Occult hypoperfusion and mortality in patients with suspected infection

Lactate and Lactylation in Sepsis: A Comprehensive Review

Sepsis is a disorder of the immune response to infection or infectious factors with high morbidity and mortality in clinical settings. The lactylation of lysine residues, fueled by lactate, plays a pivotal role in its pathophysiology. In conducting a literature review on sepsis-related research, we employed a systematic approach to ensure comprehensiveness and accuracy. Initially, we conducted an extensive literature search through the PubMed database, utilizing a range of keywords including "sepsis", "lactate", "lactylation", and "epigenetic modification". The aim was to capture the most recent research related to the pathophysiological mechanisms of sepsis, metabolic disorders, and the role of lactylation. The results of the literature review revealed a close link between sepsis and metabolic dysfunction, particularly the pivotal role of lactylation in regulating immune responses and inflammatory processes. Lactate, not only an energy metabolic byproduct produced during glycolysis, affects the activity of various proteins, including those involved in immune regulation and cell signaling, through lactylation. In the context of sepsis, changes in the levels of lactylation may be closely associated with the severity and prognosis of the disease. In summary, lactylation, as an emerging type of epigenetic modification, provides a new perspective for the diagnosis and treatment of sepsis. Future research needs to further elucidate the exact mechanisms of lactylation in sepsis and explore its potential as a therapeutic target.

Mortality Prediction by Kinetic Parameters of Lactate and S-Adenosylhomocysteine in a Cohort of Critically Ill Patients

Tissue hypoxia is associated with the development of organ dysfunction and death in critically ill patients commonly captured using blood lactate. The kinetic parameters of serial lactate evaluations are superior at predicting mortality compared with single values. S-adenosylhomocysteine (SAH), which is also associated with hypoxia, was recently established as a useful predictor of septic organ dysfunction and death. We evaluated the performance of kinetic SAH parameters for mortality prediction compared with lactate parameters in a cohort of critically ill patients. For lactate and SAH, maxima and means as well as the normalized area scores were calculated for two periods: the first 24 h and the total study period of up to five days following ICU admission. Their performance in predicting in-hospital mortality were compared in 99 patients. All evaluated parameters of lactate and SAH were significantly higher in non-survivors compared with survivors. In univariate analysis, the predictive power for mortality of SAH was higher compared with lactate in all forms of application. Multivariable models containing SAH parameters demonstrated higher predictive values for mortality than models based on lactate parameters. The optimal models for mortality prediction incorporated both lactate and SAH parameters. Compared with lactate, SAH displayed stronger predictive power for mortality in static and dynamic application in critically ill patients.

Lactate metabolism and acute kidney injury

ABSTRACT

Acute kidney injury (AKI) is a common clinically critical syndrome in hospitalized patients with high morbidity and mortality. At present, the mechanism of AKI has not been fully elucidated, and no therapeutic drugs exist. As known, glycolytic product lactate is a key metabolite in physiological and pathological processes. The kidney is an important gluconeogenic organ, where lactate is the primary substrate of renal gluconeogenesis in physiological conditions. During AKI, altered glycolysis and gluconeogenesis in kidneys significantly disturb the lactate metabolic balance, which exert impacts on the severity and prognosis of AKI. Additionally, lactate-derived posttranslational modification, namely lactylation, is novel to AKI as it could regulate gene transcription of metabolic enzymes involved in glycolysis or Warburg effect. Protein lactylation widely exists in human tissues and may severely affect non-histone functions. Moreover, the strategies of intervening lactate metabolic pathways are expected to bring a new dawn for the treatment of AKI. This review focused on renal lactate metabolism, especially in proximal renal tubules after AKI, and updated recent advances of lactylation modification, which may help to explore potential therapeutic targets against AKI.

Association between hypomagnesemia and serum lactate levels in patients with sepsis: a retrospective observational study

BACKGROUND

Sepsis-3 emphasizes the recognition of sepsis-induced cellular metabolic abnormalities, and utilizes serum lactate level as a biomarker of cellular metabolic abnormalities. Magnesium plays an important role as a cofactor in glucose metabolism, although it is not well known that magnesium deficiency causes elevated serum lactate levels. Additionally, it remains unclear how magnesium status affects the role of serum lactate levels as a marker of metabolic abnormalities in sepsis. Thus, this study aimed to investigate the association between serum magnesium and lactate levels in patients with sepsis and explore this relationship from the perspectives of time course and circulatory abnormalities.

METHODS

This retrospective observational study of adult patients with sepsis was performed at the 16-bed intensive care unit of Jichi Medical University Hospital between June 2011 and December 2017. The relationship between serum magnesium and lactate levels for 5 days from intensive care unit admission was investigated along the time course. Multivariate logistic regression analysis was performed to evaluate the association between serum magnesium and lactate levels during intensive care unit admission.

RESULTS

Among 759 patients included, 105 had hypomagnesemia (magnesium level < 1.6 mg/dL), 558 had normal serum magnesium levels (1.6-2.4 mg/dL), and 96 had hypermagnesemia (magnesium level > 2.4 mg/dL) at intensive care unit admission. From intensive care unit admission to day 5, the hypomagnesemia group had higher serum lactate levels and a higher frequency of lactic acidosis than the normal magnesium level and hypermagnesemia groups (70% vs. 51.6% vs. 50%; P < 0.001). Hypomagnesemia at intensive care unit admission was independently associated with lactic acidosis, i.e., lactic acid level > 2 mmol/L (odds ratio, 2.76; 95% confidence interval, 1.60-4.76; P < 0.001).

CONCLUSIONS

Hypomagnesemia was associated with serum lactate levels in the early and post-resuscitation phases of sepsis. Further studies are needed to elucidate whether the magnesium status is associated with sepsis-induced cellular and metabolic abnormalities.

Syndecan-1 levels predict septic shock in critically ill patients with COVID-19

BACKGROUND

The clinical picture of coronavirus disease 2019 (COVID-19)-associated sepsis is similar to that of sepsis of other aetiologies. The present study aims to analyse the role of syndecan-1 (SDC-1) as a potential predictor of septic shock in critically ill patients with COVID-19.

METHODS

This is a prospective study of 86 critically ill patients due to COVID-19 infection. Patients were followed until day 28 of hospitalization. Vascular biomarkers, such as vascular cell adhesion protein-1, SDC-1, angiopoietin-1 and angiopoietin-2, were quantified upon admission and associated with the need for vasopressors in the first 7 d of hospitalization.

RESULTS

A total of 86 patients with COVID-19 (mean age 60±16 y; 51 men [59%]) were evaluated. Thirty-six (42%) patients died during hospitalization and 50 (58%) survived. The group receiving vasopressors had higher levels of D-dimer (2.46 ng/ml [interquartile range {IQR} 0.6-6.1] vs 1.01 ng/ml [IQR 0.62-2.6], p=0.019) and lactate dehydrogenase (929±382 U/l vs 766±312 U/l, p=0.048). The frequency of deaths during hospitalization was higher in the group that received vasoactive amines in the first 24 h in the intensive care unit (70% vs 30%, p=0.002). SDC-1 levels were independently associated with the need for vasoactive amines, and admission values >269 ng/ml (95% CI 0.524 to 0.758, p=0.024) were able to predict the need for vasopressors during the 7 d following admission.

CONCLUSIONS

Syndecan-1 levels predict septic shock in critically ill patients with COVID-19.

Reverse shock index multiplied by simplified motor score as a predictor of clinical outcomes for patients with COVID-19

BACKGROUND

The reverse shock index (rSI) combined with the Simplified Motor Score (sMS), that is, the rSI-sMS, is a novel and efficient prehospital triage scoring system for patients with COVID-19. In this study, we evaluated the predictive accuracy of the rSI-sMS for general ward and intensive care unit (ICU) admission among patients with COVID-19 and compared it with that of other measures, including the shock index (SI), modified SI (mSI), rSI combined with the Glasgow Coma Scale (rSI-GCS), and rSI combined with the GCS motor subscale (rSI-GCSM).

METHODS

All patients who visited the emergency department of Taipei Tzu Chi Hospital between January 2021 and June 2022 were included in this retrospective cohort. A diagnosis of COVID-19 was confirmed through a SARS-CoV-2 reverse-transcription polymerase chain reaction test or SARS-CoV-2 rapid test with oropharyngeal or nasopharyngeal swabs and was double confirmed by checking International Classification of Diseases, Tenth Revision, Clinical Modification codes in electronic medical records. In-hospital mortality was regarded as the primary outcome, and sepsis, general ward or ICU admission, endotracheal intubation, and total hospital length of stay (LOS) were regarded as secondary outcomes. Multivariate logistic regression was used to determine the relationship between the scoring systems and the three major outcomes of patients with COVID-19, including. The discriminant ability of the predictive scoring systems was investigated using the area under the receiver operating characteristic curve, and the most favorable cutoff value of the rSI-sMS for each major outcome was determined using Youden's index.

RESULTS

After 74,183 patients younger than 20 years (n = 11,572) and without COVID-19 (n = 62,611) were excluded, 9,282 patients with COVID-19 (median age: 45 years, interquartile range: 33-60 years, 46.1% men) were identified as eligible for inclusion in the study. The rate of in-hospital mortality was determined to be 0.75%. The rSI-sMS scores were significantly lower in the patient groups with sepsis, hyperlactatemia, admission to a general ward, admission to the ICU, total length of stay ≥ 14 days, and mortality. Compared with the SI, mSI, and rSI-GCSM, the rSI-sMS exhibited a significantly higher accuracy for predicting general ward admission, ICU admission, and mortality but a similar accuracy to that of the rSI-GCS. The optimal cutoff values of the rSI-sMS for predicting general ward admission, ICU admission, and mortality were calculated to be 3.17, 3.45, and 3.15, respectively, with a predictive accuracy of 86.83%, 81.94%%, and 90.96%, respectively.

CONCLUSIONS

Compared with the SI, mSI, and rSI-GCSM, the rSI-sMS has a higher predictive accuracy for general ward admission, ICU admission, and mortality among patients with COVID-19.

Sepsis triggers and tools to support early identification in healthcare settings: An integrative review

BACKGROUND

There is no universal trigger or tool to aid sepsis diagnosis.

OBJECTIVES

The objective of this study was to identify triggers and tools to assist the early detection of sepsis that can be readily implemented across various health care settings.

METHODS

A systematic integrative review was conducted using MEDLINE, CINAHL, EMBASE, Scopus, and the Cochrane Database of Systematic Reviews. Relevant grey literature and subject-matter expert consultation also informed the review. Study types included systematic reviews, randomised controlled trials, and cohort studies. All patient populations across prehospital, emergency department, and acute hospital inpatient settings, excluding the intensive care unit, were included. Sepsis triggers and tools were evaluated for efficacy in detecting sepsis and association with process measures and patient outcomes. Methodological quality was appraised using Joanna Briggs Institute tools.

RESULTS

Of the 124 included studies, most were retrospective cohort (49.2%) in adults (83.9%) within the emergency department (44.4%). The most commonly evaluated sepsis tools were qSOFA (12 studies) and SIRS (11 studies) with a median sensitivity of 28.0% versus 51.0% and a specificity of 98.0% versus 82.0%, respectively, for sepsis diagnosis. Lactate plus qSOFA (two studies) had a sensitivity between 57.0 and 65.5%, whereas the National Early Warning Score (four studies) demonstrated median sensitivity and specificity >80%, but the latter was considered difficult to implement. Amongst triggers, lactate (18 studies) at the threshold of ≥2.0 mmol/L showed higher sensitivity for predicting sepsis-related clinical deterioration than <2.0 mmol/L. Automated sepsis alerts and algorithms (35 studies) showed median sensitivity between 58.0 and 80.0% and specificity between 60.0 and 93.1%. There were limited data for other sepsis tools and maternal, paediatric, and neonatal populations. Overall methodological quality was high.

CONCLUSION

No single sepsis tool or trigger is applicable across various settings and populations, but considering efficacy and ease of implementation, there is evidence to use lactate plus qSOFA for adult patients. More research is needed in maternal, paediatric, and neonatal populations.

Identification and Prediction of Clinical Phenotypes in Hospitalized Patients With COVID-19: Machine Learning From Medical Records

BACKGROUND

There is significant heterogeneity in disease progression among hospitalized patients with COVID-19. The pathogenesis of SARS-CoV-2 infection is attributed to a complex interplay between virus and host immune response that in some patients unpredictably and rapidly leads to "hyperinflammation" associated with increased risk of mortality. The early identification of patients at risk of progression to hyperinflammation may help inform timely therapeutic decisions and lead to improved outcomes.

OBJECTIVE

The primary objective of this study was to use machine learning to reproducibly identify specific risk-stratifying clinical phenotypes across hospitalized patients with COVID-19 and compare treatment response characteristics and outcomes. A secondary objective was to derive a predictive phenotype classification model using routinely available early encounter data that may be useful in informing optimal COVID-19 bedside clinical management.

METHODS

This was a retrospective analysis of electronic health record data of adult patients (N=4379) who were admitted to a Johns Hopkins Health System hospital for COVID-19 treatment from 2020 to 2021. Phenotypes were identified by clustering 38 routine clinical observations recorded during inpatient care. To examine the reproducibility and validity of the derived phenotypes, patient data were randomly divided into 2 cohorts, and clustering analysis was performed independently for each cohort. A predictive phenotype classifier using the gradient-boosting machine method was derived using routine clinical observations recorded during the first 6 hours following admission.

RESULTS

A total of 2 phenotypes (designated as phenotype 1 and phenotype 2) were identified in patients admitted for COVID-19 in both the training and validation cohorts with similar distributions of features, correlations with biomarkers, treatments, comorbidities, and outcomes. In both the training and validation cohorts, phenotype-2 patients were older; had elevated markers of inflammation; and were at an increased risk of requiring intensive care unit-level care, developing sepsis, and mortality compared with phenotype-1 patients. The gradient-boosting machine phenotype prediction model yielded an area under the curve of 0.89 and a positive predictive value of 0.83.

CONCLUSIONS

Using machine learning clustering, we identified and internally validated 2 clinical COVID-19 phenotypes with distinct treatment or response characteristics consistent with similar 2-phenotype models derived from other hospitalized populations with COVID-19, supporting the reliability and generalizability of these findings. COVID-19 phenotypes can be accurately identified using machine learning models based on readily available early encounter clinical data. A phenotype prediction model based on early encounter data may be clinically useful for timely bedside risk stratification and treatment personalization.

Protocolised early de-resuscitation in septic shock (REDUCE): protocol for a randomised controlled multicentre feasibility trial

BACKGROUND

Fluid overload is associated with excess mortality in septic shock. Current approaches to reduce fluid overload include restrictive administration of fluid or active removal of accumulated fluid. However, evidence on active fluid removal is scarce. The aim of this study is to assess the efficacy and feasibility of an early de-resuscitation protocol in patients with septic shock.

METHODS

All patients admitted to the intensive care unit (ICU) with a septic shock are screened, and eligible patients will be randomised in a 1:1 ratio to intervention or standard of care.

INTERVENTION

Fluid management will be performed according to the REDUCE protocol, where resuscitation fluid will be restricted to patients showing signs of poor tissue perfusion. After the lactate has peaked, the patient is deemed stable and assessed for active de-resuscitation (signs of fluid overload). The primary objective of this study is the proportion of patients with a negative cumulative fluid balance at day 3 after ICU. Secondary objectives are cumulative fluid balances throughout the ICU stay, number of patients with fluid overload, feasibility and safety outcomes and patient-centred outcomes. The primary outcome will be assessed by a logistic regression model adjusting for the stratification variables (trial site and chronic renal failure) in the intention-to-treat population.

ETHICS AND DISSEMINATION

The study was approved by the respective ethical committees (No 2020-02197). The results of the REDUCE trial will be published in an international peer-reviewed medical journal regardless of the results.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov, NCT04931485.

Detecting Diabetic Ketoacidosis with Infection: Combating a Life-Threatening Emergency with Practical Diagnostic Tools

BACKGROUND

Diabetic ketoacidosis (DKA) is a life-threatening acute complication of diabetes mellitus and can lead to patient demise if not immediately treated. From the recent literature, the diabetic ketoacidosis mortality rate, depending on age, is 2-5%. Insulin discontinuation and infection remain the two most common triggers for diabetic ketoacidosis. About 50% of cases of ketoacidosis result from bacterial infections like urinary tract infections and pneumonia. It is also important to diagnose the presence of infection in diabetic ketoacidosis patients to prevent the excessive use of antibiotics, which may lead to antibiotic resistance. Although performing bacterial culture is confirmatory for the presence or absence of bacterial infection, the time required to obtain the result is long. At the same time, emergency treatment needs to be started as early as possible.

METHODS

This narrative review examines various septic markers to identify the appropriate tools for diagnosis and to distinguish between diabetic ketoacidosis with and without infection. Electronic databases were searched using the Google engine with the keywords "Diabetes Mellitus", "Diabetic Ketoacidosis", "Infection with Diabetic Ketoacidosis", "biomarkers for infection in Diabetic Ketoacidosis", "Procalcitonin", "Inflammatory cytokines in DKA", "Lactic acidosis in DKA", and "White blood cell in infection in DKA".

RESULTS

This narrative review article presents the options for diagnosis and also aims to create awareness regarding the gravity of diabetic ketoacidosis with infection and emphasizes the importance of early diagnosis for appropriate management. Diabetes mellitus is a clinical condition that may lead to several acute and chronic complications. Acute diabetic ketoacidosis is a life-threatening condition in which an excess production of ketone bodies results in acidosis and hypovolemia. Infection is one of the most common triggers of diabetic ketoacidosis. When bacterial infection is present along with diabetic ketoacidosis, the mortality rate is even higher than for patients with diabetic ketoacidosis without infection. The symptoms and biomarkers of diabetic ketoacidosis are similar to that of infection, like fever, C reactive protein, and white blood cell count, since both create an environment of systemic inflammation. It is also essential to distinguish between the presence and absence of bacterial infection to ensure the appropriate use of antibiotics and prevent antimicrobial resistance. A bacterial culture report is confirmatory for the existence of bacterial infection, but this may take up to 24 h. Diagnosis needs to be performed approximately in the emergency room upon admission since there is a need for immediate management. Therefore, researching the possible diagnostic tools for the presence of infection in diabetic ketoacidosis patients is of great importance. Several of such biomarkers have been discussed in this research work.

Diagnostic and Prognostic Roles of Procalcitonin and Other Tools in Community-Acquired Pneumonia: A Narrative Review

Community-acquired pneumonia (CAP) is among the most common causes of death and one of the leading healthcare concerns worldwide. It can evolve into sepsis and septic shock, which have a high mortality rate, especially in critical patients and comorbidities. The definitions of sepsis were revised in the last decade as "life-threatening organ dysfunction caused by a dysregulated host response to infection". Procalcitonin (PCT), C-reactive protein (CRP), and complete blood count, including white blood cells, are among the most commonly analyzed sepsis-specific biomarkers also used in pneumonia in a broad range of studies. It appears to be a reliable diagnostic tool to expedite care of these patients with severe infections in the acute setting. PCT was found to be superior to most other acute phase reactants and indicators, including CRP as a predictor of pneumonia, bacteremia, sepsis, and poor outcome, although conflicting results exist. In addition, PCT use is beneficial to judge timing for the cessation of antibiotic treatment in most severe infectious states. The clinicians should be aware of strengths and weaknesses of known and potential biomarkers in expedient recognition and management of severe infections. This manuscript is intended to present an overview of the definitions, complications, and outcomes of CAP and sepsis in adults, with special regard to PCT and other important markers.

Implementing Pediatric Surviving Sepsis Campaign Guidelines: Improving Compliance With Lactate Measurement in the PICU

The 2020 pediatric Surviving Sepsis Campaign (pSSC) recommends measuring lactate during the first hour of resuscitation for severe sepsis/shock. We aimed to improve compliance with this recommendation for patients who develop severe sepsis/shock while admitted to the PICU.

DESIGN

Structured, quality improvement initiative.

SETTING

Single-center, 26-bed, quaternary-care PICU.

PATIENTS

All patients with PICU-onset severe sepsis/shock from December 2018 to December 2021.

INTERVENTIONS

Creation of a multidisciplinary local sepsis improvement team, education program targeting frontline providers (nurse practitioners, resident physicians), and peer-to-peer nursing education program with feedback to key stakeholders.

MEASUREMENTS AND MAIN RESULTS

The primary outcome measure was compliance with obtaining a lactate measurement within 60 minutes of the onset of severe sepsis/shock originating in our PICU using a local Improving Pediatric Sepsis Outcomes database and definitions. The process measure was time to first lactate measurement. Secondary outcomes included number of IV antibiotic days, number of vasoactive days, number of ICU days, and number of ventilator days. A total of 166 unique PICU-onset severe sepsis/shock events and 156 unique patients were included. One year after implementation of our first interventions with subsequent Plan-Do-Study-Act cycles, overall compliance increased from 38% to 47% (24% improvement) and time to first lactate decreased from 175 to 94 minutes (46% improvement). Using a statistical process control I chart, the preshift mean for time to first lactate measurement was noted to be 179 minutes and the postshift mean was noted to be 81 minutes demonstrating a 55% improvement.

CONCLUSIONS

This multidisciplinary approach led to improvement in time to first lactate measurement, an important step toward attaining our target of lactate measurement within 60 minutes of septic shock identification. Improving compliance is necessary for understanding implications of the 2020 pSSC guidelines on sepsis morbidity and mortality.

Combined Multiomics and In Silico Approach Uncovers PRKAR1A as a Putative Therapeutic Target in Multi-Organ Dysfunction Syndrome

Despite all epidemiological, clinical, and experimental research efforts, therapeutic concepts in sepsis and sepsis-induced multi-organ dysfunction syndrome (MODS) remain limited and unsatisfactory. Currently, gene expression data sets are widely utilized to discover new biomarkers and therapeutic targets in diseases. In the present study, we analyzed MODS expression profiles (comprising 13 sepsis and 8 control samples) retrieved from NCBI-GEO and found 359 differentially expressed genes (DEGs), among which 170 were downregulated and 189 were upregulated. Next, we employed the weighted gene co-expression network analysis (WGCNA) to establish a MODS-associated gene co-expression network (weighted) and identified representative module genes having an elevated correlation with age. Based on the results, a turquoise module was picked as our hub module. Further, we constructed the PPI network comprising 35 hub module DEGs. The DEGs involved in the highest-confidence PPI network were utilized for collecting pathway and gene ontology (GO) terms using various libraries. Nucleotide di- and triphosphate biosynthesis and interconversion was the most significant pathway. Also, 3 DEGs within our PPI network were involved in the top 5 significantly enriched ontology terms, with hypercortisolism being the most significant term. PRKAR1A was the overlapping gene between top 5 significant pathways and GO terms, respectively. PRKAR1A was considered as a therapeutic target in MODS, and 2992 ligands were screened for binding with PRKAR1A. Among these ligands, 3 molecules based on CDOCKER score (molecular dynamics simulated-based score, which allows us to rank the binding poses according to their quality and to identify the best pose for each system) and crucial interaction with human PRKAR1A coding protein and protein kinase-cyclic nucleotide binding domains (PKA RI alpha CNB-B domain) via active site binding residues, viz. Val283, Val302, Gln304, Val315, Ile327, Ala336, Ala337, Val339, Tyr373, and Asn374, were considered as lead molecules.

Definition of occult hypoperfusion in trauma: A systematic literature review

INTRODUCTION

Occult hypoperfusion (OH) entails inadequate tissue oxygenation in the presence of normal vital signs. Numerous studies have demonstrated that this phenomenon is associated with impaired outcome and increased mortality, however definitions of OH differ between studies. The aim of the current study was to identify and evaluate the published definitions of the term `occult hypoperfusion` in trauma (tOH).

MATERIAL & METHODS

A review of literature was performed using the Medline database. The following MeSH terms have been used: occult hypoperfusion, severe trauma, polytrauma, resuscitation. Clinical studies on OH were included and utilized definitions have been compared. A predefined data-interpretation process was applied to create an integrative definition for tOH.

RESULTS

A total of 43 publications used the term OH. A definition of OH was provided in 16 manuscripts. A pooled mean number of participants of 729 (SD: 1158) was found per study. The majority of manuscripts combine multiple parameters for inadequate tissue oxygenation and normal vital signs to define OH in trauma. In 12 manuscripts, specific cut-off values for hemodynamic parameters (SBP/PR/UP) and in 11/16 papers exact metabolic thresholds (lactate/B.E) were defined. The following definition best integrates definitions in current literature: Lactate > 2 mmol/l or BE <-3 mmol/l (to define inadequate oxygenation) plus SBP > 90 mmHg and PR < 120 bpm (to define normal macroperfusion).

CONCLUSIONS

The current systematic review demonstrates that definitions of occult hypoperfusion in trauma differ in the literature. The following comprehensive definition for (tOH) is proposed: Lactate > 2 mmol/l or BE <-3 mmol/l plus SBP > 90 mmHg and PR < 120 bpm. This recommendation appears to represent current literature on tOH and may improve the identification of trauma patients at risk for OH and related complicated courses. Further validation studies are required to demonstrate the clinical role of tOH and the proposed definition.

Addressing Cognitive Biases in Interpreting an Elevated Lactate in a Patient with Type 1 Diabetes and Thiamine Deficiency

We present the case of a young woman admitted for diabetic ketoacidosis with persistent, asymptomatic lactic acid (LA) elevation during the evolving COVID-19 pandemic. Cognitive biases in interpreting an elevated LA in this patient's care resulted in an extensive infectious workup instead of the low-cost and potentially diagnostic provision of empiric thiamine. We discuss clinical patterns and etiologies of LA elevation and the role of thiamine deficiency. We also address cognitive biases potentially affecting the interpretation of elevated lactate levels and provide guidance for clinicians to determine appropriate patients for empiric thiamine administration.

Early Lactate Clearance as a Determinant of Survival in Patients with Sepsis: Findings from a Low-resource Country

Background

Single lactate measurements have been reported to have prognostic significance, however, there is a lack of data in local literature from Pakistan. This study was done to determine prognostic role of lactate clearance in sepsis patients being managed in our lower-middle income country.

Methods

This prospective cohort study was conducted from September 2019-February 2020 at the Aga Khan University Hospital, Karachi. Patients were enrolled using consecutive sampling and categorized based on their lactate clearance status. Lactate clearance was defined as decrease by 10% or greater in repeat lactate from the initial measurement (or both initial and repeat levels <=2.0 mmol/L).

Results

A total 198 patients were included in the study, 51% (101) were male. Multi-organ dysfunction was reported in 18.6% (37), 47.7% (94) had single organ dysfunction, and 33.8% (67) had no organ dysfunction. Around 83% (165) were discharged and 17% (33) died. There were missing data for 25.8% (51) of the patients for the lactate clearance, whereas 55% (108) patients had early lactate clearance and 19.7% (39) had delayed lactate clearance.On univariate analysis, mortality rate was higher in patients with delayed lactate clearance (38.4% vs 16.6%) and patients were 3.12 times (OR = 3.12; [95% CI: 1.37-7.09]) more likely to die as compared with early lactate clearance. Patients with delayed lactate clearance had higher organ dysfunction (79.4% vs 60.1%) and were 2.56 (OR = 2.56; [95% CI: 1.07-6.13]) times likely to have organ dysfunction. On multivariate analysis, after adjusting for age and co-morbids, patients with delayed lactate clearance were 8 times more likely to die than patients with early lactate clearance [aOR = 7.67; 95% CI:1.11-53.26], however, there was no statistically significant association between delayed lactate clearance [aOR = 2.18; 95% CI: 0.87-5.49)] and organ dysfunction.

Conclusion

Lactate clearance is a better determinant of sepsis and septic shock effective management. Early lactate clearance is related to better outcomes in septic patients.

Prognostic accuracy of using lactate in addition to the quick Sequential Organ Failure Assessment score and the National Early Warning Score for emergency department patients with suspected infection

BACKGROUND

The aim of this study was to determine whether: (1) the quick Sequential (Sepsis-related) Organ Failure Assessment (qSOFA) and National Early Warning Score (NEWS) clinical prediction tools alone, (2) modified versions of these prediction tools that integrate lactate into their scores, or (3) use of the two tools in tandem with lactate better predicts in-hospital 28-day mortality among adult EDpatients with suspected infection.

METHODS

From 1 January through 31 December 2018, this retrospective cohort study enrolled consecutive adult patients with suspected infection evaluated at two EDs in France. Patients were included if blood cultures were obtained and non-prophylactic antibiotics were administered in the ED. qSOFA, NEWS criteria and lactate measurements were recorded when patients were clinically suspected of having an infection. Two composite scores (lactate qSOFA (LqSOFA) and lactate NEWS (LNEWS)) integrating lactate were created. Diagnostic test performances for predicting in-hospital mortality within 28days were assessed for qSOFA≥2, LqSOFA≥2, qSOFA≥2 or lactate≥2 mmol/L, and for NEWS≥7, LNEWS≥7, and NEWS≥7 or lactate≥2 mmol/L.

RESULTS

1003 patients were included, 130 (13%) of whom had died by day 28. Sensitivities for 28-day mortality were 50% (95%CI41% to 59%) for qSOFA≥2,69% (95% CI60% to 77%) for LqSOFA≥2,77% (95% CI69% to 84%) for qSOFA or lactate≥2 mmol/L; and 69% (95% CI60% to 77%) for NEWS≥7, 80% (95% CI72% to 86%) for LNEWS≥7, 87% (95% CI80% to 92%) for NEWS≥7 or lactate≥2 mmol/L.

CONCLUSION

Lactate used in tandem with qSOFA or NEWS yielded higher sensitivities in predicting in-hospital 28-day mortality, as compared with integration of lactate into these prediction tools or usage of the tools independently.

Septic Shock: Phenotypes and Outcomes

INTRODUCTION

Sepsis is a heterogeneous syndrome that results in life-threatening organ dysfunction. Our goal was to determine the relevant variables and patient phenotypes to use in predicting sepsis outcomes.

METHODS

We performed an ancillary study concerning 119 patients with septic shock at intensive care unit (ICU) admittance (T0). We defined clinical worsening as having an increased sequential organ failure assessment (SOFA) score of ≥ 1, 48 h after admission (ΔSOFA ≥ 1). We performed univariate and multivariate analyses based on the 28-day mortality rate and ΔSOFA ≥ 1 and determined three patient phenotypes: safe, intermediate and unsafe. The persistence of the intermediate and unsafe phenotypes after T0 was defined as a poor outcome.

RESULTS

At T0, the multivariate analysis showed two variables associated with 28-day mortality rate: norepinephrine dose and serum lactate concentration. Regarding ΔSOFA ≥ 1, we identified three variables at T0: norepinephrine dose, lactate concentration and venous-to-arterial carbon dioxide difference (P(v-a)CO₂). At T0, the three phenotypes (safe, intermediate and unsafe) were found in 28 (24%), 70 (59%) and 21 (18%) patients, respectively. We thus suggested using an algorithm featuring norepinephrine dose, lactate concentration and P(v-a)CO₂ to predict patient outcomes and obtained an area under the curve (AUC) of 74% (63-85%).

CONCLUSION

Our findings highlight the fact that identifying relevant variables and phenotypes may help physicians predict patient outcomes.

Serum lactate is associated with increased illness severity in immunocompromised pediatric hematology oncology patients presenting to the emergency department with fever

Introduction

Determining which febrile pediatric hematology/oncology (PHO) patients will decompensate from severe infection is a significant challenge. Serum lactate is a well-established marker of illness severity in general adult and pediatric populations, however its utility in PHO patients is unclear given that chemotherapy, organ dysfunction, and cancer itself can alter lactate metabolism. In this retrospective analysis, we studied the association of initial serum lactate in febrile immunosuppressed PHO patients with illness severity, defined by the incidence of clinical deterioration events (CDE) and invasive bacterial infection (IBI) within 48 hours.

Methods

Receiver operating characteristic (ROC) curves were reported using initial lactate within two hours of arrival as the sole predictor for CDE and IBI within 48 hours. Using a generalized estimating equations (GEE) approach, the association of lactate with CDE and IBI within 48 hours was tested in univariate and multivariable analyses including covariates based on Quasi-likelihood under Independence Model Criterion (QIC). Additionally, the association of lactate with secondary outcomes (i.e., hospital length of stay (LOS), intensive care unit (PICU) admission, PICU LOS, non-invasive infection) was assessed.

Results

Among 897 encounters, 48 encounters had ≥1 CDE (5%), and 96 had ≥1 IBI (11%) within 48 hours. Elevated lactate was associated with increased CDE in univariate (OR 1.77, 95%CI: 1.48-2.12, p<0.001) and multivariable (OR 1.82, 95%CI: 1.43-2.32, p<0.001) analyses, longer hospitalization (OR 1.15, 95%CI: 1.07-1.24, p<0.001), increased PICU admission (OR 1.68, 95%CI: 1.41-2.0, p<0.001), and longer PICU LOS (OR 1.21, 95%CI: 1.04-1.4, p=0.01). Elevated lactate was associated with increased IBI in univariate (OR 1.40, 95%CI: 1.16-1.69, p<0.001) and multivariable (OR 1.49, 95%CI: 1.23-1.79, p<0.001) analyses. Lactate level was not significantly associated with increased odds of non-invasive infection (p=0.09). The QIC of the model was superior with lactate included for both CDE (305 vs. 325) and IBI (563 vs. 579).

Conclusions

These data demonstrated an independent association of elevated initial lactate level and increased illness severity in febrile PHO patients, suggesting that serum lactate could be incorporated into future risk stratification strategies for this population.

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.

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.

Septic shock 3.0 criteria application in severe COVID-19 patients: An unattended sepsis population with high mortality risk

BACKGROUND

Coronavirus disease 2019 (COVID-19) can be associated with life-threatening organ dysfunction due to septic shock, frequently requiring intensive care unit (ICU) admission, respiratory and vasopressor support. Therefore, clear clinical criteria are pivotal for early recognition of patients more likely to need prompt organ support. Although most patients with severe COVID-19 meet the Sepsis-3.0 criteria for septic shock, it has been increasingly recognized that hyperlactatemia is frequently absent, possibly leading to an underestimation of illness severity and mortality risk.

AIM

To identify the proportion of severe COVID-19 patients with vasopressor support requirements, with and without hyperlactatemia, and describe their clinical outcomes and mortality.

METHODS

We performed a single-center prospective cohort study. All adult patients admitted to the ICU with COVID-19 were included in the analysis and were further divided into three groups: Sepsis group, without both criteria; Vasoplegic Shock group, with persistent hypotension and vasopressor support without hyperlactatemia; and Septic Shock 3.0 group, with both criteria. COVID-19 was diagnosed using clinical and radiologic criteria with a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) positive RT-PCR test.

RESULTS

118 patients (mean age 63 years, 87% males) were included in the analysis (n = 51 Sepsis group, n = 26 Vasoplegic Shock group, and n = 41 Septic Shock 3.0 group). SOFA score at ICU admission and ICU length of stay were different between the groups (P < 0.001). Mortality was significantly higher in the Vasoplegic Shock and Septic Shock 3.0 groups when compared with the Sepsis group (P < 0.001) without a significant difference between the former two groups (P = 0.713). The log rank tests of Kaplan-Meier survival curves were also different (P = 0.007). Ventilator-free days and vasopressor-free days were different between the Sepsis vs Vasoplegic Shock and Septic Shock 3.0 groups (both P < 0.001), and similar in the last two groups (P = 0.128 and P = 0.133, respectively). Logistic regression identified the maximum dose of vasopressor therapy used (AOR 1.046; 95%CI: 1.012-1.082, P = 0.008) and serum lactate level (AOR 1.542; 95%CI: 1.055-2.255, P = 0.02) as the major explanatory variables of mortality rates (R² 0.79).

CONCLUSION

In severe COVID-19 patients, the Sepsis 3.0 criteria of septic shock may exclude approximately one third of patients with a similarly high risk of a poor outcome and mortality rate, which should be equally addressed.

Effect of oXiris-CVVH on the Clinical Outcomes of Patients with Septic Shock: An Inverse Probability of Treatment-Weighted Analysis

BACKGROUND

Limited previous studies had proved that oXiris-continuous veno-venous hemofiltration (CVVH) could decrease endotoxins and inflammatory factors, thereby improving circulation's stability. However, conclusive data are lacking regarding the comparison between oXiris membrane (with the function of removing endotoxins and decreasing inflammatory factors) and AN69 filters (with the only function of decreasing inflammatory) on the mortality of patients with septic shock. The potential mechanisms of oXiris that might influence the mortality of septic shock patients remain unexplored.

METHODS

This is a single-center, retrospective cohort study. The experimental group (30 patients with septic shock) was treated with oXiris-CVVH, and the control group (46 patients with septic shock) was treated with AN69 filter-CVVH. We employed the inverse probability of treatment-weighting method (IPTW), doubly robust estimation, and mediating effect analysis to analyze those clinical outcomes, with a special focus on the results of 28-day mortality, 72-h lactate, the need for norepinephrine (NE) in the next 72 h.

RESULTS

A total of 76 patients with septic shock who received blood purification therapies were enrolled. After IPTW, differences in patient characteristics have been minimized. The 28-day mortality in the control group is higher than in the treatment group (73.3% vs. 47.3%, p < 0.001; median survival time: 10 vs. ≥28 days, log-rank p = 0.0366). And the 25% decrease and the 50% decrease in demand for NE in the next 72 h are different between the treatment and control groups (median time of 25% decrease in demand: 24 vs. >72 h, log-rank p = 0.0126; median time of 50% decrease in demand: 24 vs. >72 h, log-rank p = 0.0322). The 72-h lactic acid level and white blood cell (WBC) counts in the oXiris group are lower than in the control group. The 72-h lactate fully mediated the effects of oXiris on 28-day mortality after confounds adjustment.

CONCLUSIONS

For septic shock patients, the use of oXiris-CVVH was associated with lower mortality and appeared to reduce lactate, NE dosage, PCT, and WBC counts, as compared to AN69-CVVH.

Serum Lactate for Predicting Cardiac Arrest in the Emergency Department

Objectives: Early recognition and prevention of in-hospital cardiac arrest (IHCA) play an increasingly important role in the Chain of Survival. However, clinical tools for predicting IHCA in the emergency department (ED) are scanty. We sought to evaluate the role of serum lactate in predicting ED-based IHCA. Methods: Data were retrieved from 733,398 ED visits over a 7-year period in a tertiary medical centre. We selected one ED visit per person and excluded out-of-hospital cardiac arrest, children, or those without lactate measurements. Patient demographics, computerised triage information, and serum lactate levels were extracted. The initial serum lactate levels were grouped into normal (≤2 mmol/L), moderately elevated (2 < lactate ≤ 4), and highly elevated (>4 mmol/L) categories. The primary outcome was ED-based IHCA. Results: A total of 17,392 adult patients were included. Of them, 342 (2%) developed IHCA. About 50% of the lactate levels were normal, 30% were moderately elevated, and 20% were highly elevated. In multivariable analysis, the group with highly elevated lactate had an 18-fold increased risk of IHCA (adjusted odds ratio [OR], 18.0; 95% confidence interval [CI], 11.5-28.2), compared with the normal lactate group. In subgroup analysis, the poor lactate-clearance group (<2.5%/h) was associated with a 7.5-fold higher risk of IHCA (adjusted OR, 7.5; 95%CI, 3.7-15.1) compared with the normal clearance group. Conclusions: Elevated lactate levels and poor lactate clearance were strongly associated with a higher risk of ED-based IHCA. Clinicians may consider a more liberal sampling of lactate in patients at higher risk of IHCA with follow-up of abnormal levels.

Fluid Overload Phenotypes in Critical Illness-A Machine Learning Approach

BACKGROUND

The detrimental impact of fluid overload (FO) on intensive care unit (ICU) morbidity and mortality is well known. However, research to identify subgroups of patients particularly prone to fluid overload is scarce. The aim of this cohort study was to derive "FO phenotypes" in the critically ill by using machine learning techniques.

METHODS

Retrospective single center study including adult intensive care patients with a length of stay of ≥3 days and sufficient data to compute FO. Data was analyzed by multivariable logistic regression, fast and frugal trees (FFT), classification decision trees (DT), and a random forest (RF) model.

RESULTS

Out of 1772 included patients, 387 (21.8%) met the FO definition. The random forest model had the highest area under the curve (AUC) (0.84, 95% CI 0.79-0.86), followed by multivariable logistic regression (0.81, 95% CI 0.77-0.86), FFT (0.75, 95% CI 0.69-0.79) and DT (0.73, 95% CI 0.68-0.78) to predict FO. The most important predictors identified in all models were lactate and bicarbonate at admission and postsurgical ICU admission. Sepsis/septic shock was identified as a risk factor in the MV and RF analysis.

CONCLUSION

The FO phenotypes consist of patients admitted after surgery or with sepsis/septic shock with high lactate and low bicarbonate.

Risk factor analysis and nomogram for predicting in-hospital mortality in ICU patients with sepsis and lung infection

Background

Lung infection is a common cause of sepsis, and patients with sepsis and lung infection are more ill and have a higher mortality rate than sepsis patients without lung infection. We constructed a nomogram prediction model to accurately evaluate the prognosis of and provide treatment advice for patients with sepsis and lung infection.

Methods

Data were retrospectively extracted from the Medical Information Mart for Intensive Care (MIMIC-III) open-source clinical database. The definition of Sepsis 3.0 [10] was used, which includes patients with life-threatening organ dysfunction caused by an uncontrolled host response to infection, and SOFA score ≥ 2. The nomogram prediction model was constructed from the training set using logistic regression analysis, and was then internally validated and underwent sensitivity analysis.

Results

The risk factors of age, lactate, temperature, oxygenation index, BUN, lactate, Glasgow Coma Score (GCS), liver disease, cancer, organ transplantation, Troponin T(TnT), neutrophil-to-lymphocyte ratio (NLR), and CRRT, MV, and vasopressor use were included in the nomogram. We compared our nomogram with the Sequential Organ Failure Assessment (SOFA) score and Simplified Acute Physiology Score II (SAPSII), the nomogram had better discrimination ability, with areas under the receiver operating characteristic curve (AUROC) of 0.743 (95% C.I.: 0.713–0.773) and 0.746 (95% C.I.: 0.699–0.790) in the training and validation sets, respectively. The calibration plot indicated that the nomogram was adequate for predicting the in-hospital mortality risk in both sets. The decision-curve analysis (DCA) of the nomogram revealed that it provided net benefits for clinical use over using the SOFA score and SAPSII in both sets.

Conclusion

Our new nomogram is a convenient tool for accurate predictions of in-hospital mortality among ICU patients with sepsis and lung infection. Treatment strategies that improve the factors considered relevant in the model could increase in-hospital survival for these ICU patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-021-01809-8.

A portable blood lactate sensor with a non-immobilized enzyme for early sepsis diagnosis

Early determination of blood lactate levels may accelerate the detection of sepsis, one of the most time-sensitive illnesses.

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.

Clinical Significance of Serum Lactate in Acute Myocardial Infarction: A Cardiac Magnetic Resonance Imaging Study

Little is known about causality and the pathological mechanism underlying the association of serum lactate with myocardial injury in patients with acute myocardial infarction (AMI). We evaluated data from 360 AMI patients undergoing percutaneous coronary intervention (PCI) using cardiovascular magnetic resonance imaging (CMR). Of these, 119 patients had serum lactate levels > 2.5 mmol/L on admission (high serum lactate group), whereas 241 patients had serum lactate levels ≤ 2.5 mmol/L (low serum lactate group). We compared the myocardial infarct size assessed by CMR between the two groups and performed inverse probability of treatment weighting (IPTW). In CMR analysis, myocardial infarct size was significantly greater in the high serum lactate group than in the low serum lactate group (22.0 ± 11.4% in the high serum lactate group vs. 18.9 ± 10.5% in the low serum lactate group; p = 0.011). The result was consistent after IPTW adjustment (21.5 ± 11.1% vs. 19.2 ± 10.4%; p = 0.044). In multivariate analysis, high serum lactate was associated with larger myocardial infarct (odds ratio 1.59; 95% confidence interval 1.00–2.51; p = 0.048). High serum lactate could predict advanced myocardial injury in AMI patients undergoing PCI.

What Is the Utility of Measuring Lactate Levels in Patients with Sepsis and Septic Shock?

Elevations in blood lactate concentrations have been studied in sepsis and other disease states for decades and are well known to be associated with increased mortality. Many studies have also demonstrated the prognostic accuracy of serial lactate levels, and some have suggested that lactate clearance may be a useful therapeutic target for resuscitation. Lactate measurements have therefore gained an increasingly prominent role in sepsis definitions, screening protocols, management guidelines, and quality measures over the past two decades. The heavy emphasis on lactate monitoring, however, has also generated controversy and concerns. Lactate is not specific to infection and its frequent use for sepsis screening and diagnosis may therefore trigger unnecessary broad-spectrum antibiotic use in some patients. Because hyperlactatemia does not always reflect fluid-responsive hypoperfusion, titrating resuscitation to lactate clearance can also lead to unnecessary fluid and volume overload. More broadly, there is a lack of high-quality evidence demonstrating that initial and serial lactate monitoring leads to better patient-centered outcomes. Indeed, a recent randomized controlled trial comparing resuscitation strategies based on lactate clearance versus normalizing capillary refill time showed no benefit and potential harm with lactate-guided therapy. In this article, we review the basic pathobiology of lactate metabolism and delineate why the traditional paradigm that hyperlactatemia reflects tissue hypoxia is overly simplistic and incomplete. We then review the evidence behind the diagnostic, prognostic, and therapeutic uses of lactate monitoring and place this in the context of evolving sepsis diagnosis and management guidelines.

Effects of lactate in immunosuppression and inflammation: Progress and prospects

Lactate used to be considered as a waste product of glucose metabolism. However, accumulating evidence has revealed its crucial role in regulating various biological and pathological processes. Hypoxia, inflammation, viral infection, and tumor promote the production of lactate. Then lactate activates G protein-coupled receptor 81 (GPR81) or shuttles across membranes by monocarboxylate-transporters (MCTs) to execute its intricate effects. Many studies highlighted the function of lactate in regulating dendritic cells, monocytes, natural killer cells, mast cells, T cells, tumor cells, fibroblasts, macrophages polarization, and the differentiation of Th1, Th17, MDSCs, Tregs; all of which play a role in maintaining the immune homeostasis of the host when challenged with the noxious stimuli. In this review, we summarized the influence of lactate in diverse tissue-specific cells, and discuss their effects on viral infection, acute inflammation, chronic inflammation, sepsis, and tumor immunosuppression. The goal of this review is to expose that lactate has a double-edged effect on host immunity and accompanying inflammatory reactions, which could be a potentially effective target for treating the tumor and multiple infectious diseases.

Comparing Mortality Prediction by Quick Sequential Organ Failure Assessment with Emergency Physician Judgment

STUDY OBJECTIVE

The quick sequential organ failure assessment (qSOFA) was proposed to identify infected patients at risk for mortality, an indication of sepsis, in nonintensive care unit settings. This study tests whether qSOFA improves physician prediction of mortality among infected Emergency Department (ED) patients.

METHODS

We performed a secondary analysis of a prospective, observational study of potentially septic ED patients, conducted between two urban, academic medical centers, from July 2016 to December 2017. We enrolled ED patients with two or more systemic inflammatory response syndrome criteria and severe sepsis qualifying organ dysfunction, systolic blood pressure <90 mm Hg, or lactate ≥ 4.0 mmol/L. Infectious etiology was adjudicated retrospectively by paired physician review. We excluded noninfected patients. Treating ED physicians submitted judgment for in-hospital mortality (0%-100%) at hospital admission, and qSOFA was calculated retrospectively using ED data. The primary outcome was in-hospital mortality within 28 days. We used logistic regression to predict mortality using physician judgment, qSOFA, and combined physician judgment and qSOFA. To assess differences between models, 95% confidence intervals for area under the curve (AUC) were derived by bootstrapping with 1,000 iterations.

RESULTS

Of 405 patients meeting inclusion criteria, 195 (48.1%) were determined to have infection and analyzed. Of analyzed patients, 16 (8.2%) suffered in-hospital mortality within 28 days. Analyzed patients had a mean age of 58.3 (SD 16.5) years and 78 (40%) were female. qSOFA alone (AUC 0.63; 95% CI: 0.53-0.73) was not superior to unstructured physician judgment (AUC 0.80; 0.70-0.89) when predicting 28-day in-hospital mortality with mean AUC difference 0.17 (0.07-0.28) across bootstrapped datasets. Combining qSOFA with physician judgment (AUC 0.79; 0.69-0.89) did not improve performance compared with physician judgment alone.

CONCLUSION

When predicting 28-day in-hospital mortality among infected ED patients, qSOFA did not outperform or improve physician judgment.

Evaluation of the Prognostic Value of Lactate and Acid-Base Status in Patients Presenting to the Emergency Department

Background

Lactate levels predict mortality in a wide range of patients presenting to the Emergency Department (ED); however, the effect of co-existing acidosis is unknown. Here, we investigated the effect of acidosis on in-hospital mortality for patients with hyperlactataemia.

Methodology

This is a retrospective cohort study of adults cared for in the resuscitation area of one ED who received a metabolic panel on arrival. The primary outcome was in-hospital mortality for patients with normal lactate (0.0-2.0 mmol/L), intermediate lactate (2.1-4.0 mmol/L), or high lactate (>4.0 mmol/L), with and without acidosis. Odds ratios (ORs) were calculated to assess the differences in mortality rates between groups stratified by lactate and acid-base status.

Results

A total of 4,107 metabolic panels were collected and 3,238 were assessed. In total, 510 (15.8%) and 784 (24.2%) patients had a normal lactate and acidosis/no acidosis; 587 (18.1%) and 842 (26.0%) had intermediate lactate and acidosis/no acidosis; and 388 (12.0%) and 127 (3.9%) had high lactate and acidosis/no acidosis, respectively. The overall mortality was 5%. Mortality was 4.3%/0.6% in the normal lactate, 5.6%/2.6% in the intermediate lactate, and 19.3%/3.9% in the high lactate groups, with and without acidosis, respectively. Combining base excess <-6 and lactate >4 mmol/L had a sensitivity of 39%, specificity of 96%, positive predictive value of 32%, and negative predictive value of 98% for in-hospital mortality (OR: 14.0; 95% confidence interval: 9.77-20.11).

Conclusions

In an undifferentiated cohort of ED patients presenting to the resuscitation area lactaemia associated with acidosis is a more accurate predictor of in-hospital mortality than hyperlactataemia.

Infectious Diseases Society of America Position Paper: Recommended Revisions to the National Severe Sepsis and Septic Shock Early Management Bundle (SEP-1) Sepsis Quality Measure

The Centers for Medicare & Medicaid Services' Severe Sepsis and Septic Shock Early Management Bundle (SEP-1) measure has appropriately established sepsis as a national priority. However, the Infectious Diseases Society of America (IDSA and five additional endorsing societies) is concerned about SEP-1's potential to drive antibiotic overuse because it does not account for the high rate of sepsis overdiagnosis and encourages aggressive antibiotics for all patients with possible sepsis, regardless of the certainty of diagnosis or severity of illness. IDSA is also concerned that SEP-1's complex "time zero" definition is not evidence-based and is prone to inter-observer variation. In this position paper, IDSA outlines several recommendations aimed at reducing the risk of unintended consequences of SEP-1 while maintaining focus on its evidence-based elements. IDSA's core recommendation is to limit SEP-1 to septic shock, for which the evidence supporting the benefit of immediate antibiotics is greatest. Prompt empiric antibiotics are often appropriate for suspected sepsis without shock, but IDSA believes there is too much heterogeneity and difficulty defining this population, uncertainty about the presence of infection, and insufficient data on the necessity of immediate antibiotics to support a mandatory treatment standard for all patients in this category. IDSA believes guidance on managing possible sepsis without shock is more appropriate for guidelines that can delineate the strengths and limitations of supporting evidence and allow clinicians discretion in applying specific recommendations to individual patients. Removing sepsis without shock from SEP-1 will mitigate the risk of unnecessary antibiotic prescribing for noninfectious syndromes, simplify data abstraction, increase measure reliability, and focus attention on the population most likely to benefit from immediate empiric broad-spectrum antibiotics.

Impact of integrated graphical display on expert and novice diagnostic performance in critical care

OBJECTIVE

To determine the impact of a graphical information display on diagnosing circulatory shock.

MATERIALS AND METHODS

This was an experimental study comparing integrated and conventional information displays. Participants were intensivists or critical care fellows (experts) and first-year medical residents (novices).

RESULTS

The integrated display was associated with higher performance (87% vs 82%; P < .001), less time (2.9 vs 3.5 min; P = .008), and more accurate etiology (67% vs 54%; P = .048) compared to the conventional display. When stratified by experience, novice physicians using the integrated display had higher performance (86% vs 69%; P < .001), less time (2.9 vs 3.7 min; P = .03), and more accurate etiology (65% vs 42%; P = .02); expert physicians using the integrated display had nonsignificantly improved performance (87% vs 82%; P = .09), time (2.9 vs 3.3; P = .28), and etiology (69% vs 67%; P = .81).

DISCUSSION

The integrated display appeared to support efficient information processing, which resulted in more rapid and accurate circulatory shock diagnosis. Evidence more strongly supported a difference for novices, suggesting that graphical displays may help reduce expert-novice performance gaps.

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.

Discordance between lactic acidemia and hemodynamics in patients with advanced heart failure

Background

Elevated lactic acid (LA) levels carry a poor prognosis in patients with shock. Data are lacking on the significance of LA levels in patients with acute decompensated heart failure (ADHF).

Hypothesis

This study assessed the relationship between LA levels, hemodynamics and clinical outcomes.

Methods

This was a retrospective analysis of registry data of 100 advanced heart failure patients presenting for right heart catheterization (RHC) for concern of ADHF. LA levels (normal ≤2.1 mmol/L) were obtained prior to RHC; no significant changes in therapy were made between LA collection and RHC.

Results

Median age was 58 (47.3, 64.8) years; 57% were receiving inotropes prior to RHC. Median pulmonary capillary wedge pressure (PCWP) and cardiac index (CI) were 28 (21, 35) mmHg and 2.0 (1.7, 2.5) L/min/m², respectively. Eighty patients had normal LA prior to RHC. There was no correlation between LA levels and PCWP (R = 0.09, p = .38); 63% of the normal LA group had a PCWP >24 mmHg. There was a moderate inverse correlation between LA and CI (R = − 0.40; p < .001); 58% of the normal LA group had a CI <2.2 L/min/m². Thirty‐day survival free of death/hospice, inotrope dependence, progression to heart transplant/left‐ventricular assist device implant was comparable between the normal and elevated LA groups (28% vs. 20%; p = .17).

Conclusion

In patients presenting with ADHF, normal LA levels do not exclude the presence of depressed CI (a hemodynamic criteria for cardiogenic shock) and may not offer accurate risk stratification. Invasive hemodynamics should not be delayed based on normal LA levels alone.

Prognostic Accuracy of VqSOFA for Predicting 28-day Mortality in Patients with Suspected Sepsis in the Emergency Department

BACKGROUND

Sepsis screening in the emergency department (ED) is challenging. The quick Sequential Organ Failure Assessment (qSOFA) score had poor accuracy for predicting mortality in both the intensive care unit and ED. High lactate levels were associated with an increased mortality. However, a previous study using lactate levels in combination with the qSOFA score did not observe a meaningful improvement in predictive accuracy. This study assessed the prognostic accuracy of venous lactate levels plus the qSOFA (VqSOFA) score for predicting 28-day mortality.

METHODS

Patients who visited the Ramathibodi ED with suspected sepsis were enrolled. The VqSOFA, qSOFA, and Sequential Organ Failure Assessment (SOFA) scores were calculated using the initial vital signs and laboratory values. Prognostic accuracy was measured using the area under the receiver operating characteristic (AUROC) curve of the VqSOFA score and Sepsis-3 criteria for predicting 28-day mortality.

RESULTS

In total, 1,139 patients were enrolled, 118 of whom died within 28 days of admission. The AUROCs of the VqSOFA, qSOFA, and SOFA scores were 0.851 (95% CI 0.813-0.889), 0.813 (95% CI 0.772-0.854), and 0.728 (95% CI 0.671-0.784), respectively. Using VqSOFA score ≥ 3 as the cutoff, the sensitivity, specificity, and positive likelihood ratio were 74.6%, 82.5%, and 4.25%, respectively. VqSOFA ≥ 3 was linked to a low probability of 28-day survival and higher odds of vasopressor and ventilator use within 24 h.

CONCLUSIONS

VqSOFA was more predictive of 28-day mortality and vasopressor and mechanical ventilator use than the qSOFA and SOFA scores.

Effects of intraoperative adrenergic administration on postoperative hyperlactatemia in open colon surgery: an observational study

Background

Postoperative Hyperlactatemia (PO-HL) is a frequent condition associated with poor prognosis. In recent years, there has been growing evidence that adrenergic stimulation may contribute to increased lactate levels. The use of adrenergic agonists for the control of intraoperative hypotension is frequent, and its impact on the development of PO-HL is unknown.

Objective

To evaluate whether the use of intraoperative adrenergic agents is associated with the occurrence of PO-HL.

Methods

This was a prospective observational study. The inclusion criteria were undergoing elective open colon surgery, being ≥60 years old and signing informed consent. The exclusion criteria were cognitive impairment, unplanned surgery, and anticipated need for postoperative mechanical ventilation. Baseline and intraoperative variables were collected, and arterial lactate data were collected at baseline and every 6 hours postoperatively for 24 hours. Hyperlactatemia was defined as lactate >2.1 mEq.L^-1.

Results

We studied 28 patients, 61% of whom developed hyperlactatemia. The variables associated with PO-HL in the univariate analysis were anesthetic time, the total dose of intraoperative ephedrine, and lower intraoperative central venous oxygen saturation (ScvO₂). Multivariate analysis confirmed the association between the use of ephedrine (p = 0.004), intraoperative hypotension (p = 0.026), and use of phenylephrine (p = 0.001) with PO-HL.

Conclusions

The use of intraoperative ephedrine, phenylephrine and intraoperative hypotension were independently associated with the development of PO-HL. This finding should lead to new studies in this field, as well as a judicious interpretation of the finding of a postoperative increase in lactate levels.

Model for End-Stage Liver Disease-Lactate and Prediction of Inpatient Mortality in Patients With Chronic Liver Disease

BACKGROUND AND AIMS

Compared to other chronic diseases, patients with chronic liver disease (CLD) have significantly higher inpatient mortality; accurate models to predict inpatient mortality are lacking. Serum lactate (LA) may be elevated in patients with CLD due to both tissue hypoperfusion as well as decreased LA clearance. We hypothesized that a parsimonious model consisting of Model for End-Stage Liver Disease (MELD) and LA at admission may predict inpatient mortality in patients with CLD.

APPROACH AND RESULTS

We examined all patients with CLD in two large and diverse health care systems in Texas (North Texas [NTX] and Central Texas [CTX]) between 2010 and 2015. We developed (n = 3,588) and validated (n = 1,804) a model containing MELD and LA measured at the time of hospitalization. We further validated the model in a second cohort of 14 tertiary care hepatology centers that prospectively enrolled nonelective hospitalized patients with cirrhosis (n = 726). MELD-LA was an excellent predictor of inpatient mortality in development (concordance statistic [C-statistic] = 0.81, 95% confidence interval [CI] 0.79-0.82) and both validation cohorts (CTX cohort, C-statistic = 0.85, 95% CI 0.78-0.87; multicenter cohort C-statistic = 0.82, 95% CI 0.74-0.88). MELD-LA performed especially well in patients with specific cirrhosis diagnoses (C-statistic = 0.84, 95% CI 0.81-0.86) or sepsis (C-statistic = 0.80, 95% CI 0.78-0.82). For MELD score 25, inpatient mortality rates were 11.2% (LA = 1 mmol/L), 19.4% (LA = 3 mmol/L), 34.3% (LA = 5 mmol/L), and >50% (LA > 8 mmol/L). A linear increase (P < 0.01) was seen in MELD-LA and increasing number of organ failures. Overall, use of MELD-LA improved the risk prediction in 23.5% of patients compared to MELD alone.

CONCLUSIONS

MELD-LA (bswh.md/meldla) is an early and objective predictor of inpatient mortality and may serve as a model for risk assessment and guide therapeutic options.

Quantitative Assessment of Blood Lactate in Shock: Measure of Hypoxia or Beneficial Energy Source

Blood lactate concentration predicts mortality in critically ill patients and is clinically used in the diagnosis, grading of severity, and monitoring response to therapy of septic shock. This paper summarizes available quantitative data to provide the first comprehensive description and critique of the accepted concepts of the physiology of lactate in health and shock, with particular emphasis on the controversy of whether lactate release is simply a manifestation of tissue hypoxia versus a purposeful transfer ("shuttle") of lactate between tissues. Basic issues discussed include (1) effect of nonproductive lactate-pyruvate exchange that artifactually enhances flux measurements obtained with labeled lactate, (2) heterogeneous tissue oxygen partial pressure (Krogh model) and potential for unrecognized hypoxia that exists in all tissues, and (3) pathophysiology that distinguishes septic from other forms of shock. Our analysis suggests that due to exchange artifacts, the turnover rate of lactate and the lactate clearance are only about 60% of the values of 1.05 mmol/min/70 kg and 1.5 L/min/70 kg, respectively, determined from the standard tracer kinetics. Lactate turnover reflects lactate release primarily from muscle, gut, adipose, and erythrocytes and uptake by the liver and kidney, primarily for the purpose of energy production (TCA cycle) while the remainder is used for gluconeogenesis (Cori cycle). The well-studied physiology of exercise-induced hyperlactatemia demonstrates massive release from the contracting muscle accompanied by an increased lactate clearance that may occur in recovering nonexercising muscle as well as the liver. The very limited data on lactate kinetics in shock patients suggests that hyperlactatemia reflects both decreased clearance and increased production, possibly primarily in the gut. Our analysis of available data in health and shock suggests that the conventional concept of tissue hypoxia can account for most blood lactate findings and there is no need to implicate a purposeful production of lactate for export to other organs.

The role of the serum lactate level at the first admission to the emergency department in predicting mortality

INTRODUCTION

Lactate is an easily measurable laboratory parameter that is considered a potentially useful prognostic marker for determining risk in emergency department patients. The aim of this study was to investigate the role of serum lactate in the patients who were admitted to the emergency department at the time of admission.

METHODS

Patients who were admitted to the emergency department for various reasons between June 2017 and January 2018 were included in the study. Demographic data, laboratory findings, mortality and hospitalization rates of the patients were analyzed. The primary endpoint was determined as the role of serum lactate in predicting mortality, and the secondary endpoint in predicting hospitalization.

RESULTS

Of the 1382 patients, 47.4% (n = 655) were female and 52.6% (n = 727) were male. The mean age of the patients was 60.99 ± 20.04 (18-100) years. In 59.6% (n = 824) of the patients, the most common hypertension (36%) was an additional disease. Mortality was found in 43 (3.1%) patients. It was observed that 20.5% (n = 284) of the patients were hospitalized. The ages of patients with hospitalization and mortality were found to be statistically significant higher than those without hospitalization and without mortality (p = 0.001; p < 0.01). There was no statistically significant difference between the serum lactate measurements of the patients according to hospitalization (p > 0.05). The serum lactate levels of the patients with mortality were found to be statistically significant higher than those without mortality (p = 0.001; p < 0.01). The cut off point for serum lactate level in predicting mortality was found to be ≥3.6 mmol/L. The mortality rate was found to be statistically significant higher in patients with serum lactate level 3,6 mmol/L and above (p = 0,001; p < 0,01).

CONCLUSION

In conclusion, we believe in the light of the findings of our study that the serum lactate level is effective and reliable in the prediction of mortality in patients who present to emergency department for any reason. However, prospective studies with broader patient groups are required in this subject.

Evaluation of an Anti-Thrombotic Continuous Lactate and Blood Pressure Monitoring Catheter in an In Vivo Piglet Model undergoing Open-Heart Surgery with Cardiopulmonary Bypass

Blood lactate and blood pressure measurements are important predictors of life-threatening complications after infant open-heart surgeries requiring cardiopulmonary bypass (CPB). We have developed an intravascular nitric oxide (NO)-releasing 5-Fr catheter that contains a lactate sensor for continuous in-blood lactate monitoring and a dedicated lumen for third-party pressure sensor attachment. This device has antimicrobial and antithrombotic properties and can be implanted intravascularly. The importance of this design is its ability to inhibit thrombosis, due to the slow release of NO through the surface of the catheter and around the electrochemical lactate sensors, to allow continuous data acquisition for more than 48 h. An in vivo study was performed using six piglets undergoing open-heart surgery with CPB and cardioplegic arrest, in order to mimic intra-operative conditions for infants undergoing cardiac surgery with CPB. In each study of 3 h, two 5-Fr NO-releasing lactate and blood-pressure monitoring catheters were implanted in the femoral vessels (arteries and veins) and the CPB circuitry to monitor changing lactate levels and blood pressures during and immediately after aortic cross-clamp removal and separation from CBP. Electrical signals continuously acquired through the sensors were processed and displayed on the device's display and via Bluetooth to a computer in real-time with the use of a two-point in vivo calibration against blood gas results. The study results show that lactate levels measured from those sensors implanted in the CPB circuit during CPB were comparable to those acquired by arterial blood gas measurements, whereas lactate levels measured from sensors implanted in the femoral artery were closely correlated with those acquired intermittently by blood gas prior to CPB initiation, but not during CPB. Blood pressure sensors attached to one lumen of the device displayed accurate blood pressure readings compared to those measured using an FDA approved pressure sensor already on the market. We recommend that the sensor be implanted in the CPB's circuit to continuously monitor lactate during CPB, and implanted in the femoral arteries or jugular veins to monitor lactate before and after CPB. Blood pressures dramatically drop during CPB due to lower blood flow into the lower body, and we suspect that the femoral arteries are likely collapsing or constricting on the implanted catheter and disrupting the sensor-to-blood contact. This study shows that the device is able to accurately and continuously monitor lactate levels during CPB and potentially prevent post-surgery complications in infants.

Age-adjusted and Expanded Lactate Thresholds as Predictors of All-Cause Mortality in the Emergency Department

INTRODUCTION

While numerous studies have found emergency department (ED) lactate levels to be associated with increased in-hospital mortality, little information is available on the role age plays in this association. This study investigates whether age is a necessary variable to consider when using lactate levels as a marker of prognosis and a guide for management decisions in the ED.

METHODS

This was a retrospective cohort study in an urban, tertiary-care teaching hospital. A total of 13,506 lactate levels were obtained over a 4.5-year period. All adult patients who had a lactate level obtained by the treating provider in the ED were screened for inclusion. The main outcome measure was in-hospital mortality using age-adjusted cohorts and expanded lactate thresholds with secondary outcomes comparing mortality based on the primary clinical impression.

RESULTS

Of the 8796 patients in this analysis, there were 474 (5.4%) deaths. Mortality rates increased with both increasing lactate levels and increasing age. For all ages, mortality rates increased from 2.8% in the less than 2.0 millimoles per liter (mmol/L) lactate level, to 5.6% in the 2.0-2.9 mmol/L lactate level, to 8.0% in the 3.0-3.9 mmol/L lactate level, to 13.9% in the 4.0-4.9 mmol/L lactate level, to 13.7% in the 5.0-5.9 mmol/L lactate level, and to 39.1% in the 6.0 mmol/L or greater lactate level (p <0.0001). Survivors, regardless of age, had a mean lactate level <2.0 whereas non-survivors had mean lactate levels of 6.5, 4.5, and 3.7 mmol/L for age cohorts 18-39, 40-64, and ≥ 65 years, respectively.

CONCLUSION

Our findings suggest that although lactate levels can be used as a prognostic tool to risk stratify ED patients, the traditional lactate level thresholds may need to be adjusted to account for varying risk based on age and clinical impressions.

Automated prediction of sepsis using temporal convolutional network

Multiple organ failure is the trademark of sepsis. Sepsis occurs when the body's reaction to infection causes injury to its tissues and organs. As a consequence, fluid builds up in the tissues causing organ failure and leading to septic shock eventually. Some symptoms of sepsis include fever, arrhythmias, blood vessel leaks, impaired clotting, and generalised inflammation. In order to address the limitations in current diagnosis, we have proposed a cost-effective automated diagnostic tool in this study. A deep temporal convolution network has been developed for the prediction of sepsis. Septic data was fed to the model and a high accuracy and area under ROC curve (AUROC) of 98.8% and 98.0% were achieved respectively, for per time-step metrics. A relatively high accuracy and AUROC of 95.5% and 91.0% were also achieved respectively, for per-patient metrics. This is a novel study in that it has investigated per time-step metrics, compared to other studies which investigated per-patient metrics. Our model has also been evaluated by three validation methods. Thus, the recommended model is robust with high accuracy and precision and has the potential to be used as a tool for the prediction of sepsis in hospitals.

Utility of quick sepsis-related organ failure assessment (qSOFA) score to predict outcomes in out-of-ICU patients with suspected infections

Background:

Referral of sepsis patients at the level of primary care is often delayed due to the lack of an assessment tool which effectively predicts sepsis. The quick Sepsis-related Organ Failure Assessment score (qSOFA) can be used in such scenarios to improve patient outcomes.

Aim:

To assess the prognostic accuracy of qSOFA score in predicting adverse outcomes in patients with suspected infections and to compare it with the SIRS (Systemic Inflammatory Response Syndrome) and the SOFA (Sequential Organ failure Assessment Score).

Methods:

This study included 180 participants admitted in the emergency wards of the Department of Medicine, over a period of one year with suspected infection. The primary outcome was the combined outcome of mortality and/or ICU stay of more than three days. Secondary outcomes were the duration of ICU stay, duration of inotrope use, and duration of mechanical ventilation.

Statistical Analysis:

Descriptive statistics using SPSS version 19.0 was applied in the study.

Results:

Of the 180 participants, 54 had a qSOFA score of 2 at admission, 52 participants had an SIRS score of 2. The qSOFA score had the highest AUC for both mortality and the combined outcome of mortality and prolonged ICU stay (0.740 and 0.835, respectively). For a combined outcome of mortality and ICU stay >3 days, the qSOFA score had a sensitivity of 75% and a specificity of 82%. The positive likelihood ratio was 4.17.

Conclusion:

In a primary care setting, the qSOFA score of more than 2 can be used reliably to refer patients for admission and intensive care as they are likely to need longer hospital stay and can have worse outcomes.

A mortality analysis of septic shock, vasoplegic shock and cryptic shock classified by the third international consensus definitions (Sepsis-3)

INTRODUCTION

This study aimed to compare the 28-day mortality of patients with septic shock, defined by Sepsis-3 criteria and patients with vasoplegic or cryptic shock who are excluded from this new definition.

OBJECTIVES

This retrospective observational study was performed using a tertiary emergency department's septic shock registry and investigated the records of patients managed between January 2010 and December 2015. In 2,138 total patients, 1004 (47.0%) had septic shock, 476 (22.2%) had vasoplegic shock and 655 (30.6%) had cryptic shock.

RESULTS

There was significant variation in 28-day mortality among the three groups: 23.4% for septic shock, 8.8% for vasoplegic shock and 12.2% for cryptic shock (P < .001). In subgroup analysis of cryptic shock or septic shock according to lactate levels (2-3, 3-4 and >4 mmol/L), the mortality rate increased as lactate increased (cryptic shock: 9.5%, 14.8% and 18.0%; septic shock: 18.6%, 22.6% and 27.0%, respectively; P < .001). Multivariable analysis revealed odds ratios for mortality of 0.31 (95% CI 0.22-0.44; P < .001) for vasoplegic shock and 0.46 (95% CI 0.35-0.61; P < .001) for cryptic shock relative to septic shock. Survival curve analysis showed significant differences among patients with septic shock, vasoplegic shock and cryptic shock (Log rank test: P < .0001).

CONCLUSION

The new septic shock definition may be useful for identifying high-risk patients requiring intensive care. However, cryptic shock-associated mortality increased to 18.0% as serum lactate increased, which suggests that some cryptic shock patients may also require intensive management.

Physician Judgment and Circulating Biomarkers Predict 28-Day Mortality in Emergency Department Patients

OBJECTIVES

To determine whether biomarkers of endothelial activation and inflammation provide added value for prediction of in-hospital mortality within 28 days when combined with physician judgment in critically ill emergency department patients.

DESIGN

Prospective, observational study.

SETTING

Two urban, academic emergency departments, with ≈80,000 combined annual visits, between June 2016 and December 2017.

PATIENTS

Admitted patients, greater than 17 years old, with two systemic inflammatory response syndrome criteria and organ dysfunction, systolic blood pressure less than 90 mm Hg, or lactate greater than 4.0 mmol/L. Patients with trauma, intracranial hemorrhage known prior to arrival, or without available blood samples were excluded.

INTERVENTIONS

Emergency department physicians reported likelihood of in-hospital mortality (0-100%) by survey at hospital admission. Remnant EDTA blood samples, drawn during the emergency department stay, were used to measure angiopoietin-1, angiopoietin-2, tumor necrosis factor receptor-1, interleukin-6, and interleukin-8.

MEASUREMENTS AND MAIN RESULTS

We screened 421 patients and enrolled 314. The primary outcome of in-hospital mortality within 28 days occurred in 31 (9.9%). When predicting the primary outcome, the best biomarker model included angiopoietin-2 and interleukin-6 and performed moderately well (area under the curve, 0.72; 95% CI, 0.69-0.75), as did physician judgment (area under the curve, 0.78; 95% CI, 0.74-0.82). Combining physician judgment and biomarker models improved performance (area under the curve, 0.85; 95% CI, 0.82-0.87), with area under the curve change of 0.06 (95% CI, 0.04-0.09; p < 0.01) compared with physician judgment alone.

CONCLUSIONS

Predicting in-hospital mortality within 28 days among critically ill emergency department patients may be improved by including biomarkers of endothelial activation and inflammation in combination with emergency department physician judgment.