Which one is a better predictor of ICU mortality in septic patients? Comparison between serial serum lactate concentrations and its removal rate

Hierarchical Capability in Distinguishing Severities of Sepsis via Serum Lactate: A Network Meta-Analysis

Background: Blood lactate is a potentially useful biomarker to predict the mortality and severity of sepsis. The purpose of this study is to systematically review the ability of lactate to predict hierarchical sepsis clinical outcomes and distinguish sepsis, severe sepsis and septic shock. Methods: We conducted an exhaustive search of the PubMed, Embase and Cochrane Library databases for studies published before 1 October 2022. Inclusion criteria mandated the presence of case-control, cohort studies and randomized controlled trials that established the association between before-treatment blood lactate levels and the mortality of individuals with sepsis, severe sepsis or septic shock. Data was analyzed using STATA Version 16.0. Results: A total of 127 studies, encompassing 107,445 patients, were ultimately incorporated into our analysis. Meta-analysis of blood lactate levels at varying thresholds revealed a statistically significant elevation in blood lactate levels predicting mortality (OR = 1.57, 95% CI 1.48-1.65, I2 = 92.8%, p < 0.00001). Blood lactate levels were significantly higher in non-survivors compared to survivors in sepsis patients (SMD = 0.77, 95% CI 0.74-0.79, I2 = 83.7%, p = 0.000). The prognostic utility of blood lactate in sepsis mortality was validated through hierarchical summary receiver operating characteristic curve (HSROC) analysis, yielding an area under the curve (AUC) of 0.72 (95% CI 0.68-0.76), accompanied by a summary sensitivity of 0.65 (95% CI 0.59-0.7) and a summary specificity of 0.7 (95% CI 0.64-0.75). Unfortunately, the network meta-analysis could not identify any significant differences in average blood lactate values' assessments among sepsis, severe sepsis and septic shock patients. Conclusions: This meta-analysis demonstrated that high-level blood lactate was associated with a higher risk of sepsis mortality. Lactate has a relatively accurate predictive ability for the mortality risk of sepsis. However, the network analysis found that the levels of blood lactate were not effective in distinguishing between patients with sepsis, severe sepsis and septic shock.

Glucose metabolic reprogramming-related parameters for the prediction of 28-day neurological prognosis and all-cause mortality in patients after cardiac arrest: a prospective single-center observational study

BACKGROUND

We aimed to observe the dynamic changes in glucose metabolic reprogramming-related parameters and their ability to predict neurological prognosis and all-cause mortality in cardiac arrest patients after the restoration of spontaneous circulation (ROSC).

METHODS

Adult cardiac arrest patients after ROSC who were admitted to the emergency or cardiac intensive care unit of the First Affiliated Hospital of Dalian Medical University from August 1, 2017, to May 30, 2021, were enrolled. According to 28-day survival, the patients were divided into a non-survival group (n=82) and a survival group (n=38). Healthy adult volunteers (n=40) of similar ages and sexes were selected as controls. The serum levels of glucose metabolic reprogramming-related parameters (lactate dehydrogenase [LDH], lactate and pyruvate), neuron-specific enolase (NSE) and interleukin 6 (IL-6) were measured on days 1, 3, and 7 after ROSC. The Acute Physiology and Chronic Health Evaluation II (APACHE II) score and Sequential Organ Failure Assessment (SOFA) score were calculated. The Cerebral Performance Category (CPC) score was recorded on day 28 after ROSC.

RESULTS

Following ROSC, the serum LDH (607.0 U/L vs. 286.5 U/L), lactate (5.0 mmol/L vs. 2.0 mmol/L), pyruvate (178.0 μmol/L vs. 70.9 μmol/L), and lactate/pyruvate ratio (34.1 vs. 22.1) significantly increased and were higher in the non-survivors than in the survivors on admission (all P<0.05). Moreover, the serum LDH, pyruvate, IL-6, APACHE II score, and SOFA score on days 1, 3 and 7 after ROSC were significantly associated with 28-day poor neurological prognosis and 28-day all-cause mortality (all P<0.05). The serum LDH concentration on day 1 after ROSC had an area under the receiver operating characteristic curve (AUC) of 0.904 [95% confidence interval [95% CI]: 0.851-0.957]) with 96.8% specificity for predicting 28-day neurological prognosis and an AUC of 0.950 (95% CI: 0.911-0.989) with 94.7% specificity for predicting 28-day all-cause mortality, which was the highest among the glucose metabolic reprogramming-related parameters tested.

CONCLUSION

Serum parameters related to glucose metabolic reprogramming were significantly increased after ROSC. Increased serum LDH and pyruvate levels, and lactate/pyruvate ratio may be associated with 28-day poor neurological prognosis and all-cause mortality after ROSC, and the predictive efficacy of LDH during the first week was superior to others.

Intensive care unit-acquired pneumonia caused by Klebsiella pneumoniae in China: Risk factors and prediction model of mortality

Intensive care unit (ICU)-acquired pneumonia (ICUAP) is a major concern owing to its associated high mortality rate. Few studies have focused on ICUAP caused by Klebsiella pneumoniae (KP). This study aimed to investigate the risk factors for ICUAP-associated death due to KP and to develop a mortality prediction model. Patients with KP-associated ICUAP at Renji Hospital were enrolled from January 2012 to December 2017. The patients were registered from the ICU units of the Surgery, Gynecology and Obstetrics, Neurosurgery, Emergency and Geriatric Departments, and were followed for 30 days. A multivariate analysis was performed to analyze the differences between 30-day survivors and nonsurvivors, and to determine the independent risk factors. Receiver operator characteristic (ROC) curves were also used to determine the predictive power of the model. Among the 285 patients with KP-associated ICUAP, the median age was 70.55 years, and 61.6% were men. Fifty patients died. The nonsurvivors had a lower Glasgow coma score (GCS), platelet count, and albumin concentrations, but higher lactate concentrations, than the survivors. The nonsurvivors were also more likely to be admitted to the ICU for respiratory failure and surgery, and they received less appropriate empirical antimicrobial therapy than the survivors. A lower GCS (odds ratio [OR] = 0.836, 95% confidence interval [CI]: 0.770-0.907), lower albumin concentrations (OR = 0.836, 95% CI: 0.770-0.907), higher lactate concentrations (OR = 1.167, 95% CI: 1.0013-1.344) and inappropriate empirical treatment (OR = 2.559, 95% CI: 1.080-6.065) were independent risk factors for mortality in patients with KP-associated ICUAP. ROC curve analysis showed that the risk of death was higher in patients with 2 or more independent risk factors. The predictive model was effective, with an area under the ROC curve of 0.823 (95% CI: 0.773-0.865). The number of independent risk factors is positively correlated with the risk of death. Our model shows excellent predictive performance.

Comparison of lactate/albumin ratio to lactate and lactate clearance for predicting outcomes in patients with septic shock admitted to intensive care unit: an observational study

The aim of this study was to evaluate the prognostic value of the Lactate to Albumin (L/A) ratio compared to that of lactate and lactate clearance in predicting outcomes in patients with septic shock. This was a multi-center observational study of adult patients with septic shock, who admitted to intensive care units (ICUs) at Shohada and Imam Reza Hospitals, Tabriz, Iran, between Sept 2018 and Jan 2021. The area under the curve (AUC) of receiver operating characteristic (ROC) curve and multivariate logistic regression analyses were used to explore associations of the L/A ratio, lactate and lactate clearance on the primary (mortality) and secondary outcomes [ICU length of stay (LOS), duration of mechanical ventilation (MV), need of renal replacement therapy (RRT) and duration of using vasopressors] at baseline, 6 h and 24 h of septic shock recognition. Best performing predictive value for mortality were related to lactate clearance at 24 h, L/A ratio at 6 h and lactate levels at 24 h with (AUC 0.963, 95% CI 0.918-0.987, P < 0.001), (AUC 0.917, 95% CI 0.861-0.956, P < 0.001), and (AUC 0.904, 95% CI 0.845-0.946, P < 0.001), respectively. Generally, the lactate clearance at 24 h had better prognostic performance for mortality and duration of using vasopressor. However, the L/A ratio had better prognostic performance than serum lactate and lactate clearance for RRT, ICU LOS and MV duration.

Course of lactate, pH and base excess for prediction of mortality in medical intensive care patients

Introduction

As base excess had shown superiority over lactate as a prognostic parameter in intensive care unit (ICU) surgical patients we aimed to evaluate course of lactate, base excess and pH for prediction of mortality of medical ICU patients.

Materials and methods

For lactate, pH and base excess, values at the admission to ICU, at 24 ± 4 hours, maximum or minimum in the first 24 hours and in 24–48 hours after admission were collected from all patients admitted to the Medical ICU of the University Hospital Tübingen between January 2016 until December 2018 (N = 4067 at admission, N = 1715 with ICU treatment > 48 h) and investigated for prediction of in-hospital-mortality.

Results

Mortality was 22% and significantly correlated with all evaluated parameters. Strongest predictors of mortality determined by ROC were maximum lactate in 24 h (AUROC 0.74, cut off 2.7 mmol/L, hazard ratio of risk group with value > cut off 3.20) and minimum pH in 24 h (AUROC 0.71, cut off 7.31, hazard ratio for risk group 2.94). Kaplan Meier Curves stratified across these cut offs showed early and clear separation. Hazard ratios per standard deviation increase were highest for maximum lactate in 24 h (HR 1.65), minimum base excess in 24 h (HR 1.56) and minimum pH in 24 h (HR 0.75).

Conclusion

Lactate, pH and base excess were all suitable predictors of mortality in internal ICU patients, with maximum / minimum values in 24 and 24–48 h after admission altogether stronger predictors than values at admission. Base excess and pH were not superior to lactate for prediction of mortality.

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.

Comparison of cardiac output, IVC diameters and lactate levels in prediction of mortality in patients in emergency department; An observational study

Objective:

Fluid overload is an independent marker for mortality in critically ill patients. Assessment of fluid status and fluid responsiveness is crucial for the management of these patients. In this study, we compared the lactate level, inferior vena cava (IVC) diameter and non-invasive cardiac output (CO) monitoring in prediction of mortality in emergency department.

Methods:

This was a cross sectional observational study which comprised of 68 patients and was performed in ED of Tabriz University of Medical Sciences, Iran, from Sept 2016 until Sept 2017. IVC diameter was measured before the P-wave on ECG to avoid interference with a-wave and v-wave on the venous pressure curve, and during maximal inspiration and expiration to avoid Valsalva-like maneuvers. An arterial lactate sample was taken from all patients before performing the initial resuscitation. All patients underwent non-invasive CO monitoring by CO₂ rebreathing technique. Mortality was noted on day 28.

Results:

Deceased patients had a significantly low level of IVC diameters, less CO values and more lactate levels. However, based on ROC curve analysis, the prediction accuracy and validity of both CO values obtained by rebreathing CO₂ and IVC diameter was poor and the highest accuracy was obtained by lactate level assessment.

Conclusion:

Initial lactate value is a reliable parameter for prediction of mortality in non-traumatic critically ill patients. IVC diameter changes during spontaneous ventilation and non-invasive CO monitoring does not possess acceptable accuracy for prediction of mortality in these patients.

GDF3 Protects Mice against Sepsis-Induced Cardiac Dysfunction and Mortality by Suppression of Macrophage Pro-Inflammatory Phenotype

Macrophages are critical for regulation of inflammatory response during endotoxemia and septic shock. However, the mediators underlying their regulatory function remain obscure. Growth differentiation factor 3 (GDF3), a member of transforming growth factor beta (TGF-β) superfamily, has been implicated in inflammatory response. Nonetheless, the role of GDF3 in macrophage-regulated endotoxemia/sepsis is unknown. Here, we show that serum GDF3 levels in septic patients are elevated and strongly correlate with severity of sepsis and 28-day mortality. Interestingly, macrophages treated with recombinant GDF3 protein (rGDF3) exhibit greatly reduced production of pro-inflammatory cytokines, comparing to controls upon endotoxin challenge. Moreover, acute administration of rGDF3 to endotoxin-treated mice suppresses macrophage infiltration to the heart, attenuates systemic and cardiac inflammation with less pro-inflammatory macrophages (M1) and more anti-inflammatory macrophages (M2), as well as prolongs mouse survival. Mechanistically, GDF3 is able to activate Smad2/Smad3 phosphorylation, and consequently inhibits the expression of nod-like receptor protein-3 (NLRP3) in macrophages. Accordingly, blockade of Smad2/Smad3 phosphorylation with SB431542 significantly offsets rGDF3-mediated anti-inflammatory effects. Taken together, this study uncovers that GDF3, as a novel sepsis-associated factor, may have a dual role in the pathophysiology of sepsis. Acute administration of rGDF3 into endotoxic shock mice could increase survival outcome and improve cardiac function through anti-inflammatory response by suppression of M1 macrophage phenotype. However, constitutive high levels of GDF3 in human sepsis patients are associated with lethality, suggesting that GDF3 may promote macrophage polarization toward M2 phenotype which could lead to immunosuppression.

Prognostic performance of pancreatic stone protein in critically ill patients with sepsis

Aim: To assess the prognostic value for 28-day mortality of PSP in critically ill patients with sepsis. Material & methods: 122 consecutive patients with sepsis were enrolled in this study. Blood samples were collected on admission and day 2. Results: On admission, the combination of PSP and lactate achieved an area under the receiver operating characteristic (AUC-ROC) of 0.796, similar to sequential organ failure assessment score alone (AUC-ROC: 0.826). On day 2, PSP was the biomarker with the highest performance (AUC-ROC: 0.844), although lower (p = 0.041) than sequential organ failure assessment score (AUC-ROC: 0.923). Conclusion: The combination of PSP and lactate and PSP alone, on day 2, have a good performance for prognosis of 28-day mortality and could help to identify patients who may benefit most from tailored intensive care unit management.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Arterial vs venous lactate: Correlation and predictive value of mortality of patients with sepsis during early resuscitation phase

PURPOSE

To compare the lactate concentrations obtained from venous to those obtained from arterial blood in predicting hospital mortality of patients with sepsis and septic shock. To also assess lactate clearance as predictor for mortality.

METHODS

100 patients with septic shock were prospectively enrolled. Serum was sampled at baseline and after 6 h of resuscitation from arterial and venous lines. Demographic, severity indices, hemodynamic measures as well as lactate clearance levels were noted. Data were analyzed for bias and precision.

RESULTS

There was correlation between venous and arterial lactate concentrations at the baseline (R = 0.68) and at the 6-hour time point (R = 0.95). Venous concentrations were consistently higher than those obtained from an arterial access by 0.684 mg/dL. Further, arterial lactate level > 3.2 mmol/L and clearance of <20% were considered the cutoff for the mortality risk. While only 8% of the patients with no risk died, all 20 patients who had lactate level > 3.2 mmol/L and clearance of <20% died within the hospital.

CONCLUSION

Our data suggests a strong correlation between arterial and peripheral venous the lactate levels and in the initial phase of resuscitation in septic shock patients we can use venous lactate level as biomarker instead of arterial lactate level. The study also showed that combining lactate levels and its clearance is a reliable predictor of mortality in sepsis.

Predictive value of serum albumin levels on noradrenaline and fluid requirements in the first 24 h after admission to the Intensive Care Unit - A prospective observational study

PURPOSE

To determine the predictive value of serum albumin (SA) at admission to the intensive care unit (ICU) on the cumulative dose of noradrenaline, the fluids administered, the lactate level, and mortality during the first 24 h of ICU admission.

METHODS

A total of 100 ICU patients were included. The association between SA and the cumulative dose of noradrenaline was analyzed using logistic regression. For the total amount of fluids administered linear regression, for the lactate level and for 24 h mortality logistic regression was used. Age, gender, patient category, type of surgery, severe sepsis, lactate level, estimated glomerular filtration rate, c-reactive protein level, and the target mean arterial pressure were considered effect modifiers.

RESULTS

SA was significantly associated with the dose of noradrenaline (OR 0.92, 95% CI 0.84–0.99, p = 0.028), lower lactate levels (OR 1.14, 95% CI 1.00–1.30, p = 0.049), and with the amount of fluids administered (B -0.02, 95% CI −0.03/−0.00, p = 0.016), but not with mortality (OR 0.95, 95% CI 0.85–1.07, p = 0.41).

CONCLUSIONS

SA significantly predicts noradrenaline and fluid requirements as well as the change in lactate level during the first 24 h of ICU admission. Our observations have to be validated in another large cohort.