Serum lactate cut-offs as risk stratification tool for in-hospital adverse outcomes in emergency department patients screened for suspected sepsis

Dynamic changes in lactate levels within the first 24 hours in septic patients as a prognostic indicator: A retrospective cohort study utilizing latent class growth analysis

Elevated lactate levels are common in sepsis patients. This study aimed to assess the effect of dynamic changes in lactate levels within the first 24 hours following admission on patient prognosis. We extracted data from the Medical Information Mart for Intensive Care (MIMIC)-IV database and classified patients using latent class growth analysis (LCGA). This analysis classified sepsis patients into different groups based on dynamic changes in lactate levels during the initial 24 hours post-admission, dividing this time frame into four periods (0-3 h, 3-6 h, 6-12 h, and 12-24 h). The highest lactate level recorded in each period was then used for patient classification. We subsequently compared the baseline characteristics and outcomes between these different groups. Our study encompassed 7,830 patients, whom LCGA successfully divided into two classes: class 1 (steady lactate class) and class 2 (increasing lactate class). Class 2 demonstrated a worse clinical status at baseline, as indicated by vital signs, disease severity scores, and laboratory results. Importantly, class 2 also had a significantly higher 28-day mortality rate than class 1 (55.6% vs 13.5%, P < 0.001). In conclusion, LCGA effectively categorized sepsis patients into two distinct groups based on their dynamic changes in lactate levels during the first 24 hours post-admission. This methodology has potential utility in clinical practice for managing sepsis patients.

Decompensated metabolic acidosis in the emergency department: Epidemiology, sodium bicarbonate therapy, and clinical outcomes

Objective

This article aims to describe the epidemiology of decompensated metabolic acidosis, the characteristics of sodium bicarbonate (SB) administration and outcomes in emergency department (ED) patients.

Design

This is a retrospective cohort study.

Setting

ED of a tertiary referral hospital in Melbourne, Australia.

Participants

Adult patients presenting to the ED between 1 July 2011 and 20 September 2020 with decompensated metabolic acidosis diagnosed on arterial blood gas (ABG).

Main outcome measures

We compared characteristics between those treated with or without SB. We studied SB administration characteristics, change in laboratory variables, factors associated with use and dose, and clinical outcomes.

Results

Among 753,613 ED patients, 314 had decompensated metabolic acidosis on ABG, with 17.8% receiving SB. Patients in the SB group had lower median pH, CO2, bicarbonate, and base excess (BE) levels compared with the No SB group (P < 0.01). The median number of SB doses in the SB group was one treatment. This was given at a median total dose of 100 mmol and at a median of 2.8 h after the diagnostic blood gas results. Only 42% of patients in the SB group had a subsequent blood gas measured. In such patients, there was no significant change in pH, bicarbonate, or BE. SB therapy was not independently associated with mortality.

Conclusions

ABG-confirmed decompensated metabolic acidosis was rare but associated with a high mortality. SB administration occurred in a minority of patients and in more acidaemic patients. However, SB dose was stereotypical and not tailored to acidosis severity. Assessment of SB effect was infrequent and showed no correction of acidosis. Systematic studies of titrated SB therapy are required to inform current practice.

The Role of Lactate for Sepsis in Polytrauma Patients, a Time related Analysis using the IBM Watson Trauma Pathway Explorer®

The Watson Trauma Pathway Explorer ^® is an outcome prediction tool invented by the University Hospital of Zurich in collaboration with IBM^®, representing an artificial intelligence application to predict the most adverse outcome scenarios in polytrauma patients: Systemic Inflammatory Respiratory Syndrome (SIRS), sepsis within 21 days and death within 72 h. The hypothesis was how lactate values woud be associated with the incidence of sepsis. Data from 3653 patients in an internal database, with ongoing implementation, served for analysis. Patients were split in two groups according to sepsis presence, and lactate values were measured at formerly defined time points from admission until 21 days after admission for both groups. Differences between groups were analyzed; time points with lactate as independent predictor for sepsis were identified. The predictive quality of lactate at 2 and 12 h after admission was evaluated. Threshold values between groups at all timepoints were calculated. Lactate levels differed from less than 2 h after admission until the end of the observation period (21 d). Lactate represented an independent predictor for sepsis from 12 to 48 h and 14 d to 21 d after admission relative to ISS levels. AUROC was poor at 2 and 12 h after admission with a slight improvement at the 12 h mark. Lactate levels decreased over time at a range of 2 [mmol/L] for 6-8 h after admission. These insights may allow for time-dependent referencing of lactate levels and anticipation of subsequent sepsis, although further parameters must be considered for a higher predictability.

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

OBJECTIVES

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

DESIGN

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

DATA SOURCES

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

ELIGIBILITY CRITERIA

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

DATA EXTRACTION AND SYNTHESIS

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

RESULTS

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

CONCLUSIONS

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

PROSPERO REGISTRATION NUMBER

CRD42020207648.

The Association of Serum Lactate Level with the Occurrence of Contrast-Induced Acute Kidney Injury and Long-Term Prognosis in Patients Undergoing Emergency Percutaneous Coronary Intervention

Objective

The association of lactate and contrast-induced acute kidney injury (CI-AKI) has not been well established. This prospective study was planned to identify the effects of lactate level on the occurrence of CI-AKI and long-term prognosis with acute myocardial infarction (AMI) patients undergoing emergency percutaneous coronary intervention (PCI).

Methods

A total of 280 patients with AMI who underwent emergency PCI were selected from March 2018 to March 2019. A receiver operating characteristic (ROC) curve was used to analyze the optimal cut-off value of lactate on predicting CI-AKI after PCI. A multivariable logistic regression model was used to explore the significant predictors that might affect the occurrence of CI-AKI after univariate analysis. The primary endpoints were clinical outcomes including events: a combined endpoint of major adverse cardiovascular events, re-hospitalization due to heart failure, and worsening renal function. The Cox regression model was further used to analyze the predictors of the long-term prognosis after PCI.

Results

Among the 280 patients, 64 patients (22.9%) developed CI-AKI after emergency PCI procedure. Multivariable logistic regression analysis revealed that baseline lactate level was the independent risk factor for the development of CI-AKI (OR, 3.657; 95% CI, 2.237–5.978; p<0.001). The area under the ROC curve for predicting CI-AKI of lactate was 0.786, and the optimum cut-off point of lactate was 3.02 mmol/L, with sensitivity of 65.6% and specificity of 85.2%. The incidence of primary endpoints in the high lactate group (lactate ≥3.02mmol/L) was significantly increased compared with the control group [26.3% (42/160) vs 15.8% (19/120), χ²=4.430, p=0.035]. Cox regression analysis also confirmed high lactate was an independent predictor for primary endpoint outcomes at 1-year follow-up (HR, 1.916; 95% CI, 1.118–3.285; p=0.018).

Conclusion

Our study demonstrates that baseline high lactate levels may be associated with an increased risk of CI-AKI and are the important predictors of long-term poor cardiorenal outcomes in AMI patients undergoing emergency PCI.

Risk Factors for Mortality, Intensive Care Unit Admission, and Bacteremia in Patients Suspected of Sepsis at the Emergency Department: A Prospective Cohort Study

Background

There is a clear need for a better assessment of independent risk factors for in-hospital mortality, intensive care unit admission, and bacteremia in patients presenting with suspected sepsis at the emergency department.

Methods

A prospective observational cohort study including 1690 patients was performed. Two multivariable logistic regression models were used to identify independent risk factors.

Results

Sequential organ failure assessment (SOFA) score of ≥2 and serum lactate of ≥2mmol/L were associated with all outcomes. Other independent risk factors were individual SOFA variables and systemic inflammatory response syndrome variables but varied per outcome. Mean arterial pressure <70 mmHg negatively impacted all outcomes.

Conclusions

These readily available measurements can help with early risk stratification and prediction of prognosis.

Early prognostic capacity of serum lactate for severe postpartum hemorrhage

OBJECTIVE

To evaluate whether the concentration of serum lactate during the diagnosis of postpartum hemorrhage (bleeding ≥500 mL during labor or ≥1000 mL during cesarean delivery) predicts severe hemorrhage (SPPH; blood loss ≥1500 mL at end of labor or in the following 24 h).

METHODS

A prospective cohort pilot study was conducted of women with a vaginal or cesarean delivery from February 2018 to March 2019 who presented with bleeding ≥500 mL measured by the gravimetric method in a reference hospital in San Luis Potosi, Mexico. Venous blood samples were taken for analysis of serum lactate. A receiver operating characteristic curve determined the serum lactate threshold value for SPPH and χ² test assessed the difference in serum lactate elevation between SPPH and non-SPPH groups. Lastly, the prognostic capacity between the thresholds was compared.

RESULTS

SPPH developed in 43.33% of the 30 women in the study group. The best prognostic threshold was 2.68 mmol/L of serum lactate (odds ratio [OR] 17.88, 95% confidence interval [CI] 2.7-16.8, P < 0.001); sensitivity was 0.85 (95% CI 0.55-0.98); specificity was 0.76 (95% CI 0.50-0.93).

CONCLUSION

Serum lactate may be a useful prognostic marker for SPPH, more studies are needed to validate these findings.

Accuracy of prehospital point-of-care lactate in early in-hospital mortality

BACKGROUND

Emergency medical services (EMS) routinely face complex scenarios where decisions should be taken with limited clinical information. The development of fast, reliable and easy to perform warning biomarkers could help in such decision-making processes. The present study aims at characterizing the validity of point-of-care lactate (pLA) during prehospital tasks for predicting in-hospital mortality within two days after the EMS assistance.

MATERIALS AND METHODS

Prospective, multicentric, ambulance-based and controlled observational study without intervention, including six advanced life support and five hospitals. The pLA levels were recorded during EMS assistance of adult patients. The validity of pLA to determine the in-hospital mortality was assessed by the area under the curve (AUC) of the receiver operating curve (ROC).

RESULTS

A total of 2997 patients were considered in the study, with a median of 69 years (IQR 54-81) and 41.4% of women. The median pLA value was 2.7 mmol/L (1.9-3.8) in survivors and 5.7 mmol/L (4.4-7.6) in nonsurvivors. The global discrimination level of pLA reached an AUC of 0.867, being 1.9 mmol/L and 4 mmol/L the cut-off point for low and high mortality. The discrimination value of pLA was not affected by sex, age or pathology.

CONCLUSIONS

Our results highlight the clinical importance of prehospital pLA to determine the in-hospital risk of mortality. The incorporation of pLA into the EMS protocols could improve the early identification of risky patients, leading to a better care of such patients.

National Early Warning Score (NEWS) as Prognostic Triage Tool for Septic Patients

Purpose

We assessed the National Early Warning Score (NEWS) in emergency triage for predicting sepsis-related outcomes.

Methods

A retrospective chart review of all cases enrolled in the sepsis management protocol for a one-year duration. The protocol utilized the NEWS as a screening tool for sepsis in the triage area. Primary outcomes of interest were hyperlactatemia, admission to ICU and intrahospital mortality. Sensitivity, specificity, and area under the curve (AUC) were calculated for a given NEWS.

Results

A total of 444 patients were reviewed from July 2018 to June 2019, with a mean age of 58.7 years. A NEWS ≥5 was more than 88% sensitive in predicting hyperlactatemia, ICU admission, and/or mortality. Specificity, on the other hand, was as low as 12%. The AUC for the NEWS was 0.667 for predicting hyperlactatemia and 0.602 for predicting ICU admission or mortality.

Conclusion

The NEWS was a sensitive screening tool for predicting sepsis-related outcomes. However, it was not specific, and further studies are recommended to assess the integration of other factors to improve specificity.

Immature platelet indices alongside procalcitonin for sensitive and specific identification of bacteremia in the intensive care unit

Hematological markers that can be rapidly analyzed and regularly monitored during a patient's stay on ICU, and that can identify bacterial causes of sepsis are being extensively sought. The significance of platelets in early immunological responses provides justification for assessing their usefulness in the identification of bacteremia amongst sepsis patients. In this preliminary study, the full blood count, including the platelet count by impedance (PLT-I), Immature Platelet Fraction (IPF%) and absolute immature platelet count (AIPC), were analyzed in eighty-two sepsis patients daily over the first 5 days stay on ICU. C-Reactive Protein (CRP), procalcitonin (PCT), and lactate were also analyzed daily. Blood cultures confirmed or excluded the presence of bacteremia. PCT provided the earliest indicator of bacteremia, with significant differences between the two cohorts on day 1. The change in IPF% and AIPC from day 1 to day 2 (Δ IPF% and Δ AIPC) provided the most accurate indication; A combination of Δ IPF% and day 2 PCT, provided a positive predictive value and negative predictive value of 100% and 96.10%, respectively. These data provide strong justification for larger multi-center validation studies to confirm the usefulness of these platelet indices during the assessment of sepsis on the ICU.

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.

Management of Patients With Sepsis in Canadian Community Emergency Departments: A Retrospective Multicenter Observational Study

BACKGROUND

Sepsis is a life-threatening syndrome and a leading cause of morbidity and mortality representing significant financial burden on the health-care system. Early identification and intervention is crucial to maximizing positive outcomes. We studied a quality improvement initiative with the aim of reviewing the initial management of patients with sepsis in Canadian community emergency departments, to identify areas for improving the delivery of sepsis care. We present a retrospective, multicenter, observational study during 2011 to 2015 in the community setting.

METHODS

We collected data on baseline characteristics, clinical management metrics (triage-to-physician-assessment time, triage-to-lactate-drawn time, triage-to-antibiotic time, and volume of fluids administered within the first 6 hours of triage), and outcomes (intensive care unit [ICU] admission, in-hospital mortality) from a regional database.

RESULTS

A total of 2056 patients were analyzed. The median triage-to-physician-assessment time was 50 minutes (interquartile range [IQR]: 25-104), triage-to-lactate-drawn time was 50 minutes (IQR: 63-94), and triage-to-antibiotics time was 129 minutes (IQR: 70-221). The median total amount of fluid administered within 6 hours of triage was 2.0 L (IQR: 1.5-3.0). The ICU admission rate was 36% and in-hospital mortality was 25%. We also observed a higher ICU admission rate (51% vs 24%) and in-hospital mortality (44% vs 14%) in those with higher lactate concentration (≥4 vs ≤2 mmol/L), independent of other sepsis-related parameters.

CONCLUSION

Time-to-physician-assessment, time-to-lactate-drawn, time-to-antibiotics, and fluid resuscitation in community emergency departments could be improved. Future quality improvement interventions are required to optimize management of patients with sepsis. Elevated lactate concentration was also independently associated with ICU admission rate and in-hospital mortality rate.

Serum lactate levels are associated with glioma malignancy grade

OBJECTIVE

Recent studies have suggested that high grade gliomas are associated with elevated serum lactate concentrations. The aim of the present study is to assess these findings in a sample of patients.

PATIENTS AND METHODS

We reviewed the anesthetic charts of patients with low-grade and high-grade glioma who underwent resection surgery and collected serum lactate concentration before tumor resection, as well as other demographic and tumor-related data (age, gender, WHO grade, and size of the tumor). A statistical comparison between patients with normal (<2 mmol/L) and elevated (≥ 2 mmol/L) serum lactate was performed.

RESULTS

We included a total of 152 patients (mean age 49.07 years). 62.5% of patients (n = 95) had a high-grade glioma and 37.5% (n = 67) a low-grade glioma. The multivariate regression showed that high grade gliomas had significantly higher lactate concentration (p < 0.01). The OR for elevated pre-resection serum lactate increased from 4.94 to 14.33 after adjusting for age and pre-surgical corticosteroid use, and the AUC for the final regression model was 0.98.

CONCLUSION

This study reinforces the role of serum lactate as a potential biomarker of brain tumors malignancy, and its results encourage further research on this subject, in order to improve the understanding of this phenomenon and to assess its potential as prognostic and therapeutic monitoring tool.

Is prehospital lactate testing useful in improving clinical assessment?

Introduction:

Lactate devices offer the potential for paramedics to improve patient triage and escalation of care for specific presentations. There is also scope to improve existing prehospital tools by including lactate measurement.

Method:

A literature search was conducted using the Medline, CINAHL, Academic Search Premier, Sciencedirect and Scopus databases.

Findings:

Acquiring prehospital lactate measurement in trauma settings improved triage and recognition of the need for critical care. Within a medical setting, studies offered mixed results in relating prehospital lactate measurement to diagnosis, escalating treatments and mortality. The accuracy of prehospital lactate measurements acquired varies, which could impact decision making.

Conclusion:

Prehospital lactate thresholds could aid decision making, although the literature is limited and evidence varies. Lactate values of ≥4 mmol/litre in medical and ≥2.5 mmol/litre in trauma patients could signify that care should be escalated to an appropriate facility, and that resuscitative measures should be initiated, particularly with sepsis, as reflected by standardised lactate values that guide treatment in hospitals. Similarly, a lactate value of <2 mmol/litre could mean de-escalating care into the community, although further research is warranted on this.

Shock index and modified shock index as triage screening tools for sepsis

BACKGROUND

Fever is one of the common conditions encountered in the emergency department, which related to a spectrum of diseases severity. Identifying sepsis patients from uncomplicated febrile patients is challenging in the emergency triage areas and pre-hospital settings.

OBJECTIVES

Assess the triage shock index (SI) and modified shock index (MSI) in febrile patients as predictors for sepsis and sepsis-related outcomes.

DESIGN

A retrospective cohort study.

SETTING

Patients presented to the Emergency Department of King Khalid University Hospital.

PATIENTS AND METHODS

The analysis included all febrile adult patients triaged with a temperature of 38 °C or more from January 2016 to December 2017. Based on triage vital sign we calculate the SI with cut-off levels of ≥0.7 and ≥1 and MSI with cut-off levels of ≥1 and ≥1.3. We report the Relative Risk, Sensitivity, Specificity, Positive and Negative Predictive Values of the predictors.

MAIN OUTCOME MEASURES

Sepsis and sepsis-related outcomes such as hyperlactatemia, ICU admission, and 28 days mortality.

SAMPLE SIZE

274 patients.

RESULTS

274 patients met our inclusion/exclusion criteria. Of the 274 patients, 252 patient (92%) were septic, 62 patients (22%) had hyperlactatemia, 20 patients admitted to the ICU, and 5 patient died within 28 days. An MSI of ≥1 had a sensitivity of 90% for sepsis predication, 85% for ICU admission and 100% for 28 days mortality. MSI of ≥1.3 showed a specificity (59%-100%) for all the outcomes of interest. Non-significant statistical trends of greater accuracy of MSI over SI.

CONCLUSION

MSI and SI were found to be promising predictors in triaging febrile patients. However no single cut-off values of MSI or SI were found to have an optimal accuracy for prediction of sepsis and sepsis-related outcomes. Further studies are required to assess the incorporation of MSI in a multi-item scaling system for the prediction of sepsis and its related outcomes.

LIMITATIONS

Small single center study and the results may not be generalizable.

Central venous oxygen saturation is not predictive of early complications in cancer patients presenting to the emergency department

Central venous oxygen saturation (ScvO₂) is easily observable in oncology patients with long-term central venous catheters (CVC), and has been studied as a prognostic factor in patients with sepsis. We sought to investigate the association between ScvO₂ and early complications in cancer patients presenting to the ED. We prospectively enrolled adult cancer patients with pre-existing CVC who presented to the ED. ScvO₂ was measured on their CVC. The outcome was admission to the intensive care unit (ICU) or mortality by day 7. ScvO₂ was first studied as a continuous variable (%) with a ROC analysis and as a categorical variable (cut-off at < 70%) with a multivariate analysis. A total of 210 cancer patients were enrolled. At baseline, ScvO₂ showed no significant difference between patients who were admitted to the ICU or died before day 7, and patients who did not (67%; IQR 62-68% vs. 71%; IQR 65-78% respectively, P = 0.3). The ROC analysis showed the absence of discrimination accuracy for ScvO₂ to predict the outcome (AUC = 0.56). By multivariate analysis, ScvO₂ < 70% was not associated with the outcome (OR 1.67; 95% CI 0.64-4.36). Variables that were associated with ICU admission or death by day 7 included a shock-index (heart rate/systolic blood pressure) > 1 and a performance status > 2 (OR 4.76; 95% CI 1.81-12.52 and OR 6.23, 95% CI 2.40-16.17, respectively). This study does not support the use of ScvO₂ to risk stratify cancer patients presenting to the ED.