Serum lactate and acute mesenteric ischaemia: An observational, controlled multicentre study.

BACKGROUND: Early diagnosis and prompt management of acute mesenteric ischaemia (AMI) are key to survival but remain extremely difficult, due to vague and non-specific symptoms. Serum lactate (SL) is commonly presented as a useful biomarker for the diagnosis or prognosis of AMI. The aim of our study was test SL (1) as a diagnostic marker and (2) as a prognostic marker for AMI. STUDY DESIGN: This was an ancillary multicentre case-control study. Patients with AMI at intensive care unit (ICU) admission were included (AMI group) and matched to ICU patients without AMI (control group). SL was measured and compared on day 0 (D0) and day 1 (D1). Diagnosis and prognosis accuracy were assessed by receiver operating characteristic (ROC) and their area under the curve (AUC). RESULTS: Each group consisted of 137 matched ICU patients. There was no significant difference of SL between the two groups at D0 or at D1 (p = 0.26 and p = 0.29 respectively). SL was a poor marker of AMI: at D0 and D1, AUC were respectively 0.57 [0.51; 0.63] and 0.60 [0.53; 0.67]. SL at D0 and D1 correctly predicted ICU mortality, independently of AMI (AUC D0: 0.69 [0.59; 0.79] vs. 0.74 [0.65; 0.82]; p = 0.51 and D1: 0.74 [0.64; 0.84] vs. 0.76 [0.66; 0.87]; p = 0.77, respectively, for control and AMI groups]. CONCLUSIONS: SL has no specific link with AMI, both for diagnosis and prognosis. SL should not be used for the diagnosis of AMI but, despite its lack of specificity, it may help to assess severity.

Immune Profiling Demonstrates a Common Immune Signature of Delayed Acquired Immunodeficiency in Patients With Various Etiologies of Severe Injury.

OBJECTIVES: The host response plays a central role in the pathophysiology of sepsis and severe injuries. So far, no study has comprehensively described the overtime changes of the injury-induced immune profile in a large cohort of critically ill patients with different etiologies. DESIGN: Prospective observational cohort study. SETTING: Adult ICU in a University Hospital in Lyon, France. PATIENTS: Three hundred fifty-three septic, trauma, and surgical patients and 175 healthy volunteers were included in the REAnimation Low Immune Status Marker study. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Extensive immune profiling was performed by assessing cellular phenotypes and functions, protein, and messenger RNA levels at days 1-2, 3-4, and 5-7 after inclusion using a panel of 30 standardized immune markers. Using this immunomonitoring panel, no specificity in the immune profile was observed among septic, trauma, and surgical patients. This common injury-induced immune response was characterized by an initial adaptive (i.e., physiologic) response engaging all constituents of the immune system (pro- and anti-inflammatory cytokine releases, and innate and adaptive immune responses) but not associated with increased risk of secondary infections. In contrary, the persistence in a subgroup of patients of profound immune alterations at the end of the first week after admission was associated with increased risk of secondary infections independently of exposure to invasive devices. The combined monitoring of markers of pro-/anti-inflammatory, innate, and adaptive immune responses allowed a better enrichment of patients with risk of secondary infections in the selected population. CONCLUSIONS: Using REAnimation Low Immune Status Marker immunomonitoring panel, we detected delayed injury-acquired immunodeficiency in a subgroup of severely injured patients independently of primary disease. Critically ill patients' immune status could be captured through the combined monitoring of a common panel of complementary markers of pro-/anti-inflammatory, innate, and adaptive immune responses. Such immune monitoring needs to be incorporated in larger study cohorts with more extensive immune surveillance to develop specific hypothesis allowing for identification of biological systems affecting altered immune function related to late infection in the setting of acute systemic injury.

Evolution of Practices in a French Trauma Centre: Decrease in Blood Transfusions and Fresh Frozen Plasma to Red Blood Cell Ratios.

OBJECTIVE: The aim of this study was to describe the evolution of transfusion practices following the introduction of tranexamic acid (TXA) and ROTEMVR in a trauma resuscitation unit (TRU) from a French teaching hospital (FTH). METHODS: This is a single-centre, retrospective study at a TRU from a FTH. All trauma patients aged 18 years or more and transfused with at least 4 red blood cells (RBCs) within 24 hours after trauma, from 2011 to 2016, were included. The primary objective was to analyse transfusion practices over this time period. The secondary objectives aimed at assessing differences between populations according to the fresh frozen plasma (FFP):RBC ratio applied. RESULTS: A total of 122 patients were included. There was a significant decrease in the proportion of patients requiring at least 4 RBCs 24 hours after trauma (9% vs. 3%, P trend < .0001) as well as a decrease in the proportion of patients with a high FFP:RBC ratio (86% vs. 62% at 6 hours, P trend » .0056 and 86% vs. 56% at 24 hours, P trend » .0047). After 2013, fibrinogen was administered to more than 70% of patients and TXA to 100% of them. The observed mortality was lower than the predicted one, irrespective of FFP:RBC ratio. CONCLUSION: An important evolution of practices occurred including a decrease in the proportion of transfusions and use of high FFP:RBC ratios. The origin of these changes is multifactorial, likely including the systematic use of TXA and optimisation of the ROTEM protocol for fibrinogen administration.

Blood Purification Techniques for Sepsis and Septic AKI.

Sepsis is the primary cause of acute kidney injury in critically ill patients. During the past decades, several extracorporeal blood purification techniques have been developed for sepsis and sepsis-induced acute kidney injury management. These therapies could act on both the infectious agent itself and the host immune response. In this article, we review the available literature discussing the different extracorporeal blood purification techniques, including high-volume hemofiltration, cascade hemofiltration, hemoperfusion, coupled plasma filtration adsorption, plasma exchange, and specific optimized renal replacement therapy membranes.

oXiris® Use in Septic Shock: Experience of Two French Centres.

BACKGROUND: Sepsis is a dysregulated host response to an infection and can result in organ dysfunctions and death. Extracorporeal blood purification techniques aim to improve the prognosis of these patients by modulating the unbalanced immune response. This study reports our experience with the use of the oXiris® membrane for septic shock patients requiring continuous renal replacement therapy (CRRT). SUMMARY: Thirty-one patients were diagnosed with septic shock and underwent CRRT with the oXiris® membrane between 2014 and 2019. We compared the observed hospital mortality with that predicted by the Simplified Acute Physiology Score II (SAPS II). Change in the Sequential Organ Failure Assessment (SOFA) score and of the main clinical and biological parameters over time were analyzed. Hospital mortality was lower than predicted for the most severe patients (60 vs. 91% for the [74-87] SAPS II quartile and 70 vs. 98% for the [87-163] SAPS II quartile, p < 0.02). There was no significant improvement in the SOFA score from 0h to 48 h. An 88% relative decrease in norepinephrine infusion was observed (median at 0 h was 1.69 [0.52-2.45] µg/kg/min; at 48 h it was 0.20 [0.09-1.14] µg/kg/min, p = 0.002). Lactataemia and pH were significantly improved over time. Patients with intra-abdominal sepsis as well as those with Gram-negative bacilli (GNB) infections seemed to benefit the most from the therapy. Key Messages: CRRT with the oXiris® haemofilter resulted in higher observed survival than predicted by a severity score (SAPS II) for the most severe patients. Haemodynamic status and lactataemia appeared to improve, especially in intra-abdominal sepsis and GNB infections.

Dialysis catheters in the ICU: selection, insertion and maintenance.

PURPOSE OF REVIEW: Choosing the best catheter for renal replacement therapy (RRT) is not an easy task. Beyond catheter length, many of its properties can influence effectiveness of the RRT session. Maintenance between sessions, particularly the locking solution, also impacts catheter lifespan and infection rates. RECENT FINDINGS: Many innovations in dialysis catheters have been proposed by the industry over the past decade, including the material used, the shape of the lumens and the position of the inflow and outflow holes. Impregnated catheters have also been developed to prevent catheter-related infections. Many locking solutions are available, either for maintaining catheter patency or for preventing infections. SUMMARY: Although studies conducted in the specific context of the ICU are still scarce, some conclusions can be drawn. Catheter length must be adapted to the insertion site to reach an area of high blood flow. Kidney-shape lumens appear to be less thrombogenic and seem to prevent catheter dysfunction. Catheter tip and lumen holes also affect catheter function. For catheter locking, 4% citrate appears nowadays as one of the best options, but taurolidine-based solutions are also interesting.

Intra-cellular lactate concentration in T lymphocytes from septic shock patients - a pilot study.

BACKGROUND: Sepsis-associated hyperlactatemia is a widely used biomarker, associated with initial severity and poor outcomes. This increased circulating lactate concentration has been proposed to result in part from a mismatch between oxygen delivery and demand in organs. However, other mechanisms may participate. In particular, a metabolic reprogramming similar to the Warburg effect initially described in cancer cells could lead to increased lactate production by immune cells such as T lymphocytes after sepsis. The objective of this study was to set up a protocol for lactate measurement in T lymphocytes, and to evaluate whether lactate production by T lymphocytes was increased in septic shock patients. METHODS: We first optimized protocols for lactate and pyruvate measurements in T lymphocytes purified from healthy volunteers' blood, either stimulated with phytohaemagglutinine (PHA) or left untreated. We then conducted a pilot study to confirm the feasibility of this protocol in samples from septic shock patients. RESULTS: PHA stimulation induced aerobic glycolysis in human lymphocytes ex vivo, with increased lactate and pyruvate productions. To correctly measure this phenomenon, minimal cell number was 250,000 and optimal culture duration was 40 h. We also observed a significant correlation between lactate concentration in T lymphocytes and in their culture supernatants. We were able to measure lactate concentration in T lymphocytes from septic shock patients. Our preliminary results showed that intra-lymphocyte lactate concentration was not different between patients and healthy volunteers. CONCLUSION: This protocol should now be tested in a larger cohort of patients. The association between immune cell metabolic reprogramming as measured by lactate concentration in T cells and functionality represents an exciting field for research.

IL-7 Restores T Lymphocyte Immunometabolic Failure in Septic Shock Patients through mTOR Activation.

T lymphocyte alterations are central to sepsis pathophysiology, whereas related mechanisms remain poorly understood. We hypothesized that metabolic alterations could play a role in sepsis-induced T lymphocyte dysfunction. Samples from septic shock patients were obtained at day 3 and compared with those from healthy donors. T cell metabolic status was evaluated in the basal condition and after T cell stimulation. We observed that basal metabolic content measured in lymphocytes by nuclear magnetic resonance spectroscopy was altered in septic patients. Basal ATP concentration, oxidative phosphorylation (OXPHOS), and glycolysis pathways in T cells were decreased as well. After stimulation, T lymphocytes from patients failed to induce glycolysis, OXPHOS, ATP production, GLUT1 expression, glucose entry, and proliferation to similar levels as controls. This was associated with significantly altered mTOR, but not Akt or HIF-1α, activation and only minor AMPKα phosphorylation dysfunction. IL-7 treatment improved mTOR activation, GLUT1 expression, and glucose entry in septic patients' T lymphocytes, leading to their enhanced proliferation. mTOR activation was central to this process, because rapamycin systematically inhibited the beneficial effect of recombinant human IL-7. We demonstrate the central role of immunometabolism and, in particular, mTOR alterations in the pathophysiology of sepsis-induced T cell alterations. Our results support the rationale for targeting metabolism in sepsis with recombinant human IL-7 as a treatment option.

Modulation of LILRB2 protein and mRNA expressions in septic shock patients and after ex vivo lipopolysaccharide stimulation.

Septic patients develop immune dysfunctions, the intensities and durations of which are associated with deleterious outcomes. LILRB2 (leukocyte immunoglobulin-like receptors subfamily B, member 2), an inhibitory member of the LILR family of receptors, is known for its immunoregulatory properties. In a microarray study, we identified LILRB2 as an upregulated gene in septic shock patients. On monocytes primed with LPS ex vivo, LILRB2 mRNA and protein expressions were dose-dependently downregulated and subsequently highly upregulated versus non-stimulated cells. This is concordant with clinical data, since both LILRB2 mRNA and protein expressions were significantly increased in septic shock patients at day 3. In a cohort of more than 700 patients, only after septic shock were LILRB2 mRNA levels increased compared with non-infected or less severely infected patients. This was preceded by a phase of downregulated mRNA expression during the first hours after septic shock. Interestingly, the intensity of this decrease was associated with increased risk of death after septic shock. LILRB2 protein and mRNA expressions are deregulated on monocytes after septic shock and this can be reproduced ex vivo after LPS challenge. Considering LILRB2 inhibitory properties, we can hypothesize that LILRB2 may participate in the altered immune response after septic shock.

Biological markers of injury-induced immunosuppression.

Severe injuries such as severe sepsis, burn, trauma and major surgery lead to an overlapping development of pro- and anti- inflammatory responses. It is now well established that these injuries are associated with the secondary development of immune suppression, which results in significant morbidity and mortality. Recent data suggest that immunostimulatory drugs might prevent these complications. However, intensive care patients are heterogeneous, making patient stratification essential for a targeted treatment. In the present review, we discuss potential biomarkers of injury-induced immunoparalysis, mainly focusing on these that have been associated with poor outcome in various clinical settings. We namely present clinical data on monocyte human leukocyte antigen DR, lymphopenia, PD-1/PD-L1 and transcriptomic approach.

Apoptosis-induced lymphopenia in sepsis and other severe injuries.

Sepsis and other acute injuries such as severe trauma, extensive burns, or major surgeries, are usually followed by a period of marked immunosuppression. In particular, while lymphocytes play a pivotal role in immune response, their functions and numbers are profoundly altered after severe injuries. Apoptosis plays a central role in this process by affecting immune response at various levels. Indeed, apoptosis-induced lymphopenia duration and depth have been associated with higher risk of infection and mortality in various clinical settings. Therapies modulating apoptosis represent an interesting approach to restore immune competence after acute injury, although their use in clinical practice still presents several limitations. After briefly describing the apoptosis process in physiology and during severe injuries, we will explore the immunological consequences of injury-induced lymphocyte apoptosis, and describe associations with clinically relevant outcomes in patients. Therapeutic perspectives targeting apoptosis will also be discussed.

An optimized protocol for adenosine triphosphate quantification in T lymphocytes of lymphopenic patients.

In several clinical contexts, the measurement of ATP concentration in T lymphocytes has been proposed as a biomarker of immune status, predictive of secondary infections. However, the use of such biomarker in lymphopenic patients requires some adaptations in the ATP dosage protocol. We used blood from healthy volunteers to determine the optimal experimental settings. We investigated technical aspects such as the type of anticoagulant for blood sampling, the effect of freeze and thaw cycles, the reagent and sample mixing sequence, and the optimal dilution buffer. We also shortened the incubation time to 8h, and even showed that a 30min incubation may be sufficient. To evaluate the ATP rise upon lymphocyte activation, the optimal dose of stimulant was defined to be 4µg/mL of phytohaemagglutinin. Lastly, we determined that the number of T cells needed for this measurement was as low as 50,000, which is compatible with the existing lymphopenia in clinical settings. This optimized protocol appears ready to be assessed in lymphopenic patients to further investigate the interconnection between T lymphocyte metabolism and impaired phenotype and functions.