has driven profound evolutionary adaptation, with prominent impacts on physiological mechanisms important for surviving critical illness. Pathways of interest include inflammation, mitochondrial function, energy metabolism, hypoxic signaling, apoptosis, and defenses against reactive oxygen species. Regulation of these by the cellular circadian clock (BMAL-1 and its network) has an important influence on pulmonary inflammation; ventilator-associated lung injury; septic shock; brain injury, including vasospasm; and overall mortality in both animals and humans. Whether it is cytokines, the inflammasome, or mitochondrial biogenesis, circadian medicine represents exciting opportunities for translational therapy in intensive care, which is currently lacking. Circadian medicine also represents a link to metabolic determinants of outcome, such as diabetes and cardiovascular disease. More than ever, we are appreciating the problem of circadian desynchrony in intensive care. This review explores the rationale and evidence for the importance of the circadian clock in surviving critical illness.

Risk factors and prognoses of invasive Candida infection in surgical critical ill patients with perforated peptic ulcer

BACKGROUND

The risk of invasive Candida infection (ICI) is high in patients with perforated peptic ulcer (PPU) who received laparotomy or laparoscopic surgery, but the risk factors and predictors of morbidity outcomes remain uncertain. This study aims to identify the risk factors of ICI in surgical critically ill PPU patients and to evaluate the impact on patient's outcomes.

METHODS

This is a single-center, retrospective study, with a total of 170 surgical critically ill PPU patients. Thirty-seven patients were ICI present and 133 were ICI absent subjects. The differences in pulmonary complications according to invasive candidiasis were determined by the Mann-Whitney U test. Evaluation of predictors contributing to ICI and 90-day mortality was conducted by using multivariate logistic regression analysis.

RESULTS

Candida albicans was the primary pathogen of ICI (74.29%). The infected patients had higher incidence of bacteremia (p < 0.001), longer intensive care unit (p < 0.001) and hospital (p < 0.001) stay, longer ventilator duration (p < 0.001) and increased hospital mortality (p = 0.02). In the multivariate analysis, serum lactate level measured at hospital admission was independently associated with the occurrence of ICI (p = 0.03). Liver cirrhosis (p = 0.03) and Sequential Organ Failure Assessment (SOFA) score (p = 0.007) were independently associated with the 90-day mortality.

CONCLUSIONS

Blood lactate level measured at hospital admission could be a predictor of ICI and the surgical critically ill PPU patients with liver cirrhosis and higher SOFA score are associated with poor outcomes.

The Positive and Negative Effects of Calcium Supplementation on Mortality in Septic ICU Patients Depend on Disease Severity: A Retrospective Study from the MIMIC-III

Background. Calcium administration in septic patients with hypocalcemia is a controversial issue. The present study preliminarily investigated the effects of calcium supplementation on the length of hospitalization and mortality in septic ICU patients with different severities of hypocalcemia and disease. Method. A total of 5761 eligible septic patients, including 2689 who received calcium supplementation and 3072 who did not receive calcium supplementation, were extracted from the Medical Information Mart for Intensive Care III (MIMIC-III) database. The cofounding covariates between the calcium supplement and nonsupplement groups were balanced using the propensity score matching model. We compared the length of stay (LOS) in the ICU and hospital with 28-day and hospital mortality and stratified the analysis according to the sequential organ failure assessment (SOFA) score and ionized calcium (iCa) at the first ICU admission in the matched groups. Results. The results showed that iCa at the first ICU admission was associated with mortality in sepsis patients (HR: 0.421; 95% CI: 0.211∼0.837), but the lowest mortality rate was observed in patients with mild hypocalcemia. A total of 993 paired patients were included in the analysis after propensity score matching. Regardless of the SOFA score or presence of iCa, the LOS in the ICU was higher in the calcium supplement group than in the nonsupplement group. The survival analysis was stratified by the SOFA score and showed that calcium supplementation reduced mortality when the patient’s SOFA score was ≥8 ( $p=0.002$ ), and it worsened the outcome when the patient’s SOFA score was ≤4 ( $p=0.010$ ). It had no significant effect on patients with SOFA scores ranging from 5 to 7 ( $p=0.911$ ). Conclusion. Our results showed that mild hypocalcemia may be protective in septic patients, and calcium supplementation may have positive and negative effects on mortality depending on disease severity. The SOFA score may be a valuable clinical index for decisions regarding calcium administration.

Bioelectronic Sensor with Magnetic Modulation to Quantify Phagocytic Activity of Blood Cells Employing Machine Learning

Microbial infections result in activating an immune response in the human body, which triggers inflammatory pathways resulting in recognition and subsequent killing of the pathogens. Quantifying the blood cells' natural ability to kill pathogens, i.e., phagocytosis, is critical to demonstrating the effectiveness of an individual's response in combating pathogens. Current laboratory processes and equipment that can be used to monitor phagocytic activity are costly and time-consuming and require significant technical expertise to run such assays. Here, we design and develop a novel biosensing platform capable of quantifying the phagocytic ability of blood cells. The sensor design is composed of electronic sensing and magnetic modulation sub-systems that work in conjunction to monitor phagocytic activity in microfluidic channels. The phagocytes internalize the IgG-coated magnetic beads, and when infused into the sensor, their speed will be modulated using the quadrupole magnetic field configuration as they pass through microfluidic channels where microfabricated electrodes are placed. The electronic sensor will generate the voltage pulse for each passage of the phagocyte, whose distinct features are correlative to the phagocytic activity. We experimentally tested this device using 17 blood samples collected from patients at Robert Wood Johnson Medical Hospital. Further, we developed artificial neural networks (ANN) to improve the accuracy of the phagocytic activity detection. ANN model detected the phagocytic activity with 88.2% accuracy. This novel sensing platform can potentially be used to triage high risk patients and develop personalized theranostics for the septic patients in the future.

Smart implanted access port catheter for therapy intervention with pH and lactate biosensors

Totally implanted access ports (TIAP) are widely used with oncology patients requiring long term central venous access for the delivery of chemotherapeutic agents, infusions, transfusions, blood sample collection and parenteral nutrition. Such devices offer a significant improvement to the quality of life for patients and reduced complication rates, particularly infection, in contrast to the classical central venous catheters. Nevertheless, infections do occur, with biofilm formation bringing difficulties to the treatment of infection-related complications that can ultimately lead to the explantation of the device. A smart TIAP device that is sensor-enabled to detect infection prior to extensive biofilm formation would reduce the cases for potential device explantation, whereas biomarkers detection within body fluids such as pH or lactate would provide vital information regarding metabolic processes occurring inside the body. In this paper, we propose a novel batteryless and wireless device suitable for the interrogation of such markers in an embodiment model of an TIAP, with miniature biochemical sensing needles. Device readings can be carried out by a smartphone equipped with Near Field Communication (NFC) interface at relative short distances off-body, while providing radiofrequency energy harvesting capability to the TIAP, useful for assessing patient's health and potential port infection on demand.

Early diagnosis of sepsis using an E-health application for a clinical early warning system outside of the intensive care unit: a case report

Background

Elderly and frail patients who are unable to call for help in case of vital distress can develop complications during their hospitalization. As a supplement to clinical monitoring by the nursing staff, these patients can also be monitored in real time, with the Sensium E-health technology. An application notifies clinical staff of any change in their vital signs (heart rate, respiratory rate, temperature) outside of normal ranges, suggestive of physiological decline. Nurses and physicians are notified of these abnormal changes by email and also via mobile application (iPhone or iPad), allowing early intervention to prevent further deterioration.

Case presentation

An 86-year-old Caucasian female, with chronic kidney disease, was hospitalized in our medical unit for pyelonephritis associated with a moderate deterioration of serum creatinine. Remote continuous monitoring allowed us to diagnose clinical deterioration early and adjust her treatment. The treatment improved her clinical condition and amended the secondary sepsis with circulation failure in 2 days.

Conclusions

The prognosis for patients with acute complicated pyelonephritis is much worse than for those with uncomplicated pyelonephritis. Remote continuous monitoring might be helpful to early diagnose urosepsis. This technology leads to improved prognosis of patients without initial vital distress, allowing early treatment and admission to intensive care unit.

Hyperlactatemia in diabetic ketoacidosis

AIMS

The study examined the prevalence and degree of lactate elevation in diabetic ketoacidosis, and explored which biochemical abnormalities predicted L-lactate levels.

METHODS

We reviewed episodes of diabetic ketoacidosis from 79 diabetes patients (one episode per patient). Separate univariate linear regression models were specified to predict lactate level from each of nine biochemical variables. Significant predictors from the univariate models were included in a final multivariate linear regression model to predict lactate levels.

RESULTS

Mean (SD) lactate level was 3.05 (1.66) mmol/L; about 65% of patients had lactate levels >2 mmol/L. In the final multivariate linear regression model (R²  = 0.45), higher lactate levels were associated with greater hydrogen ion concentration (standardised β = .60, t = 4.16, p < 0.0001), higher blood glucose (standardised β = .28, t = 2.67, p = 0.009) and lower glomerular filtration rate estimated from creatinine (standardised β = -.23, t = 2.29, p = 0.025). Bicarbonate, beta-hydroxybutyrate, body mass index, mean arterial pressure and calculated osmolality were not significant predictors of lactate level. There were three distinct patterns of lactate levels with treatment of diabetic ketoacidosis: group 1 = gradual decline, group 2 = initial increase and then decline and group 3 = initial decline followed by a transient peak and subsequent decline.

CONCLUSIONS

Elevated lactate level is the norm in patients with diabetic ketoacidosis. Higher blood glucose levels and higher hydrogen ion concentrations are related to greater lactate. With treatment, there are different patterns of decline in lactate levels.

Clarifying the link between the blood lactate concentration and cardiovascular risk

The blood lactate value at rest (Lac_rest) is linked to cardiovascular outcomes. It is unclear whether this association holds true in younger, healthy subjects, especially as the pathophysiological connection between Lac_rest and cardiometabolic disease is not well understood. The aim of this study is clarifying the link between Lac_rest and cardiovascular risk, and to study explanatory factors for the variance of Lac_rest concerning metabolism and physical activity in a population of healthy patient-athletes. The distribution and intra-individual variability of Lac_rest was assessed based on 9051 samples. The 10-year cardiovascular risk was then approximated using the Framingham risk score in a group of 1315 samples from patient-athletes. Cross-validated linear regression was used to analyze explanatory variables for Lac_rest and 10-year cardiovascular risk. Lac_rest is weakly associated with the Framingham score. This association disappears when adjusting for blood lipids. Lac_rest is also linked to the predominant type of exercise with endurance athletes featuring a higher Lac_rest. Lac_rest does not independently predict the estimated cardiovascular risk but is associated with lipid parameters. Moreover, the intra-individual variability of Lac_rest is high in a relevant number of subjects, which does not point towards the feasibility to use Lac_rest as an individual risk factor.

The incidence and characteristics of bacteremia in cardiac arrest

BACKGROUND

Despite improvements in both preventative and post-event care, cardiac arrest still occurs frequently with high morbidity and mortality. Bacteremia is a potential cause or complication of cardiac arrest that has received increasing notoriety in recent years.

OBJECTIVES

To identify the incidence of and predictive factors for bacteremia in both inside and outside of hospital cardiac arrest patients.

METHODS

Retrospective, single centered, cohort study conducted at an academic medical center. Patients 18 years of age or older with cardiac arrest and blood cultures drawn within 24 h of the event were included.

RESULTS

Two-hundred sixty-three cardiac arrest patients were included, of which forty-three patients (16.3%) were bacteremic. Patients with bacteremia had higher rates of home parenteral nutrition and a history of known infection before cardiac arrest. Bacteremic patients had a higher blood urea nitrogen (30 mg/dL vs. 23, p = 0.02), serum creatinine (2.40 mg/dL  vs. 1.70, p = 0.05), and troponin (0.39 ng/mL vs. 0.12, p = 0.03) compared with the non-bacteremic group. There were no differences in duration of mechanical ventilation, hospital length of stay or ICU length of stay. Mortality at 28-days was higher in the bacteremic group (79%) compared to the non-bacteremic group (60.9%, p = 0.02). No factors associated with bacteremia were identified.

CONCLUSION

Bacteremia was observed in 16.3% of patients, with significant differences between the bacteremic and non-bacteremic group regarding home parenteral nutrition and known infection before the event, cardiac arrest characteristics (blood urea nitrogen, serum creatinine, and troponin), and 28-day mortality.

GEM-IL: A highly responsive fluorescent lactate indicator

Lactate metabolism has been shown to have increasingly important implications in cellular functions as well as in the development and pathophysiology of disease. The various roles as a signaling molecule and metabolite have led to interest in establishing a new method to detect lactate changes in live cells. Here we report our development of a genetically encoded metabolic indicator specifically for probing lactate (GEM-IL) based on superfolder fluorescent proteins and mutagenesis. With improvements in its design, specificity, and sensitivity, GEM-IL allows new applications compared with the previous lactate indicators, Laconic and Green Lindoblum. We demonstrate the functionality of GEM-IL to detect differences in lactate changes in human oncogenic neural progenitor cells and mouse primary ventricular myocytes. The development and application of GEM-IL show promise for enhancing our understanding of lactate dynamics and roles.

Neutrophil extracellular traps and organ dysfunction in sepsis

Sepsis is a clinical syndrome resulting from infection followed by inflammation and is one of the significant causes of mortality worldwide. The underlying reason is the host's uncontrolled inflammatory response due to an infection led to multiple organ dysfunction/failure. Neutrophils, an innate immune cell, are forerunners to reach the site of infection/inflammation for clearing the infection and resolute the inflammation during sepsis. A relatively new neutrophil effector function, neutrophil extracellular traps (NETs), have been demonstrated to kill the pathogens by releasing DNA decorated with histone and granular proteins. A growing number of pieces of shreds of evidence suggest that unregulated incidence of NETs have a significant influence on the pathogenesis of sepsis-induced multiple organ damage, including arterial hypotension, hypoxemia, coagulopathy, renal, neurological, and hepatic dysfunction. Thus, excessive production and improper resolution of NETs are of significant therapeutic value in combating sepsis-induced multiple organ failure. The purpose of this review is intended to highlight the role of NETs in sepsis-induced organ failure. Furthermore, the current status of therapeutic strategies to intersect the harmful effects of NETs to restore organ functions is discussed.

Point-of-critical-care diagnostics for sepsis enabled by multiplexed micro and nanosensing technologies

Sepsis is responsible for the highest economic and mortality burden in critical care settings around the world, prompting the World Health Organization in 2018 to designate it as a global health priority. Despite its high universal prevalence and mortality rate, a disproportionately low amount of sponsored research funding is directed toward diagnosis and treatment of sepsis, when early treatment has been shown to significantly improve survival. Additionally, current technologies and methods are inadequate to provide an accurate and timely diagnosis of septic patients in multiple clinical environments. For improved patient outcomes, a comprehensive immunological evaluation is critical which is comprised of both traditional testing and quantifying recently proposed biomarkers for sepsis. There is an urgent need to develop novel point-of-care, low-cost systems which can accurately stratify patients. These point-of-critical-care sensors should adopt a multiplexed approach utilizing multimodal sensing for heterogenous biomarker detection. For effective multiplexing, the sensors must satisfy criteria including rapid sample to result delivery, low sample volumes for clinical sample sparring, and reduced costs per test. A compendium of currently developed multiplexed micro and nano (M/N)-based diagnostic technologies for potential applications toward sepsis are presented. We have also explored the various biomarkers targeted for sepsis including immune cell morphology changes, circulating proteins, small molecules, and presence of infectious pathogens. An overview of different M/N detection mechanisms are also provided, along with recent advances in related nanotechnologies which have shown improved patient outcomes and perspectives on what future successful technologies may encompass. This article is categorized under: Diagnostic Tools > Biosensing.

Sample-to-Answer Diagnostic System for the Detection of Circulating Histones in Whole Blood

Severe internal trauma results in millions of hospitalizations each year, including thousands of deaths caused by subsequent multiple organ failure. The majority of these deaths occur within the first 24 h, and thus, rapid diagnosis of internal trauma severity is necessary for immediate treatment. For early organ damage identification, diagnosis in point-of-care settings is crucial for rapid triage and treatment. Recent reports suggest that circulating histones may serve as a biomarker for severe organ damage and the risk of multiple organ failure. Here, we report a point-of-care diagnostic system that utilizes the inherent interactions between histones and DNA for the fluorescence-based detection of histones in whole blood. In the assay, histones within the sample are wrapped by DNA, thus preventing an intercalating dye from binding the DNA and fluorescing. To allow for quantitative fluorescent measurements to be made in a point-of-care setting, we integrate a rapid, automated blood separation step into our assay. Furthermore, we eliminate manual reagent additions using a thermally responsive alkane partition (TRAP), thus making the system sample-to-answer. Finally, we demonstrate the assay in a portable fluorescence reader compatible with a point-of-care environment. We report a limit of detection 112 ng/mL in whole blood, suggesting that our device can be used to rapidly diagnose internal trauma severity and the likelihood of multiple organ failure in near-patient settings.

Extracellular vesicles derived from cardiosphere-derived cells as a potential antishock therapeutic

BACKGROUND

Extracellular vesicles (EVs) isolated from cardiosphere-derived cells (CDC-EVs) are coming to light as a unique cell-free therapeutic. Because of their novelty, however, there still exist prominent gaps in knowledge regarding their therapeutic potential. Herein the therapeutic potential of CDC-EVs in a rat model of acute traumatic coagulopathy induced by multiple injuries and hemorrhagic shock is outlined.

METHODS

Extracellular vesicle surface expression of procoagulant molecules (tissue factor and phosphatidylserine) was evaluated by flow cytometry. Extracellular vesicle thrombogenicity was tested using calibrated thrombogram, and clotting parameters were assessed using a flow-based adhesion model simulating blood flow over a collagen-expressing surface. The therapeutic efficacy of EVs was then determined in a rat model of acute traumatic coagulopathy induced by multiple injuries and hemorrhagic shock.

RESULTS

Extracellular vesicles isolated from cardiosphere-derived cells are not functionally procoagulant and do not interfere with platelet function. In a rat model of multiple injuries and hemorrhagic shock, early administration of EVs significantly reduced the elevation of lactate and creatinine and did not significantly enhance coagulopathy in rats with acute traumatic coagulopathy.

CONCLUSION

The results of this study are of great relevance to the development of EV products for use in combat casualty care, as our studies show that CDC-EVs have the potential to be an antishock therapeutic if administered early. These results demonstrate that research using CDC-EVs in trauma care needs to be considered and expanded beyond their reported cardioprotective benefits.

Monitoring of Lactate in Interstitial Fluid, Saliva and Sweat by Electrochemical Biosensor: The Uncertainties of Biological Interpretation

Lactate electrochemical biosensors were fabricated using Pediococcus sp lactate oxidase (E.C. 1.1.3.2), an external polyurethane membrane laminate diffusion barrier and an internal ionomeric polymer barrier (sulphonated polyether ether sulphone polyether sulphone, SPEES PES). In a needle embodiment, a Pt wire working electrode was retained within stainless steel tubing serving as pseudoreference. The construct gave linearity to at least 25 mM lactate with 0.17 nA/mM lactate sensitivity. A low permeability inner membrane was also unexpectedly able to increase linearity. Responses were oxygen dependent at pO2 < 70 mmHg, irrespective of the inclusion of an external diffusion barrier membrane. Subcutaneous tissue was monitored in Sprague Dawley rats, and saliva and sweat during exercise in human subjects. The tissue sensors registered no response to intravenous Na lactate, indicating a blood-tissue lactate barrier. Salivary lactate allowed tracking of blood lactate during exercise, but lactate levels were substantially lower than those in blood (0–3.5 mM vs. 1.6–12.1 mM), with variable degrees of lactate partitioning from blood, evident both between subjects and at different exercise time points. Sweat lactate during exercise measured up to 23 mM but showed highly inconsistent change as exercise progressed. We conclude that neither tissue interstitial fluid nor sweat are usable as surrogates for blood lactate, and that major reappraisal of lactate sensor use is indicated for any extravascular monitoring strategy for lactate.

Recognition and management of sepsis: the nurse's role

Caring for a patient with suspected sepsis is a challenging nursing role. Early recognition and appropriate management of a patient with sepsis saves lives. Nurses play a fundamental role in detecting changes in physiological observations that could indicate the onset of sepsis. Additionally, an awareness of the pathophysiology of sepsis allows the nurse to better understand how rapid intervention prevents the onset of septic shock. Furthermore, knowledge and use of clinical guidelines and sepsis screening tools are established methods to help reduce patient mortality. Nurse familiarity with 'red flag' criteria for sepsis and thorough completion of early warning scores facilitate earlier recognition and time critical intervention. Delivery of the 'sepsis six' within 1 hour of suspected sepsis saves lives.

Profiling single-cell level phagocytic activity distribution with blood lactate levels

The ability to kill infecting microbes is an essential facet of our immune response to an infection. However, phagocytic ability is often overlooked as a part of immunological profile in infected patients' diagnosis, as the understanding of phagocytic capabilities in disease states is incomplete. In this work, we have evaluated for the first time the relationship between blood lactate level and the neutrophil phagocytic activity at a single-cell level. Blood samples (N = 19) were grouped on the basis of their blood lactate levels i.e., below (control) or above 2 mmol L⁻¹ (high-risk) (i.e., 2 mmol L⁻¹ is a common clinical lactate threshold used for patients' triage). Neutrophils were isolated from whole blood and then incubated with fluorescent IgG coated beads for 40 minutes, and the ability of each neutrophil to internalize beads was quantified. Single-cell phagocytic activity analysis has shown interesting findings such as: (i) a single neutrophil was able to internalize up to 7 beads, (ii) for a control group, 39.76% cells didn't internalize any beads, while for a high-risk group, 30.65% cells didn't show any phagocytic activity, (iii) similarly, 30.46% cells internalize only 1 bead in a control group, while for a high-risk group the activity is slightly higher with only 31.73% cells showing single bead internalization, and (iv) 7 bead internalization activity was much higher for samples in a high-risk group (0.6% cells) compared to a control group (0.17% cells). We used multiple statistical tests to compare these differences. For a two-tailed T-test, we used the mean phagocytic activity of the cells (i.e., the average number of beads internalized by cells) isolated from the blood samples in the two groups (1.14 vs. 1.35) and found the p-value to be 0.08. We also used principal component analysis (PCA) on this high dimensional phagocytic activity distribution data and performed dimension reduction. However, the first 3 principal components didn't show a clear distinction between groups. Next, we developed machine learning models using artificial neural networks (ANNs) to differentiate between the distribution of phagocytic activity in neutrophil populations of the two groups. Our models yielded area under curve (AUC) values below 0.7 for receiver operator characteristic curves. Although our study highlighted interesting phagocytic activity findings at a single cell level, it further highlights the need for integration of an individual patient's medical record to get more personalized insights into individual phagocytic activity in the future.

Investigating the relationship between neutrophil phagocytic activity and blood lactate levels by employing single-cell data.

Implementation of point-of-care blood gas testing at a large community hospital: Cost analysis, sepsis bundle compliance, and employee engagement

INTRODUCTION/BACKGROUND

Point-of-care testing (POCT) platforms support patient-centered approaches to health care delivery and may improve patient care. We evaluated implementation of a POCT platform at a large, acute care hospital in the Midwestern United States.

METHODS

We used lactate testing as part of a sepsis bundle protocol to evaluate compliance and mortality outcomes. Respiratory team members were surveyed to assess perception of efficiency, ease of use, timely patient care, and overall engagement with the POCT system. Annualized cost per test of a benchtop analyzer and a POCT platform were compared across 3 years for each platform.

RESULTS

Lactate testing volume increased from 61% to 91%, which was associated with improved sepsis bundle protocol compliance. Employees reported high levels of engagement, improvements in efficiency and time savings, and better patient care with POCT. Average cost per test was $10.02 for the benchtop system and $6.21 for the POCT platform. POCT saved our institution $88,476 annually in labor costs.

DISCUSSION

Combined with a robust training program emphasizing the use of lactate testing in the context of the overall clinical picture, POCT enabled adherence to the sepsis bundle protocol and may have contributed to lower mortality. Additionally, the COVID-19 pandemic has provided us with unanticipated benefits of using POCT; it has enhanced our ability to deal with stringent infectious disease protocols, saving time and minimizing patient and staff exposure.

CONCLUSIONS

Implementation of a POCT platform was associated with improved compliance to our sepsis protocol, reduced sepsis mortality, high employee engagement, and cost savings.

Effects of remote ischemic preconditioning on the deformability and aggregation of red blood cells in a rat endotoxemia model

BACKGROUND

The prevention of rheologic alterations in erythrocytes may be important for reducing sepsis-associated morbidity and mortality. Remote ischemic preconditioning (RIPC) has been shown to prevent tissue damage caused by severe ischemia and mortality resulting from sepsis. However, the effect of RIPC on erythrocytes in sepsis is yet to be determined.

OBJECTIVE

To investigate the effect of RIPC on rheologic alterations in erythrocytes in sepsis.

METHODS

Thirty male Sprague-Dawley rats were used in this study. An endotoxin-induced sepsis model was established by intraperitoneally injecting 20 mg/kg LPS (LPS group). RIPC was induced in the right hind limb using a tourniquet, with three 10-minute of ischemia and 10 min of reperfusion cycles immediately before the injection of LPS (RIPC/LPS group) or phosphate-buffered saline (RIPC group). The aggregation index (AI), time to half-maximal aggregation (T1/2), and maximal elongation index (EImax) of the erythrocytes were measured 8 h after injection.

RESULTS

The AI, T1/2, and EImax values in the LPS and RIPC/LPS groups differed significantly from those in the RIPC group, but there were no differences between the values in the LPS and RIPC/LPS groups.

CONCLUSIONS

RIPC did not prevent rheologic alterations in erythrocytes in the rat model of LPS-induced endotoxemia.

Serum Lactate: A Predictor of Septic Shock in Childhood Cancers with Febrile Neutropenia

Early recognition and management are the key elements to prevent febrile neutropenia associated mortality. The prospective observational study aimed to investigate prognostic accuracy of serum lactate to predict septic shock within 48 hours among hemodynamically stable children with febrile neutropenia. In all, 99 pediatric oncology patients who developed febrile neutropenia were enrolled in the study. Clinical information during 48 hours and serum lactate at the time of enrollment were analyzed. Among 99 participating patients, 10 developed septic shock and 4 of those expired. No significant difference was found of patients’ baseline characteristics and basic laboratory parameters between patients with and without septic shock. Serum lactate was significantly elevated among patients developing septic shock (P-value < .001) and those who expired (P-value .002). Receiver operating characteristic (ROC) curve was created to identify the best cutoff value for initial serum lactate associated with the development of septic shock within 48 hours. Baseline serum lactate more than 2.5 mmol/L showed the largest area under the ROC curve to predict the septic shock development within 48 hours (ROC area, 0.90; 95% confidence interval [CI], 0.81-0.98), with sensitivity, specificity, negative predictive value, and accuracy of 80.0%, 92.1%, 97.6%, and 90.9%, respectively. Serum lactate level determined early at the time of febrile neutropenia was an effective surrogate marker for developing septic shock within 48 hours among hemodynamically stable, pediatric oncology patients. The level more than 2.5 mmol/L was the best threshold to start preemptive aggressive hemodynamic monitoring and prompt treatment to ensure adequate tissue perfusion.

A systematic review of biomarkers associated with maternal infection in pregnant and postpartum women

BACKGROUND

Serum biomarkers are commonly used to support the diagnosis of infection in non-pregnant patients whose clinical presentation suggests infection. The utility of serum biomarkers for infection in pregnant and postpartum women is uncertain.

SEARCH STRATEGY

PubMed, CINAHL, EMBASE, ClinicalTrials.gov, Cochrane Library, CINAHL, and SCOPUS were searched from inception to February 2020.

SELECTION CRITERIA

Full-text manuscripts in English were included if they reported the measurement of maternal serum biomarkers-and included a control group-to identify infection in pregnant and postpartum women.

DATA COLLECTION AND ANALYSIS

two authors independently screened manuscripts, extracted data, and assessed methodologic quality.

MAIN RESULTS

Interleukin-6 (IL-6), C-reactive protein, procalcitonin, insulin-like growth factor binding protein 1, tumor necrosis factor-α, calgranulin B, neopterin, and interferon-γ inducible protein 10 reliably indicated infection. Intercellular adhesion molecule 1, monocyte chemotactic and activating factor, soluble IL-6 receptor, and IL-8 were not useful markers in pregnant and postpartum women.

CONCLUSIONS

Findings suggest that certain biomarkers have diagnostic value when maternal infection is suspected, but also confirms limitations in this population.

Developing a Novel Scoring System for Risk Stratification in Living Donor Liver Transplantation

Background: We aimed to develop a novel scoring system for risk stratification specific to living donor liver transplantation (LDLT) recipients, to improve the accuracy of predicting short-term outcomes. Methods: The sequential organ failure assessment (SOFA) score at postoperative day 7 was collected and simplified by dichotomization, and these categories and other clinical factors were subjected to univariate and multivariate logistic regression analyses to select independent risks in constructing a “graft-to-recipient weight ratio (GRWR)-SOFA” scoring system. Results: We enrolled 519 patients who underwent LDLT. The GRWR-SOFA score comprises a sum of six factors: cardiovascular (mean arterial pressure < 70 mmHg, scored 3), coagulation (serum platelet < 50 × 10³/μL, scored 2), renal (creatinine > 1.2 mg/dL, scored 2), liver (serum total bilirubin > 5.9 mg/dL, scored 5), neurological (Glasgow coma scale < 15, scored 2), and GRWR < 0.8, scored 2. The GRWR-SOFA contained four classes: The early mortality rate at 3 months and 1 year after LDLT was 1.3% and 6.9% for class I (scores of 0–4), 9.1% and 16.7% for class II (scores of 5–8), 25.5% and 34% for class III (scores of 9–10), and 61.3% and 67.7% for class IV (scores ≥ 11), respectively. The area under the receiver operating characteristic curve of GRWR-SOFA in the 3-month mortality prediction was 0.881 (95% confidence interval (CI): 0.818–0.944). Conclusions: The GRWR-SOFA model demonstrates superior discriminatory power for predicting short-term mortality. It enables clinicians to identify the right level of care for distinct subgroups of patients receiving LDLT.

A Point-of-Care Serum Lactate Level and Mortality in Adult Sepsis Patients: A Community Hospital Setting

Introduction:

Sepsis is a serious and emergency condition that may lead to acute circulatory failure associated with infection. Serum lactate level of over 4 mmol/L is associated with sepsis mortality. However, there is limited data on using a point of care (POC) for fingertip lactate level on sepsis mortality in community hospital setting. This study aimed to evaluate roles of POC for serum lactate with combination of clinical factors on mortality prediction in sepsis patients.

Methods:

This was a retrospective cohort study conducted at 7 community hospitals. The inclusion criteria were adult patients with diagnosis of sepsis who were tested for POC lactate level. Electronic chart reviews of eligible patients were performed. Predictors for mortality were computed using clinical factors and POC lactate level.

Results:

There were 1641 patients met the study criteria. The mortality rate was 8.96% (147 patients). There were 3 independent factors associated with mortality: age, co-morbid diseases, and POC lactate level. The adjusted odds ratio (95% CI) of POC lactate level was 1.025 (1.002, 1.048). The cut point of serum lactate was 1.6 mmol/L gave sensitivity of 79.59% and specificity of 32.10%.

Conclusion:

POC serum lactate level may be associated with mortality in sepsis patients at community hospitals. Lactate level of 1.6 mmol/L may be an indicator for mortality with good sensitivity. Physicians may consider more aggressive and prompt management in individuals with sepsis and POC serum lactate of 1.6 mmol/L or over.

Arterial or cuff pressure: Clinical predictors among patients in shock in a critical care resuscitation unit

OBJECTIVES

Blood pressure (BP) measurement is essential for managing patients with hypotension. There are differences between invasive arterial blood pressure (IABP) and noninvasive blood pressure (NIBP) measurements. However, the clinical applicability of these differences in patients with shock [need for vasopressor or serum lactate ≥ 4 millimole per liter (mmol/L)] has not been reported. This study investigated differences in IABP and NIBP as well as changes in clinical management in critically ill patients with shock.

METHODS

This was a retrospective study involving adult patients admitted to the Critical Care Resuscitation Unit (CCRU). Adult patients who received IABP upon admission between 01/01/2017-12/31/2017 with non-hypertensive diseases were eligible. The primary outcome, clinically relevant difference (CRD), was defined as difference of 10 mm of mercury (mmHg) between IABP and NIBP and change of blood pressure management according to goal mean arterial pressure (MAP) ≥ 65 mmHg. We performed forward stepwise multivariable logistic regression to measure associations.

RESULTS

Sample size calculation recommended 200 patients, and we analyzed 263. 121 (46%) patients had shock, 23 (9%) patients had CRD. Each mmol/L increase in serum lactate was associated with 11% higher likelihood of having CRD (OR 1.11, 95%CI 1.002-1.2). Peripheral artery disease and any kidney disease was significantly associated with higher likelihood of MAP difference ≥ 10 mmHg.

CONCLUSION

Approximately 9% of patients with shock had clinically-relevant MAP difference. Higher serum lactate was associated with higher likelihood of CRD. Until further studies are available, clinicians should consider using IABP in patients with shock.