Normal-range blood lactate concentration in septic shock is prognostic and predictive

[Vasoactive agents in septic shock-individualized strategies]

Hemodynamic stabilization and preservation of organ perfusion are central elements in the management of septic shock. This is achieved by fluid resuscitation and by administration of vasoactive agents. Current guidelines recommend norepinephrine as the first-line vasoactive substance. In cases of high norepinephrine requirements the addition of nonadrenergic vasopressors is recommended. Furthermore, evidence suggests that early use of complementary vasoactive substances may provide additional benefits. Such a regimen, in terms of a broad-spectrum vasopressor approach, appears physiologically plausible. Post hoc analyses of studies investigating vasopressin or angiotensin II also suggest that specific subphenotypes may particularly benefit from individual vasoactive agents. Adjunctive therapy with hydrocortisone and fludrocortisone can improve vasopressor responsiveness and reduce mortality. In cases of cardiac dysfunction, a trial with dobutamine or a switch from norepinephrine to epinephrine is recommended. To enhance inodilator effects, milrinone or levosimendan may represent additional therapeutic options for certain patients. Although short-acting beta-blockers are not part of the standard treatment for septic shock, they may, in selected cases, contribute to hemodynamic improvement in patients with inadequately high sinus tachycardia or atrial tachyarrhythmias. Based on pathophysiological considerations and the currently available evidence, targeted use of specific vasoactive substances in defined subphenotypes may be justified. An initial broad-spectrum vasopressor strategy incorporating biomarkers such as renin and patient-specific characteristics followed by a focused de-escalation approach could represent a promising concept. However, the effectiveness of these strategies requires further investigation in randomized controlled trials.

Temperature-dependent microfluidic impedance spectroscopy for non-invasive biofluid characterization

Remote health monitoring has the potential to enable individuals to take control of their own health and well-being and to facilitate a transition toward preventative and personalized healthcare. Sweat can be sampled non-invasively and contains a wealth of information about the metabolic state of an individual, making it an excellent candidate for remote health monitoring. An accurate, rapid, and low-cost biofluid characterization technique is required to enable the widespread use of remote health monitoring. We previously introduced microfluidic impedance spectroscopy for the detection of electrolyte concentration in fluids, whereby a novel device architecture, measurement method, and analysis technique were presented for the characterization of cationic species. The purely electrical nature of this measurement technique removes the intermediate steps inherent in common rival technologies such as optical and electrochemical sensing, offering a range of advantages. In this work, we investigate the effect of temperature on microfluidic impedance spectroscopy of ionic species commonly present in biofluids. We find that the impedance spectra and concentration determination are temperature-dependent; remote health monitoring devices must be calibrated appropriately as they are likely to experience temperature fluctuations. Importantly, we demonstrate the ability of the method to measure the concentration of anionic species alongside that of cationic species, enabling the detection of chloride and lactate, which are useful biomarkers for hydration, cystic fibrosis, fatigue, sepsis, and hypoperfusion. We show that the presence of neutral species does not impair accurate determination of ionic concentration, thus, demonstrating the suitability of microfluidic impedance spectroscopy for non-invasive biofluid characterization.

Vasopressor Therapy

Vasopressor therapy represents a key part of intensive care patient management, used to increase and maintain vascular tone and thus adequate tissue perfusion in patients with shock. Norepinephrine is the preferred first-line agent because of its reliable vasoconstrictor effects, with minimal impact on heart rate, and its mild inotropic effects, helping to maintain cardiac output. Whichever vasopressor is used, its effects on blood flow must be considered and excessive vasoconstriction avoided. Other vasoactive agents include vasopressin, which may be considered in vasodilatory states, and angiotensin II, which may be beneficial in patients with high renin levels, although more data are required to confirm this. Dobutamine should be considered, along with continued fluid administration, to help maintain adequate tissue perfusion in patients with reduced oxygen delivery. In this narrative review, we consider the different vasopressor agents, focusing on the importance of tailoring therapy to the individual patient and their hemodynamic response.

Risk factors for mortality in patients with sepsis on extracorporeal membrane oxygenation and/or continuous renal replacement therapy: a retrospective cohort study based on MIMIC-IV database

OBJECTIVE

This study aimed to identify risk factors for mortality in septic patients undergoing extracorporeal membrane oxygenation (ECMO) and/or continuous renal replacement therapy (CRRT).

METHODS

Data from the MIMIC-IV database were retrospectively reviewed for 24,502 septic patients treated with ECMO or CRRT between 2008 and 2019. After applying inclusion and exclusion criteria, 70 patients receiving ECMO, 513 receiving CRRT, and 22 receiving both were included in the final analysis. Univariate and multivariate stepwise Cox regression analyses were performed to identify independent risk factors for mortality. Model performance was assessed using receiver operating characteristic (ROC) curve analysis. We also provided model-agnostic explanations for each Cox regression model.

RESULTS

For septic patients on ECMO, prothrombin time (per 1-s increase, HR 1.037, 95% CI 1.007-1.068, p = .015) was the key independent risk factor. For septic patients undergoing CRRT, SOFA score (per one-point increase, HR 1.100, 95% CI 1.055-1.147, p < .001) was the most significant factor. For septic patients requiring both ECMO and CRRT, prior history of hypertension (HR 4.342, 95% CI 1.332-14.153, p = .015) was the sole independent risk factor. ROC analysis showed satisfactory model performance (AUC > 0.75).

CONCLUSION

For septic patients requiring ECMO, prothrombin time was the key independent risk factor. For those needing CRRT, SOFA score was the most significant independent risk factor. Prior history of hypertension was the primary independent risk factor for septic patients needing both CRRT and ECMO.

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.

Lactate dynamics in paediatric patients with severe sepsis: insights from a prospective cohort study

BACKGROUND

Sepsis is an infection-related systemic inflammatory response that often leads to elevated lactate levels. Monitoring lactate levels during severe sepsis is vital for influencing clinical outcomes. The aim of this study was to assess the association between plasma lactate levels and mortality in children with severe sepsis or septic shock.

METHODS

The current prospective study was conducted in the PICU of University Children's Hospital. The International Paediatric Sepsis Consensus Conference criteria for Definitions of Sepsis and Organ Failure in 2005 were used to diagnose patients with sepsis. We measured plasma lactate levels upon admission (Lac H0) and 6 h later (Lac H6). The static indices included the absolute lactate values (Lac H0 and Lac H6), while the dynamic indices included the delta-lactate level (ΔLac) and the 6-hour lactate clearance. The 6-hour lactate clearance was calculated using the following formula: [(Lac H0-Lac H6)100/Lac H0]. ΔLac was calculated as the difference between the Lac H0 and Lac H6 levels. Patient survival or death after a PICU stay was the primary outcome.

RESULTS

A total of 46 patients were included in this study: 25 had septic shock, and 21 had severe sepsis. The mortality rate was 54.3%. The Lac H0 did not significantly differ between survivors and nonsurvivors. In contrast, the survivors had significantly lower Lac H6 levels, higher ΔLac levels, and higher 6-hour lactate clearance rates than nonsurvivors. Lactate clearance rates below 10%, 20%, and 30% were significantly associated with mortality. The best cut-off values for the lactate clearance rate and Lac H6 for the prediction of mortality in the PICU were < 10% and ≥ 4 mmol/L, respectively. Patients with higher Lac H6 levels and lower lactate clearance rates had significantly higher PICU mortality based on Kaplan-Meier survival curve analysis.

CONCLUSIONS

This study highlights the significance of lactate level trends over time for the prediction of mortality in the PICU in patients with severe sepsis or septic shock. Elevated lactate levels and decreased lactate clearance six hours after hospitalisation are associated with a higher mortality rate.

Biomarkers and sepsis severity as predictors of mechanical ventilation and mortality in COVID-19

Introduction

Patients with septic shock face an elevated risk of mortality compared to those with sepsis. Several biomarkers, including lactate dehydrogenase, albumin, and lactate/albumin (L/A), have been associated with increased mortality in COVID-19 patients. This study aims to assess the relationship between sepsis, septic shock, and mortality, as well as the need for mechanical ventilation in COVID-19 patients. Demographic, sepsis severity factors, and biomarkers are examined.

Methods

A retrospective case series from June 2020 to March 2021 included 490 patients diagnosed with sepsis or septic shock secondary to SARS-CoV-2 pneumonia. Time-to-event analyses were conducted for mechanical ventilation and mortality. Statistical significance was set at p ≤ .0038. Serum lactate, albumin, lactate/albumin ratio, C-reactive protein, platelet levels, and three sepsis severity scales, (CCI, SOFA, APACHE IV) were assessed.

Results

Sepsis was identified in 352 patients (71.8%), while 138 had septic shock. Patients with septic shock were more likely to require invasive ventilator support. Factors associated with a higher risk of intubation included higher APACHE IV scores, elevated serum albumin levels, and increased L/A ratio. L/A ratio and serum lactate levels demonstrated the best diagnostic accuracy for mechanical ventilation (AUC, 0.964 and 0.946, respectively), mortality (AUC, 0.926 and 0.887, respectively).

Discussion

Increased C-reactive protein, combined with increased serum lactate and a high lactate/albumin ratio, may assist clinicians in identifying COVID-19 patients at risk of mechanical ventilation and mortality upon admission. Optimal cut-off values for lactate (1.45-1.65 mmol/L) and L/A ratio (0.413) can aid in prioritizing medical care for at risk COVID-19 patients.

Prolyl hydroxylase domain inhibitor is an effective pre-hospital pharmaceutical intervention for trauma and hemorrhagic shock

Pre-hospital potentially preventable trauma related deaths are mainly due to hypoperfusion-induced tissue hypoxia leading to irreversible organ dysfunction at or near the point of injury or during transportation prior to receiving definitive therapy. The prolyl hydroxylase domain (PHD) is an oxygen sensor that regulates tissue adaptation to hypoxia by stabilizing hypoxia inducible factor (HIF). The benefit of PHD inhibitors (PHDi) in the treatment of anemia and lactatemia arises from HIF stabilization, which stimulates endogenous production of erythropoietin and activates lactate recycling through gluconeogenesis. The results of this study provide insight into the therapeutic roles of MK-8617, a pan-inhibitor of PHD-1, 2, and 3, in the mitigation of lactatemia in anesthetized rats with polytrauma and hemorrhagic shock. Additionally, in an anesthetized rat model of lethal decompensated hemorrhagic shock, acute administration of MK-8617 significantly improves one-hour survival and maintains survival at least until 4 h following limited resuscitation with whole blood (20% EBV) at one hour after hemorrhage. This study suggests that pharmaceutical interventions to inhibit prolyl hydroxylase activity can be used as a potential pre-hospital countermeasure for trauma and hemorrhage at or near the point of injury.

Treatment of a patient with severe lactic acidosis and multiple organ failure due to mitochondrial myopathy: A case report

BACKGROUND

Mitochondrial myopathy is a rare genetic disease with maternal inheritance that may involve multiple organ systems. Due to the lack of typical characteristics, its clinical diagnosis is difficult, and it is often misdiagnosed or even missed.

CASE SUMMARY

The patient was a young college student. When he presented at the hospital, he had severe lactic acidosis, respiratory failure, and shock with multiple organ dysfunction syndrome (MODS). He was treated by mechanical ventilation, veno-arterial extracorporeal membrane oxygenation, and other organ support. However, his condition continued to worsen. After a thorough and detailed medical and family history was taken, a mitochondrial crisis was suspected. A muscle biopsy was taken. Further genetic testing confirmed a mitochondrial gene mutation (TRNL1 3243A>G). The final diagnosis of mitochondrial myopathy was made. Although there is no known specific treatment, intravenous methylprednisone and intravenous immunoglobulin were started. The patient's shock eventually improved. The further course was complicated by severe infection in multiple sites, severe muscle weakness, and recurrent MODS. After 2 mo of multidisciplinary management and intensive rehabilitation, the patient could walk with assistance 4 mo after admission and walk independently 6 mo after admission.

CONCLUSION

More attention should be paid to mitochondrial myopathy to avoid missed diagnosis and misdiagnosis.

Treatment of a patient with severe lactic acidosis and multiple organ failure due to mitochondrial myopathy: A case report

BACKGROUND

Mitochondrial myopathy is a rare genetic disease with maternal inheritance that may involve multiple organ systems. Due to the lack of typical characteristics, its clinical diagnosis is difficult, and it is often misdiagnosed or even missed.

CASE SUMMARY

The patient was a young college student. When he presented at the hospital, he had severe lactic acidosis, respiratory failure, and shock with multiple organ dysfunction syndrome (MODS). He was treated by mechanical ventilation, veno-arterial extracorporeal membrane oxygenation, and other organ support. However, his condition continued to worsen. After a thorough and detailed medical and family history was taken, a mitochondrial crisis was suspected. A muscle biopsy was taken. Further genetic testing confirmed a mitochondrial gene mutation (TRNL1 3243A>G). The final diagnosis of mitochondrial myopathy was made. Although there is no known specific treatment, intravenous methylprednisone and intravenous immunoglobulin were started. The patient’s shock eventually improved. The further course was complicated by severe infection in multiple sites, severe muscle weakness, and recurrent MODS. After 2 mo of multidisciplinary management and intensive rehabilitation, the patient could walk with assistance 4 mo after admission and walk independently 6 mo after admission.

CONCLUSION

More attention should be paid to mitochondrial myopathy to avoid missed diagnosis and misdiagnosis.

Treatment of a patient with severe lactic acidosis and multiple organ failure due to mitochondrial myopathy: A case report

BACKGROUND

Mitochondrial myopathy is a rare genetic disease with maternal inheritance that may involve multiple organ systems. Due to the lack of typical characteristics, its clinical diagnosis is difficult, and it is often misdiagnosed or even missed.

CASE SUMMARY

The patient was a young college student. When he presented at the hospital, he had severe lactic acidosis, respiratory failure, and shock with multiple organ dysfunction syndrome (MODS). He was treated by mechanical ventilation, veno-arterial extracorporeal membrane oxygenation, and other organ support. However, his condition continued to worsen. After a thorough and detailed medical and family history was taken, a mitochondrial crisis was suspected. A muscle biopsy was taken. Further genetic testing confirmed a mitochondrial gene mutation (TRNL1 3243A>G). The final diagnosis of mitochondrial myopathy was made. Although there is no known specific treatment, intravenous methylprednisone and intravenous immunoglobulin were started. The patient’s shock eventually improved. The further course was complicated by severe infection in multiple sites, severe muscle weakness, and recurrent MODS. After 2 mo of multidisciplinary management and intensive rehabilitation, the patient could walk with assistance 4 mo after admission and walk independently 6 mo after admission.

CONCLUSION

More attention should be paid to mitochondrial myopathy to avoid missed diagnosis and misdiagnosis.

The utility of bandemia in prognostication and prediction of mortality in sepsis

Background: Bandemia, defined as a band count >10%, is indicative of underlying infection and is increasingly being used for early detection of sepsis. While an absolute band level has been linked to worse outcomes, its trend has not been extensively studied as a prognostic marker. In this study, we assessed patients admitted to the ICU with sepsis or septic shock and evaluated the correlation between bandemia trends and clinical trajectory among these patients. Methods: This study was a retrospective chart review. Band counts, serum lactate levels, and SOFA scores at 0 and 72 h after admission to the ICU were collected. Patients were risk stratified into groups depending on their SOFA trends, and corresponding band trends and serum lactate levels were compared. Results: 134 patients were included for analysis. There was a statistically significant decrease in bandemia trends for patients with a reduction in SOFA scores [median (IQR)-4.5 (-11, 0); p < 0.0001], and a statistically significant increase in bandemia trends for patients with worsening SOFA scores [median (IQR) 4 (0, 8); p = 0.0007]. Conclusion: Early trends of serum band levels in patients with sepsis or septic shock may help to predict a clinical trajectory and overall prognosis. More investigation is warranted as to whether incorporating bandemia trends, when used in conjunction with other known markers such as lactate levels, may help to guide bedside clinical decisions such as risk stratification, tailored therapies, and ultimately improve outcomes.

HYPOTENSION AT THE TIME OF SEPSIS RECOGNITION IS NOT ASSOCIATED WITH INCREASED MORTALITY IN SEPSIS PATIENTS WITH NORMAL LACTATE LEVELS

ABSTRACT

Background and Objective: Although sepsis is heterogeneous, data on sepsis patients with normal lactate levels are very limited. We explored whether hypotension at the time of sepsis recognition (i.e., time zero) was significant in terms of survival when lactate levels were normal in sepsis patients. Patients and Design: This was a prospective multicenter observational study conducted in 19 hospitals (20 intensive care units [ICUs]). Adult sepsis patients with normal lactate levels (≤2 mmol/L) admitted to ICUs were divided by the mean arterial pressure at time zero into hypotensive (<65 mm Hg) and nonhypotensive groups (≥65 mm Hg). Measurements and Results: Of 2,032 patients with sepsis (not septic shock), 617 with normal lactate levels were included in the analysis. The hypotensive group (n = 237) was characterized by higher rates of abdominal or urinary infections, and bacteremia, whereas the nonhypotensive group (n = 380) was characterized by higher rates of pulmonary infections and systemic inflammatory response. However, the Simplified Acute Physiology Score 3 and Sequential Organ Failure Assessment score (excluding the cardiovascular score) were not different between the groups. During sepsis resuscitation, the rates of antibiotic administration within 1, 3, and 6 h of time zero were higher in the hypotensive than nonhypotensive group ( P < 0.05 for all time points), and the amounts of pre-ICU fluids given were also higher in the hypotensive group. However, despite a higher rate of vasopressor use in the hypotensive group, ICU and in-hospital mortality rates were not different between the groups (12.7% vs. 13.9% [ P = 0.648] and 19.4% vs. 22.4% [ P = 0.382], respectively). In multivariable analysis, the use of appropriate antibiotics and early lactate measurement were significant risk factors for in-hospital mortality. Conclusions: In sepsis patients with normal lactate levels, neither hypotension nor vasopressor use adversely impacted the hospital outcome. Our results emphasize the importance of early interventions and appropriate use of antibiotics regardless of whether a patient is or is not hypotensive.

Distinct subsets of neutrophils crosstalk with cytokines and metabolites in patients with sepsis

Sepsis is a life-threatening condition caused by a dysregulated host response to infection. Despite continued efforts to understand the pathophysiology of sepsis, no effective therapies are currently available. While singular components of the aberrant immune response have been investigated, comprehensive studies linking different data layers are lacking. Using an integrated systems immunology approach, we evaluated neutrophil phenotypes and concomitant changes in cytokines and metabolites in patients with sepsis. Our findings identify differentially expressed mature and immature neutrophil subsets in patients with sepsis. These subsets correlate with various proteins, metabolites, and lipids, including pentraxin-3, angiopoietin-2, and lysophosphatidylcholines, in patients with sepsis. These results enabled the construction of a statistical model based on weighted multi-omics linear regression analysis for sepsis biomarker identification. These findings could help inform early patient stratification and treatment options, and facilitate further mechanistic studies targeting the trifecta of surface marker expression, cytokines, and metabolites.

Elevated Circulating Lactate Levels and Widespread Expression of Its Cognate Receptor, Hydroxycarboxylic Acid Receptor 1 (HCAR1), in Ovarian Cancer

Background: Augmented glycolysis in cancer cells is a process required for growth and development. The Warburg effect provides evidence of increased glycolysis and lactic acid fermentation in cancer cells. The lactate end-product of glycolysis is receiving growing traction for its role as a cell signalling molecule. Ovarian cancer (OvCa) is also characterised by altered glucose metabolism. We aim to explore circulating lactate levels in patients with high-grade serous OvCa (HGSOC) and to elucidate the expression of the lactate receptor hydroxycarboxylic acid receptor 1 (HCAR1) in OvCa. Methods: HCAR1 expression was detected in patient biopsy cores using immunohistochemistry, while lactate was measured from whole blood with a Biosen-C line clinic measuring system. Results: We noted significantly elevated lactate levels in OvCa patients (4.3 ± 1.9 mmol/L) compared with healthy controls (1.4 ± 0.6 mmol/L; p < 0.0001), with an AUC of 0.96. The HCAR1 gene is overexpressed in OvCa compared to healthy controls (p < 0.001). Using an OvCa tissue microarray (>75% expression in 100 patients), high protein expression was also recorded across all epithelial OvCa subtypes and ovarian normal adjacent tissue (NAT). Conclusions: Lactate monitoring is a simple, cost-efficient test that can offer point-of-care results. Our data suggest that the potential of circulating lactate as a screening biomarker in OvCa merits further research attention.

Rapid Measurement of Lactate in the Exhaled Breath Condensate: Biosensor Optimization and In-Human Proof of Concept

Lactate concentration is of increasing interest as a diagnostic for sepsis, septic shock, and trauma. Compared with the traditional blood sample media, the exhaled breath condensate (EBC) has the advantages of non-invasiveness and higher user acceptance. An amperometric biosensor was developed and its application in EBC lactate detection was investigated in this paper. The sensor was modified with PEDOT:PSS-PB, and two different lactate oxidases (LODs). A rotating disk electrode and Koutecky-Levich analysis were applied for the kinetics analysis and gel optimization. The optimized gel formulation was then tested on disposable screen-printed sensors. The disposable sensors exhibited good performance and presented a high stability for both LOD modifications. Finally, human EBC analysis was conducted from a healthy subject at rest and after 30 min of intense aerobic cycling exercise. The sensor coulometric measurements showed good agreement with fluorometric and triple quadrupole liquid chromatography mass spectrometry reference methods. The EBC lactate concentration increased from 22.5 μM (at rest) to 28.0 μM (after 30 min of cycling) and dropped back to 5.3 μM after 60 min of rest.

Does lactate enhance the prognostic accuracy of the quick Sequential Organ Failure Assessment for adult patients with sepsis? A systematic review

OBJECTIVES

To investigate whether adding lactate to the quick Sequential (sepsis-related) Organ Failure Assessment (qSOFA) improves the prediction of mortality in adult hospital patients, compared with qSOFA alone.

DESIGN

Systematic review in accordance with Preferred Reporting Items for a Systematic Review and Meta-analysis of Diagnostic Test Accuracy Studies guidelines.

DATA SOURCES

Embase, Medline, PubMed, SCOPUS, Web of Science, CINAHL and Open Grey databases were searched in November 2020.

ELIGIBILITY CRITERIA

Original research studies published after 2016 comparing qSOFA in combination with lactate (LqSOFA) with qSOFA alone in adult patients with sepsis in hospital. The language was restricted to English.

DATA EXTRACTION AND SYNTHESIS

Title and abstract screening, full-text screening, data extraction and quality assessment (using Quality Assessment of Diagnostic Accuracy Studies-2) were conducted independently by two reviewers. Extracted data were collected into tables and diagnostic test accuracy was compared between the two tests.

RESULTS

We identified 1621 studies, of which 11 met our inclusion criteria. Overall, there was a low risk of bias across all studies. The area under the receiver operating characteristic (AUROC) curve for qSOFA was improved by the addition of lactate in 9 of the 10 studies reporting it. Sensitivity was increased in three of seven studies that reported it. Specificity was increased in four of seven studies that reported it. Of the six studies set exclusively within the emergency department, five published AUROCs, all of which reported an increase following the addition of lactate. Sensitivity and specificity results varied throughout the included studies. Due to insufficient data and heterogeneity of studies, a meta-analysis was not performed.

CONCLUSIONS

LqSOFA is an effective tool for identifying mortality risk both in adult inpatients with sepsis and those in the emergency department. LqSOFA increases AUROC over qSOFA alone, particularly within the emergency department. However, further original research is required to provide a stronger base of evidence in lactate measurement timing, as well as prospective trials to strengthen evidence and reduce bias.

PROSPERO REGISTRATION NUMBER

CRD42020207648.

Restrictive fluids versus standard care in adults with sepsis in the emergency department (REFACED): A multicenter, randomized feasibility trial

BACKGROUND

Fluid treatment in sepsis is a challenge and clinical equipoise exists regarding intravenous (IV) volumes. We aimed to determine whether a 24-h protocol restricting IV fluid was feasible in adult patients with sepsis without shock presenting to the emergency department (ED).

METHODS

The REFACED Sepsis trial is an investigator-initiated, multicenter, randomized, open-label, feasibility trial, assigning sepsis patients without shock to 24 h of restrictive, crystal IV fluid administration or standard care. In the IV fluid restriction group fluid boluses were only permitted if predefined criteria for hypoperfusion occurred. Standard care was at the discretion of the treating team. The primary outcome was total IV crystalloid fluid volumes at 24 h after randomization. Secondary outcomes included total fluid volumes, feasibility measures, and patient-centered outcomes.

RESULTS

We included 123 patients (restrictive 61 patients and standard care 62 patients) in the primary analysis. A total of 32% (95% confidence interval [CI] 28%-37%) of eligible patients meeting all inclusion criteria and no exclusion criteria were included. At 24 h, the mean (±SD) IV crystalloid fluid volumes were 562 (±1076) ml versus 1370 (±1438) ml in the restrictive versus standard care group (mean difference -801 ml, 95% CI -1257 to -345 ml, p = 0.001). Protocol violations occurred in 21 (34%) patients in the fluid-restrictive group. There were no differences between groups in adverse events, use of mechanical ventilation or vasopressors, acute kidney failure, length of stay, or mortality.

CONCLUSIONS

A protocol restricting IV crystalloid fluids in ED patients with sepsis reduced 24-h fluid volumes compared to standard care. A future trial powered toward patient-centered outcomes appears feasible.

Risk stratification of patients with acute respiratory distress syndrome complicated with sepsis using lactate trajectories

Background

No consensus has been reached on an optimal blood lactate evaluation system although several approaches have been reported in the literature in recent years. A group-based trajectory modeling (GBTM) method could better stratify patients with acute respiratory distress syndrome (ARDS) complicated with sepsis in the intensive care unit (ICU).

Patients and methods

760 patients from the comprehensive ICU of Tianjin Medical University General Hospital with ARDS complicated with sepsis were eligible for analysis. Serial serum lactate levels were measured within 48 h of admission. In addition to the GBTM lactate groups, the initial lactate, peak lactate level, the area under the curve of serial lactate (lactate AUC), and lactate clearance were also considered for comparison. The short- and long-term outcomes were the 30- and 90-day mortality, respectively.

Results

Three lactate groups were identified based on GBTM, with group 3 exhibiting the worse short- [hazard ratio (HR) for 30-day mortality: 2.96, 95% confidence interval (CI) 1.79–4.87, P < 0.001] and long term (HR for 90-day mortality: 3.49, 95% CI 2.06–5.89, P < 0.001) outcomes followed by group 2 (HR for 30-day mortality: 2.05, 95% CI 1.48–2.84, P < 0.001 and HR for 90-day mortality: 1.99, 95% CI 1.48–2.67, P < 0.001). GBTM lactate groups exhibited significantly improved diagnostic performance of initial lactate + SOFA scores/APACHE II scores models. Based on the multivariable fractional polynomial interaction (MFPI) approach, GBTM lactate groups could better differentiate high-risk patients than the initial lactate groups in short- and long-term outcomes.

Conclusions

To the best of our knowledge, this is the first report that GBTM-based serial blood lactate evaluations significantly improve the diagnostic capacity of traditional critical care evaluation systems and bring many advantages over previously documented lactate evaluation systems.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-022-02132-6.

Blood Lactate Decreased by Foam Rolling Post-Quarter Marathon

BACKGROUND: New training methods, increased volume, the prolonged duration could induce the delayed onset of muscle soreness (DOMS), and it is associated with blood lactate (BL). Foam roller (FR) is known as a tool for active recovery. AIM: The study’s purposes are to assess the effect of the Quarter Marathon (QM) and Foam Roller (FR) on blood lactate (BL). METHODS: This is a pilot study with a quasi-repeated-measures design. Ten trained young males were voluntarily signed up using the purposive sampling technique. The Accutrend-Plus by Roche was used to measure BL. Blood lactate was measured 6 times. Combination FR protocols from the Master of Muscle and Casall were used. Repeated-measures ANOVA test was used to analyze the changes in BL. RESULTS: Blood lactate significantly increased 4.90 ± 3.0 (mmol/L) post-QM as p < 0.05, pre-test 2.23 ± 0.8 (mmol/L) compared to post-running 7.1 ± 2.6 (mmol/L). It was decreased after foam rolling activity 4.33 ± 0.7 (mmol/L), and 3.06 ± 0.5 (mmol/L) at 120 min post-running, then returned to normal after 24 h post-QM 2.44 ± 0.5 (mmol/L). CONCLUSION: Foam rolling potentially decreased BL after QM.

Reduced Monocyte Subsets, Their HLA-DR Expressions, and Relations to Acute Phase Reactants in Severe COVID-19 Cases

Monocytes are one of the principal immune defense cells that encounter infectious agents. However, an essential role of monocytes has been shown in the spread of viruses throughout the human body. Considering this dilemma, this study aimed to evaluate monocyte subsets and Human Leukocyte Antigen-DR isotype (HLA-DR) expressions in clinical coronavirus disease 2019 (COVID-19) cases. This prospective, multicenter, case-control study was conducted with COVID-19 patients and healthy controls. The patient group was divided into two subgroups according to disease severity (severe and non-severe). Three monocyte subsets (classical, CL; intermediate, INT; non-classical, NC) were analyzed with flow cytometry upon the patients' hospital admission. A total of 42 patients with COVID-19 and 30 controls participated in this study. The patients' conditions were either severe (n = 23) or non-severe (n = 19). All patients' monocyte and HLA-DR expressions were decreased compared with the controls (p < 0.05). Per disease severity, all monocyte subsets were not significant with disease severity; however, the HLA-DR expressions of CL monocytes (p = 0.002) and INT monocytes (p = 0.025) were more decreased in the severe patient group. In patients with various clinical features, NC monocytes were more affected. Based on these results, NC monocytes were more decreased in acute COVID-19 cases, though related various clinics decreased all monocyte subsets in these patients. Decreased monocyte HLA expressions may be a sign of immune suppression in severe patients, even when the percentage of monocyte levels has not decreased yet.

Electrochemical enzyme-based blood ATP and lactate sensor for a rapid and straightforward evaluation of illness severity

This study aimed to develop an electrochemical system for measuring blood ATP and lactate levels in a single format. The ratio of lactate to ATP levels was previously reported to provide an alternative illness severity score. Although severity evaluation is crucial to treat patients with acute disease admitted to intensive care units, no sensors are currently available to simply and rapidly measure ATP and lactate levels using the same detection method. Therefore, we constructed an integrated sensing system for ATP and lactate using enzymatic reactions and two sets of electrodes integrated into a chip connected to a single potentiostat operated by a microcontroller. The enzymatic system involves adenylate kinase, pyruvate kinase, and pyruvate oxidase for ATP, and lactate oxidase for lactate, both of which produce hydrogen peroxide. Multiplex enzyme-based reactions were designed to minimize the corresponding operations significantly without enzyme immobilization onto the electrodes. The system was robust in the presence of potentially interfering blood components, such as ascorbate, pyruvate, ADP, urate, and potassium ions. The ATP and lactate levels in the blood were successfully measured using the new sensor with good recoveries. The analytical results of blood samples obtained using our sensor were in good agreement with those using conventional methods. Integrating electrode-based analysis and a microcontroller-based system saved further operations, enabling the straightforward measurement of ATP and lactate levels within 5 min. The proposed sensor may serve as a useful tool in the management of serious infectious diseases.

Assessment of Metabolic Dysfunction in Sepsis in a Retrospective Single-Centre Cohort

Objective

Our primary aim was to assess selected metabolic dysfunction parameters, both independently and as a complement to the SOFA score, as predictors of short-term mortality in patients with infection admitted to the intensive care unit (ICU).

Methods

We retrospectively enrolled all consecutive adult patients admitted to the eight ICUs of Lille University Hospital, between January 2015 and September 2016, with suspected or confirmed infection. We selected seven routinely measured biological and clinical parameters of metabolic dysfunction (maximal arterial lactatemia, minimal and maximal temperature, minimal and maximal glycaemia, cholesterolemia, and triglyceridemia), in addition to age and the Charlson's comorbidity score. All parameters and SOFA scores were recorded within 24 h of admission.

Results

We included 956 patients with infection, among which 295 (30.9%) died within 90 days. Among the seven metabolic parameters investigated, only maximal lactatemia was associated with higher risk of 90-day hospital mortality in SOFA-adjusted analyses (SOFA-adjusted OR, 1.17; 95%CI, 1.10 to 1.25; p < 0.001). Age and the Charlson's comorbidity score were also statistically associated with a poor prognosis in SOFA-adjusted analyses. We were thus able to develop a metabolic failure, age, and comorbidity assessment (MACA) score based on scales of lactatemia, age, and the Charlson's score, intended for use in combination with the SOFA score.

Conclusions

The maximal lactatemia level within 24 h of ICU admission is the best predictor of short-term mortality among seven measures of metabolic dysfunction. Our combined "SOFA + MACA" score could facilitate early detection of patients likely to develop severe infections. Its accuracy requires further evaluation.

Recent Advances in Bedside Device-Based Early Detection of Sepsis

Early detection of sepsis is challenging to achieve with current diagnostic methods, leading to expenditures of $27 billion annually in the United States with significant associated mortality. Various scoring systems have been proposed such as the sequential organ failure assessment (SOFA) and systemic inflammatory response syndrome (SIRS) criteria for identification of sepsis, but their sensitivities range from 60% to 70% when used in the emergency department triage. Other methods for the recognition of sepsis may rely on laboratory work, in addition to vitals monitoring, and are often outpaced by the development of sepsis. Automated alerts have not shown any reduction in mortality thus far. New technology may fill a critical gap in the early detection of sepsis. The ideal bedside screening device for would demonstrate rapid time to result, high portability, and high sensitivity to not miss cases, but also reasonable specificity to prevent provider fatigue from excessive false alerts. Non-invasive end-organ perfusion devices analyzing lactate and capillary refill time (CRT) tend to perform well in speed and portability, but may be less sensitive. Biomarker devices demonstrate a wider array of performance metrics. Those analyzing a single biomarker tend to be more sensitive but are less specific to the diagnosis of sepsis than technologies that assess multiple biomarkers, which in turn have lower sensitivity. Additionally, biomarker devices are generally invasive requiring blood samples, which may or may not be feasible in all patients especially when serial draws are needed. Sepsis is a complex disease process and most likely will require a combination of improved technology in addition to vital signs and high-risk patient history for better recognition. This review examines recent advances in the device-based early detection of sepsis between 2017 and 2020 with emphasis on bedside diagnostics, divided into markers of perfusion and biomarkers commonly implicated in sepsis.

Prediction of 90-Day Mortality among Sepsis Patients Based on a Nomogram Integrating Diverse Clinical Indices

Background

Sepsis is prevalent among intensive care units and is a frequent cause of death. Several studies have identified individual risk factors or potential predictors of sepsis-associated mortality, without defining an integrated predictive model. The present work was aimed at defining a nomogram for reliably predicting mortality.

Methods

We carried out a retrospective, single-center study based on 231 patients with sepsis who were admitted to our intensive care unit between May 2018 and October 2020. Patients were randomly split into training and validation cohorts. In the training cohort, multivariate logistic regression and a stepwise algorithm were performed to identify risk factors, which were then integrated into a predictive nomogram. Nomogram performance was assessed against the training and validation cohorts based on the area under receiver operating characteristic curves (AUC), calibration plots, and decision curve analysis.

Results

Among the 161 patients in the training cohort and 70 patients in the validation cohort, 90-day mortality was 31.6%. Older age and higher values for the international normalized ratio, lactate level, and thrombomodulin level were associated with greater risk of 90-day mortality. The nomogram showed an AUC of 0.810 (95% CI 0.739 to 0.881) in the training cohort and 0.813 (95% CI 0.708 to 0.917) in the validation cohort. The nomogram also performed well based on the calibration curve and decision curve analysis.

Conclusion

This nomogram may help identify sepsis patients at elevated risk of 90-day mortality, which may help clinicians allocate resources appropriately to improve patient outcomes.

Understanding critically ill sepsis patients with normal serum lactate levels: results from U.S. and European ICU cohorts

While serum lactate level is a predictor of poor clinical outcomes among critically ill patients with sepsis, many have normal serum lactate. A better understanding of this discordance may help differentiate sepsis phenotypes and offer clues to sepsis pathophysiology. Three intensive care unit datasets were utilized. Adult sepsis patients in the highest quartile of illness severity scores were identified. Logistic regression, random forests, and partial least square models were built for each data set. Features differentiating patients with normal/high serum lactate on day 1 were reported. To exclude that differences between the groups were due to potential confounding by pre-resuscitation hyperlactatemia, the analyses were repeated for day 2. Of 4861 patients included, 47% had normal lactate levels. Patients with normal serum lactate levels had lower 28-day mortality rates than those with high lactate levels (17% versus 40%) despite comparable physiologic phenotypes. While performance varied between datasets, logistic regression consistently performed best (area under the receiver operator curve 87–99%). The variables most strongly associated with normal serum lactate were serum bicarbonate, chloride, and pulmonary disease, while serum sodium, AST and liver disease were associated with high serum lactate. Future studies should confirm these findings and establish the underlying pathophysiological mechanisms, thus disentangling association and causation.

Prognostic Value of Procalcitonin, C-Reactive Protein, and Lactate Levels in Emergency Evaluation of Cancer Patients with Suspected Infection

Simple Summary

Cancer patients are at increased risk of infections and related complications, including sepsis. We developed a scoring system for mortality prediction based on readily available clinical and laboratory data, including the quick sequential organ failure assessment (qSOFA) score, cancer subtype, and several laboratory markers (procalcitonin, C-reactive protein, lactate dehydrogenase, and albumin) that can be used in emergency departments for cancer patients with suspected infection. The prediction score, which stratifies patients into four different risk groups (from low risk to very high risk), achieved excellent performance in predicting 14-day mortality, with an area under the receiver operating characteristic curve value of 0.88 (95% confidence interval 0.85–0.91). The score was also effective in predicting intensive care unit admission and 30-day mortality.

Abstract

Cancer patients have increased risk of infections, and often present to emergency departments with infection-related problems where physicians must make decisions based on a snapshot of the patient’s condition. Although C-reactive protein, procalcitonin, and lactate are popular biomarkers of sepsis, their use in guiding emergency care of cancer patients with infections is unclear. Using these biomarkers, we created a prediction model for short-term mortality in cancer patients with suspected infection. We retrospectively analyzed all consecutive patients who visited the emergency department of MD Anderson Cancer Center between 1 April 2018 and 30 April 2019. A clinical decision model was developed using multiple logistic regression for various clinical and laboratory biomarkers; coefficients were used to generate a prediction score stratifying patients into four groups according to their 14-day mortality risk. The prediction score had an area under the receiver operating characteristic curve value of 0.88 (95% confidence interval 0.85–0.91) in predicting 14-day mortality. The prediction score also accurately predicted intensive care unit admission and 30-day mortality. Our simple new scoring system for mortality prediction, based on readily available clinical and laboratory data, including procalcitonin, C-reactive protein, and lactate, can be used in emergency departments for cancer patients with suspected infection.

Monitoring skin blood flow to rapidly identify alterations in tissue perfusion during fluid removal using continuous veno-venous hemofiltration in patients with circulatory shock

Background

Continuous veno-venous hemofiltration (CVVH) can be used to reduce fluid overload and tissue edema, but excessive fluid removal may impair tissue perfusion. Skin blood flow (SBF) alters rapidly in shock, so its measurement may be useful to help monitor tissue perfusion.

Methods

In a prospective, observational study in a 35-bed department of intensive care, all patients with shock who required fluid removal with CVVH were considered for inclusion. SBF was measured on the index finger using skin laser Doppler (Periflux 5000, Perimed, Järfälla, Sweden) for 3 min at baseline (before starting fluid removal, T0), and 1, 3 and 6 h after starting fluid removal. The same fluid removal rate was maintained throughout the study period. Patients were grouped according to absence (Group A) or presence (Group B) of altered tissue perfusion, defined as a 10% increase in blood lactate from T0 to T6 with the T6 lactate ≥ 1.5 mmol/l. Receiver operating characteristic curves were constructed and areas under the curve (AUROC) calculated to identify variables predictive of altered tissue perfusion. Data are reported as medians [25th–75th percentiles].

Results

We studied 42 patients (31 septic shock, 11 cardiogenic shock); median SOFA score at inclusion was 9 [8–12]. At T0, there were no significant differences in hemodynamic variables, norepinephrine dose, lactate concentration, ScvO₂ or ultrafiltration rate between groups A and B. Cardiac index and MAP did not change over time, but SBF decreased in both groups (p < 0.05) throughout the study period. The baseline SBF was lower (58[35–118] vs 119[57–178] perfusion units [PU], p = 0.03) and the decrease in SBF from T0 to T1 (ΔSBF%) higher (53[39–63] vs 21[12–24]%, p = 0.01) in group B than in group A. Baseline SBF and ΔSBF% predicted altered tissue perfusion with AUROCs of 0.83 and 0.96, respectively, with cut-offs for SBF of ≤ 57 PU (sensitivity 78%, specificity 87%) and ∆SBF% of ≥ 45% (sensitivity 92%, specificity 99%).

Conclusion

Baseline SBF and its early reduction after initiation of fluid removal using CVVH can predict worsened tissue perfusion, reflected by an increase in blood lactate levels.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13613-021-00847-z.

Lactate/albumin ratio is more effective than lactate or albumin alone in predicting clinical outcomes in intensive care patients with sepsis

This study aimed to compare the value of lactate, albumin, and lactate/albumin ratio for the prediction of mortality in sepsis patients. Patients admitted to the intensive care unit (ICU) due to sepsis between January 2016 and January 2019 were evaluated retrospectively. Lactate, albumin, and lactate/albumin ratio values were compared between surviving and non-surviving patients and their predictive value for mortality was evaluated. A total of 1136 sepsis patients admitted to the ICU were included in the study. The mortality rate was 42.7% (485/1136 patients). In ROC analysis for mortality prediction, the area under the curve and optimal cut-off values were 0.816 and >2.2 mmol/L for lactate, 0.812 and ≤26 g/L for albumin, and 0.869 and >0.71 for lactate/albumin ratio, respectively. Our analysis of lactate, albumin, and lactate/albumin ratio in the largest patient sample to date showed that lactate/albumin ratio was a stronger parameter than lactate or albumin alone in predicting mortality among sepsis patients in the ICU. Lactate/albumin ratio is an easily obtained parameter with potential value for critically ill patients.

Significance of lactate clearance in septic shock patients with high bilirubin levels

Lactate clearance is affected by hepatic function. However, it is unclear whether the association between hepatic dysfunction and lactate clearance can act as a prognostic marker of clinical outcomes in patients with septic shock. We aimed to evaluate the association between lactate clearance and mortality in two cohorts of septic shock patient who had hepatic dysfunction based on their total serum bilirubin levels (TBIL). Lactate clearance at 24 h after the onset of septic shock was analyzed using two cohorts, sub-categorized into two groups based on TBIL: < 2 mg/dL and ≥ 2 mg/dL. In the derivation cohort, lactate clearance was lower in non-survivors than in survivors with TBIL ≥ 2 mg/dL, while there was no significant difference in lactate clearance between non-survivors and survivors with TBIL < 2 mg/dL. Multivariate logistic regression analysis revealed that increased lactate clearance was significantly associated with decreased 28-day mortality in the TBIL ≥ 2 mg/dL group (10% lactate clearance, adjusted odds ratio [OR]: 0.88, 95% confidence interval (CI): 0.80-0.97, P = 0.0075), Creatinine level ≥ 2 mg/dL group (adjusted OR: 0.88, 95% CI: 0.81-0.95, P = 0.00069) and APACHE II score ≥ 35 group (adjusted OR: 0.93, 95% CI: 0.87-0.98, P = 0.013). In the validation cohort, lactate clearance was lower in non-survivors than in survivors with TBIL ≥ 2 mg/dL, while no significant difference in lactate clearance was observed between non-survivors and survivors with TBIL < 2 mg/dL. Increased lactate clearance was significantly associated with decreased 28-day mortality in the TBIL ≥ 2 mg/dL group (10% lactate clearance, adjusted OR: 0.89, 95% CI: 0.83-0.96, P = 0.0038) and the association was just about significant in APACHE II score ≥ 35 group (adjusted OR: 0.86, 95% CI: 0.74-1.00, P = 0.051). In conclusion, increased lactate clearance in septic shock patients with hepatic dysfunction (TBIL ≥ 2 mg/dL) or high severity (APACHE II score ≥ 35) was associated with decreased 28-day mortality.

Correlation of the changing trends of red cell distribution width and serum lactate as a prognostic factor in sepsis and septic shock

Background and Aims:

Various biomarkers are used for predicting outcome from sepsis and septic shock but single value doesn't give clear-cut picture. Changing trends of serum lactate and red cell distribution width (RDW) gives more accurate information of patient outcome. So, aim of this prospective observational study was to identify the correlation, for initial and changing trend of blood lactate level and RDW, with 28-day mortality in sepsis and septic shock.

Material and Methods:

Patient who fulfills the criteria of sepsis and septic shock, according to the consensus conference published in 2016, were included in this study. All patients were resuscitated and managed according to institutional protocol for sepsis and septic shock. Serum lactate and RDW was obtained from arterial blood gas and complete blood count, respectively. Serum lactate and RDW were recorded at 0 h, 6 h, 24 h, day 2, day 3, day 7, week 2, and week 3. Mean between two groups were compared with student t-test. Pearson and Spearman correlation coefficient was used for establishing correlation between two continuous data. P value < 0.05 indicates significant difference between two groups.

Results:

There is positive correlation between serum lactate and RDW at all-time point in non-survival group while negative correlation was found in survival group except on day1 and 2.

Conclusion:

Changing trends of serum lactate and RDW can be used as a prognostic marker in patient of sepsis and septic shock.

This is your toolkit in hemodynamic monitoring

PURPOSE OF REVIEW

To appraise the basic and more advanced methods available for hemodynamic monitoring, and describe the definitions and criteria for the use of hemodynamic variables.

RECENT FINDINGS

The hemodynamic assessment in critically ill patients suspected of circulatory shock follows a step-by-step algorithm to help determine diagnosis and prognosis. Determination of accurate diagnosis and prognosis in turn is crucial for clinical decision-making. Basic monitoring involving clinical examination in combination with hemodynamic variables obtained with an arterial catheter and a central venous catheter may be sufficient for the majority of patients with circulatory shock. In case of uncertainty of the underlying cause or to guide treatment in severe shock may require additional advanced hemodynamic technologies, and each is utilized for different indications and has specific limitations. Future developments include refining the clinical examination and performing studies that demonstrate better patient outcomes by targeting hemodynamic variables using advanced hemodynamic monitoring.

SUMMARY

Determination of accurate diagnosis and prognosis for patients suspected of circulatory shock is essential for optimal decision-making. Numerous techniques are available, and each has its specific indications and value.

Sodium lactate promotes stemness of human mesenchymal stem cells through KDM6B mediated glycolytic metabolism

Mesenchymal stem cells (MSCs) are an important cell source for tissue homeostasis and repair due to their stemness characteristic. Lots of intrinsic signaling pathways have been reported to regulate MSC stemness, but the extrinsic signals such as sodium lactate, particularly in physiological conditions, are poorly understood. Herein, we evaluated the effect of sodium lactate on human MSC stemness regulation by examining colony-forming ability, energy metabolism, multi-lineage differentiation ability, and pluripotent gene and protein expression. The underlying mechanism was further investigated with gene knockdown as well as small molecule interference and rescue experiments. We found that: (1) low concentration (1 mM) of sodium lactate promoted the stemness of human MSCs; (2) the upregulation of glycolysis was responsible for the MSC stemness promotion; (3) lysine demethylase 6B (KDM6B) was the key regulator which mediated sodium lactate-induced glycolysis and human MSC stemness enhancement. This study indicated that sodium lactate played an important role in human MSC stemness maintenance in physiological conditions, which could be related to KDM6B mediated metabolic regulation. It would provide new insight into stem cell biology, and contribute to cell transplantation and tissue regeneration strategies.

A Physiologic Approach to Hemodynamic Monitoring and Optimizing Oxygen Delivery in Shock Resuscitation

The approach to shock resuscitation focuses on all components of oxygen delivery, including preload, afterload, contractility, hemoglobin, and oxygen saturation. Resuscitation focused solely on preload and fluid responsiveness minimizes other key elements, resulting in suboptimal patient care. This review will provide a physiologic and practical approach for the optimization of oxygen delivery utilizing available hemodynamic monitoring technologies. Venous oxygen saturation (SvO₂) and lactate will be discussed as indicators of shock states and endpoints of resuscitation within the framework of resolving oxygen deficit and oxygen debt.

Biomarker Panels in Critical Care

Biomarker panels have the potential to advance the field of critical care medicine by stratifying patients according to prognosis and/or underlying pathophysiology. This article discusses the discovery and validation of biomarker panels, along with their translation to the clinical setting. The current literature on the use of biomarker panels in sepsis, acute respiratory distress syndrome, and acute kidney injury is reviewed.

Vasopressin Plasma Concentrations Are Not Associated with Hemodynamic Response to Exogenous Vasopressin for Septic Shock

INTRODUCTION

Positive hemodynamic response to vasopressin after 6 hours of infusion was independently associated with lower mortality in a previous retrospective study of patients with septic shock. However, factors previously associated with higher plasma vasopressin concentration were not associated with response, and the relationship between plasma vasopressin concentration and hemodynamic response has not been evaluated.

OBJECTIVES

This cross-sectional study compared plasma vasopressin concentrations in hemodynamic responders and nonresponders to vasopressin in patients with septic shock to evaluate plasma vasopressin concentration as a therapeutic target for hemodynamic response to vasopressin.

METHODS

Adult patients with septic shock were included if they were treated with fixed-dose vasopressin as an adjunct to catecholamines for at least 3 hours. Patients were assigned to groups based on vasopressin response.

RESULTS

Ten hemodynamic responders to vasopressin and eight nonresponders were included. Blood samples for plasma vasopressin concentration were collected 3-6 hours after vasopressin initiation. Baseline characteristics were similar between groups. No difference was detected in plasma vasopressin concentrations between hemodynamic responders and nonresponders (median 88.6 pg/ml [interquartile range (IQR) 84.4-107.5 pg/ml] vs 89.9 pg/ml [IQR 67.5-157.4 pg/ml], p=0.79, respectively). We also did not detect a difference between groups after correcting for vasopressin dose; median vasopressin plasma concentration per 0.01 units/minute of vasopressin infusion for responders was 25.9 pg/ml (IQR 21.8-31.8 pg/ml) versus 29.5 pg/ml (IQR 23.0-57.5 pg/ml, p=0.48) for nonresponders. No difference in clinical outcomes was detected between groups. The findings were robust to multiple sensitivity analyses.

CONCLUSIONS

This study does not support the use of plasma vasopressin concentrations as a therapeutic target to predict hemodynamic response to exogenous vasopressin in septic shock.

Simultaneous quantification of multiple biomarkers on a self-calibrating microfluidic paper-based analytic device

In this study, we developed a point-of-care assay platform with simultaneous detection and self-calibration capabilities for multiple targets based on a microfluidic paper-based analytical device (μPAD). This system is easily manufactured using a wax printing method on chromatographic paper. The design pattern consists of a zone of detection and a calibrant zone for controlled loading using wax barriers with different thicknesses. We showed the utility and applicability of this approach by a proof-of-concept study for two clinically important markers: glucose and lactate. With the naked eye, the results could be fully distinguished and recorded to evaluate the analytical performance with a flatbed scanner. The detection limits of glucose and lactate were 0.3125 mM and 0.2975 mM, respectively, and simultaneous detection was possible from a small sample (0.4 μL) with high sensitivity. Furthermore, this device has a self-calibration function, which minimizes the influence of environmental conditions (i.e., ambient light intensity, temperature, humidity, and pressure). Therefore, the developed multiplex paper-based device is promising for clinical multianalyte point-of-care testing since it is easy to manufacture, cost-effective, user-friendly, and highly sensitive.

[Causes, diagnosis and treatments of circulatory shocks]

Shock states are the leading causes of intensive care admission and are nowadays associated with high morbidity and mortality. They are driven by a complex physiopathology and most frequently a multifactorial mechanism. They can be separated in whether a decrease of oxygen delivery (quantitative shock) or an abnormal cell distribution of cardiac output (distributive shock). Septic, cardiogenic and hypovolemic shocks represent more than 80% of shock etiologies. Clinical presentation is mostly characterized by frequent arterial hypotension and sign of poor clinical perfusion. Hyperlactatemia occurs in most of shock states. The diagnostic of shock or earlier reversible "pre-shock" states is urgent in order to initiate adequate therapy. Therefore, orientation and therapies must be discussed with intensive care physiologists in a multidisciplinary approach. Etiologic investigation and correction is a primary concern. Hemodynamic and respiratory support reflect another part of initial therapy toward normalization of cell oxygenation. Fluid resuscitation is the corner stone part of initial therapy of any form of shock. Vasoconstrictive drugs or inotropic support still often remain necessary. The primary goal of initial resuscitation should be not only to restore blood arterial pressure but also to improve clinical perfusion markers. On the biological side, decrease of lactate concentration is associated with better outcome.

Conservative vs liberal fluid therapy in septic shock (CLASSIC) trial-Protocol and statistical analysis plan

INTRODUCTION

Intravenous (IV) fluid is a key intervention in the management of septic shock. The benefits and harms of lower versus higher fluid volumes are unknown and thus clinical equipoise exists. We describe the protocol and detailed statistical analysis plan for the conservative versus liberal approach to fluid therapy of septic shock in the Intensive Care (CLASSIC) trial. The aim of the CLASSIC trial is to assess benefits and harms of IV fluid restriction versus standard care in adult intensive care unit (ICU) patients with septic shock.

METHODS

CLASSIC trial is an investigator-initiated, international, randomised, stratified, and analyst-blinded trial. We will allocate 1554 adult patients with septic shock, who are planned to be or are admitted to an ICU, to IV fluid restriction versus standard care. The primary outcome is mortality at day 90. Secondary outcomes are serious adverse events (SAEs), serious adverse reactions (SARs), days alive at day 90 without life support, days alive and out of the hospital at day 90 and mortality, health-related quality of life (HRQoL), and cognitive function at 1 year. We will conduct the statistical analyses according to a pre-defined statistical analysis plan, including three interim analyses. For the primary analysis, we will use logistic regression adjusted for the stratification variables comparing the two interventions in the intention-to-treat (ITT) population.

DISCUSSION

The CLASSIC trial results will provide important evidence to guide clinicians' choice regarding the IV fluid therapy in adults with septic shock.

Demystifying Lactate in the Emergency Department

The role of lactic acid and its conjugate base, lactate, has evolved during the past decade in the care of patients in the emergency department (ED). A recent national sepsis quality measure has led to increased use of serum lactate in the ED, but many causes for hyperlactatemia exist outside of sepsis. We provide a review of the biology of lactate production and metabolism, the many causes of hyperlactatemia, and evidence on its use as a marker in prognosis and resuscitation. Additionally, we review the evolving role of lactate in sepsis care. We provide recommendations to aid lactate interpretation in the ED and highlight areas for future research.

Is blood a necessary component of the perfusate during isolated limb perfusion - a randomized controlled trial

Background: Isolated limb perfusion (ILP) is a treatment option for malignancies localized to an extremity and is performed by surgical isolation of the limb which is connected to an extracorporeal circulation system. A high concentration of a chemotherapeutic agent is perfused through the limb, while systemic toxicity is avoided. Currently, the use of packed red blood cells in the priming solution is the norm during ILP. The aim of this study was to investigate the possibility to replace an erythrocyte-based prime solution with a crystalloid-based prime solution while maintaining the regional metabolic oxygen demand during ILP. Methods: In a single-center, randomized controlled, non-blinded, non-inferiority clinical trial, 21 patients scheduled for treatment with ILP were included and randomized 1:1 to either an erythrocyte-based prime solution (control) or a crystalloid-based prime solution (intervention). Results: There was a significant difference in lactate level (mmol/L) during the perfusion between the intervention group and the control group (1.6 ± 0.4 vs. 3.6 ± 0.7, p = .001). No significant differences in oxygen extraction (%) (22 ± 11 vs. 14 ± 4, p = .06), oxygen delivery (ml/min) (90 ± 49 vs. 108 ± 38, p = .39), oxygen consumption (ml/min) (14 ± 2 vs. 14 ± 5, p = .85), regional central venous saturation (%) (83 ± 10 vs. 91 ± 4, p = .07) or INVOS (%) (76 ± 14 vs. 81 ± 11, p = .42) were found between the intervention group and the control group. Conclusion: This study showed no significant improvement with the addition of packed red blood cells into the prime solution in ensuring the metabolic oxygen demand in the treated extremity during ILP, and we, therefore, recommend that a crystalloid-based prime solution should be used.

Lactate Predicts Both Short- and Long-Term Mortality in Patients With and Without Sepsis

Objective

To measure the relationship between lactate and mortality in hospital inpatients. Main outcomes of interest were 3-day, 30-day, and 1-year all-cause mortality.

Design

Retrospective cohort study, October 2011 to September 2013.

Setting

University-affiliated US Veterans Affairs Hospital.

Patients

All inpatients with lactate level measured during the study period.

Measurements

Analysis of peak lactate level (mmol/L) during the most recent admission for patients who died, and peak lactate level during an admission for surviving patients. Covariates including sepsis, ICU admission, code blue and rapid response calls, medical vs surgical ward, liver disease, kidney disease, and hospice status were recorded.

Results

In total, 3325 inpatients were included; 564 patients had sepsis. Median lactate 1.7 mmol/L (interquartile range [IQR] 1.2-2.6). The 3-day, 30-day, and 1-year mortality were 2.5%, 10%, and 24%, respectively. A lactate level cutoff of ⩾4 mmol/L had best test characteristics (sensitivity 52.4%, specificity 91.4%) to predict increased 3-day mortality. Unadjusted risk ratio of death in 3 days for lactate ⩾4 was 10.3 (95% confidence interval [CI] 6.8-15.7). Patients with sepsis had a consistently higher risk of death compared with patients without sepsis for any given level of lactate. Adjusted odds ratio (OR) of 3-day mortality for lactate ⩾4 was 7.6 (95% CI 4.6-12.5); 30-day mortality was 2.6 (95% CI 1.9-3.6); and 1-year mortality was 1.8 (95% CI 1.4-2.6). Lactates in the normal range (<1.7) were also independently associated with 30-day and 1-year mortality.

Conclusions

Lactate predicts risk of death in all patients, although patients with sepsis have a higher mortality for any given lactate level. We report the novel finding that serum lactate, including normal values, is associated with long-term mortality.

Optimal cut-off for hourly lactate reduction in ICU-treated patients with septic shock

BACKGROUND

A decrease in lactate concentration over time during septic shock is associated with favourable outcomes. However, if this applies to hourly intervals during the initial time period in the ICU is unknown. The aim of this study was to investigate whether there is an early hourly reduction rate of lactate that is related to clinical outcome in septic shock patients treated in the ICU.

METHODS

A cohort of adult septic shock patients admitted to the ICU with an initial lactate level >2 mmol/L and receiving vasopressor was retrospectively analysed. Mean hourly reduction rate of lactate (ΔLact/h) was calculated individually from all lactate concentrations measured from inclusion until normalization of lactate (≤1.5 mmol/L) within 24 hours. The mortality at 30 days following ICU admission was evaluated.

RESULTS

Among 1405 ICU admissions during 2 years, 104 patients were eligible. Mortality rate at 30 days was 34%. The optimal cut-off values of baseline lactate and ΔLact/h for 30-day mortality were 4 mmol/L and 2.5%/h. When stratifying the patients by these cut-points, those with baseline lactate > 4 mmol/L and ΔLact/h < 2.5%/h had lowest probability of survival (27%). Multivariable logistic regression showed that ΔLact/h <2.5%/h, baseline lactate >4 mmol/L and high Simplified Acute Physiology Score III were independent risk factors of 30-day mortality.

CONCLUSIONS

In this retrospective pilot cohort, a mean reduction rate of lactate <2.5%/h within the first 24 hours of ICU stay was associated with an increased risk of 30-day mortality in septic shock patients.

Serum Lactate as an Independent Predictor of In-Hospital Mortality in Intensive Care Patients

PURPOSE

The aim of this study was to check if serum lactate was independently associated with mortality among critically ill patients.

MATERIALS AND METHODS

This was a single-center, retrospective cohort study. All adult patients (>18 years of age) who had at least 1 measurement of lactate within 24 hours of admission to intensive care unit (ICU) between January 2002 and December 2017 were included in the analysis. Patients were stratified into 3 groups: those with a serum lactate of <2 mmol/L (normal level), 2 to 4 mmol/L (intermediate level), and >4 mmol/L (high level). The primary outcome was in-hospital mortality. Secondary outcomes included ICU and hospital lengths of stay and mechanical ventilation duration. To determine the association between lactate level and hospital mortality, bivariate and multivariate logistic regression analyses were performed.

RESULTS

Of the 16,447 patients admitted to the ICU, 8167 (49.65%) had normal levels, 4648 (28.26%) had an intermediate, and 3632 (22.09%) had high lactate levels. Hospital mortality was the highest in high lactate level, followed by the intermediate and the normal level group (47.4% vs 26.5% vs 19.6%; P < .0001). Intermediate and high lactate levels were independent predictors of hospital mortality (odds ratio [OR], 1.32; 95% confidence interval [CI]: 1.20-1.46, and 1.94; 95% CI, 1.75-2.16, respectively) as well as ICU mortality (OR, 1.47; 95% CI, 1.30-1.66 and 2.56; 95% CI, 2.27-2.88, respectively).

CONCLUSIONS

Intensive care unit serum lactate is associated with increased ICU and hospital mortality, independent of comorbidities, organ dysfunction, or hemodynamic status.

Lactic Acid Inhibits Lipopolysaccharide-Induced Mast Cell Function by Limiting Glycolysis and ATP Availability

Sepsis has a well-studied inflammatory phase, with a less-understood secondary immunosuppressive phase. Elevated blood lactate and slow lactate clearance are associated with mortality; however, regulatory roles are unknown. We hypothesized that lactic acid (LA) contributes to the late phase and is not solely a consequence of bacterial infection. No studies have examined LA effects in sepsis models in vivo or a mechanism by which it suppresses LPS-induced activation in vitro. Because mast cells can be activated systemically and contribute to sepsis, we examined LA effects on the mast cell response to LPS. LA significantly suppressed LPS-induced cytokine production and NF-κB transcriptional activity in mouse bone marrow-derived mast cells and cytokine production in peritoneal mast cells. Suppression was MCT-1 dependent and reproducible with sodium lactate or formic acid. Further, LA significantly suppressed cytokine induction following LPS-induced endotoxemia in mice. Because glycolysis is linked to inflammation and LA is a byproduct of this process, we examined changes in glucose metabolism. LA treatment reduced glucose uptake and lactate export during LPS stimulation. LA effects were mimicked by glycolytic inhibitors and reversed by increasing ATP availability. These results indicate that glycolytic suppression and ATP production are necessary and sufficient for LA effects. Our work suggests that enhancing glycolysis and ATP production could improve immune function, counteracting LA suppressive effects in the immunosuppressive phase of sepsis.