Evaluating the Utility of High Sensitivity Troponin in Blunt Cardiac Injury.

INTRODUCTION: Screening for blunt cardiac injury (BCI) includes obtaining a serum troponin level and an electrocardiogram for patients diagnosed with a sternal fracture. Our institution has transitioned to the use of a high sensitivity troponin I (hsTnI). The aim of this study was to determine whether hsTnI is comparable to troponin I (TnI) in identifying clinically significant BCI. MATERIALS AND METHODS: Trauma patients presenting to a level I trauma center over a 24-mo period with the diagnosis of sternal fracture were screened for BCI. Any initial TnI more than 0.04 ng/mL or hsTnI more than 18 ng/L was considered positive for potential BCI. Clinically significant BCI was defined as a new-bundle branch block, ST wave change, echocardiogram change, or need for cardiac catheterization. RESULTS: Two hundred sixty five patients with a sternal fracture were identified, 161 underwent screening with TnI and 104 with hsTnI. For TnI, the sensitivity and specificity for detection of clinically significant BCI was 0.80 and 0.79, respectively. For hsTnI, the sensitivity and specificity for detection of clinically significant BCI was 0.71 and 0.69, respectively. A multivariate analysis demonstrated the odds ratio for significant BCI with a positive TnI was 14.4 (95% confidence interval, 3.9-55.8, P < 0.0001) versus an odds ratio of 5.48 (95% confidence interval 1.9-15.7, P = 0.002) in the hsTnI group. CONCLUSIONS: The sensitivity of hsTnI is comparable to TnI for detection of significant BCI. Additional investigation is needed to determine the necessity and interval for repeat testing and the need for additional diagnostic testing.

Olfactomedin 4-Positive Neutrophils Are Upregulated after Hemorrhagic Shock.

Neutrophils are vital to both the inflammatory cascade and tissue repair after an injury. Neutrophil heterogeneity is well established but there is less evidence for significant, different functional roles for neutrophil subsets. OLFM4 (Olfactomedin-4) is expressed by a subset of neutrophils, and high expression of OLFM4 is associated with worse outcomes in patients with sepsis and acute respiratory distress syndrome. We hypothesized that an increased number of OLFM4+ neutrophils would occur in trauma patients with worse clinical outcomes. To test this, we prospectively enrolled patients who suffered a blunt traumatic injury. Blood was collected at the time of admission, Day 3, and Day 7 and analyzed for the percentage of neutrophils expressing OLFM4. We found that a subset of patients who suffered blunt traumatic injury upregulated their percentage of OLFM4+ neutrophils. Those who upregulated their OLFM4 had an increased length of stay, days in the ICU, and ventilator days. A majority of these patients also suffered from hemorrhagic shock. To establish a potential role for OLFM4+ neutrophils, we used a murine model of hemorrhagic shock because mice also express OLFM4 in a subset of neutrophils. These studies demonstrated that wild type mice had higher concentrations of cytokines in the plasma and myeloperoxidase in the lungs compared with OLFM4-null mice. In addition, we used an anti-OLFM4 antibody, which when given to wild type mice led to the reduction of myeloperoxidase in the lungs of mice. These findings suggest that OLFM4+ neutrophils are a unique subset of neutrophils that affect the inflammatory response after tissue injury.

Acute and Chronic Hematologic Implications of Emergency and Elective Splenectomy.

INTRODUCTION: Thrombocytosis and leukocytosis are common after splenectomy. The potential effect of emergency surgery on these postoperative findings is unknown. We hypothesized that emergency splenectomy leads to a more profound and persistent hematologic change as compared to elective splenectomy. METHODS: A retrospective review was conducted of patients who underwent elective or trauma splenectomy. Records were queried for platelet (PLT) and white blood cell (WBC) count prior to splenectomy, on postoperative days 1-5, and at day 14, 1 month, 3 months, 6 months, and 1 year. Complications, including thromboembolic events, infection, need for repeat operation, and readmission within 30 days of discharge, were recorded. RESULTS: 463 patients were identified as being eligible for the study, with 173 patients in the elective cohort and 145 patients in each of the isolated trauma splenectomy and polytrauma cohorts. Both cohorts had peak thrombocytosis at week 2 postoperatively. However, polytrauma patients had a significantly higher peak platelet count (P < 0.01). The PLT:WBC ratio was lower in both trauma cohorts pre-operatively and postoperative day 1. Trauma splenectomy had a higher PLT:WBC ratio on days 2 and 3 whereas polytrauma had a lower ratio on days 4 and 5. Emergency cases had greater reoperation and infection rates, whereas elective cases were more likely to require readmission. Postoperative thromboembolic events were only higher in the polytrauma cohort. CONCLUSIONS: While trauma splenectomy resulted in more profound postoperative leukocytosis and thrombocytosis, there was no correlation with timing of infection or risk of thromboembolic events. These findings suggest that thrombocytosis and leukocytosis may be associated with thrombotic and infectious events but their presence alone does not indicate direct risks of concomitant infection or thrombosis.

Hitting the Vasopressor Ceiling: Finding Norepinephrine Associated Mortality in the Critically Ill.

BACKGROUND: There is no consensus on what dose of norepinephrine corresponds with futility. The purpose of this study was to investigate the maximum infusion and cumulative doses of norepinephrine associated with survival for patients in medical and surgical intensive care units (MICU and SICU). MATERIALS AND METHODS: A retrospective review was conducted of 661 critically ill patients admitted to a large academic medical center who received norepinephrine. Univariate, multivariate, and area under the curve analyses with optimal cut offs for maximum infusion rate and cumulative dosage were determined by Youden Index. RESULTS: The population was 54.9% male, 75.8% white, and 58.7 ± 16.1 y old with 384 (69.8%) admitted to the MICU and 166 (30.2%) admitted to the SICU, including 38 trauma patients. Inflection points in mortality were seen at 18 mcg/min and 17.6 mg. The inflection point was higher in MICU patients at 21 mcg/min and lower in SICU patients at 11 mcg/min. MICU patients also had a higher maximum cumulative dosage of 30.7 mg, compared to 2.7 mg in SICU patients. In trauma patients, norepinephrine infusions up to 5 mcg/min were associated with a 41.7% mortality rate. CONCLUSION: A maximum rate of 18 mcg/min and cumulative dose of 17.6 mg were the inflection points for mortality risk in ICU patients, with SICU patients tolerating lower doses. In trauma patients, even low doses of norepinephrine were associated with higher mortality. These data suggest that MICU, SICU, and trauma patients differ in need for, response to, and outcome from escalating norepinephrine doses.

Consumptive coagulopathy is associated with organ dysfunction during PICS.

Patients who survive the acute phase of sepsis can progress to persistent inflammation, immunosuppression, and catabolism syndrome (PICS). Although sepsis is characterized by early hypercoagulability and delayed hypocoagulability, coagulopathy during chronic critical illness is not fully understood. The objective of this study was to determine whether sepsis-induced PICS is associated with coagulation abnormalities. Using our previously described murine PICS model, outbred mice underwent cecal ligation and puncture, and coagulability was characterized after 8 days. We found that during PICS the spleen became markedly enlarged with increased splenocytes and splenic megakaryocytes without a concomitant increase in circulating platelets. Microscopy revealed a nearly sevenfold increase in pulmonary microvascular thrombi in PICS mice, along with significantly decreased pulmonary tidal volumes and inspiratory times and with significantly increased respiratory rates. Thromboelastometry showed that PICS mice had significantly delayed clot initiation time but increased clot firmness. Finally, PICS mice displayed delayed thrombin production and decreased overall thrombin concentrations. All together, these data demonstrate a general dysregulation of coagulation resulting in microthrombus formation and compromised lung function. On the basis of these findings, we propose that consumptive coagulopathy constitutes another cardinal feature of PICS and may contribute to the ongoing tissue damage and multiple organ failure that can occur in chronic critical illness.

Amitriptyline Reduces Inflammation and Mortality in a Murine Model of Sepsis.

BACKGROUND/AIMS: During sepsis, an unchecked pro-inflammatory response can be detrimental to the host. We investigated the potential protective effect of amitriptyline (AT). METHODS: We used two murine models of sepsis: Cecal ligation and puncture and endotoxemia following LPS challenge. Aural temperatures were taken and cytokines quantified by cytometric bead assay. Lung injury was determined histologically and by protein determination in bronchoalveolar lavage fluid. Cell accumulation in the peritoneum was analyzed by flow cytometry, as well as cytokine production and p38-phosphorylation. Neutrophil chemotaxis was evaluated using an in vitro transwell assay. RESULTS: Our findings demonstrate that AT-treated septic mice have improved survival and are protected from pulmonary edema. Treatment with AT significantly decreased serum levels of KC and monocyte chemoattractant protein-1, as well as the accumulation of neutrophils and monocytes in the peritoneum of septic mice. Peritoneal IL-10 levels in septic mice were increased upon AT treatment. Direct treatment of septic mice with IL-10 recapitulated the effects of AT. Endotoxemic mice also exhibited enhanced IL-10 production upon AT-administration and peritoneal macrophages were identified as the ATinfluenced producers of IL-10. Treatment of these cells with AT in vitro resulted in increased p38-phosphorylation and IL-10 generation, whereas ceramide and p38 inhibition had the opposite effect. CONCLUSION: Altogether, AT treatment improved survival, increased IL-10 levels, and mitigated a pro-inflammatory response during sepsis. We conclude that AT is a promising therapeutic to temper inflammation during septic shock.

Lower Extremity Duplex Ultrasound Screening Protocol for Moderate- and High-Risk Trauma Patients.

BACKGROUND: Deep vein thrombosis (DVT) remains a significant cause of morbidity after injury. Lower extremity duplex ultrasound screening (LEDUS) is designed to identify early, asymptomatic DVTs in moderate and high risk patients. We sought to describe when thrombus is detected and identify which trauma patients benefit from LEDUS. MATERIALS AND METHODS: A retrospective review was conducted on trauma patients who were moderate or high risk for venous thromboembolism based on risk assessment profile (RAP) scoring. Patients with RAP scores ≥5 underwent LEDUS on hospital Day 4 and then weekly. We defined moderate venous thromboembolism risk as an RAP score of 5-9 and high risk as an RAP score of ≥10. Demographics, injury characteristics, and chemoprophylaxis type and timing were analyzed. RESULTS: A total of 579 trauma patients underwent a total of 820 ultrasounds in 1 y. Eighty-eight acute DVTs were identified. There was only one progression of a below- to above-the-knee DVT. Patients with RAP scores ≥10 had significantly higher rates of DVTs compared with patients with lower RAP scores in addition to longer lengths of stay and time to DVT prophylaxis. Moderate- and high-risk patients had similar rates of pulmonary embolism. Two-thirds of all DVTs were diagnosed on the first screening examination. The rate of DVTs in patients with RAP scores 7-9 was 15.4% compared with 6.1% of those with RAP scores of 5-6. CONCLUSIONS: LEDUS allows for early identification of asymptomatic DVTs. Moderate-risk patients with RAP scores of ≥7 should be considered for LEDUS, given higher rates of DVT.

Optimizing Lower Extremity Duplex Ultrasound Screening After Traumatic Injury.

BACKGROUND: The risk assessment profile (RAP) score has been used to determine patients who would most benefit from lower extremity duplex ultrasound screening (LEDUS). We hypothesized that revising our LEDUS protocol to perform screening ultrasound examinations in patients with an RAP ≥8 within 48 h of admission would reduce the number of LEDUS performed without changing outcomes. METHODS: A retrospective review was conducted on trauma patients admitted from July 1, 2014, to June 30, 2015, and July 1, 2016, to June 30, 2017. In 2014-2015, patients with an RAP score ≥5 underwent weekly LEDUS examinations starting on hospital day 4. In 2016-2017, the protocol was changed to start screening patients with an RAP score ≥8 by hospital day 2. Both protocols screened with weekly ultrasounds after the first examination. Demographic data, injury characteristics, LEDUS examination findings, chemoprophylaxis type, and venous thromboembolism incidence were collected. RESULTS: A total of 602 patients underwent LEDUS examination in 2014-2015, whereas only 412 underwent LEDUS in 2016-2017. No significant difference was seen in the number of patients diagnosed with deep vein thrombosis (DVT) or pulmonary embolism. DVTs were most often identified on the first LEDUS examination in both cohorts. Of patients diagnosed with a DVT on an LEDUS examination, a significantly higher RAP score (12 versus 10), and a shorter time to first duplex (1 versus 3 d), and DVT diagnosis (2 versus 4 d) were observed in the 2016-2017 cohort. In patients diagnosed with a pulmonary embolism, no significant differences were demonstrated between cohorts. CONCLUSIONS: Refinement of LEDUS protocols can decrease overutilization of hospital resources without compromising trauma patient outcomes.

Sooner is better: use of a real-time automated bedside dashboard improves sepsis care.

BACKGROUND: Minimizing the interval between diagnosis of sepsis and administration of antibiotics improves patient outcomes. We hypothesized that a commercially available bedside clinical surveillance visualization system (BSV) would hasten antibiotic administration and decrease length of stay (LOS) in surgical intensive care unit (SICU) patients. METHODS: A BSV, integrated with the electronic medical record and displayed at bedside, was implemented in our SICU in July 2016. A visual sepsis screen score (SSS) was added in July 2017. All patients admitted to SICU beds with bedside displays equipped with a BSV were analyzed to determine mean SSS, maximum SSS, time from positive SSS to antibiotic administration, SICU LOS, and mortality. RESULTS: During the study period, 232 patients were admitted to beds equipped with the clinical surveillance visualization system. Thirty patients demonstrated positive SSS followed by confirmed sepsis (23 Pre-SSS versus 7 Post-SSS). Mean and maximum SSS were similar. Time from positive SSS to antibiotic administration was decreased in patients with a visual SSS (55.3 ± 15.5 h versus 16.2 ± 9.2 h; P < 0.05). ICU and hospital LOS was also decreased (P < 0.01). CONCLUSIONS: Implementation of a visual SSS into a BSV led to a decreased time interval between the positive SSS and administration of antibiotics and was associated with shorter SICU and hospital LOS. Integration of a visual decision support system may help providers adhere to Surviving Sepsis Guidelines.

Sphingosine rescues aged mice from pulmonary pseudomonas infection.

BACKGROUND: Bacterial lung infection is a leading cause of death for those 65 y or older, often requiring intensive care unit admission and mechanical ventilation, which consumes considerable health care resources. Although administration of antibiotics is the standard of care for bacterial pneumonia, its overuse has led to the emergence of multidrug resistant organisms. Therefore, alternative strategies to help minimize the effects of bacterial pneumonia in the elderly are necessary. As studies have shown that sphingosine (SPH) has inherent bacterial killing properties, our goal was to assess whether it could act as a prophylactic treatment to protect aged mice from pulmonary infection by Pseudomonas aeruginosa. METHODS: Aged (51 wk) and young (8 wk) C57Bl/6 mice were used in this study. Pulmonary SPH levels were determined by histology. SPH content of microparticles was quantified using a SPH kinase assay. Pneumonia was induced by intranasally treating mice with 106 Colony Forming Unit (CFU) P aeruginosa. Microparticles were isolated from young mice, whereas some were further incubated with SPH. RESULTS: We observed that SPH levels are reduced in the bronchial epithelial cells as well as the bronchoalveolar lavage microparticles isolated from aged mice, which correlates with a susceptibility to infection. We demonstrate that SPH or microparticle treatment can protect aged mice from pulmonary P aeruginosa infection. Finally, we observed that enriching microparticles with SPH before treatment eliminated the bacterial load in P aeruginosa-infected aged mice. CONCLUSIONS: These data suggest that prophylactic treatment with SPH could reduce lung bacterial infections for the at-risk elderly population.

A Murine Model of Persistent Inflammation, Immune Suppression, and Catabolism Syndrome.

Critically ill patients that survive sepsis can develop a Persistent Inflammation, Immunosuppression, and Catabolism Syndrome (PICS), which often leads to extended recovery periods and multiple complications. Here, we utilized a cecal ligation and puncture (CLP) method in mice with the goal of creating a model that concurrently displays all the characteristics of PICS. We observed that, after eight days, mice that survive the CLP develop persistent inflammation with significant myelopoiesis in the bone marrow and spleen. These mice also demonstrate ongoing immune suppression, as evidenced by the decreased total and naïve splenic CD4 and CD8 T cells with a concomitant increase in immature myeloid cells. The mice further display significant weight loss and decreased muscle mass, indicating a state of ongoing catabolism. When PICS mice are challenged with intranasal Pseudomonas aeruginosa, mortality is significantly elevated compared to sham mice. This mortality difference is associated with increased bacterial loads in the lung, as well as impaired neutrophil migration and neutrophil dysfunction in the PICS mice. Altogether, we have created a sepsis model that concurrently exhibits PICS characteristics. We postulate that this will help determine the mechanisms underlying PICS and identify potential therapeutic targets to improve outcomes for this patient population.

The Use of Poloxamer 188 in Burn Injury Treatment: A Systematic Literature Review.

ABSTRACT: Although there have been numerous advancements in burn wound management, burn injuries are still a major cause of morbidity and mortality in the United States and novel therapeutic are still needed to improve outcomes. Poloxamer 188 (P188) is a synthetic copolymer with FDA approval that has many biological applications. This study aimed to review the literature on P188 in burn injuries and its effects based on burn mechanisms. We employed the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines to complete this systematic literature review. We searched the databases of Google Scholar, PubMed, and SCOPUS using the keywords burn, p188, poloxamer 188, and pluronic F68 in combination. Two reviewers independently screened the articles for inclusion. Articles that were not in English, were book chapters or conference proceedings, or did not evaluate P188 in the setting of burn injuries were excluded. We included a total of 33 full-text articles with both in vivo and in vitro pre-clinical studies. P188 was found to beneficial in animal and cell studies evaluating electrical and thermal burn injuries. P188 was also found to be useful in burn wound management. Although its utility may be limited in radiation injuries, P188 may be helpful in delaying the initial damage caused by radiation burns. P188 therefore has the potential to be used as a therapy in both burn wound management and in the treatment of systemic injuries sustained through burns. Future studies should aim to assess the efficacy of P188 in clinical models of burn injury.

Effects of poloxamer 188 on traumatic brain injury.

Traumatic Brain Injury (TBI) is a major cause of severe disability and death, resulting in significant health care and economic burden. Poloxamer 188, a synthetic tri-block copolymer approved by the FDA, has been studied for its potential effects on traumatic brain injury (TBI). The neuroprotective abilities of P188 have attracted significant attention. This systematic review aims to compile evidence of P188's effect on the treatment of TBI. A comprehensive literature search was conducted using PubMed, SCOPUS, and Google Scholar databases, which yielded 20 articles that satisfied the inclusion criteria. These articles have shown direct protective effects of P188 on brain tissue following TBI, including restitution of the increase cell membrane permeability, attenuation of neuronal necrosis and apoptosis, improvement of mitochondrial viability, reduction in axonal disruption, and restoration of the blood brain barrier. In animals, P188 has been shown to improve sensorimotor functions, as well as spatial learning and memory.

Tracheostomy decreases continuous analgesia and sedation requirements.

BACKGROUND: The goals of sedation in the critically ill surgical patient are to minimize pain, anxiety, and agitation without hindering cardiopulmonary function. One potential benefit of tracheostomy during endotracheal intubation is the reduction of sedation and analgesia; however, there are little data to support this supposition. We hypothesized that patients undergoing tracheostomy would have a rapid reduction in sedation and analgesia following tracheostomy. METHODS: A retrospective review of tracheostomies performed at a single Level I trauma center from January 2013 to June 2018 was completed. An evaluation of Glasgow Coma Scale, Richmond Agitation-Sedation Scale, and Confusion Assessment Method for the intensive care unit 72 hours pretracheostomy to 72 hours posttracheostomy was performed. The total daily dose of sedation, anxiolytic, and analgesic medications administered were recorded. Mixed-effects models were used to evaluate longitudinal drug does over time (hours). RESULTS: Four hundred sixty-eight patients included for analysis with a mean age of 58.8 ± 18.3 years. There was a significant decrease in propofol and fentanyl utilization from 24 hours pretracheostomy to 24 hours posttracheostomy in both dose and number of patients receiving these continuous intravenous medications. Similarly, total morphine milligram equivalents (MME) use and continuous midazolam significantly decreased from 24 hours pretracheostomy to 24 hours posttracheostomy. By contrast, intermittent enteral quetiapine and methadone administration increased after tracheostomy. Importantly, Richmond Agitation-Sedation Scale, Glasgow Coma Scale, and Confusion Assessment Method scoring were also significantly improved as early as 24 hours posttracheostomy. Total MME use was significantly elevated in patients younger than 65 years and in male patients pretracheostomy compared with female patients. Patients admitted to the medical intensive care unit had significantly higher MME use compared with those in the surgical intensive care unit pretracheostomy. CONCLUSION: Tracheostomy allows for a rapid and significant reduction in intravenous sedation and analgesia medication utilization. Posttracheostomy sedation can transition to intermittent enteral medications, potentially contributing to the observed improvements in postoperative mental status and agitation. LEVEL OF EVIDENCE: Therapeutic/Care Management; Level III.

Burn Injury Impairs Neutrophil Chemotaxis Through Increased Ceramide.

ABSTRACT: Infection is a common and often deadly complication after burn injury. A major underlying factor is burn-induced immune dysfunction, particularly with respect to neutrophils as the primary responders to infection. Temporally after murine scald injury, we demonstrate impaired bone marrow neutrophil chemotaxis toward CXCL1 ex vivo. Additionally, we observed a reduced recruitment of neutrophils to the peritoneal after elicitation 7 days after injury. We demonstrate that neutrophil ceramide levels increase after burn injury, and this is associated with decreased expression of CXCR2 and blunted chemotaxis. A major signaling event upon CXCR2 activation is Akt phosphorylation and this was reduced when ceramide was elevated. In contrast, PTEN levels were elevated and PTEN-inhibition elevated phospho-Akt levels and mitigated the burn-induced neutrophil chemotaxis defect. Altogether, this study identifies a newly described pathway of ceramide-mediated suppression of neutrophil chemotaxis after burn injury and introduces potential targets to mitigate this defect and reduce infection-related morbidity and mortality after burn.

Lymphocyte Immunosuppression and Dysfunction Contributing to Persistent Inflammation, Immunosuppression, and Catabolism Syndrome (PICS).

ABSTRACT: Persistent Inflammation, Immune Suppression, and Catabolism Syndrome (PICS) is a disease state affecting patients who have a prolonged recovery after the acute phase of a large inflammatory insult. Trauma and sepsis are two pathologies after which such an insult evolves. In this review, we will focus on the key clinical determinants of PICS: Immunosuppression and cellular dysfunction. Currently, relevant immunosuppressive functions have been attributed to both innate and adaptive immune cells. However, there are significant gaps in our knowledge, as for trauma and sepsis the immunosuppressive functions of these cells have mostly been described in acute phase of inflammation so far, and their clinical relevance for the development of prolonged immunosuppression is mostly unknown. It is suggested that the initial immune imbalance determines the development of PCIS. Additionally, it remains unclear what distinguishes the onset of immune dysfunction in trauma and sepsis and how this drives immunosuppression in these cells. In this review, we will discuss how regulatory T cells (Tregs), innate lymphoid cells, natural killer T cells (NKT cells), TCR-a CD4- CD8- double-negative T cells (DN T cells), and B cells can contribute to the development of post-traumatic and septic immunosuppression. Altogether, we seek to fill a gap in the understanding of the contribution of lymphocyte immunosuppression and dysfunction to the development of chronic immune disbalance. Further, we will provide an overview of promising diagnostic and therapeutic interventions, whose potential to overcome the detrimental immunosuppression after trauma and sepsis is currently being tested.

Interleukin-6 contributes to age-related alteration of cytokine production by macrophages.

Here, we studied in vitro cytokine production by splenic macrophages obtained from young and aged BALB/c wild type (WT) and IL-6 knockout (IL-6 KO) mice. Relative to macrophages obtained from young WT mice given lipopolysaccharide (LPS), those from aged WT mice had decreased production of proinflammatory cytokines. In contrast, when compared to macrophages from young IL-6 KO mice, LPS stimulation yielded higher levels of these cytokines by cells from aged IL-6 KO mice. Aging or IL-6 deficiency did not affected the percentage of F4/80(+) macrophages, or the surface expression of Toll-like receptor 4 (TLR4) and components of the IL-6 receptor. Overall, our results indicate that IL-6 plays a role in regulating the age-related defects in macrophages through alteration of proinflammatory cytokines, adding to the complexity of IL-6-mediated impairment of immune cell function with increasing age.

Distinct Neutrophil Populations in the Spleen During PICS.

While mortality after acute sepsis has decreased, the long-term recovery for survivors is still poor, particularly those developing persistent inflammation, immunosuppression, and catabolism syndrome (PICS). While previously thought that activated neutrophils responding to the acute phase of sepsis migrate to the spleen to undergo cell death and contribute to immunosuppression, our data show a significant accumulation of distinct, yet functional, neutrophil populations in the spleen in a murine model of PICS. The exact role and function of neutrophils in this response is still unclear. The objective of our study was to better define the immune function of splenic neutrophils to determine if this could give insight into the pathogenesis of PICS. Using a murine model of cecal ligation and puncture (CLP), which demonstrates all characteristics of PICS by 8 days, spleens were harvested, and neutrophils were identified by Ly6G and CD11b expression via flow cytometry. Nearly all splenic neutrophils expressed CD54, but there were distinct CD54hi and CD54lo cells, with the majority being CD54lo cells during PICS. The CD54hi population showed traditional, proinflammatory properties, but a relatively decreased chemotactic response, while CD54lo cells had significantly higher chemotaxis, yet significantly decreased proinflammatory functions. Using 5-ethynyl-2'-deoxyuridine (EdU) incorporation, we found that the CD54hi population on day 2 after CLP may be participating in emergency myelopoiesis. However, the vast majority of the CD54lo population were paused in the G1 phase at this time point and not proliferating. By day 8 after CLP, most of the CD54hi cells in the spleen were no longer proliferating, while the CD54lo cells were, indicating that CD54lo dominate in extramedullary myelopoiesis at later time points. Almost none of the neutrophils produced arginase or inducible nitric oxide synthase (iNOS), indicating that these are not suppressor cells. Overall, our data demonstrate that neutrophil accumulation in the spleen during PICS is related to extramedullary myelopoiesis, leading to the production of immature neutrophils. While not suppressor cells, the majority have greater chemotactic function but less inflammatory responsiveness, which may contribute to the immunosuppression seen in PICS. Attention to these distinct neutrophil populations after septic or other systemic inflammatory responses is therefore critical to understanding the mechanisms of PICS.

Staging and Personalized Intervention for Infection and Sepsis.

Background: Sepsis is defined as a dysregulated host response to infection, resulting in life-threatening organ dysfunction. It is now understood that this dysregulation not only constitutes excessive inflammation, but also sustained immune suppression. Immune-modulatory therapies thus have great potential for novel sepsis therapies. Here, we provide a review of biomarkers and functional assays designed to immunologically stage patients with sepsis as well as therapies designed to alter the innate and adaptive immune systems of patients with sepsis beneficially. Methods: A search of PubMed/MEDLINE and clinicaltrials.gov was performed between October 1, 2019 and December 22, 2019 using search terms such as "sepsis immunotherapy," "sepsis biomarkers," "sepsis clinical trials," and variations thereof. Results: Despite more than 30 years of research, there is still no Food and Drug Administration (FDA)-cleared biomarker that has proven to be effective in either identifying patients with sepsis who are at an increased risk of adverse outcomes or responsive to specific interventions. Similarly, past clinical trials investigating new treatment strategies have rarely stratified patients with sepsis. Overall, the results of these trials have been disappointing. Novel efforts to properly gauge an individual patient's immune response and choose an appropriate immunomodulatory agent based on the results are underway. Conclusion: Our evolving understanding of the different mechanisms perturbing immune homeostasis during sepsis strongly suggests that future successes will depend on finding the right therapy for the right patient and administering it at the right time. For such a personalized medicine approach, novel biomarkers and functional assays to properly stage the patient with sepsis will be crucial. The growing repertoire of immunomodulatory agents at our disposal, as well as re-appraisal of agents that have already been tested in unstratified cohorts of patients with sepsis, may finally translate into successful treatment strategies for sepsis.

Enigmatic role of coagulopathy among sepsis survivors: a review of coagulation abnormalities and their possible link to chronic critical illness.

There are sparse clinical data addressing the persistence of disordered coagulation in sepsis and its role in chronic critical illness. Coagulopathy in the absence of anticoagulant therapy and/or liver disease can be highly variable in sepsis, but it tends to be prolonged in patients in the intensive care unit with a length of stay greater than 14 days. These coagulation abnormalities tend to precede multisystem organ failure and persistence of these coagulation derangements can predict 28-day mortality. The studies evaluated in this review consistently link sepsis-associated coagulopathy to poor long-term outcomes and indicate that disordered coagulation is associated with unfavorable outcomes in chronic critical illness. However, the causative mechanism and the definitive link remain unclear. Longer follow-up and more granular data will be required to fully understand coagulopathy in the context of chronic critical illness.