The impact of serial lactate monitoring on emergency department resuscitation interventions and clinical outcomes in severe sepsis and septic shock: an observational cohort study

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

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

Enhancing sepsis biomarker development: key considerations from public and private perspectives

Implementation of biomarkers in sepsis and septic shock in emergency situations, remains highly challenging. This viewpoint arose from a public-private 3-day workshop aiming to facilitate the transition of sepsis biomarkers into clinical practice. The authors consist of international academic researchers and clinician-scientists and industry experts who gathered (i) to identify current obstacles impeding biomarker research in sepsis, (ii) to outline the important milestones of the critical path of biomarker development and (iii) to discuss novel avenues in biomarker discovery and implementation. To define more appropriately the potential place of biomarkers in sepsis, a better understanding of sepsis pathophysiology is mandatory, in particular the sepsis patient's trajectory from the early inflammatory onset to the late persisting immunosuppression phase. This time-varying host response urges to develop time-resolved test to characterize persistence of immunological dysfunctions. Furthermore, age-related difference has to be considered between adult and paediatric septic patients. In this context, numerous barriers to biomarker adoption in practice, such as lack of consensus about diagnostic performances, the absence of strict recommendations for sepsis biomarker development, cost and resources implications, methodological validation challenges or limited awareness and education have been identified. Biomarker-guided interventions for sepsis to identify patients that would benefit more from therapy, such as sTREM-1-guided Nangibotide treatment or Adrenomedullin-guided Enibarcimab treatment, appear promising but require further evaluation. Artificial intelligence also has great potential in the sepsis biomarker discovery field through capability to analyse high volume complex data and identify complex multiparametric patient endotypes or trajectories. To conclude, biomarker development in sepsis requires (i) a comprehensive and multidisciplinary approach employing the most advanced analytical tools, (ii) the creation of a platform that collaboratively merges scientific and commercial needs and (iii) the support of an expedited regulatory approval process.

Erector spinae muscle-based nomogram for predicting in-hospital mortality among older patients with severe community-acquired pneumonia

BACKGROUND

No multivariable model incorporating erector spinae muscle (ESM) has been developed to predict clinical outcomes in older patients with severe community-acquired pneumonia (SCAP). This study aimed to construct a nomogram based on ESM to predict in-hospital mortality in patients with SCAP.

METHODS

Patients aged ≥ 65 years with SCAP were enrolled in this prospective observational study. Least absolute selection and shrinkage operator and multivariable logistic regression analyses were used to identify risk factors for in-hospital mortality. A nomogram prediction model was constructed. The predictive performance was evaluated using the concordance index (C-index), calibration curve, net reclassification improvement (NRI), integrated discrimination improvement (IDI), and decision curve analysis.

RESULTS

A total of 490 patients were included, and the in-hospital mortality rate was 36.1%. The nomogram included the following independent risk factors: mean arterial pressure, peripheral capillary oxygen saturation, Glasgow Coma Scale score (GCS), lactate, lactate dehydrogenase, blood urea nitrogen levels, and ESM cross-sectional area. Incorporating ESM into the base model with other risk factors significantly improved the C-index from 0.803 (95% confidence interval [CI], 0.761-0.845) to 0.836 (95% CI, 0.798-0.873), and these improvements were confirmed by category-free NRI and IDI. The ESM-based nomogram demonstrated a high level of discrimination, good calibration, and overall net benefits for predicting in-hospital mortality compared with the combination of confusion, urea, respiratory rate, blood pressure, and age ≥ 65 years (CURB-65), Pneumonia Severity Index (PSI), Acute Physiology and Chronic Health Evaluation II (APACHEII), and Sequential Organ Failure Assessment (SOFA).

CONCLUSIONS

The proposed ESM-based nomogram for predicting in-hospital mortality among older patients with SCAP may help physicians to promptly identify patients prone to adverse outcomes.

TRIAL REGISTRATION

This study was registered at www.chictr.org.cn (registration number Chi CTR-2300070377).

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

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

Could lactate clearance be a marker of mortality in pediatric intensive care unit?

BACKGROUND

Hyperlactatemia is a common finding in critically ill patients and has significant prognostic implications. However, a single lactate measurement has not been correlated to mortality consistently. In this study, we aimed to correlate the clinical efficacy of lactate clearance for the prediction of mortality in pediatric intensive care unit patients.

METHODS

This retrospective observational study was performed in the pediatric intensive care unit in patients with lactate level >3 mmol/lt. Initial, 6th h, and 24th h lactate levels were recorded and lactate clearance was calculated using these values (lactate level at admission - level 6 h later × 100/lactate level at admission).

RESULTS

A total of 172 patients were included in the study. Forty-four out of 172 patients died. Median (IQR) lactate (mmol/L) at admission was low in those who survived in comparison to nonsurvivors 4.4 (3.1) vs. 5.75 (7.7) (p = 0.002). Clearance at 6th h was significantly lower in those who died (11.7%) than those who survived (36.7) (p = 0.001). 6th h lactate clearance level <20.7% predicted mortality with a sensitivity of 63.6% and specificity of 69.5% along with a positive predictive value of 41.8 and a negative predictive value of 84.8 (p = 0.004). Both lactate levels and lactate clearance values were significantly predictive factors for mortality (p < 0.05). Only a positive moderate correlation was found between the percentage of PRISM-IV % and 6th h lactate level.

DISCUSSION

The present study revealed that lactate clearance is a simple and rapid risk-stratification tool holding to be a potential biomarker of managing the treatment efficacy of children in the pediatric intensive care unit.

Prognostic Value of Arterial Lactate Metabolic Clearance Rate in Moderate and Severe Acute Pancreatitis

PURPOSE

High lactate levels at hospital admission are significantly associated with poor prognosis in acute pancreatitis patients. Early high lactate clearance is a vital marker for predicting persistent organ failure and mortality in critical illness; however, its value in acute pancreatitis remains unclear.

METHOD

Data were collected from patients who were diagnosed with moderately severe acute pancreatitis and severe acute pancreatitis from January 2017 to December 2020. Initial lactate (within 2 hours after admission) and repeat lactate at 24 hours after admission were measured to determine lactate clearance. Low clearance was defined as a reduction in repeat lactate of less than 30% compared to the first measurement. High clearance was defined as a repeat lactate decrease ≥30% of the first measurement or both first and second lactate levels <2 mmol/L. Baseline data, laboratory data, mortality rate, persistent organ failure rate, and other outcomes such as the incidence of septic pancreatic necrosis and sepsis and the length of hospital stay and intensive care unit (ICU) stay were compared in the low and high lactate clearance groups. Multivariate logistic regression analyses were used to assess the value of lactate clearance for predicting death.

RESULT

Among 4425 acute pancreatitis patients, 3040 patients were diagnosed with moderate or severe acute pancreatitis, and 1028 patients had initial lactate measured. Finally, 390 patients who had initial and 24-hour repeat lactate data were included in the study. Patients who had elevated initial lactate had poor outcomes, and 51 patients in the initial elevated lactate group died. In the lactate normalization group analysis, 293 patients had 24-hour lactate normalization; compared with patients in the nonnormalization group, they had a lower rate of mortality (12.6% vs. 33%). In the lactate clearance group analysis, 70 (21.9%) patients had a low clearance after 24 hours; compared with patients in the high clearance group, they had a higher rate of developing persistent multiorgan failure (P = 0.045), and the incidence of death was higher (15% vs. 28.6%, P = 0.007). Multivariate logistic analysis showed that 24-hour lactate clearance (OR: 2.007; 95% CI:1.032-3.903, P = 0.04), elevated initial lactate (OR: 2.011; 95% CI:1.023-3.953, P = 0.043), blood urea nitrogen (OR: 2.316; 95% CI:1.061-5.056, P = 0.035), and white blood count (OR: 1.982; 95% CI:1.026-3.829, P = 0.042) were independent predictors of hospital mortality.

CONCLUSION

The 24-hour clearance of lactate is a reliable marker to predict the outcome of moderate and severe acute pancreatitis, and low lactate clearance may indicate that the patient's condition will worsen, requiring aggressive treatments to improve patient outcomes.

A Novel Strategy for Predicting 72-h Mortality After Admission in Patients With Polytrauma: A Study on the Development and Validation of a Web-Based Calculator

Background

Early and accessible screening of patients with polytrauma at a high risk of hospital death is essential. The purpose of this research was to seek an accurate and convenient solution to predict deaths occurring within 72 h after admission of these patients.

Methods

A secondary analysis was conducted on 3,075 patients with polytrauma from the Dryad database. We imputed missing values in eligible individuals with the k-nearest neighbor algorithm and then randomly stratified them into the training group (n = 2,461) and the validation group (n = 614) based on a proportion of 8:2. The restricted cubic spline, univariate, backward stepwise, and multivariate logistic regression methods were employed to determine the suitable predictors. Calibration and receiver operating characteristic (ROC) curves were applied to assess the calibration and discrimination of the obtained model. The decision curve analysis was then chosen as the measure to examine the clinical usage.

Results

Age, the Glasgow Coma Scale score, the Injury Severity Score, base excess, and the initial lactate level were inferred as independent prognostic factors related to mortality. These factors were then integrated and applied to construct a model. The performance of calibration plots, ROC curves, and decision curve analysis indicated that the model had satisfactory predictive power for 72-h mortality after admission of patients with polytrauma. Moreover, we developed a nomogram for visualization and a web-based calculator for convenient application (https://songandwen.shinyapps.io/DynNomapp/).

Conclusions

A convenient web-based calculator was constructed to robustly estimate the risk of death in patients with polytrauma within 72 h after admission, which may aid in further rationalization of clinical decision-making and accurate individual treatment.

The impact of lactate clearance on outcomes according to infection sites in patients with sepsis: a retrospective observational study

Whether lactate clearance (LC) influences outcomes differently depending on the infection site in sepsis cases is not fully elucidated. Herein, we analyzed LC's clinical utility as a predictor of patient outcomes according to infection site. This retrospective study, conducted at two tertiary emergency critical care medical centers in Japan, included patients with sepsis or septic shock. The associations between infection site (lungs vs. other organs) and in-hospital mortality and ventilator-free days (VFDs) were evaluated using univariable and multivariate analyses. We assessed LC's ability to predict in-hospital mortality using the area under the receiver operating characteristic curve. Among 369 patients with sepsis, infection sites were as follows: lungs, 186 (50.4%); urinary tract, 45 (12.2%); abdomen, 102 (27.6%); and other, 36 (9.8%). Patients were divided into a pneumonia group or non-pneumonia group depending on their infection site. The pneumonia group displayed a higher in-hospital mortality than the non-pneumonia group (24.2% vs. 15.8%, p = 0.051). In the multivariate analysis, lower LC was associated with higher in-hospital mortality [adjusted odds ratio (AOR), 0.97; 95% confidence interval (CI) 0.96-0.98; p < 0.001] and fewer VFD [adjusted difference p value (AD), - 1.23; 95% CI - 2.42 to - 0.09; p = 0.025] in the non-pneumonia group. Conversely, LC did not affect in-hospital mortality (AOR 0.99; 95% CI 0.99-1.00; p = 0.134) and VFD (AD - 0.08; 95% CI - 2.06 to 1.91; p = 0.854) in the pneumonia group. Given the differences in the impact of LC on outcomes between the pneumonia and non-pneumonia groups, this study suggests that optimal treatment strategies might improve outcomes. Further studies are warranted to validate our results and develop optimal therapeutic strategies for sepsis patients.

The relationship between pre-procedural elevated arterial lactate and contrast-induced nephropathy following primary percutaneous coronary intervention

Background

Risk stratification has been one of the main steps in preventing contrast-induced nephropathy (CIN), which is a common complication after percutaneous coronary intervention (PCI). Elevated arterial lactate is a biomarker indicating severe disease condition and post-intervention complications. The relationship between lactate and CIN has not been established. This study is performed to investigate the relationship between elevated arterial lactate level and contrast-induced nephropathy (CIN).

Methods

Patients diagnosed with ST-segment elevated myocardial infarction (STEMI) were prospectively enrolled, with lactate measured within 0.5–1 hours before primary percutaneous coronary intervention (PCI). Patients with cardiopulmonary resuscitation, any forms of severe anaerobic condition, or end-stage renal disease undergoing dialysis were excluded. CIN was defined as an increase in serum creatinine ≥0.5 mg/dL or 25% within 72 hours after PCI. The Mehran Risk Score (MRS) is widely regarded as a classic risk model for CIN and the risk factors of MRS were applied in our multivariate regression analysis.

Results

Of the 227 enrolled patients, 47 (20.7%) developed CIN according to the definition. The mean lactate level was higher in the CIN group than in the non-CIN group (2.68±2.27 vs. 1.74±1.94, P<0.001). The arterial lactate level ≥2.0 mmol/L had 57.5% sensitivity and 75.6% specificity in predicting CIN. The performance of the lactate level in discriminating CIN was similar to that of the MRS (AUC_lac =0.707 vs. AUC_MRS =0.697, P=0.86). After adjusting for other risk factors, lactate ≥2.0 mmol/L still significantly predicted CIN (odds ratio =3.77, 95% CI, 1.77–7.99, P=0.001).

Conclusions

An arterial lactate level of ≥2.0 mmol/L is associated with CIN in STEMI patients after primary 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.

Retrospective evaluation of the prognostic utility of plasma lactate concentration and serial lactate measurements in dogs and cats presented to the emergency room (January 2012 - December 2016): 4863 cases

OBJECTIVE

To determine the prognostic significance of plasma lactate concentration, plasma lactate clearance, and delta lactate in dogs and cats presented to an emergency room (ER).

DESIGN

Retrospective study.

SETTING

University teaching hospital.

ANIMALS

A total of 8,321 animals with a plasma lactate concentration measured with 4,863 presenting to the ER and 1,529 dogs and 444 cats having a measurement within 4 hours of admission.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Plasma lactate concentration of dogs and cats presented to a university teaching hospital was retrospectively evaluated. Of dogs and cats with a plasma lactate concentration measured within 4 hours of admission to the ER, hyperlactatemia was common, and the prevalence of hyperlactatemia for dogs 78% (361/462) and cats 67% (78/116) was highest when evaluated within the first 30 minutes following admission. The distribution of patient's plasma lactate concentration was significantly higher in non-survivors compared to survivors at all time points evaluated (P < 0.001). Both lactate clearance (P = 0.010) and delta lactate (P = 0.013) were significantly different between survivors and nonsurvivors. A delta lactate > 4.5 mmol/L was 100% (95% CI: 95 to 100%) specific for nonsurvival in patients with hyperlactatemia measured within 1 hour of admission to the ER. The most common cause of hyperlactatemia was shock in dogs (24%) and urinary tract diseases in cats (22%). Shock was associated with the highest mortality rate in both dogs (61%) and cats (77%). Hyperlactatemia was significantly associated with increased mortality for dogs with shock (P = 0.001), respiratory diseases (P = 0.022), diabetes mellitus (P = 0.018), and liver dysfunction (P = 0.006).

CONCLUSIONS

Hyperlactatemia was associated with mortality in both dogs and cats when measured at any time point in the 4 hours following admission to the ER. Serial lactate measurement may also be a valuable tool to guide clinical management decisions.

Comparison of base excess, lactate and pH predicting 72-h mortality of multiple trauma

Objective

To compare the predictive values of base excess (BE), lactate and pH of admission arterial blood gas for 72-h mortality in patients with multiple trauma.

Methods

This was a secondary analysis based on a publicly shared trauma dataset from the Dryad database, which provided the clinical data of 3669 multiple trauma patients with ISS > = 16. The records of BE, lactate, pH and 72-h prognosis data without missing values were selected from this dataset and 2441 individuals were enrolled in the study. Logistic regression model was performed to calculate the odds ratios (ORs) of variables. Area under the curve (AUC) of receiver operating curve (ROC) was utilized to evaluate the predictive value of predictors for 72 h in-hospital mortality. Pairwise comparison of AUCs was performed using the Delong’s test.

Results

The statistically significant correlations were observed between BE and lactate (r = − 0.5861, p < 0.05), lactate and pH (r = − 0.5039, p < 0.05), and BE and pH (r = − 0.7433, p < 0.05). The adjusted ORs of BE, lactate and pH for 72-h mortality with the adjustment for factors including gender, age, ISS category were 0.872 (95%CI: 0.854–0.890), 1.353 (95%CI: 1.296–1.413) and 0.007 (95%CI: 0.003–0.016), respectively. The AUCs of BE, lactate and pH were 0.693 (95%CI: 0.675–0.712), 0.715 (95%CI: 0.697–0.733), 0.670 (95%CI: 0.651–0.689), respectively.

Conclusions

There are significant correlations between BE, lactate and pH of the admission blood gas, all of them are independent predictors of 72-h mortality for multiple trauma. Lactate may have the best predictive value, followed by BE, and finally pH.

Clinical evaluation of a novel subcutaneous lactate monitor

Lactate levels are commonly used as an indirect measure to assess metabolic stress in clinical conditions like sepsis. Dynamic lactate measurements are recommended to assess and guide treatment in patients with shock and other critical care conditions. A minimally invasive, continuous lactate monitor has potential to improve clinical decisions and patient care. The purpose of the study was to evaluate continuous lactate measurements of a novel enzymatic Continuous Lactate Monitor (CLM) developed in our laboratory. Lactate levels were monitored during incremental cycling exercise challenges as a tool for hyperlactatemia. Six healthy individuals 18–45 y/o (4 males, 2 females) participated in the study. CLM devices were inserted subcutaneously in the postero-lateral trunk below the renal angle, one hour before the exercise challenge. Each exercise challenge consisted of a 3 to 12-min warm up period, followed by up to 7, 4-min incremental workload bouts separated by rest intervals. Continuous lactate measurements obtained from CLM were compared with commercial lactate analyzer (Abbott iSTAT) measurements of venous blood (plasma) drawn from the antecubital vein. Blood was drawn at up to 25 time points spanning the duration of before exercise, during exercise, and up to 120 min post exercise. Area under the curve (AUC), and delay time were calculated to compare the CLM readings with plasma lactate concentration. Average plasma lactate concentration increased from 1.02 to 16.21 mM. Ratio of AUC derived from CLM to plasma lactate was 1.025 (0.990–1.058). Average dynamic delay time of CLM to venous plasma lactate was 5.22 min (2.87–10.35). Insertion sites examined 48 h after CLM removal did not show signs of side effects and none required medical attention upon examination. The newly developed CLM has shown to be a promising tool to continuously measure lactate concentration in a minimally invasive fashion. Results indicate the CLM can provide needed trends in lactate over time. Such a device may be used in the future to improve treatment in clinical conditions such as sepsis.

Utility of venous blood gases for the assessment of traumatic shock: a prospective observational study

BACKGROUND

ABG samples are often obtained in trauma patients to assess shock severity. Venous blood gas (VBG) sampling, which is less invasive, has been widely used to assess other forms of shock. The study aim was to determine the agreement between VBG and ABG measurements in trauma.

METHODS

Patients were enrolled at an Australian trauma centre between October 2016 and October 2018. Bland-Altman limits of agreement (LOA) between paired blood gas samples taken <30 min apart were used to quantify the extent of agreement. The impact of using only VBG measurements was considered using an a priori plan. Cases where venous sampling failed to detect 'concerning levels' were flagged using evidence-based cut-offs: pH ≤7.2, base deficit (BD) ≤-6, bicarbonate <21 and lactate ≥4. Case summaries of these patients were assessed by independent trauma clinicians as to whether an ABG would change expected management.

RESULTS

During the study period 176 major trauma patients had valid paired blood gas samples available for analysis. The median time difference between paired measurements was 11 min (IQR 6-17). There was a predominance of men (81.8%) and blunt trauma (92.0%). Median Injury Severity Score was 13 (range 1-75) and inpatient mortality was 6.3%. Mean difference (ABG-VBG) and LOA between paired arterial and venous measurements were 0.036 (LOA -0.048 to 0.120) for pH, -1.27 mmol/L (LOA -4.35 to 1.81) for BD, -0.64 mmol/L (LOA -1.86 to 0.57) for lactate and -1.97 mmol/L (LOA -5.49 to 1.55) for bicarbonate. Independent assessment of the VBG 'false negative' cases (n=20) suggested an ABG would change circulatory management in two cases.

CONCLUSIONS

In trauma patients VBG and ABG parameters displayed suboptimal agreement. However, in cases flagged as VBG 'false negative' independent review indicated that the availability of an ABG was unlikely to change management.

[Lactate in emergency medicine]

The basis of all metabolic processes in the human body is the production and metabolism of carriers of energy. Lactate is the end-product of anaerobic glycolysis. Lactate can serve as a substrate for gluconeogenesis and as an oxidation substrate. Hyperlactatemia can be detected as the result of a multitude of acute events (e.g. shock, sepsis, cardiac arrest, trauma, seizure, ischemia, diabetic ketoacidosis, thiamine deficiency, liver failure and intoxication). Hyperlactatemia can be associated with increased mortality, therefore in emergency medicine the search for the cause of hyperlactatemia is just as important as an effective causal treatment. Repetitive measurements of lactate are components of several treatment algorithms as observation of the dynamic development of blood lactate concentrations can help to make a better assessment of the acute medical condition of the patient and to evaluate the effectiveness of the measures undertaken.

The origins of the Lacto-Bolo reflex: the mythology of lactate in sepsis

The use of lactate as a marker of the severity of circulatory shock was popularized by Dr. Weil in the 1970's. Dr. Weil promoted the idea that blood lactate concentration increased in circulatory shock due to anaerobic metabolism following decreased oxygen delivery. This concept becomes entrenched with 1992 ACCP/SCCM consensus conference definition of sepsis. Since then, the central role of lactate in the definition and management of septic shock has only been expanded and become more ingrained. This review will discuss the wisdom of such an approach, an updated model describing the origins of hyperlactatemia in sepsis, and how such improvements in our knowledge of the underlying physiology should change our approach to resuscitation in patients presenting with septic shock.

Blood lactate and lactate kinetics as treatment and prognosis markers for tissue hypoperfusion

Objective: Blood lactate concentration (L) and lactate kinetic (LK) over time might be a helpful marker of the shock severity. The purpose of this study is to analyze whether the L and LK could correlate with the outcome and the therapy of patients with different types of shock.Methods: Design: A 3.5-year retrospective observational study. Patients: Eighteen years of age or older, diagnosed with shock were included. Arterial L measurements were performed upon admission and approximatively 3 and 6 h later. The evolution of lactate over this period of time was correlated with the outcome and therapy. Interventions: Univariate and multivariable statistical tests were performed to examine the relation between the initial L/LK and the in-hospital mortality, total mortality, length of stay (LOS), the LOS at the intensive care unit and the administered therapy. The optimal cut-off point of the LK over time to predict the mortality was calculated.Results: The initial L and the 6 h LK were significantly associated with the outcome. The higher the initial L and lower the LK, the higher the risk of mortality in the hospital or within 6 months. Moreover, the higher the initial L and lower the 6 h LK, the longer was the LOS. A relation between the initial L/LK and the required therapy was found. The optimal cut-off for the 6-h LK is 38.1%. Patients with a 6 h LK >38.1% had a significantly higher chance of survival.Conclusions: A significant relationship between the L/6-h LK and the outcome and treatment was found. The optimal survival cut-off point of 6 h LK in our study was 38.1%.

Prognostic value of serial lactate levels in septic patients with and without shock

To analyze the prognostic value of lactate levels for day-7 and in-hospital mortality, in septic patients with and without shock. In the period November 2011-December 2016, we enrolled 268 patients, admitted to our High-Dependency Unit with a diagnosis of sepsis. Lactate dosage was performed at ED-HDU admission (T0), after 2 h (T2), 6 h (T6) and 24 h (T24); lactate clearance was calculated at T2 and T6 [T2: ((LAC T0-LAC T2/LAC T0)*100)]; T6: [(LAC T0-LAC T6/LAC T0)*100]. The end-points were day-7 and in-hospital mortality. At every evaluation, the lactate level was higher in patients with shock than in those without (T0 3.8 ± 3.8 vs 2.4 ± 2.1; T6 2.9 ± 3.2 vs 1.6 ± 1.1; T24 3.0 ± 4.4 vs 1.4 ± 0.9 meq/L, all p < 0.001). Among patients with shock, an analysis for repeated measures confirmed a more marked lactate level reduction in survivors compared with non-survivors, both by day-7 and in-hospital mortality (p = 0.057 and p = 0.006). A Kaplan-MeIer analysis confirmed a significantly better day-7 survival in patients with T6 (with shock 86% vs 70%; without shock 93% vs 82, all p < 0.05) and T24 (with shock 86% vs 70%; without shock 93% vs 82, all p < 0.05) lactate ≤ 2 meq/L, compared with patients with higher levels. A T6 lactate clearance > 10% was more frequent among in-hospital survivors in the whole study population (57% vs 39%) and in patients with shock (74% vs 46%, all p < 0.05). Higher lactate levels and decreased clearance were associated with an increased short-term and intermediate-term mortality regardless of the presence of shock.

Lactate Level Versus Lactate Clearance for Predicting Mortality in Patients With Septic Shock Defined by Sepsis-3

OBJECTIVES

This study aimed to compare the prognostic value of lactate level and lactate clearance at 6 hours after septic shock recognition. And, we performed it to determine lactate kinetics in the Sepsis-3 defined septic shock.

DESIGN

This retrospective study was performed from a prospective septic shock registry.

SETTINGS

This study was performed at single urban tertiary center. And, all patients were treated with protocol-driven resuscitation bundle therapy between 2010 and 2016.

PATIENTS

We included septic shock patients who met the Sepsis-3 definition, which involves lactate levels greater than or equal to 2 mmol/L and vasopressor use.

INTERVENTIONS

Serum lactate levels were measured at initial and 6 hours from septic shock recognition.

MEASUREMENTS AND MAIN RESULTS

Lactate clearance was calculated as ([initial lactate - 6-hr lactate]/initial lactate) × 100. The prognostic value of measured lactate levels and lactate clearance for 28-day mortality was analyzed and compared with that of subsequent lactate levels greater than or equal to 2 mmol/L, greater than or equal to 3 mmol/L, and greater than or equal to 4 mmol/L and less than 10%, less than 20%, and less than 30% lactate clearance. A total of 1,060 septic shock patients by Sepsis-3, 265 patients died (28-d mortality: 25%). In survivor, groups had lower median 6-hour lactate level and higher lactate clearance than nonsurvivors (2.5 vs 4.6 mmol/L and 35.4% vs 14.8%; p < 0.01). Both lactate and lactate clearance were associated with mortality after adjusting for confounders (odd ratio, 1.27 [95% CI, 1.21-1.34] and 0.992 [95% CI, 0.989-0.995]), but lactate had a significantly higher prognostic value than lactate clearance (area under the curve, 0.70 vs 0.65; p < 0.01). The prognostic value of subsequent lactate levels (≥ 2, ≥ 3, and ≥ 4 mmol/L) and lactate clearances (< 10%, < 20%, and < 30%) was not significantly differed. However, lactate levels of greater than or equal to 2 mmol/L had the greatest sensitivity (85.3%).

CONCLUSIONS

Our findings indicate lactate and lactate clearance are both useful targets in patients with septic shock defined by Sepsis-3. Serum lactate level at 6-hour can be an easier and more effective tool for prognosis of septic shock patients who were treated with protocol-driven resuscitation bundle therapy.

Demystifying Lactate in the Emergency Department

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

Lactate clearance prognosticates outcome in pediatric septic shock during first 24 h of intensive care unit admission

This study was undertaken to examine the clinical utility of lactate clearance as an indicator of mortality in pediatric septic shock, and to compare the performance of lactate clearance at 6, 12, and 24 h for predicting in-hospital and 60-day mortality. Pediatric patients with septic shock were prospectively studied. Vital signs, laboratory values, Pediatric Risk of Mortality Score, and pediatric logistic organ dysfunction score were obtained at presentation (hour 0), hour 6, hour 24 and over the first 72 h of hospitalization. Lactate clearance was obtained at 6, 12, and 24 h of hospital admission. Therapy received, outcome parameters of mortality, and duration of hospitalization were recorded. The primary outcome variable of 60-day mortality rate was 31.25%. Only lactate clearance at 6 and 24 h was significantly associated with mortality, with odds of 0.97 (95% CI, 0.951-981; p < 0.001) and 0.975 (95% CI, 0.964-0.986; p < 0.001), respectively. Approximately there was a 24% decrease in likelihood of mortality for each 10% increase in lactate clearance at 24 h. At a threshold value of 10% 6-h lactate clearance had a sensitivity of 0.948 and specificity of 0.571, while at a threshold of 20% 24-h lactate clearance had a sensitivity of 0.922 and specificity of 0.629. The comparison of clearance at 6 and 24 h using receiver operating characteristic showed that former was "fair" (area under the curve = 0.753) and later was "good" (area under the curve = 0.81) in predicting mortality in pediatric septic shock.

Conclusion

We concluded that optimal lactate clearance in pediatric septic shock both during the early presentation and after the initial "golden hours" is associated with lower in-hospital and 60-day mortality. Further, 24-h lactate clearance appears superior to 6 h lactate clearance in predicting mortality in such patients.

Pcv-aCO2/Ca-cvO2 Combined With Arterial Lactate Clearance Rate as Early Resuscitation Goals in Septic Shock

BACKGROUND

We aimed to investigate the prognostic significance of central venous-arterial carbon dioxide tension to arterial-central venous oxygen content ratio (Pcv-aCO₂/Ca-cvO₂) combined with arterial lactate clearance rate (LCR) as early resuscitation goals in septic shock.

MATERIALS AND METHODS

We enrolled 145 septic shock patients admitted to our department from March 2013 to May 2017 in this study. They all received an initial resuscitation therapy according to the Surviving Sepsis Campaign guideline, and were classified into 4 groups according to Pcv-aCO₂/Ca-cvO₂ and LCR at 6 hours after resuscitation (T6): Group A: Pcv-aCO₂/Ca-cvO₂ > 1.8, LCR < 30%; Group B: Pcv-aCO₂/Ca-cvO₂ > 1.8, LCR ≥ 30%; Group C: Pcv-aCO₂/Ca-cvO₂ ≤ 1.8, LCR < 30% and Group D: Pcv-aCO₂/Ca-cvO₂ ≤ 1.8, LCR ≥ 30%. General demographics, hemodynamic parameters, metabolic parameters, Acute Physiology and Chronic Health Evaluation II scores, Sequential Organ Failure Assessment scores, length of intensive care unit stay and 28-day mortality were compared among groups.

RESULTS

Group D had the lowest Acute Physiology and Chronic Health Evaluation II and Sequential Organ Failure Assessment score at day 3, the shortest intensive care unit stay and the lowest 28-day mortality. Kaplan-Meier survival curves up to day 28 showed group D had the longest median survival time. Pcv-aCO₂/Ca-cvO₂ and LCR at T6 were independent predictors of 28-day mortality. The area under ROC curve for Pcv-aCO₂/Ca-cvO₂ combined with LCR was significantly greater than either Pcv-aCO₂/Ca-cvO₂ or LCR alone (both P < 0.05).

CONCLUSIONS

Combination of Pcv-aCO₂/Ca-cvO₂ ratio and LCR is better than either alone to predict the adverse outcomes in septic shock, and may provide useful information for assessing the adequacy of resuscitation in early-stage septic shock.

Assessment of changes in lactate concentration with intravascular microdialysis during high-risk cardiac surgery using the trend interchangeability method

Background

Blood lactate is a strong predictor of mortality, and repeated blood lactate assays are recommended during surgery in high-risk patients. We hypothesized that the use of intravascular microdialysis incorporated in a central venous catheter would be interchangeable with the reference blood gas technique to monitor changes in blood lactate.

Methods

Microdialysis and central venous blood lactate measurements were recorded simultaneously in high-risk cardiac surgical patients. The correlation between absolute values was determined by linear regression, and the Bland-Altman test for repeated measurements was used to compare bias, precision, and limits of agreement. Changes in lactate measurements were evaluated with a four-quadrant plot and trend interchangeability method (TIM).

Results

In the 23 patients analysed, the central venous catheter was used as part of standard care, with no complications. The correlation coefficient for absolute values ( n =104) was 0.96 ( P <0.0001). The bias, precision, and limits of agreement were -0.19, 0.51, and -1.20 to 0.82 mmol litre -1 , respectively. The concordance rate for changes in blood lactate measurements ( n =80) was 94% with the four-quadrant plot. In contrast, the TIM showed that 23 (29) changes in lactate measurements were not interpretable, and among the remaining 57 (71) interpretable changes, 18 (32) were interchangeable, 8 (14) were in the grey zone, and 31 (54) were not interchangeable.

Conclusions

Microdialysis with a central venous catheter appears to provide reliable absolute blood lactate values. Although changes in blood lactate measurements showed an excellent concordance rate, changes between the two methods were poorly interchangeable with the TIM.

Clinical trial registration

NCT02296593.

Plasma lactate measurement as an example of encountered gaps between routine clinical laboratory processes and manufactures' sample-handling instructions

Objectives

Deviation from manufacturers’ pre-analytical sample handling recommendations necessitates extensive validation studies. This report uses plasma lactate testing, where a recommended 15 min room temperature sample handling limit cannot be met by the clinical laboratory, as an example for studies to bridge the gap with practice.

Design and Methods

Triplicate blood samples were collected from patients (n = 51) with lactate requests by clinicians and from normal volunteers (n = 50). One tube was transported on ice (4 °C), the others were maintained at room temperature (23 °C). Tubes stored at 4 °C were processed at 30 min from collection. Tubes stored at 23 °C were processed at 15 and at 30 min from collection. Lactate levels were measured using Roche Diagnostics Cobas 6000® analyzer.

Results

Lactate levels in normal subjects ranged from 0.6 to 3.1 mmol/L (median 1.1). Patient lactate levels ranged from 0.8 to 26.3 mmol/L (median 2.2). Bias in lactate levels following extended storage of samples from both normal subjects and patients ranged from − 1.3 to2.2 and from − 1.0–1.0 mmol/L when stored for 30 min at 23 °C or at 4 °C, respectively. The bias between lactate levels at 30 min at 23 °C and 4 °C was − 1.2 to − 0.5 mmol/L for both populations. Although the bias was not statistically significant for all variables, a clinically significant (>0.2 mmol/L) bias was observed in 28% of normal and 7.0% of patient samples.

Conclusion

Extending the pre-analytical time to 30 min at 23 °C did not significantly impact clinical utility of lactate measurement in our patient population.

•

Pre-analytical gaps exist between manufacturers’ recommendation and clinical practice.

•

Sample handling time for lactate testing was extended to reflect clinical practice.

•

Normal subjects, often preferred, showed high variability compared to patients.

•

Patient samples must always be included in pre-analytics studies.

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Doubling handling time at 23 °C did not have significant clinical impact.

Clinical use of plasma lactate concentration. Part 2: Prognostic and diagnostic utility and the clinical management of hyperlactatemia

OBJECTIVE

To review the current literature pertaining to the use of lactate as a prognostic indicator and therapeutic guide, the utility of measuring lactate concentrations in body fluids other than blood or plasma, and the clinical management of hyperlactatemia in dogs, cats, and horses.

DATA SOURCES

Articles were retrieved without date restrictions primarily via PubMed, Scopus, and CAB Abstracts as well as by manual selection.

HUMAN AND VETERINARY DATA SYNTHESIS

Increased plasma lactate concentrations are associated with increased morbidity and mortality. In populations with high mortality, hyperlactatemia is moderately predictive in identifying nonsurvivors. Importantly, eulactatemia predicts survival better than hyperlactatemia predicts death. Consecutive lactate measurements and calculated relative measures appear to outperform single measurements. The use of lactate as a therapeutic guide has shown promising results in people but is relatively uninvestigated in veterinary species. Increased lactate concentrations in body fluids other than blood should raise the index of suspicion for septic or malignant processes. Management of hyperlactatemia should target the underlying cause.

CONCLUSION

Lactate is a valuable triage and risk stratification tool that can be used to separate patients into higher and lower risk categories. The utility of lactate concentration as a therapeutic target and the measurement of lactate in body fluids shows promise but requires further research.

Timing of Repeated Lactate Measurement in Patients With Septic Shock at the Emergency Department

BACKGROUND

The objective of this study was to evaluate the prognostic value of lactate levels during the first 12 hours after shock development and to identify the optimal timing for repeated lactate measurements in patients with septic shock.

METHODS

We conducted a retrospective cohort study using a prospective data registry, and enrolled 2,226 consecutive adult patients with septic shock between January 2010 and December 2015. Blood lactate was measured at shock development, and after 2, 4, 6 and 12 hours (T₀, T₂, T₄, T₆ and T₁₂) during protocol-driven resuscitation bundle therapy. The prognostic value of lactate levels for 28-day mortality was analyzed using logistic regression and receiver operating characteristic curve analysis.

RESULTS

A total of 829 patients with septic shock were included in the study, among whom 211 died during the study period. The lactate levels at each time point were associated with increased 28-day mortality, and the lactate level at 6 hours had the greatest prognostic value (area under the curve of T₀ = 0.61; T₂ = 0.65; T₄ = 0.69; T₆ = 0.72 and T₁₂ = 0.62, and odds ratio (OR) of T₀, 1.17 [95% CI: 1.11-1.23]; T₂, 1.23 [95% CI: 1.17-1.30]; T₄, 1.30 [95% CI: 1.22-1.38]; T₆, 1.33 [95% CI: 1.26-1.42] and T₁₂, 1.24 [95% CI: 1.19-1.30]). Hyperlactatemia over 2mmol/L and 4mmol/L at 6 hours from shock was associated with 4-times higher mortality (≥2mmol/L, OR = 3.89 [95% CI: 2.48-6.09]; ≥4mmol/L, OR = 3.93 [95% CI: 2.83-5.44]).

CONCLUSIONS

During the first 12 hours following shock development, the optimal time point of repeated blood lactate measurement was 6 hours, which was the greatest prognostic value for mortality.

Evidence Underpinning the Centers for Medicare & Medicaid Services' Severe Sepsis and Septic Shock Management Bundle (SEP-1): A Systematic Review

This article has been corrected. To see what has changed, please read the Letter to the Editor and the authors' response. The original version (PDF) is appended to this article as a Supplement.

Background

The Severe Sepsis and Septic Shock Early Management Bundle (SEP-1), the sepsis performance measure introduced in 2015 by the Centers for Medicare & Medicaid Services (CMS), requires the reporting of up to 5 hemodynamic interventions, as many as 141 tasks, and 3 hours to document for a single patient.

Purpose

To evaluate whether moderate- or high-level evidence shows that use of the 2015 SEP-1 or its hemodynamic interventions improves survival in adults with sepsis.

Data Sources

PubMed, Embase, Scopus, Web of Science, and ClinicalTrials.gov from inception to 28 November 2017 with no language restrictions.

Study Selection

Randomized and observational studies of death among adults with sepsis who received versus those who did not receive either the entire SEP-1 bundle or 1 or more SEP-1 hemodynamic interventions, including serial lactate measurements; a fluid infusion of 30 mL/kg of body weight; and assessment of volume status and tissue perfusion with a focused examination, bedside cardiovascular ultrasonography, or fluid responsiveness testing.

Data Extraction

Two investigators independently extracted study data and assessed each study's risk of bias; 4 authors rated level of evidence by consensus using CMS criteria published in 2013. High- or moderate-level evidence required studies to have no confounders and low risk of bias.

Data Synthesis

Of 56 563 references, 20 studies (18 reports) met inclusion criteria. One single-center observational study reported lower in-hospital mortality after implementation of the SEP-1 bundle. Sixteen studies (2 randomized and 14 observational) reported increased survival with serial lactate measurements or 30-mL/kg fluid infusions. None of the 17 studies were free of confounders or at low risk of bias. In 3 randomized trials, fluid responsiveness testing did not alter survival.

Limitations

Few trials, poor-quality and confounded studies, and no studies (with survival outcomes) of the focused examination or bedside cardiovascular ultrasonography. Use of the 2015 version of SEP-1 and 2013 version of CMS evidence criteria, both of which were updated in 2017.

Conclusion

No high- or moderate-level evidence shows that SEP-1 or its hemodynamic interventions improve survival in adults with sepsis.

Primary Funding Source

National Institutes of Health. (PROSPERO: CRD42016052716).

Blood pressure variability as an indicator of sepsis severity in adult emergency department patients

STUDY OBJECTIVE

Quantify the correlation between blood pressure variability (BPV) and markers of illness severity: serum lactate (LAC) or Sequential Organ Failure Assessment (SOFA) scores.

METHODS

We performed a secondary analysis of data from a prospective, observational study evaluating fluid resuscitation on adult, septic, ED patients. Vital signs and fluid infusion volumes were recorded every 15min during the 3h following ED arrival. BPV was assessed via average real variability (ARV): the average of the absolute differences between consecutive BP measurements. ARV was calculated for the time periods before and after 3 fluid infusion milestones: 10-, 20-, and 30-mL/kg total body weight (TBW). Spearman's rho correlation coefficient analysis was utilized. A p-value<0.05 was considered statistically significant.

RESULTS

Forty patients were included. Mean fluid infusion was 33.7mL/kg TBW (SD 22.1). All patients received fluid infusion≥10mL/kg TBW, 25 patients received fluid infusion>20mL/kg TBW, and 16 patients received fluid infusion>30mL/kg TBW. Mean initial LAC was 4.0mmol/L (SD 3.2). Mean repeat LAC was 3.1mmol/L (SD 3.2), obtained an average of 6.6h (SD 5.3) later. Mean SOFA score was 7.0 (SD 4.4). BPV correlated with both follow-up LAC (r=0.564; p=0.023) and SOFA score (r=0.544; p=0.024) among the cohort that received a fluid infusion>20-mL/kg TBW.

CONCLUSION

With the finding of a positive correlation between BPV and markers of illness severity (LAC and SOFA scores), this pilot study introduces BPV analysis as a real-time, non-invasive tool for continuous sepsis monitoring in the ED.

[Changes in blood oxygen metabolism indices and their clinical significance in children with septic shock]

The key to the treatment of septic shock is to provide adequate oxygen supply and improve tissue perfusion. Lactate and central venous oxygen saturation (ScvO2) are commonly used as the indices of oxygen metabolism, but tissue hypoxia may still exist even when lactate and ScvO2 are within the normal range. Arteriovenous difference in carbon dioxide partial pressure (CO2 gap) can accurately reflect oxygen delivery when ScvO2 is in the normal range. This article reviews the advantages and shortages of lactate, lactate clearance rate, ScvO2, and CO2 gap in evaluating tissue hypoxia, in order to provide a reference for treatment and severity evaluation of septic shock.

[Changes in blood oxygen metabolism indices and their clinical significance in children with septic shock]

The key to the treatment of septic shock is to provide adequate oxygen supply and improve tissue perfusion. Lactate and central venous oxygen saturation (ScvO₂) are commonly used as the indices of oxygen metabolism, but tissue hypoxia may still exist even when lactate and ScvO₂ are within the normal range. Arteriovenous difference in carbon dioxide partial pressure (CO₂ gap) can accurately reflect oxygen delivery when ScvO₂ is in the normal range. This article reviews the advantages and shortages of lactate, lactate clearance rate, ScvO₂, and CO₂ gap in evaluating tissue hypoxia, in order to provide a reference for treatment and severity evaluation of septic shock.

Admission lactate predicts poor prognosis independently of the CRB/CURB-65 scores in community-acquired pneumonia

OBJECTIVES

Community-acquired pneumonia (CAP) is associated with a high risk of respiratory failure or septic organ dysfunction. Lactate is an established early marker of prognosis and sepsis severity, but few data exist in patients with CAP.

METHODS

We performed a retrospective cohort study of consecutive adult CAP patients without treatment restrictions or direct intensive care unit admission. Lactate was measured as a point-of-care test within the capillary admission blood gas analysis, and its prognostic value was compared to the CRB/CURB-65 criteria by multivariate and receiver operating characteristic (ROC) curve analysis. The primary endpoint was the combination of need for mechanical ventilation, vasopressors, intensive care unit admission or hospital mortality.

RESULTS

Of 303 included patients, 75 (25%) met the primary endpoint. After ROC analysis, lactate predicted the primary endpoint (area under the curve 0.67) with an optimal cutoff of >1.8 mmol/L. Of the 76 patients with lactate above this threshold, 35 (46%) met the primary endpoint. After multivariate analysis, the predictive value of lactate was independent of the CRB/CURB-65 scores. The addition of lactate >1.8 mmol/L to the CRB/CURB-65 scores resulted in significantly improved area under the curves (0.69 to 0.74, p 0.005 and 0.71 to 0.75, p 0.008 respectively). Fourteen (42%) of 33 and 11 (39%) of 28 patients meeting the endpoint despite presenting with 0 or 1 CRB/CURB-65 criteria had lactate >1.8 mmol/L.

CONCLUSIONS

Admission lactate levels significantly improved the prognostic value of the CRB/CURB-65 scores in CAP patients. Lactate may therefore be considered a rapid, cheap and broadly available additional criterion for the assessment of risk in patients with CAP.

The long-term burden of severe sepsis and septic shock: Sepsis recidivism and organ dysfunction

BACKGROUND

Severe sepsis and septic shock mortality has improved; however, rates of persistent (28-90 days) and long-term (>90 day) organ dysfunction in sepsis survivors are unknown.

METHODS

Secondary analysis of a prospective cohort of adult emergency department patients with severe sepsis.

RESULTS

Of 110 sepsis admissions, we obtained follow-up on 51 of 78 survivors of whom 41% (21 of 51) had persistent organ dysfunction: pulmonary, 18% (9 of 51); renal, 22% (11 of 51); coagulopathy, 10% (5 of 51); cardiovascular, 6% (3 of 51); hepatic, 2% (1 of 51); and neurologic, 3% (3 of 51). We obtained follow-up on 40 of 73 survivors at more than 90 days of whom 38% (15 of 40) had long-term organ dysfunction: pulmonary, 13% (5 of 40); renal, 18% (7 of 40); coagulopathy, 3% (1 of 40); cardiovascular, 5% (2 of 40); hepatic, 0%; and neurologic, 5% (2 of 40). Readmission rate within 90 days was 32% (25 of 78), and recurrent sepsis was the cause of readmission in 52% (13 of 25). Baseline SOFA scores from the index sepsis admission were compared using Wilcoxon rank-sum test and were significantly different in participants with organ dysfunction versus those without organ dysfunction at less than 90 days (z, -2.51; p = 0.01).

CONCLUSION

Readmission with recurrent sepsis and organ dysfunction occurs frequently in sepsis survivors. Baseline SOFA score may be predictive of sepsis recidivism and persistent or recurrent organ dysfunction.

LEVEL OF EVIDENCE

Prognostic/epidemiologic study, level IV.

The value of blood lactate kinetics in critically ill patients: a systematic review

BACKGROUND

The time course of blood lactate levels could be helpful to assess a patient's response to therapy. Although the focus of published studies has been largely on septic patients, many other studies have reported serial blood lactate levels in different groups of acutely ill patients.

METHODS

We performed a systematic search of PubMed, Science Direct, and Embase until the end of February 2016 plus reference lists of relevant publications. We selected all observational and interventional studies that evaluated the capacity of serial blood lactate concentrations to predict outcome. There was no restriction based on language. We excluded studies in pediatric populations, experimental studies, and studies that did not report changes in lactate values or all-cause mortality rates. We separated studies according to the type of patients included. We collected data on the number of patients, timing of lactate measurements, minimum lactate level needed for inclusion if present, and suggested time interval for predictive use.

RESULTS

A total of 96 studies met our criteria: 14 in general ICU populations, five in general surgical ICU populations, five in patients post cardiac surgery, 14 in trauma patients, 39 in patients with sepsis, four in patients with cardiogenic shock, eight in patients after cardiac arrest, three in patients with respiratory failure, and four in other conditions. A decrease in lactate levels over time was consistently associated with lower mortality rates in all subgroups of patients. Most studies reported changes over 6, 12 or 24 hrs, fewer used shorter time intervals. Lactate kinetics did not appear very different in patients with sepsis and other types of patients. A few studies suggested that therapy could be guided by these measurements.

CONCLUSIONS

The observation of a better outcome associated with decreasing blood lactate concentrations was consistent throughout the clinical studies, and was not limited to septic patients. In all groups, the changes are relatively slow, so that lactate measurements every 1-2 hrs are probably sufficient in most acute conditions. The value of lactate kinetics appears to be valid regardless of the initial value.

Cost-effectiveness analysis of early point-of-care lactate testing in the emergency department

PURPOSE

To determine the cost-effectiveness of implementing a point-of-care (POC) Lactate Program in the emergency department (ED) for patients with suspected sepsis to identify patients who can benefit from early resuscitation.

MATERIALS AND METHODS

We constructed a cost-effectiveness model to examine an ED with 30 000 patients annually. We evaluated a POC lactate program screening patients with suspected sepsis for an elevated lactate ≥4 mmol/L. Those with elevated lactate levels are resuscitated and their lactate clearance is evaluated by serial POC lactate measurements. The POC Lactate Program was compared with a Usual Care Strategy in which all patients with sepsis and an elevated lactate are admitted to the intensive care unit. Costs were estimated from the 2014 Medicare Inpatient and National Physician Fee schedules, and hospital and industry estimates.

RESULTS

In the base-case, the POC Lactate Program cost $39.53/patient whereas the Usual Care Strategy cost $33.20/patient. The screened patients in the POC arm resulted in 1.07 quality-adjusted life years for an incremental cost-effectiveness ratio of $31 590 per quality-adjusted life year gained, well below accepted willingness-to-pay-thresholds.

CONCLUSIONS

Implementing a POC Lactate Program for screening ED patients with suspected sepsis is a cost-effective intervention to identify patients responsive to early resuscitation.

Freestanding Emergency Critical Care During the Aftermath of Hurricane Sandy: Implications for Disaster Preparedness and Response

OBJECTIVE

To assess the impact of an emergency intensive care unit (EICU) established concomitantly with a freestanding emergency department (ED) during the aftermath of Hurricane Sandy.

METHODS

We retrospectively reviewed records of all patients in Bellevue's EICU from freestanding ED opening (December 10, 2012) until hospital inpatient reopening (February 7, 2013). Temporal and clinical data, and disposition upon EICU arrival, and ultimate disposition were evaluated.

RESULTS

Two hundred twenty-seven patients utilized the EICU, representing approximately 1.8% of freestanding ED patients. Ambulance arrival occurred in 31.6% of all EICU patients. Median length of stay was 11.55 hours; this was significantly longer for patients requiring airborne isolation (25.60 versus 11.37 hours, P<0.0001 by Wilcoxon rank sum test). After stabilization and treatment, 39% of EICU patients had an improvement in their disposition status (P<0.0001 by Wilcoxon signed rank test); upon interhospital transfer, the absolute proportion of patients requiring ICU and SDU resources decreased from 37.8% to 27.1% and from 22.2% to 2.7%, respectively.

CONCLUSIONS

An EICU attached to a freestanding ED achieved significant reductions in resource-intensive medical care. Flexible, adaptable care systems should be explored for implementation in disaster response. (Disaster Med Public Health Preparedness. 2016;10:496-502).

Blood pressure targets for vasopressor therapy: a systematic review

Physicians often prescribe vasopressors to correct pathological vasodilation and improve tissue perfusion in patients with septic shock, but the evidence to inform practice on vasopressor dosing is weak. We undertook a systematic review of clinical studies evaluating different blood pressure targets for the dosing of vasopressors in septic shock. We searched MEDLINE, EMBASE, CENTRAL (to November 2013), reference lists from included articles, and trial registries for randomized controlled trials (RCTs) and observational and crossover intervention studies comparing different blood pressure targets for vasopressor therapy in septic shock. Two reviewers independently selected eligible studies and extracted data on standardized forms. We identified 2 RCTs and 10 crossover trials but no observational studies meeting our criteria. Only one RCT measured clinical outcomes after comparing mean arterial pressure targets of 80 to 85 mmHg versus 65 to 70 mmHg. There was no effect on 28-day mortality, but confidence intervals were wide (hazard ratio, 95% confidence interval [95% CI] 0.84 - 1.38). In contrast, this intervention was associated with a greater risk of atrial fibrillation (relative risk, 2.36; 95% CI, 1.18 - 4.72) and a lower risk of renal replacement therapy in hypertensive patients (relative risk, 0.75; 95% CI, 0.57 - 1.0). Crossover trials suggest that achieving higher blood pressure targets by increasing vasopressor doses increases heart rate and cardiac index with no effect on serum lactate. Our findings underscore the paucity of clinical evidence to guide the administration of vasopressors in critically ill patients with septic shock. Further rigorous research is needed to establish an evidence base for vasopressor administration in this population.

Lactic Acidosis in Sepsis: It's Not All Anaerobic: Implications for Diagnosis and Management

Increased blood lactate concentration (hyperlactatemia) and lactic acidosis (hyperlactatemia and serum pH < 7.35) are common in patients with severe sepsis or septic shock and are associated with significant morbidity and mortality. In some patients, most of the lactate that is produced in shock states is due to inadequate oxygen delivery resulting in tissue hypoxia and causing anaerobic glycolysis. However, lactate formation during sepsis is not entirely related to tissue hypoxia or reversible by increasing oxygen delivery. In this review, we initially outline the metabolism of lactate and etiology of lactic acidosis; we then address the pathophysiology of lactic acidosis in sepsis. We discuss the clinical implications of serum lactate measurement in diagnosis, monitoring, and prognostication in acute and intensive care settings. Finally, we explore treatment of lactic acidosis and its impact on clinical outcome.

Brief report: Serial capillary lactate measurement predict the evolution of early sepsis

OBJECTIVE

In intensive care settings, blood lactate level measurement proved to be an excellent predictor of outcomes. In patients requiring less urgent treatment, the arterial blood lactate is less sensitive and its usefulness remains to be proven. Capillary blood lactate dosing, an emergent point-of-care technique readily available should be more sensitive to changes in these settings.

METHOD

prospective, observational, monocentric study conducted in a polyvalent internal medicine ward in a French University Hospital. The inclusion criteria were the existence of new symptoms of abrupt onset in an otherwise stable patient. All the patients had a point of care measurement of baseline capillary and venous lactate levels (EDGE, ApexBio) and standardized control before any therapeutic means were initiated. A follow-up test was performed once again within 12 to 36 hours. All the patients received standard medical care adapted to their condition. The primary outcomes were considered dying within 30 days or requiring intensive care or invasive therapeutic procedures.

RESULTS

13 patients were analyzed. Seven patients reached the composite outcome with 3 deaths. The superimposed complication proved to be infectious in every case. The median lactate levels were at baseline (mmol/ l): capillary Mc0=5.2(2.16), venous Mv0=2.3(2.0) and arterial Ma0=1.8(1.7) and at follow-up (mmol/ l) capillary: Mc1=3.3(1.1), venous Mv1=1.8(1.8) and arterial Ma1=1.3(0.7). In nonparametric analysis, the absence of normalization of capillary lactate at follow-up was correlated well with poor outcomes (p=.05). This was not the case of arterial or venous lactate measurements. The positive lactate clearance was present in the majority of patients (83.3%) but it did not predict the outcomes (p=.435) and there was no correlation between the baseline lactate and the clinical outcome (p>.05).

CONCLUSION

In non intensive care settings, capillary lactate level could be a more sensitive method than the classical lactate measurement for predicting the outcomes of acute conditions, especially infectious. A persistently high lactate level rather than its initial value or clearance seems to correlate better with poorer outcomes.

ABBREVIATIONS

SSC = Surviving sepsis campaign, ED = Emergency department, ICU = intensive care unit, , POC = Point of care, ICC = inter class coefficient.

Sepsis-associated pulmonary complications in emergency department patients monitored with serial lactate: An observational cohort study

PURPOSE

Patients with severe sepsis and septic shock are at high risk for development of pulmonary complications, including acute respiratory distress syndrome (ARDS). Serial lactate monitoring is a useful tool to gauge global tissue hypoxia in emergency department (ED) patients with sepsis. We hypothesized that patients undergoing serial lactate monitoring (SL) would demonstrate a decreased incidence of pulmonary complications.

METHODS

This is a retrospective observational cohort study of adult severe sepsis and septic shock patients with elevated lactate presenting to a large academic ED. A total of 243 patients were assigned to SL (n=132) or no serial lactate monitoring (NL; n=111). The primary outcome was a composite of pulmonary complications: (1) ARDS development and (2) respiratory failure.

RESULTS

Twenty-eight patients (21%) in the SL group and 37 patients (33%) in the NL group developed the primary outcome (P=.03). Multivariate analysis demonstrated an association between the NL group and development of pulmonary complications (adjusted odds ratio [aOR], 2.1; confidence interval [CI], 1.15-3.78). Emergency department mechanical ventilation was independently associated with development of ARDS (aOR, 3.5; 1.8-7.0). In the a priori subgroup of patients mechanically ventilated in the ED (n=97), those who developed ARDS received higher tidal volumes compared to patients who did not develop ARDS (8.7 mL/kg predicted body weight [interquartile range, 7.6-9.5] vs 7.6 [interquartile range, 6.8-9.0]; P<.01).

CONCLUSIONS

Serial lactate monitoring is associated with a decrease in major pulmonary complications in severe sepsis and septic shock. Acute respiratory distress syndrome incidence is also influenced by ED-based mechanical ventilation. These results provide 2 potentially modifiable variables to be targeted in future studies to prevent pulmonary complications in this patient subset.

The prognostic role of non-critical lactate levels for in-hospital survival time among ED patients with sepsis

OBJECTIVE

This study describes emergency department (ED) sepsis patients with non-critical serum venous lactate (LAC) levels (LAC <4.0 mmol/L) who suffered in-hospital mortality and examines LAC in relation to survival times.

METHODS

An ED based retrospective cohort study accrued September 2010 to August 2014. Inclusion criteria were ED admission, LAC sampling, >2 systemic inflammatory response syndrome criteria with an infectious source (sepsis), and in-hospital mortality. Kaplan-Meier curves were used for survival estimates. An a priori sub-group analysis for patients with repeat LAC within 6 hours of initial sampling was undertaken. The primary outcome was time to in-hospital death evaluated using rank-sum tests and regression models.

RESULTS

One hundred ninety-seven patients met inclusion criteria. Pulmonary infections were the most common (44%) and median LAC was 1.9 mmol/L (1.5, 2.5). Thirteen patients (7%) died within 24 hours and 79% by ≤28 days. Median survival was 11 days (95% CI, 8.0-13). Sixty-two patients had repeat LAC sampling with 14 (23%) and 48 (77%) having decreasing increasing levels, respectively. No significant differences were observed in treatment requirements between the LAC subgroups. Among patients with decreasing LAC, median survival was 24 days (95% CI, 5-32). For patients with increasing LAC median survival was significantly shorter (7 days; 95% CI, 4-11, P = .04). Patients with increasing LAC had a non-significant trend toward reduced survival (HR = 1.6 95% CI, 0.90-3.0, P = .10).

CONCLUSIONS

In septic ED patients experiencing in-hospital death, non-critical serum venous lactate may be utilized as a risk-stratifying tool for early mortality, while increasing LAC levels may identify those in danger of more rapid deterioration.

Supportive Care of the First 2 Ebola Virus Disease Patients at the Monrovia Medical Unit

We describe the first 2 patients admitted to the Monrovia Medical Unit, a facility established to treat Liberian and international response workers with suspected or known Ebola virus disease (EVD). Their recoveries illustrate the value of local point-of-care diagnostics, parenteral therapies, and electrolyte replacement in EVD supportive care.