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

Review: sepsis guidelines and core measure bundles

Sepsis is a major cause of mortality worldwide and is the third-leading cause of death in the United States. Sepsis is resource-intensive and requires prompt recognition and treatment to reduce mortality. The impact of sepsis is not only on in-hospital survival but extends into post-discharge quality of life and risk of re-admission. As the understanding of sepsis physiology evolved, so have the recommended screening tools and treatment protocol which challenge prior standards of care. There have been noteworthy efforts by the Surviving Sepsis Campaign, the Third International Consensus Definitions for Sepsis and the Centers for Medicare and Medicaid Services to establish core measure bundles. This review highlights both the 2021 SSC International Guidelines and the 2015 CMS Severe Sepsis/Septic Shock Core Measure Bundle, or SEP-1. Notably, the SEP-1 bundle was implemented as a value-based purchasing program, linking care of sepsis patients to financial incentives. The objective is to explore the most current evidence-based data to inform clinical practice while utilizing the available guidelines as a roadmap.

Severe hyperlactatemia in the emergency department: clinical characteristics, etiology and mortality

BACKGROUND

Severe hyperlactatemia (lactate level ≥ 10 mmol/L) is associated with high mortality rates in critically ill patients. However, there is limited data on emergency department (ED) patients. We aimed to investigate the clinical characteristics, etiology and outcomes of patients with severe hyperlactatemia in the ED setting.

METHODS

A retrospective cohort study was conducted at a tertiary care hospital in Thailand. We included adult patients with a venous lactate sample taken in the ED within one hour. We excluded patients after out-of-hospital cardiac arrest, transferred to/from another hospital or those with missing clinical data. Mortality rates were evaluated among patients with increasing degrees of lactate elevation and among patients with severe hyperlactatemia, stratified by causative etiology.

RESULTS

We analyzed venous lactate levels in 40,047 patients, with 26,680 included in the analysis. Among these, 1.7% had severe hyperlactatemia (lactate ≥ 10 mmol/L), 10.5% moderate (4-9.99 mmol/L), 28.8% mild (2-3.99 mmol/L), and 59.0% normal levels (< 2 mmol/L). Severe hyperlactatemia was associated with high mortality rates of 29%, 37%, and 38% at 7, 28, and 60 days respectively, significant ICU admissions and mechanical ventilation rates. Patients with severe hyperlactatemia were stratified into high (> 50% mortality), moderate (21-50%), and low (< 20%) 28-day mortality risk groups. High-risk conditions included non-septic shock, traumatic injuries/burns, and neurological issues, with mortality rates of 51.1%, 61.8%, and 57.1%, respectively. In the moderate risk group, namely infection without shock showed a high prevalence, with a mortality rate of 36%. In the low-risk group, seizures and fainting were associated with lower mortality, exhibiting mortality rates of 0%.

CONCLUSIONS

Severe hyperlactatemia is associated with higher rates of ICU admission and mortality compared to other degrees of lactate elevation in a general ED population. However, mortality rates can vary considerably, depending on the underlying etiology associated with different primary diagnoses.

Lactate metabolism and acute kidney injury

ABSTRACT

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

Influence of blood lactate variations and passive exercise on cardiac responses

[Purpose] This study aimed to investigate cardiovascular responses, including heart rate (HR) and heart rate variability (HRV), to various hyperlactatemia-passive exercise interactions. [Participants and Methods] Nine healthy male participants performed upper limb passive cycling movement, and their HR and HRV were assessed while their blood lactate levels were manipulated by sustained handgrip exercise at control, 15% maximum voluntary contraction (MVC), and 30% MVC, followed by postexercise circulatory occlusion. [Results] HR and root mean squared standard difference (rMSSD) of HRV response remained constant at all blood lactate levels during passive exercise (HR: control, 75.8 ± 3.4 bpm; 15% MVC, 76.9 ± 2.7 bpm; and 30% MVC, 77.0 ± 3.7 bpm; rMSSD: control, 33.2 ± 6.9 ms; 15% MVC, 36.3 ± 7.3 ms; and 30% MVC, 37.3 ± 8.9 ms). [Conclusion] Manipulating metaboreflex activation did not significantly alter HR or HRV during passive exercise. These results suggest that, in healthy participants, the interactions between mechanical and metabolic stimuli do not affect HR and HRV responses, implying that passive exercise may be safely implemented.

Unmeasured Organic Anions as Predictors of Clinical Outcomes in Lactic Acidosis due to Sepsis

Background and Objectives: In lactic acidosis, lactate can only explain 30% of the variance in the anion gap (AG), and the elevated AG not explained by lactate is due to unmeasured organic anions (UOAs). Some studies using less precise surrogates for UOA have suggested that UOA may predict clinical outcomes better than lactate. The aim of this study was to determine whether UOA predicts clinical outcomes better than lactate levels. Design, Setting, Participants, & Measurements: This was a retrospective cohort study of adult ICU patients with sepsis. Baseline AG and albumin measurements were obtained. An albumin-corrected delta AG was calculated. UOAs were estimated using the formula: Delta AG - serum lactate. A multivariate logistic regression model with its respective ROC curve was constructed to explore the relationship between in-hospital mortality, UOA, and lactate. Results: 526 patients were included. In the combined model examining both lactate and UOA, the odds ratio (OR) [95% CI] for predicting ICU length of stay (LOS) was 1.050 [1.029-1.072] and 1.022 [1.009-1.035], respectively; the OR [95% CI] for predicting in-hospital mortality was 1.224 [1.104-1.358] and 0.997 [0.943-1.054], respectively. The ROC curve for in-hospital mortality demonstrated that the Area Under the Curve (AUC) for lactate, UOA, and combined lactate and UOA was 0.7726, 0.7486, and 0.7732, respectively. The AUC for combined lactate and UOA were not statistically significantly higher than the AUC for lactate alone (P .9193). Conclusions: As expected, serum lactate predicted both ICU LOS and in-hospital mortality. UOA did predict ICU LOS, although the reason for this association is not known. UOA did not predict in-hospital mortality based on the OR and the ROC curve's AUC, contrary to some previous studies. However, our study used a more precise quantitative estimate of UOA, including the use of baseline albumin-corrected AG. Prior studies attempting to identify UOA have identified Krebs cycle intermediates including citrate and isocitrate, suggesting that in our study these anions associated with the Krebs cycle contributed to the UOA.

Postoperative hyperlactataemia and preoperative cardiopulmonary exercise testing in an elective noncardiac surgical cohort: a retrospective observational study

Background

Blood lactate concentration in the postoperative period is a marker of physiological stress and a predictor of complications and mortality. Cardiopulmonary exercise testing (CPET) is a common preoperative risk stratification tool. We aimed to investigate the association between preoperative CPET results and postoperative lactate concentration with postoperative mortality after major noncardiac surgery.

Methods

We analysed data from patients undergoing major noncardiac surgery in a tertiary UK centre between 2007 and 2014 who had preoperative CPET and postoperative lactate measurements. Univariate and multivariate analyses were performed to assess the association between lactate concentration, CPET results, or both and mortality.

Results

We analysed data from 1075 patients. A mean lactate concentration >2 mM in the first 12, 24, and 48 h after surgery was associated with odds ratios (ORs) and 95% confidence intervals (CIs) for 30-day mortality of 3.9 (2.1-7.3; P<0.005), 4.5 (2.4-8.4; P<0.005), and 6.1 (3.3-11.5; P<0.005), respectively. The dichotomous CPET variable, ventilatory equivalence for CO2 (V̇E/V̇co2; cut-off 34), was associated with increased risk of 30-day mortality (OR 2.5; 95% CI: 1.3-4.8; P<0.005). In a multivariable model, hyperlactataemia and poor V̇E/V̇co2 retained their significant associations with 30- and 90-day mortality when adjusted for age, BMI, and surgical risk. When looking at the combined effect of the dichotomous hyperlactataemia in the first 24 h (cut-off 2 mM) and preoperative V̇E/V̇co2, the OR for 30-day mortality was 11.53 (95% CI: 4.6-28.8; P≤0.005).

Conclusions

Our study suggests that postoperative hyperlactataemia and preoperative poor V̇E/V̇co2 are independently associated with an increased risk of mortality after major noncardiac surgery.

The combination of lactate level, lactate clearance and APACHE II score better predicts short-term outcomes in critically Ill patients: a retrospective cohort study

BACKGROUND

The mortality rate is high in critically ill patients due to the difficulty of diagnosis and treatment. Thus, it is very important to explore the predictive value of different indicators related to prognosis in critically ill patients.

METHODS

This was a retrospective cohort study of patients in the intensive care unit (ICU) of the Sixth People's Hospital in Shanghai, China. A total of 1465 ICU patients had lactate values > 2.1 mmol/L at least once within 24 h of ICU admission, and arterial blood gas was monitored more than twice during the ICU stay.

RESULTS

The predictive value of lactate clearance at 24 h was not high, and the sensitivity and specificity were lower. The predictive value of the lactate level at baseline and the APACHE II score was higher than that of lactate clearance at 24 h in critically ill patients. The predictive value of the lactate level at baseline combined with the APACHE II score was higher than that of the lactate level at baseline or the APACHE II score alone. In addition, the predictive value of lactate clearance at 24 h combined with the APACHE II score was also significantly higher than that of lactate clearance at 24 h or the APACHE II score alone. In particular, the area under the ROC curve reached 0.900, the predictive value was markedly higher than that of the ROC alone, and the sensitivity and specificity were better when these three indicators were combined.

CONCLUSIONS

The combination of lactate level, lactate clearance and APACHE II score better predicts short-term outcomes in critically ill patients.

Serum Lactate and Mortality during Pediatric Admissions: Is 2 Really the Magic Number?

The primary objective of this study was to determine if serum lactate level at the time of hospital admission can predict mortality in pediatric patients. A systematic review was conducted to identify studies that assessed the utility of serum lactate at the time of admission to predict mortality in pediatric patients. The areas under the curve from the receiver operator curve analyses were utilized to determine the pooled area under the curve. Additionally, standardized mean difference was compared between those who survived to discharge and those who did not. A total of 12 studies with 2,099 patients were included. Out of these, 357 (17%) experienced mortality. The pooled area under the curve for all patients was 0.74 (0.67-0.80, p  < 0.01). The pooled analyses for all admissions were higher in those who experienced mortality (6.5 vs. 3.3 mmol/L) with a standardized mean difference of 2.60 (1.74-3.51, p  < 0.01). The pooled area under the curve for cardiac surgery patients was 0.63 (0.53-0.72, p  < 0.01). The levels for cardiac surgery patients were higher in those who experienced mortality (5.5 vs. 4.1 mmol/L) with a standardized mean difference of 1.80 (0.05-3.56, p  = 0.04). Serum lactate at the time of admission can be valuable in identifying pediatric patients at greater risk for inpatient mortality. This remained the case when only cardiac surgery patients were included.

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

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

A multicenter randomized clinical trial of pharmacological vitamin B1 administration to critically ill patients who develop hypophosphatemia during enteral nutrition (The THIAMINE 4 HYPOPHOSPHATEMIA trial)

BACKGROUND

Hypophosphatemia may be a useful biomarker to identify thiamine deficiency in critically ill enterally-fed patients. The objective was to determine whether intravenous thiamine affects blood lactate, biochemical and clinical outcomes in this group.

METHOD

This randomized clinical trial was conducted across 5 Intensive Care Units. Ninety critically ill adult patients with a serum phosphate ≤0.65 mmol/L within 72 h of commencing enteral nutrition were randomized to intravenous thiamine (200 mg every 12 h for up to 14 doses) or usual care (control). The primary outcome was blood lactate over time and data are median [IQR] unless specified.

RESULTS

Baseline variables were well balanced (thiamine: lactate 1.2 [1.0, 1.6] mmol/L, phosphate 0.56 [0.44, 0.64] mmol/L vs. control: lactate 1.0 [0.8, 1.3], phosphate 0.54 [0.44, 0.61]). Patients randomized to the intervention received a median of 11 [7.5, 13.5] doses for a total of 2200 [1500, 2700] mg of thiamine. Blood lactate over the entire 7 days of treatment was similar between groups (mean difference = -0.1 (95 % CI -0.2 to 0.1) mmol/L; P = 0.55). The percentage change from lactate pre-randomization to T = 24 h was not statistically different (thiamine: -32 (-39, -26) vs. control: -24 (-31, -16) percent, P = 0.09). Clinical outcomes were not statistically different (days of vasopressor administration: thiamine 2 [1, 4] vs. control 2 [0, 5.5] days; P = 0.37, and deaths 9 (21 %) vs. 5 (11 %); P = 0.25).

CONCLUSIONS

In critically ill enterally-fed patients who developed hypophosphatemia, intravenous thiamine did not cause measurable differences in blood lactate or clinical outcomes.

TRIAL REGISTRATION

Australian and New Zealand Clinical Trials Registry (ACTRN12619000121167).

Lactate is Associated with Increased 30-Day Mortality in Critically Ill Patients with Alcohol Use Disorder

Purpose

To investigate the predictive value of lactate for prognosis in critically ill patients with AUD.

Methods

A retrospective cohort study was performed using data extracted from a freely accessible critical care database (MIMIC-III). We studied all patients with AUD from the database for whom lactate was available. The clinical outcomes were 30-day mortality. Analyses included LOWESS curve fitting, logistic multivariate regression model, receiver operating characteristic (ROC) analysis and subgroup analysis.

Results

A total of 1296 eligible critically ill patients with AUD were included and there were 223 non-survivors (17.2%). The non-survivors had a higher lactate than the survivors (p < 0.001). A nonlinear relationship between lactate and 30-day mortality was observed. Multivariate logistic regression indicated lactate could be an independent risk factors to predict the prognosis of critically ill patients with AUD. According to ROC curve analysis, the area under the curve predicted by lactate for 30-day mortality was 0.672 (95% CI, 0.634 to 0.711). Subgroup analysis did not find obvious interaction in most subgroups.

Conclusion

High lactate was associated with increased mortality in critically ill patients with AUD.

Risk Factors for 28-Day Mortality in a Surgical ICU: A Retrospective Analysis of 347 Cases

Purpose

Advances in surgical techniques and intensive care over the past decades have significantly reduced the mortality rates of critically ill surgical patients. However, evaluations of risk factors associated with mortality in surgical intensive care units (ICUs) are limited. The aim of this study was to analyze the independent risk factors for 28-day mortality of surgical ICU patients.

Patients and Methods

The clinical data of adult patients who were admitted to the surgical ICU in the First Affiliated Hospital of Xi’an Jiaotong University from June 2013 to June 2017 were collected. Univariate and multivariable logistic regression analyses were performed to examine risk factors associated with 28-day mortality.

Results

A total of 347 patients were included in this analysis. The overall 28-day mortality rate was 32.6%. The major causes of surgical ICU admission were gastrointestinal diseases (46.7%), infection (20.5%), trauma (8.9%), respiratory diseases (8.9%) and cardiovascular diseases (6.6%). The univariate analysis showed age, total bilirubin, prothrombin time, international normalized ratio, arterial lactate level, APACHE II and SOFA score at ICU admission were significantly associated with 28-day mortality. In the multivariate analysis, however, age [Odds Ratio (OR): 2.899, 95% CI: 1.427–5.890, P=0.003], hypertension [OR: 3.630, 95% CI: 1.545–8.531, P=0.003], platelet count [OR: 1.004, 95% CI: 1.001–1.007, P=0.015], arterial lactate level [OR: 1.186, 95% CI: 1.088–1.293, P<0.001] and SOFA score [OR: 1.289, 95% CI: 1.131–1.469, P<0.001] were identified as the independent risk factors for 28-day mortality of patients in the surgical ICU.

Conclusion

In patients admitted to the surgical ICU, age 65 and older, a high arterial lactate level and SOFA score at ICU admission were associated with increased 28-day mortality.

Stepwise lactate kinetics in critically ill patients: prognostic, influencing factors, and clinical phenotype

Background

To investigate the optimal target e of lactate kinetics at different time during the resuscitation, the factors that influence whether the kinetics achieve the goals, and the clinical implications of different clinical phenotypes.

Methods

Patients with hyperlactatemia between May 1, 2013 and December 31, 2018 were retrospectively analyzed. Demographic data, basic organ function, hemodynamic parameters at ICU admission (T0) and at 6 h, 12 h, 24 h, 48 h, and 72 h, arterial blood lactate and blood glucose levels, cumulative clinical treatment conditions at different time points and final patient outcomes were collected.

Results

A total of 3298 patients were enrolled, and the mortality rate was 12.2%. The cutoff values of lactate kinetics for prognosis at 6 h, 12 h, 24 h, 48 h, and 72 h were 21%, 40%, 57%, 66%, and 72%. The APACHE II score, SOFA score, heart rate (HR), and blood glucose were risk factors that correlated with whether the lactate kinetics attained the target goal. Based on the pattens of the lactate kinetics, eight clinical phenotypes were proposed. The odds ratios of death for clinical phenotypes VIII, IV, and II were 4.39, 4.2, and 5.27-fold of those of clinical phenotype I, respectively.

Conclusion

Stepwise recovery of lactate kinetics is an important resuscitation target for patients with hyperlactatemia. The APACHE II score, SOFA score, HR, and blood glucose were independent risk factors that influenced achievement of lactate kinetic targets. The cinical phenotypes of stepwise lactate kinetics are closely related to the prognosis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12871-021-01293-x.

Clinical Utility of Delta Lactate for Predicting Early In-Hospital Mortality in Adult Patients: A Prospective, Multicentric, Cohort Study

One of the challenges in the emergency department (ED) is the early identification of patients with a higher risk of clinical deterioration. The objective is to evaluate the prognostic capacity of ΔLA (correlation between prehospital lactate (pLA) and hospital lactate (hLA)) with respect to in-hospital two day mortality. We conducted a pragmatic, multicentric, prospective and blinded-endpoint study in adults who consecutively attended and were transported in advanced life support with high priority from the scene to the ED. The corresponding area under the receiver operating characteristics curve (AUROC) was obtained for each of the outcomes. In total, 1341 cases met the inclusion criteria. The median age was 71 years (interquartile range: 54–83 years), with 38.9% (521 cases) females. The total 2 day mortality included 106 patients (7.9%). The prognostic precision for the 2 day mortality of pLA and hLA was good, with an AUROC of 0.800 (95% CI: 0.74–0.85; p < 0.001) and 0.819 (95% CI: 0.76–0.86; p < 0.001), respectively. Of all patients, 31.5% (422 cases) had an ΔLA with a decrease of <10%, of which a total of 66 patients (15.6%) died. A lactate clearance ≥ 10% is associated with a lower risk of death in the ED, and this value could potentially be used as a guide to determine if a severely injured patient is improving in response to the established treatment.

Endoscopic decompression of acute intestinal distension is associated with reduced mortality in critically ill patients

Background

Endoscopic placement of intestinal decompression tubes is a feasible technique for treatment of acute intestinal dilation. Given the heterogeneity of the underlying diseases leading to intestinal obstruction data on the significance of endoscopic procedures for treatment of these conditions are sparse.

Methods

In the study period from 2008 to 2019 all patients receiving a decompression tube were identified by retrospective chart review and analyzed.

Results

A total of 59 decompression tubes were placed in 50 patients. Technical success was achieved in 98% (58/59 tubes). As major complication one small bowel perforation occurred (1/59; 1.7%). Causes for impaired intestinal transit comprised tumor stenoses 22% (11/50), infections 18% (9/50), post-operative paralysis 14% (7/50), neurological diseases 8% (4/50), trauma 2% (1/50) and others 36% (18/50). Most patients (74%; 37/50) were critically ill and treated on intensive care unit. Treatment response after tube insertion was documented in 76% of patients (38/50) whereas 24% (12/50) did not fulfill response criteria. Patients with treatment response showed a significantly better outcome compared to non-responders. Responders had a median survival of 113 days (95% CI 41–186) compared to 15 days (95% CI 6–24) in non-responders (p = 0.002). Analysis of laboratory parameters after stratification in responders and non-responders to endoscopic therapy showed that non-responders had significantly higher levels of CRP and lower platelet count at baseline (CRP 262 mg/L (IQR 101–307) vs. 94 mg/L (IQR 26–153): p = 0.027; platelets 69 thsd/μL (IQR 33–161) vs. 199 thsd/μL (IQR 138–289): p = 0.009).

Conclusions

Endoscopic decompression is a safe procedure for acute management of impaired intestinal transit even in critically ill patients. Response to therapy is associated with improved outcome and markers of inflammation and organ function such as CRP, platelet count and serum lactate have to be taken into account for therapy monitoring and evaluation of prognosis.

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.