Mildly elevated lactate levels are associated with microcirculatory flow abnormalities and increased mortality: a microSOAP post hoc analysis

Impaired glucose utilization in the brain of patients with delirium following hip fracture

Alterations in brain energy metabolism have long been proposed as one of several neurobiological processes contributing to delirium. This is supported by previous findings of altered CSF lactate and neuron-specific enolase concentrations and decreased glucose uptake on brain-PET in patients with delirium. Despite this, there are limited data on metabolic alterations found in CSF samples, and targeted metabolic profiling of CSF metabolites involved in energy metabolism has not been performed. The aim of the study was to investigate whether metabolites related to energy metabolism in the serum and CSF of patients with hip fracture are associated with delirium. The study cohort included 406 patients with a mean age of 81 years (standard deviation 10 years), acutely admitted to hospital for surgical repair of a hip fracture. Delirium was assessed daily until the fifth postoperative day. CSF was collected from all 406 participants at the onset of spinal anaesthesia, and serum samples were drawn concurrently from 213 participants. Glucose and lactate in CSF were measured using amperometry, whereas plasma glucose was measured in the clinical laboratory using enzymatic photometry. Serum and CSF concentrations of the branched-chain amino acids, 3-hydroxyisobutyric acid, acetoacetate and β-hydroxybutyrate were measured using gas chromatography-tandem mass spectrometry (GC-MS/MS). In total, 224 (55%) patients developed delirium pre- or postoperatively. Ketone body concentrations (acetoacetate, β-hydroxybutyrate) and branched-chain amino acids were significantly elevated in the CSF but not in serum among patients with delirium, despite no group differences in glucose concentrations. The level of 3-hydroxyisobutyric acid was significantly elevated in both CSF and serum. An elevation of CSF lactate during delirium was explained by age and comorbidity. Our data suggest that altered glucose utilization and a shift to ketone body metabolism occurs in the brain during delirium.

Association of Sublingual Microcirculation Parameters and Capillary Refill Time in the Early Phase of ICU Admission

OBJECTIVES

This observational study was conducted to investigate capillary refill time (CRT) during the early phase of ICU admission in relationship with microvascular flow alteration and outcome in critically ill patients.

DESIGN

Prospective, observational, pilot study.

SETTING

ICU in a university hospital.

PATIENTS

Two hundred eighty-two critically ill adult patients admitted to the ICU.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

All patients underwent simultaneous measurements by CRT and sidestream dark field imaging within 24 hours of ICU admission. Other clinical data such as demographic characteristics, hemodynamics, laboratory values, treatment, and physiologic parameters were also included simultaneously. Microcirculatory measurements were performed at 10.2 ± 5.7 hours after ICU admission. Of the 282 included patients, 106 (37.6%) were female, the median (interquartile range) age was 63 years (53-74 yr), and the median Sequential Organ Failure Assessment (SOFA) score was 5 (2-7). The primary finding was the association between CRT and simultaneous the condition of peripheral circulation (microvascular flow index [MFI]: r = -0.4430, p < 0.001; proportion of perfused vessels: r = -0.3708, p < 0.001; heterogeneity index: r = 0.4378, p < 0.001; perfused vessel density: r = -0.1835, p = 0.0020; except total vessel density: p = 0.9641; and De Backer score: p = 0.5202) in critically ill patients. In addition, this relationship was also maintained in subgroups. Microcirculatory flow abnormalities, 28-day mortality, and SOFA score appeared to be more severe for increasing CRT. In a multivariable analysis, prolonged CRT was independently associated with microvascular flow abnormalities (MFI < 2.6; odds ratio [OR], 1.608; 95% CI, 2.1-10.2; p < 0.001). Similarly, multivariable analysis identified CRT as an independent predictor of 28-day mortality (OR, 1.296; 95% CI, 1.078-1.558; p = 0.006).

CONCLUSIONS

In our ICU population, a single-spot prolonged CRT was independently associated with abnormal microcirculation and increased mortality.

Novelties in the evaluation of microcirculation in septic shock

Microvascular alterations were first described in critically ill patients about 20 years ago. These alterations are characterized by a decrease in vascular density and presence of non-perfused capillaries close to well-perfused vessels. In addition, heterogeneity in microvascular perfusion is a key finding in sepsis. In this narrative review, we report our actual understanding of microvascular alterations, their role in the development of organ dysfunction, and the implications for outcome. Herein, we discuss the state of the potential therapeutic interventions and the potential impact of novel therapies. We also discuss how recent technologic development may affect the evaluation of microvascular perfusion.

Association of lactate detection with in-hospital mortality in critically ill patients with acute myocardial infarction: a retrospective cohort study

OBJECTIVES

To assess the associations of lactate level or lactate clearance at different time points with in-hospital mortality in critically ill patients with acute myocardial infarction (AMI).

DESIGN

A cohort study.

SETTING

The Medical Information Mart for Intensive Care III database.

PARTICIPANT

490 AMI patients.

INTERVENTION

None.

PRIMARY AND SECONDARY OUTCOME MEASURES

In-hospital mortality of patients.

RESULTS

In total, 120 (24.49%) patients died at the end of follow-up. After adjusting for confounders, increased risk of in-hospital mortality in patients with AMI was observed in those with high lactate level (24 hours) (HR=1.156, 95%CI: 1.002 to 1.333). Increased lactate clearance (24 hours) was correlated with a decreased risk of in-hospital mortality in patients with AMI (HR=0.995, 95% CI: 0.994 to 0.997). The area under the curves (AUCs) of lactate level (24 hours) and lactate clearance (24 hours) were 0.689 (95% CI: 0.655 to 0.723) and 0.672 (95% CI: 0.637 to 0.706), respectively. The AUC of lactate level (24 hours) and lactate clearance (24 hours) was higher than lactate level (baseline).

CONCLUSIONS

Increased lactate level (24 hours) was associated with an elevated risk of in-hospital mortality in patients with AMI and increased lactate clearance (24 hours) was correlated with a decreased risk of in-hospital mortality in patients with AMI despite the age and genders.

Ratio of carbon dioxide veno-arterial difference to oxygen arterial-venous difference is not associated with lactate decrease after fluid bolus in critically ill patients with hyperlactatemia: results from a prospective observational study

BACKGROUND

High ratio of the carbon dioxide veno-arterial difference to the oxygen arterial-venous difference (P_vaCO₂/C_avO₂) is associated with fluid bolus (FB) induced increase in oxygen consumption (VO₂). This study investigated whether P_vaCO₂/C_avO₂ was associated with decreases in blood-lactate levels FB in critically ill patients with hyperlactatemia.

METHODS

This prospective observational study examined adult patients in the intensive care unit (ICU) with lactate levels > 1.5 mmol/L who received FBs. Blood-lactate levels were measured before and after FB under unchanged metabolic, respiratory, and hemodynamic conditions. The primary outcome was blood-lactate levels after FB. Significant decreases in blood-lactate levels were considered as blood-lactate levels < 1.5 mmol/L or a decrease of more than 10% compared to baseline.

RESULTS

The study enrolled 40 critically ill patients, and their median concentration of blood lactate was 2.6 [IQR:1.9 - 3.8] mmol/L. There were 27 (68%) patients with P_vaCO₂/C_avO₂ ≥ 1.4 mmHg/ml, and 10 of them had an increase in oxygen consumption (dVO₂) ≥ 15% after FB, while 13 (32%) patients had P_vaCO₂/C_avO₂ < 1.4 mmHg/ml before FB, and none of them had dVO₂ ≥ 15% after FB. FB increased the cardiac index in patients with high and low preinfusion P_vaCO₂/C_avO₂ (13.4% [IQR: 8.3 - 20.2] vs. 8.8% [IQR: 2.9 - 17.4], p = 0.34). Baseline P_vaCO₂/C_avO₂ was not found to be associated with a decrease in blood lactate after FB (OR: 0.88 [95% CI: 0.39 - 1.98], p = 0.76). A positive correlation was observed between changes in blood lactate and baseline P_vaCO₂/C_avO₂ (r = 0.35, p = 0.02).

CONCLUSIONS

In critically ill patients with hyperlactatemia, P_vaCO₂/C_avO₂ before FB cannot be used to predict decreases in blood-lactate levels after FB. Increased P_vaCO₂/C_avO₂ is associated with less decrease in blood-lactate levels.

Characteristics and predictors of ICU-mortality in critically ill patients with hyperlactatemia requiring CRRT: A retrospective cohort study

BACKGROUND

Hyperlactatemia is a common complication in critically ill patients with high morbidity and mortality. Hyperlactatemia patients who require continuous renal replacement therapy (CRRT) constitute a subgroup with increased mortality risk. The clinical significance of serum lactate in these patients was not well understood and clearance of lactate using CRRT shown no survival benefits. The aim of this study is to investigate the incidence and non-lactate risk factors for ICU mortality in hyperlactatemia patients who underwent CRRT.

METHOD

Hyperlactatemia patients with a serum lactate level >2 μmol/L who underwent CRRT between January, 2014 and May, 2021 were retrospectively investigated. Demographic characteristics and clinical data were collected from the electronic medical record system. The primary endpoint was predictors for ICU mortality which were identified by using multivariate logistic regression analysis.

RESULTS

A total of 178 eligible patients were finally included with a mean age of 56.6 ± 17.9 years and a median APACHE II score of 18 (IQR (14-22)). The multivariate regression results showed that male gender (OR 0.55 (95%CI 0.27-1.12), p = 0.1), mechanical ventilation (OR 2.60 (95%CI 1.27-5.34), p = 0.008), history of hypertension (OR 2.40 (95%CI 1.12-5.14), p = 0.02), SOFA score (OR 1.16 (95%CI 1.05-1.28), p = 0.002), AST (OR 1.0005 (95%CI 0.99-1.001), p = 0.08), and PT (OR 1.08 (95%CI 0.99-1.17), p = 0.06) were independently associated with ICU mortality. After adjusting for age, illness severity (APACHE II score), and serum lactate level, the statistical significances of SOFA score (OR 1.16 (95%CI 1.04-1.29), p = 0.005), hypertension (OR 2.25 (95%CI 1.02-4.95), p = 0.04), and mechanical ventilation (OR 2.54 (95%CI 1.22-5.25), p = 0.01) were not affected. The overall ICU mortality was 58.4% (104/178).

CONCLUSION

The hyperlactatemia patients who underwent CRRT were at increased ICU mortality. Gender, AST, PT, SOFA score, history of hypertension, and mechanical ventilation were independent predictors for ICU mortality. Future studies with prospectively design, large sample size, and subgroup analyses are warranted to validate these findings.

Hyperlactatemia in children following brain tumor resection: prevalence, associated factors, and clinical significance

PURPOSE

Hyperlactatemia is associated with worse outcome among critically ill patients. The prevalence of hyperlactatemia in children following craniotomy for intracranial tumor resection is unknown. This study was designed to assess the prevalence, associated factors, and significance of postoperative hyperlactatemia in this context.

METHODS

A retrospective study was conducted at an intensive care unit of a tertiary, pediatric medical center. Children younger than 18 years admitted following craniotomy for brain tumor resection between October 2004 and November 2019 were included.

RESULTS

Overall, 222 elective craniotomies performed in 178 patients were analyzed. The mean age ± SD was 8.5 ± 5.5 years. All but two patients survived to discharge. All were hemodynamically stable. Early hyperlactatemia, defined as at least one blood lactate level ≥ 2.0 mmol/L during the first 24 h into admission, presented following 74% of the craniotomies; lactate normalized within a mean ± SD of 11 ± 6.1 h. The fluid balance per body weight at 12 h and 24 h into the intensive care unit admission was similar in children with and without hyperlactatemia [7.0 ± 17.6 vs 3.5 ± 16.4 ml/kg, p = 0.23 and 4.0 ± 27.2 vs 4.6 ± 29.4 ml/kg, p = 0.96; respectively]. Hyperlactatemia was associated with higher maximal blood glucose, older age, and a pathological diagnosis of glioma. Intensive care unit length of stay was similar following craniotomies with and without hyperlactatemia (p = 0.57).

CONCLUSIONS

Hyperlactatemia was common in children following craniotomy for brain tumor resection. It was not associated with hemodynamic impairment or with a longer length of stay.

Low Microcirculatory Perfused Vessel Density and High Heterogeneity are Associated With Increased Intensity and Duration of Lactic Acidosis After Cardiac Surgery with Cardiopulmonary Bypass

INTRODUCTION

Lactic acidosis after cardiac surgery with cardiopulmonary bypass is common and associated with an increase in postoperative morbidity and mortality. A number of potential causes for an elevated lactate after cardiopulmonary bypass include cellular hypoxia, impaired tissue perfusion, ischemic-reperfusion injury, aerobic glycolysis, catecholamine infusions, and systemic inflammatory response after exposure to the artificial cardiopulmonary bypass circuit. Our goal was to examine the relationship between early abnormalities in microcirculatory convective blood flow and diffusive capacity and lactate kinetics during early resuscitation in the intensive care unit. We hypothesized that patients with impaired microcirculation after cardiac surgery would have a more severe postoperative hyperlactatemia, represented by the lactate time-integral of an arterial blood lactate concentration greater than 2.0 mmol/L.

METHODS

We measured sublingual microcirculation using incident darkfield video microscopy in 50 subjects on intensive care unit admission after cardiac surgery. Serial measurements of systemic hemodynamics, blood gas, lactate, and catecholamine infusions were recorded each hour for the first 6 h after surgery. Lactate area under the curve (AUC) was calculated over the first 6 h. The lactate AUC was compared between subjects with normal and low perfused vessel density (PVD < 18 mm/mm2), high microcirculatory heterogeneity index (MHI > 0.4), and low vessel-by-vessel microvascular flow index (MFIv < 2.6).

RESULTS

Thirteen (26%) patients had a low postoperative PVD, 20 patients (40%) had a high MHI, and 26 (52%) patients had a low MFIv. Patients with low perfused vessel density had higher lactate AUC compared with subjects with a normal PVD (22.3 [9.4-31.0] vs. 2.6 [0-8.8]; P < 0.0001). Patients with high microcirculatory heterogeneity had a higher lactate AUC compared with those with a normal MHI (2.5 [0.1-8.2] vs. 13.1 [3.7-31.1]; P < 0.001). We did not find a difference in lactate AUC when comparing high and low MFIv.

CONCLUSION

Low perfused vessel density and high microcirculatory heterogeneity are associated with an increased intensity and duration of lactic acidosis after cardiac surgery with cardiopulmonary bypass.

Time of dissociation between microcirculation, macrocirculation, and lactate levels in a rabbit model of early endotoxemic shock

Background

The relationship between macrocirculation and microcirculation remains controversial. The loss of coherence between microcirculation and macrocirculation has already been found in late-stage sepsis shock. The objective of this study was to determine the earliest possible time of detecting the loss of coherence between microcirculation and macrocirculation in early-stage endotoxemic shock.

Methods

We randomized 24 female New Zealand white rabbits into two groups: endotoxemic shock group (n = 14) and control group (n = 10). Rabbits in the endotoxemic shock group were equipped with arterial and venous catheters and received an intravenous infusion of Escherichia coli lipopolysaccharide (LPS, 2 mg/kg over 10 min). Rabbits in the control group received the same dose of saline infusion. Microcirculatory perfusion parameters were assessed in the sublingual mucosa using sidestream dark-field video microscopy. Systemic hemodynamics and blood lactate levels were measured at baseline and over a 120-min period.

Results

Ninety minutes after completing LPS infusion, all animals in the endotoxemic shock group developed a hypodynamic septic condition, characterized by low cardiac output and increased systemic vascular resistance; 120 min after completing LPS infusion, the mean arterial pressure decreased by 25% (P = 0.01), confirming ongoing endotoxemic shock. However, significant decreases in sublingual microcirculatory parameters of small vessels (microvascular flow index, perfused vessel density, and proportion of small perfused vessels) were observed 30 min after completing LPS infusion (P = 0.01, for all), and threshold decreases of 30% were found 60 min after completing LPS infusion (P = 0.001, for all) in the endotoxemic shock group. Lactate levels significantly increased to more than 2 mm/L at 90 min and more than 4 mm/L at 120 min in the endotoxemic shock group (P = 0.02 and P = 0.01, respectively).

Conclusions

Changes in microcirculatory perfusion precede changes in macrocirculation and lactate levels in a rabbit model of endotoxemia shock. Microcirculation, macrocirculation, and oxygen metabolism are distinct in early-stage endotoxic shock.

Microcirculatory Changes in Pediatric Patients During Congenital Heart Defect Corrective Surgery

A prospective, observational single-center study was carried out. Pediatric patients undergoing congenital heart defect surgery were evaluated before, during, and after surgery. At each time point, sublingual microcirculation and clinical parameters were assessed, along with analytical variables. Twenty-four patients were included. All microcirculatory parameters worsened during cardiopulmonary bypass and returned to baseline values after surgery (p ≤ 0.001). In the intraoperative evaluation, body temperature correlated with perfused small vessel density (p = 0.014), proportion of perfused small vessels (p < 0.001), small vessel microvascular flow index (p = 0.003), and small vessel heterogeneity index (p < 0.002). Patients with cyanotic disease exhibited higher small vessel density (p < 0.008) and higher density of perfused small vessels (p < 0.022) at baseline, and a lower microvascular flow index (p = 0.022) and higher heterogeneity (p = 0.026) in the intraoperative phase. Children with congenital heart disease exhibited decreased vascular density and microvascular blood flow and increased heterogeneity during cardiopulmonary bypass. All these parameters returned to baseline values after surgery.

Monitoring skin blood flow to rapidly identify alterations in tissue perfusion during fluid removal using continuous veno-venous hemofiltration in patients with circulatory shock

Background

Continuous veno-venous hemofiltration (CVVH) can be used to reduce fluid overload and tissue edema, but excessive fluid removal may impair tissue perfusion. Skin blood flow (SBF) alters rapidly in shock, so its measurement may be useful to help monitor tissue perfusion.

Methods

In a prospective, observational study in a 35-bed department of intensive care, all patients with shock who required fluid removal with CVVH were considered for inclusion. SBF was measured on the index finger using skin laser Doppler (Periflux 5000, Perimed, Järfälla, Sweden) for 3 min at baseline (before starting fluid removal, T0), and 1, 3 and 6 h after starting fluid removal. The same fluid removal rate was maintained throughout the study period. Patients were grouped according to absence (Group A) or presence (Group B) of altered tissue perfusion, defined as a 10% increase in blood lactate from T0 to T6 with the T6 lactate ≥ 1.5 mmol/l. Receiver operating characteristic curves were constructed and areas under the curve (AUROC) calculated to identify variables predictive of altered tissue perfusion. Data are reported as medians [25th–75th percentiles].

Results

We studied 42 patients (31 septic shock, 11 cardiogenic shock); median SOFA score at inclusion was 9 [8–12]. At T0, there were no significant differences in hemodynamic variables, norepinephrine dose, lactate concentration, ScvO₂ or ultrafiltration rate between groups A and B. Cardiac index and MAP did not change over time, but SBF decreased in both groups (p < 0.05) throughout the study period. The baseline SBF was lower (58[35–118] vs 119[57–178] perfusion units [PU], p = 0.03) and the decrease in SBF from T0 to T1 (ΔSBF%) higher (53[39–63] vs 21[12–24]%, p = 0.01) in group B than in group A. Baseline SBF and ΔSBF% predicted altered tissue perfusion with AUROCs of 0.83 and 0.96, respectively, with cut-offs for SBF of ≤ 57 PU (sensitivity 78%, specificity 87%) and ∆SBF% of ≥ 45% (sensitivity 92%, specificity 99%).

Conclusion

Baseline SBF and its early reduction after initiation of fluid removal using CVVH can predict worsened tissue perfusion, reflected by an increase in blood lactate levels.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13613-021-00847-z.

Identification of novel sublingual parameters to analyze and diagnose microvascular dysfunction in sepsis: the NOSTRADAMUS study

Background

The availability of handheld, noninvasive sublingual video-microscopes allows for visualization of the microcirculation in critically ill patients. Recent studies demonstrate that reduced numbers of blood-perfused microvessels and increased penetration of erythrocytes into the endothelial glycocalyx are essential components of microvascular dysfunction. The aim of this study was to identify novel microvascular variables to determine the level of microvascular dysfunction in sepsis and its relationship with clinical variables.

Methods

This observational, prospective, cross-sectional study included 51 participants, of which 34 critically ill sepsis patients were recruited from intensive care units of a university hospital. Seventeen healthy volunteers served as controls. All participants underwent sublingual videomicroscopy by sidestream darkfield imaging. A new developed version of the Glycocheck™ software was used to quantify vascular density, perfused boundary region (PBR-an inverse variable of endothelial glycocalyx dimensions), red blood cell (RBC) velocity, RBC content, and blood flow in sublingual microvessels with diameters between 4 and 25 µm.

Results

A detailed analysis of adjacent diameter classes (1 µm each) of vessels between 4 and 25 µm revealed a severe reduction of vascular density in very small capillaries (5–7 µm), which correlated with markers of sepsis severity. Analysis of RBC velocity (V_RBC) revealed a strong dependency between capillary and feed vessel V_RBC in sepsis patients (R² = 0.63, p < 0.0001) but not in healthy controls (R² = 0.04, p = 0.43), indicating impaired capillary (de-)recruitment in sepsis. This finding enabled the calculation of capillary recruitment and dynamic capillary blood volume (CBV_dynamic). Moreover, adjustment of PBR to feed vessel V_RBC further improved discrimination between sepsis patients and controls by about 50%. By combining these dynamic microvascular and glycocalyx variables, we developed the microvascular health score (MVHS_dynamic™), which decreased from 7.4 [4.6–8.7] in controls to 1.8 [1.4–2.7] in sepsis patients (p < 0.0001) and correlated with sepsis severity.

Conclusion

We introduce new important diameter-specific quantification and differentiated analysis of RBC kinetics, a key to understand microvascular dysfunction in sepsis. MVHS_dynamic, which has a broad bandwidth to detect microvascular (dys-) function, might serve as a valuable tool to detect microvascular impairment in critically ill patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13054-021-03520-w.

Evaluation of a shorter algorithm in an automated analysis of sublingual microcirculation

OBJECTIVE

Diagnostic and risk stratification in intensive and emergency medicine must be fast, accurate, and reliable. The assessment of sublingual microcirculation is a promising tool for this purpose. However, its value is limited because the measurement is time-consuming in unstable patients. This proof-of-concept validation study examines the non-inferiority of a reduced frame rate in image acquisition regarding quality, measurement results, and time.

METHODS

This prospective observational study included healthy volunteers. Sublingual measurement of microcirculation was performed using a sidestream dark field camera (SDF, MicroVision Medical®). Video-quality was evaluated with a modified MIQS (microcirculation image quality score). AVA 4.3C software calculated microcirculatory parameters.

RESULTS

Thirty-one volunteers were included. There was no impact of the frame rate on the time needed by the software algorithm to measure one video (4.5 ± 0.5 minutes) for AVA 4.3C. 86 frames per video provided non inferior video quality (MIQS 1.8 ± 0.7 for 86 frames versus MIQS 2.2 ± 0.6 for 215 frames, p < 0.05), equal results for all microcirculatory parameters, but did not result in an advantage in terms of speed. No complications occurred.

CONCLUSION

Video captures with 86 frames offer equal video quality and results for consensus parameters compared to 215 frames. However, there was no advantage regarding the time needed for the overall measurement procedure.

Hyperlactatemia of dialysis-dependent patients after cardiac surgery impacts on in-hospital mortality: a two-center retrospective study

Background

Lactate is a well-known marker to estimate prognosis after cardiac surgery and critically ill patients. The liver and kidney have a major role in lactate metabolism; however, there was less characterized about the change of lactate and threshold to predict in-hospital mortality in dialysis-dependent patients undertaking cardiac surgery. We conducted this retrospective observational study to characterize when and how lactate values after cardiac surgery affected in-hospital mortality.

Methods

This two-center retrospective study included dialysis-dependent patients who underwent cardiac surgery with a cardiopulmonary bypass from January 2014 to December 2018. Lactate values were collected at three points: at ICU admission (T1), the maximum level of lactate within 24 h postoperatively (T2), and 24 h after ICU admission (T3). We determined hyperlactatemia as more than 2 mmol/L following previous studies.

Results

We enrolled 122 dialysis-dependent patients. The mean age was 73 ± 8 years and hyperlactatemia was observed in 100 patients (81.9%). In-hospital mortality was 11.4%. Univariate analysis and area under curve in ROC suggested that T2 lactate was the most significantly associated with in-hospital mortality (AUC = 0.845). Multivariate logistic analysis showed a significant association between in-hospital mortality when patients showed early peak lactate levels of > 4.5 mmol/L after ICU admission (adjusted OR 8.35; 95% CI: 1.44–57.13).

Conclusions

In dialysis-dependent patients after cardiac surgery, the early-onset of a maximum arterial lactate concentration of > 4.5 mmol/L was significantly associated with in-hospital mortality.

Assessment of microcirculation in cardiogenic shock

PURPOSE OF REVIEW

Adequate tissue perfusion is of utmost importance to avoid organ failure in patients with cardiogenic shock. Within the recent years, the microcirculation, defined as the perfusion of the smallest vessels, has been identified to play a crucial role. Microcirculatory changes may include capillary flow disturbances as well as changes in the density of perfused vessels. Due to the availability of new technologies to assess the microcirculation, interesting new data came up and it is the purpose of this review to summarize recent studies in the field.

RECENT FINDINGS

Nowadays, an increasing number of studies confirm parameters of the microcirculation, derived by intravital microscopy, to represent strong outcome predictors in cardiogenic shock. In addition, microcirculation as read-out parameter in innovative clinical studies has meanwhile been accepted as serious endpoint. Treatment strategies such as mechanical assist devices, blood pressure regulating agents or fluids use tissue perfusion and microcirculatory network density as targets in addition to clinical perfusion evaluation and decreasing serum lactate levels.

SUMMARY

The parameter most frequently used to detect tissue malperfusion is serum lactate. Novel, noninvasive methods to quantify microvascular perfusion have the potential to guide treatment in terms of optimizing organ perfusion and oxygenation probably paving the way for an individualized therapy.

Serum lactate level upon admission to the neuro-intensive care unit and 90-day mortality: A retrospective study

The serum lactate level is a useful predictor of mortality in critically ill patients. However, little is known about the association between the serum lactate level and mortality in patients admitted to neuro-intensive care units (NCUs). The present study aimed to investigate the association between the initial lactate level and 90-day mortality in NCU patients. This retrospective observational study was conducted by reviewing the medical records of adult (age ≥18 years) patients admitted to the NCU at a single tertiary care academic hospital during 2013-2017. The initial lactate level (mmol L^-1) was defined as the serum lactate level measured within 6 h following NCU admission. The final analysis included 2737 patients, of whom 280 (10.2%) died within 90 days of NCU admission. In a receiver operating characteristic (ROC) analysis, the estimated area under the curve (AUC) for the initial lactate level in predicting overall 90-day mortality was 0.55 [95% confidence interval (CI): 0.52-0.59]. The corresponding values for neurologic and non-neurologic disease-related 90-day mortality were 0.76 (95% CI: 0.71-0.82) and 0.49 (95% CI: 0.45-0.53), respectively. In a multivariable Cox regression analysis, a 1-mmol L^-1 increase in the initial lactate level was associated with 1.17- and 1.22-fold increases in overall and neurologic disease-related 90-day mortality, respectively, but not with non-neurological disease-related 90-day mortality (P = 0.422). Elevated lactate levels were related with an increase in overall 90-day mortality among NCU patients. This association was specifically attributed to neurologic disease-related 90-day mortality.

Improving the prognostic value of ∆PCO2 following cardiac surgery: a prospective pilot study

Conflicting results have been published on prognostic significance of central venous to arterial PCO₂ difference (∆PCO₂) after cardiac surgery. We compared the prognostic value of ∆PCO₂ on intensive care unit (ICU) admission to an original algorithm combining ∆PCO₂, ERO₂ and lactate to identify different risk profiles. Additionally, we described the evolution of ∆PCO₂ and its correlations with ERO₂ and lactate during the first postoperative day (POD1). In this monocentre, prospective, and pilot study, 25 patients undergoing conventional cardiac surgery were included. Central venous and arterial blood gases were collected on ICU admission and at 6, 12 and 24 h postoperatively. High ∆PCO₂ (≥ 6 mmHg) on ICU admission was found to be very frequent (64% of patients). Correlations between ∆PCO₂ and ERO₂ or lactate for POD1 values and variations were weak or non-existent. On ICU admission, a high ∆PCO₂ did not predict a prolonged ICU length of stay (LOS). Conversely, a significant increase in both ICU and hospital LOS was observed in high-risk patients identified by the algorithm: 3.5 (3.0–6.3) days versus 7.0 (6.0–8.0) days (p = 0.01) and 12.0 (8.0–15.0) versus 8.0 (8.0–9.0) days (p < 0.01), respectively. An algorithm incorporating ICU admission values of ∆PCO₂, ERO₂ and lactate defined a high-risk profile that predicted prolonged ICU and hospital stays better than ∆PCO₂ alone.

Lactate and number of organ failures predict intensive care unit mortality in patients with acute-on-chronic liver failure

BACKGROUND AND AIMS

Patients with acute-on-chronic liver failure (ACLF) have high mortality rates. Most prognostic scores were not developed for the intensive care unit (ICU) setting. We aimed to improve risk stratification for patients with ACLF in the ICU.

METHODS

A training set with 240 patients with cirrhosis and organ failures (Chronic Liver Failure Sequential Organ Failure Assessment score [CLIF-SOFA]) from Curry Cabral Hospital (Portugal) and University of Alberta Hospital (Canada) in 2010-2016 was used to derive a prognostic model for ICU mortality. A validation set with 237 patients with cirrhosis and organ failures from Vancouver General Hospital (Canada) in 2000-2011 was used to evaluate its performance.

RESULTS

Amongst patients in the training set, ICU and hospital mortality rates were 39.2% and 54.6% respectively. Median lactate (4.4 vs 2.5 mmol/L) and number of organ failures (3 vs 2) on admission to ICU were associated with higher likelihood of ICU mortality (P < 0.001 for both). The lactate and organ failures predictive model (LacOF) was derived to predict ICU mortality: -2.420 + 0.072 × lactate + 0.569 × number of organ failures (area under-the-curve [AUC], 0.76). In the validation set, the LacOF model discriminative ability (AUC, 0.85) outperformed the CLIF-SOFA (AUC, 0.79), Chronic Liver Failure Consortium Acute-on-Chronic Liver Failure (AUC, 0.73), Model for End-stage Liver Disease score (AUC, 0.78) and Acute Physiology and Chronic Health Evaluation II scores (AUC, 0.74; P < 0.05 for all). The LacOF model calibration was good up to the 25% likelihood of ICU mortality.

CONCLUSIONS

In patients with ACLF, lactate and number of organ failures on admission to ICU are useful to predict ICU mortality. This early prognostic evaluation may help to better stratify the risk of ICU mortality and thus optimize organ support strategies.

Mottling score is a strong predictor of 14-day mortality in septic patients whatever vasopressor doses and other tissue perfusion parameters

Background

Mottling score, a tissue perfusion parameter, is correlated with outcome in septic shock patients. However, its predictive value on mortality according to prognostic covariates such as vasopressor dose and other tissue perfusion parameters remains unknown.

Methods

Mottling score and tissue perfusion parameters were recorded at ICU admission (H0), H-6, H 12, and H-24 and used to assess the predictive value of mottling score on 14-day mortality in a development cohort. Results were then validated in an independent cohort of septic shock patients in Brazil.

Results

Overall, 259 patients with sepsis or septic shock were included, 14-day mortality was 37%. Factors associated with death were mottling score (OR 2.26 [95% CI, 1.72–2.97]), arterial lactate level (OR 1.29 [1.11–1.5]), and urine output < 0.5 ml/Kg/h (OR 3.03 [1.37–6.69]). The C statistic for the model was 0.90 in the development cohort and 0.76 in the validation cohort. The predictive value of mottling score was not affected by vasopressor doses (p for interaction = 0.33): OR for mottling score ranged from 2.34 [1.10–3.15] in patients without vasopressor to 3.84 [1.98–7.43] in patients infused with high doses of vasopressor (> 0.8 μg/kg/min). There was no difference in the effect of mottling score on mortality according to mean arterial pressure, heart rate, cardiac index, and urine output, but we found a significant interaction between arterial lactate level and mottling score (p = 0.04). The predictive value of the mottling score remains significant when using the recent SEPSIS-3 definition of septic shock. Finally, a decrease of mottling score during resuscitation was significantly associated with better outcome after adjustment on SOFA score (p = 0.001).

Conclusions

Our results support the high prognostic value of mottling score for 14-day mortality in septic patients, whatever vasopressor dosage and other perfusion parameters. Mottling score variations during resuscitation are also predictive of mortality.

Electronic supplementary material

The online version of this article (10.1186/s13054-019-2496-4) contains supplementary material, which is available to authorized users.

Real-world clinical experience with the percutaneous extracorporeal life support system: Results from the German Lifebridge® Registry

BACKGROUND

The concept of percutaneous extracorporeal life support (ECLS) is based on immediate cardiovascular stabilization allowing for sufficient end-organ perfusion, thus improving the outcome in patients with circulatory arrest. Lifebridge^® (Zoll Medical GmbH, Germany) is a portable ECLS device designed for rapid application due to its automated set-up.

METHODS

A total of 60 tertiary cardiovascular centers were interrogated with regard to application and short-term results after use of Lifebridge ECLS system. Detailed data were collected by standardized case report forms in all centers consented to participate in the study. Demographic and clinical baseline characteristics of the patient population, procedural and follow-up data were recorded and analyzed.

RESULTS

In total, 444 patients were analyzed regarding mortality. The detailed study cohort consisted of 112 patients. A total of 80% of the study subjects represented patients post cardiopulmonary resuscitation, 43% were in cardiogenic shock and 50% suffered from acute myocardial infarction. The survival rates were 36% immediately after device implementation and 16% after 30 days. Multivariable analysis revealed that only serum lactate concentration at admission could be proven as independent predictor of patients' outcome. Patients with lactate concentrations above 10 mmol/L exhibited > 95% mortality (p < 0.05 versus below 10 mmol/L).

CONCLUSION

The present study provides real-world clinical data of patients treated with a transportable automated ECLS system. In conclusion, Lifebridge is a safely applicable cardiorespiratory stabilization tool associated with acceptable complication rates. Nevertheless, mortality rates were high in these critically ill patients, especially in those showing high lactate concentrations at admission.

Blood urea nitrogen (BUN) independently predicts mortality in critically ill patients admitted to ICU: A multicenter study

BACKGROUND AND PURPOSE

The Microcirculatory Shock Occurrence in Acutely Ill Patients (micro-SOAP) study investigated associations of microcirculation and mortality. Risk stratification in critically ill patients is of utmost interest. Established score such as APACHE2 (Acute Physiology And Chronic Health Evaluation 2) are relatively complex and might therefore be of limited use. Blood urea nitrogen (BUN) was described to be associated with mortality in various diseases. We therefore aimed (i) to evaluate BUN for prediction of mortality in a cohort of critically ill patients and (ii) to investigate associations of BUN with microcirculation.

METHODS

412 patients were included in our post-hoc analysis of the prospective multicenter microSOAP study. Assesment of the sublingual microcirculation (Sidestream Dark Field (SDF) imaging) and collection of laboratory values were performed on the same day in this point prevalence study. Evaluation of associations with mortality was done by logistic regression analysis. An optimal BUN cut-off was calculated by means of the Youden Index.

RESULTS

Median BUN was 9.0 mmol/L. BUN was associated with in-hospital-mortality in a logistic regression analysis (HR 1.03; 95% CI 1.01-1.05; p < 0.001). Per quartile (BUN 0-5.4 mmol/L, 5.4-9.0 mmol/L, 9.0-15.9 mmol/L and above 15.9 mmol/L) in-hospital mortality increased by as much as 51% (HR 1.51; 95% CI 1.23-1.85; p < 0.001). ROC analysis was done (AUC 0.63 95% CI 0.58-0.67) and the statistically optimal cut-off calculated by means of the Youden Index: 9.7 mmol/L. This cut-off was associated with a significant 3-fold increase in mortality (HR 2.97 95% CI 1.88-4.70; p < 0.001) and remained robustly associated with adverse outcome after correction for APACHE2 (HR 2.71 95% CI 1.61-4.59; p < 0.001), renal function as expressed by creatinine (HR 2.63 95% CI 1.59-4.33; p = 0.001), as well in an integrative model (MAP<60 mmHg, tachycardia (heart rate >90/min), lactate above 1.5 mmol/L, age above 80 years; HR 2.43 95% CI 1.50-3.92; p < 0.001). Parameters of microvascular perfusion were associated neither with BUN nor mortality.

CONCLUSIONS

BUN is associated with hospital mortality and a combination of BUN and clinical signs might constitute a powerful but easy-to-use tool for risk stratification in critically ill patients and help improve their outcome. BUN was not associated with parameters of microcirculation which were not associated with mortality.

Model for End-Stage Liver Disease Excluding INR (MELD-XI) score is associated with hemodynamic impairment and predicts mortality in critically ill patients

PURPOSE

We aimed (i) to evaluate Model for End-stage Liver Disease excluding INR (MELD-XI) score for prediction of mortality in a cohort of critically ill patients and (ii) to investigate associations of MELD-XI with microcirculation and (iii) to evaluate microcirculation for prediction of mortality in high-risk patients, e.g., with high MELD-XI scores.

METHODS

308 patients were included in our retrospective analysis, a subgroup of the multicenter micro-SOAP-study. Microcirculation was evaluated by Sidestream Dark Field (SDF) imaging. Evaluation of associations with mortality was done by logistic regression analysis, an optimal cut-off was calculated by means of the Youden Index. We divided the cohort in two sub-groups based on their MELD-XI score at the optimal cut-off (12 score points).

RESULTS

Patients with a MELD-XI > 12 points were of similar age (60 ± 1 years vs 62 ± 2 years; p = 0.32), but clinically sicker as mirrored by higher APACHE II scores (20 ± 1 vs 16 ± 1; p < 0.001). In the MELD-XI > 12 cohort in-hospital mortality was significantly higher compared to the MELD ≤ 12 group (48% vs 24%%; HR 2.98 95%CI 1.76-5.04; p = 0.003) and MELD-XI score was associated with mortality even after correction for relevant clinical confounders (HR 1.04 95%CI 1.01-1.07; p = 0.004) There were no associations between MELD-XI and parameters of microvascular perfusion.

CONCLUSIONS

MELD-XI is associated with in-hospital mortality and constitutes a useful tool for risk stratification in intensive care medicine. Interestingly, there were no associations between MELD-XI and microcirculation. Possibly parameters of the microcirculation present an online tool of hemodynamic assessment while MELD-XI presents an assessment of already established organ failure.