Long-term Host Immune Response Trajectories Among Hospitalized Patients With Sepsis

Immunomonitoring of Monocyte and Neutrophil Function in Critically Ill Patients: From Sepsis and/or Trauma to COVID-19

Immune cells and mediators play a crucial role in the critical care setting but are understudied. This review explores the concept of sepsis and/or injury-induced immunosuppression and immuno-inflammatory response in COVID-19 and reiterates the need for more accurate functional immunomonitoring of monocyte and neutrophil function in these critically ill patients. in addition, the feasibility of circulating and cell-surface immune biomarkers as predictors of infection and/or outcome in critically ill patients is explored. It is clear that, for critically ill, one size does not fit all and that immune phenotyping of critically ill patients may allow the development of a more personalized approach with tailored immunotherapy for the specific patient. In addition, at this point in time, caution is advised regarding the quality of evidence of some COVID-19 studies in the literature.

Cerebral dysfunctions caused by sepsis during ageing

Systemic inflammation elicited by sepsis can induce an acute cerebral dysfunction known as sepsis-associated encephalopathy (SAE). Recent evidence suggests that SAE is common but shows a dynamic trajectory over time. Half of all patients with sepsis develop SAE in the intensive care unit, and some survivors present with sustained cognitive impairments for several years after initial sepsis onset. It is not clear why some, but not all, patients develop SAE and also the factors that determine the persistence of SAE. Here, we first summarize the chronic pathology and the dynamic changes in cognitive functions seen after the onset of sepsis. We then outline the cerebral effects of sepsis, such as neuroinflammation, alterations in neuronal synapses and neurovascular changes. We discuss the key factors that might contribute to the development and persistence of SAE in older patients, including premorbid neurodegenerative pathology, side effects of sedatives, renal dysfunction and latent virus reactivation. Finally, we postulate that some of the mechanisms that underpin neuropathology in SAE may also be relevant to delirium and persisting cognitive impairments that are seen in patients with severe COVID-19.

In this Review, Manabe and Heneka examine how the systemic inflammation associated with sepsis can lead to acute cerebral dysfunction known as sepsis-associated encephalopathy (SAE). Moreover, they suggest that some of the mechanisms involved in SAE may be relevant for understanding the cognitive impairments that develop in some patients with COVID-19.

The immunology of sepsis

Sepsis is defined as a life-threatening organ dysfunction caused by a dysregulated host response to an infection. This recently implemented definition does not capture the heterogeneity or the underlying pathophysiology of the syndrome, which is characterized by concurrent unbalanced hyperinflammation and immune suppression. Here, we review current knowledge of aberrant immune responses during sepsis and recent initiatives to stratify patients with sepsis into subgroups that are more alike from a clinical and/or pathobiological perspective, which could be key for identification of patients who are more likely to benefit from specific immune interventions.

Immune Dysfunction is Associated with Readmission in Survivors of Sepsis Following Infected Pancreatic Necrosis

Objective

Immunosuppression is common in patients with infected pancreatic necrosis (IPN) and associated with morbidity and mortality. This study aimed to investigate the impact of immune status on mortality and readmission after hospital discharge in patients with IPN-related sepsis.

Methods

In this prospective observational study, eligible adult patients with IPN-related sepsis requiring ICU admission were included. Monocytic human leukocyte antigen DR (mHLA-DR), expression of regulatory T cells (Treg), and neutrophil CD88 (nCD88) were measured on the diagnosis of sepsis, ICU discharge, hospital discharge, and 15, 30, 60 days after hospital discharge. Logistic regression model was used to assess potential risk factors for readmission 60-days within the index discharge.

Results

A total of 53 patients were included, 13 died during hospitalization and one withdrew the consent soon after discharge. Among the survivors, a tendency of immune recovery was observed during the consecutive follow-ups, evidenced by the increased expression of mHLA-DR. Sixteen patients (41.03%) were readmitted within 60 days after the index discharge. In the multivariable regression model, APACHE II score when sepsis was diagnosed >9 and mHLA-DR at discharged <14,591 AB/C were found to be independent risk factors affecting readmission.

Conclusion

Immunosuppression is common in patients with IPN-related sepsis and can persist until two months after discharge. The compromised mHLA-DR level at discharge was associated with readmission within two months after discharge.

Long term sepsis readmission, mortality and cause of death following Gram negative bloodstream infection: a propensity matched observational linkage study

OBJECTIVES

Understand the long-term mortality, risk of readmission for sepsis and cause of death following a gram-negative bloodstream infection (GN-BSI).

METHODS

This was a propensity-matched study using data linkage of Queensland hospital data, Australia. GN-BSIs were collected from 2005 to 2010 and matched 1:1 to hospital admissions without BSI for age, gender, year of culture collection, frequency of admissions in the prior year and Charlson-Deyo Comorbidity score and each comorbidity within the Charlson-Deyo score. Readmissions for sepsis, mortality and causes of death were evaluated.

RESULTS

Cases of GN-BSI were propensity-matched 1:1 to culture-negative hospital admissions (n = 14016). Readmissions for sepsis were higher in the GN-BSI cohort from 91 to 365 days (P < 0.001) and in the four subsequent years (P < 0.001). The five-year survival in the GN-BSI cohort was 52% versus 65% in the culture-negative cases (P < 0.001). Infection was only a common underlying cause of death within the first 90 days. Sepsis was the most common contributing cause of death (CCOD) for the two years following index culture in the GN-BSI cohort.

CONCLUSIONS

Compared to a similarly vulnerable group of hospital attendees, GN-BSI had higher mortality and demonstrated a persistent long-term risk of readmission for sepsis and sepsis as a CCOD.

Sepsis-Induced Immunosuppression

Sepsis is expected to have a substantial impact on public health and cost as its prevalence increases. Factors contributing to increased prevalence include a progressively aging population, advances in the use of immunomodulatory agents to treat a rising number of diseases, and immune-suppressing therapies in organ transplant recipients and cancer patients. It is now recognized that sepsis is associated with profound and sustained immunosuppression, which has been implicated as a predisposing factor in the increased susceptibility of patients to secondary infections and mortality. In this review, we discuss mechanisms of sepsis-induced immunosuppression and biomarkers that identify a state of impaired immunity. We also highlight immune-enhancing strategies that have been evaluated in patients with sepsis, as well as therapeutics under current investigation. Finally, we describe future challenges and the need for a new treatment paradigm, integrating predictive enrichment with patient factors that may guide the future selection of tailored immunotherapy. Expected final online publication date for the Annual Review of Physiology, Volume 84 is February 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

The Concentration of Large Extracellular Vesicles Differentiates Early Septic Shock From Infection

Septic shock represents a subset of sepsis with severe physiological aberrations and a higher mortality rate than sepsis alone. Currently, the laboratory tools which can be used to identify the state of septic shock are limited. In pre-clinical studies, extracellular vesicles (EVs), especially large EVs (lEVs), have been demonstrated a role as functional inflammatory mediators of sepsis. However, its longitudinal trend during the disease course has not been explored. In this study, the quantities and subtypes of plasma-derived lEVs were longitudinally compared between patients with septic shock (n = 21) and non-sepsis infection (n = 9), who presented within 48 h of their symptom onset. Blood specimens were collected for seven consecutive days after hospital admission. lEVs quantification and subtyping were performed using an imaging flow cytometer. The experiments revealed a higher lEVs concentration in septic shock patients than infected patients at the onset of the disease. In septic shock patients, lEVs concentration decreased over time as opposed to infected patients whose lEVs concentration is relatively static throughout the study period. The major contributors of lEVs in both septic shock and infected patients were of non-leukocyte origins; platelets, erythrocytes, and endothelial cells released approximately 40, 25, and 15% of lEVs, respectively. Among lEVs of leukocyte origins, neutrophils produced the highest number of EVs. Nevertheless, the proportion of each subtype of lEVs among the given amount of lEVs produced was similar between septic shock and infected patients. These findings raise the possibility of employing lEVs enumeration as a septic shock identifying tool, although larger studies with a more diverse group of participants are warranted to extrapolate the findings to a general population.

Biomarker Evidence of the Persistent Inflammation, Immunosuppression and Catabolism Syndrome (PICS) in Chronic Critical Illness (CCI) After Surgical Sepsis

OBJECTIVE

To analyze serial biomarkers of the persistent inflammation, immunosuppression, and catabolism syndrome (PICS) to gain insight into the pathobiology of chronic critical illness (CCI) after surgical sepsis.

BACKGROUND

Although early deaths after surgical intensive care unit sepsis have decreased and most survivors rapidly recover (RAP), one third develop the adverse clinical trajectory of CCI. However, the underlying pathobiology of its dismal long-term outcomes remains unclear.

METHODS

PICS biomarkers over 14 days from 124 CCI and 225 RAP sepsis survivors were analyzed to determine associations and prediction models for (1) CCI (≥14 intensive care unit days with organ dysfunction) and (2) dismal 1-year outcomes (Zubrod 4/5 performance scores). Clinical prediction models were created using PIRO variables (predisposition, insult, response, and organ dysfunction). Biomarkers were then added to determine if they strengthened predictions.

RESULTS

CCI (vs RAP) and Zubrod 4/5 (vs Zubrod 0-3) cohorts had greater elevations in biomarkers of inflammation (interleukin [IL]-6, IL-8, interferon gamma-induced protein [IP-10], monocyte chemoattractant protein 1), immunosuppression (IL-10, soluble programmed death ligand-1), stress metabolism (C-reactive protein, glucagon-like peptide 1), and angiogenesis (angiopoietin-2, vascular endothelial growth factor, vascular endothelial growth factor receptor-1, stromal cell-derived factor) at most time-points. Clinical models predicted CCI on day 4 (area under the receiver operating characteristics curve [AUC] = 0.89) and 1 year Zubrod 4/5 on day 7 (AUC = 0.80). IL-10 and IP-10 on day 4 minimally improved prediction of CCI (AUC = 0.90). However, IL-10, IL-6, IL-8, monocyte chemoattractant protein 1, IP-10, angiopoietin-2, glucagon-like peptide 1, soluble programmed death ligand-1, and stromal cell-derived factor on day 7 considerably improved the prediction of Zubrod 4/5 status (AUC = 0.88).

CONCLUSIONS

Persistent elevations of PICS biomarkers in the CCI and Zubrod 4/5 cohorts and their improved prediction of Zubrod 4/5 validate that PICS plays a role in CCI pathobiology.

Systemic inflammation induced the delayed reduction of excitatory synapses in the CA3 during ageing

Sepsis-associated encephalopathy (SAE) represents diverse cerebral dysfunctions in response to pathogen-induced systemic inflammation. Peripheral exposure to lipopolysaccharide (LPS), a component of the gram-negative bacterial cell wall, has been extensively used to model systemic inflammation. Our previous studies suggested that LPS led to hippocampal neuron death and synaptic destruction in vivo. However, the underlying roles of activated microglia in these neuronal changes remained unclear. Here, LPS from two different bacterial strains (Salmonella enterica or E. coli) were compared and injected in 14- to 16-month-old mice and evaluated for neuroinflammation and neuronal integrity in the hippocampus at 7 or 63 days post-injection (dpi). LPS injection resulted in persistent neuroinflammation lasting for seven days and a subsequent normalisation by 63 dpi. Of note, increases in proinflammatory cytokines, microglial morphology and microglial mean lysosome volume were more pronounced after E. coli LPS injection than Salmonella LPS at 7 dpi. While inhibitory synaptic puncta density remained normal, excitatory synaptic puncta were locally reduced in the CA3 region of the hippocampus at 63 dpi. Finally, we provide evidence that excitatory synapses coated with complement factor 3 (C3) decreased between 7 dpi and 63 dpi. Although we did not find an increase of synaptic pruning by microglia, it is plausible that microglia recognised and eliminated these C3-tagged synapses between the two time-points of investigation. Since a region-specific decline of CA3 synapses has previously been reported during normal ageing, we postulate that systemic inflammation may have accelerated or worsened the CA3 synaptic changes in the ageing brain.

Association between sepsis survivorship and long-term cardiovascular outcomes in adults: a systematic review and meta-analysis

PURPOSE

We aimed to determine the association between sepsis and long-term cardiovascular events.

METHODS

We conducted a systematic review of observational studies evaluating post-sepsis cardiovascular outcomes in adult sepsis survivors. MEDLINE, Embase, and the Cochrane Controlled Trials Register and Database of Systematic Reviews were searched from inception until April 21st, 2021. Two reviewers independently extracted individual study data and evaluated risk of bias. Random-effects models estimated the pooled crude cumulative incidence and adjusted hazard ratios (aHRs) of cardiovascular events compared to either non-septic hospital survivors or population controls. Primary outcomes included myocardial infarction, stroke, and congestive heart failure; outcomes were analysed at maximum reported follow-up (from 30 days to beyond 5 years post-discharge).

RESULTS

Of 12,649 screened citations, 27 studies (25 cohort studies, 2 case-crossover studies) were included with a median of 4,289 (IQR 502-68,125) sepsis survivors and 18,399 (IQR 4,028-83,506) controls per study. The pooled cumulative incidence of myocardial infarction, stroke, and heart failure in sepsis survivors ranged from 3 to 9% at longest reported follow-up. Sepsis was associated with a higher long-term risk of myocardial infarction (aHR 1.77 [95% CI 1.26 to 2.48]; low certainty), stroke (aHR 1.67 [95% CI 1.37 to 2.05]; low certainty), and congestive heart failure (aHR 1.65 [95% CI 1.46 to 1.86]; very low certainty) compared to non-sepsis controls.

CONCLUSIONS

Surviving sepsis may be associated with a long-term, excess hazard of late cardiovascular events which may persist for at least 5 years following hospital discharge.

Hemostasis and fibrinolysis in COVID-19 survivors 6 months after intensive care unit discharge

BACKGROUND

The prothrombotic phenotype has been extensively described in patients with acute coronavirus disease 2019 (COVID-19). However, potential long-term hemostatic abnormalities are unknown.

OBJECTIVE

To evaluate the changes in routine hemostasis laboratory parameters and tissue-type plasminogen activator (tPA) rotational thromboelastometry (ROTEM) 6 months after COVID-19 intensive care unit (ICU) discharge in patients with and without venous thromboembolism (VTE) during admission.

METHODS

Patients with COVID-19 of the Maastricht Intensive Care COVID cohort with tPA ROTEM measurement at ICU and 6-month follow-up were included. TPA ROTEM is a whole blood viscoelastic assay that illustrates both clot development and fibrinolysis due to simultaneous addition of tissue factor and tPA. Analyzed ROTEM parameters include clotting time, maximum clot firmness (MCF), lysis onset time (LOT), and lysis time (LT).

RESULTS

Twenty-two patients with COVID-19 were included and showed extensive hemostatic abnormalities before ICU discharge. TPA ROTEM MCF (75 mm [interquartile range, 68-78]-59 mm [49-63]; P ≤ .001), LOT (3690 seconds [2963-4418]-1786 seconds [1465-2650]; P ≤ .001), and LT (7200 seconds [6144-7200]-3138 seconds [2591-4389]; P ≤ .001) normalized 6 months after ICU discharge. Of note, eight and four patients still had elevated fibrinogen and D-dimer concentrations at follow-up, respectively. In general, no difference in median hemostasis parameters at 6-month follow-up was observed between patients with (n=14) and without (n=8) VTE, although fibrinogen appeared to be lower in the VTE group (VTE-, 4.3 g/L [3.7-4.7] vs VTE+, 3.4 g/L [3.2-4.2]; P = .05).

CONCLUSIONS

Six months after COVID-19 ICU discharge, no persisting hypercoagulable or hypofibrinolytic profile was detected by tPA ROTEM. Nevertheless, increased D-dimer and fibrinogen concentrations persist up to 6 months in some patients, warranting further exploration of the role of hemostasis in long-term morbidity after hospital discharge.

Association of fluid balance trajectories with clinical outcomes in patients with septic shock: a prospective multicenter cohort study

BACKGROUND

Septic shock has a high incidence and mortality rate in Intensive Care Units (ICUs). Earlier intravenous fluid resuscitation can significantly improve outcomes in septic patients but easily leads to fluid overload (FO), which is associated with poor clinical outcomes. A single point value of fluid cannot provide enough fluid information. The aim of this study was to investigate the impact of fluid balance (FB) latent trajectories on clinical outcomes in septic patients.

METHODS

Patients were diagnosed with septic shock during the first 48 h, and sequential fluid data for the first 3 days of ICU admission were included. A group-based trajectory model (GBTM) which is designed to identify groups of individuals following similar developmental trajectories was used to identify latent subgroups of individuals following a similar progression of FB. The primary outcomes were hospital mortality, organ dysfunction, major adverse kidney events (MAKE) and severe respiratory adverse events (SRAE). We used multivariable Cox or logistic regression analysis to assess the association between FB trajectories and clinical outcomes.

RESULTS

Nine hundred eighty-six patients met the inclusion criteria and were assigned to GBTM analysis, and three latent FB trajectories were detected. 64 (6.5%), 841 (85.3%), and 81 (8.2%) patients were identified to have decreased, low, and high FB, respectively. Compared with low FB, high FB was associated with increased hospital mortality [hazard ratio (HR) 1.63, 95% confidence interval (CI) 1.22-2.17], organ dysfunction [odds ratio (OR) 2.18, 95% CI 1.22-3.42], MAKE (OR 1.80, 95% CI 1.04-2.63) and SRAE (OR 2.33, 95% CI 1.46-3.71), and decreasing FB was significantly associated with decreased MAKE (OR 0.46, 95% CI 0.29-0.79) after adjustment for potential covariates.

CONCLUSION

Latent subgroups of septic patients followed a similar FB progression. These latent fluid trajectories were associated with clinical outcomes. The decreasing FB trajectory was associated with a decreased risk of hospital mortality and MAKE.

Long-term survivors of murine sepsis are predisposed to enhanced LPS-induced lung injury and proinflammatory immune reprogramming

Millions of people who survive sepsis each year are rehospitalized and die due to late pulmonary complications. To prevent and treat these complications, biomarkers and molecular mediators must be identified. Persistent immune reprogramming in the form of immunoparalysis and impaired host defense is proposed to mediate late pulmonary complications after sepsis, particularly new pulmonary infections. However, immune reprogramming may also involve enhanced/primed responses to secondary stimuli, although their contribution to long-term sepsis complications remains understudied. We hypothesize that enhanced/primed immune responses in the lungs of sepsis survivors are associated with late pulmonary complications. To this end, we developed a murine sepsis model using cecal ligation and puncture (CLP) followed 3 wk later by administration of intranasal lipopolysaccharide to induce inflammatory lung injury. Mice surviving sepsis exhibit enhanced lung injury with increased alveolar permeability, neutrophil recruitment, and enhanced Ly6C^hi monocyte Tnf expression. To determine the mediators of enhanced lung injury, we performed flow cytometry and RNA sequencing of lungs 3 wk after CLP, prior to lipopolysaccharide. Sepsis survivor mice showed expanded Ly6C^hi monocytes populations and increased expression of many inflammatory genes. Of these, S100A8/A9 was also elevated in the circulation of human sepsis survivors for months after sepsis, validating our model and identifying S100A8/A9 as a potential biomarker and therapeutic target for long-term pulmonary complications after sepsis. These data provide new insight into the importance of enhanced/primed immune responses in survivors of sepsis and establish a foundation for additional investigation into the mechanisms mediating this response.

Pathophysiology and Treatment Strategies of Acute Myopathy and Muscle Wasting after Sepsis

Sepsis survivors experience a persistent myopathy characterized by skeletal muscle weakness, atrophy, and an inability to repair/regenerate damaged or dysfunctional myofibers. The origins and mechanisms of this persistent sepsis-induced myopathy are likely complex and multifactorial. Nevertheless, the pathobiology is thought to be triggered by the interaction between circulating pathogens and impaired muscle metabolic status. In addition, while in the hospital, septic patients often experience prolonged periods of physical inactivity due to bed rest, which may exacerbate the myopathy. Physical rehabilitation emerges as a potential tool to prevent the decline in physical function in septic patients. Currently, there is no consensus regarding effective rehabilitation strategies for sepsis-induced myopathy. The optimal timing to initiate the rehabilitation intervention currently lacks consensus as well. In this review, we summarize the evidence on the fundamental pathobiological mechanisms of sepsis-induced myopathy and discuss the recent evidence on in-hospital and post-discharge rehabilitation as well as other potential interventions that may prevent physical disability and death of sepsis survivors.

PD-1 signaling pathway in sepsis: Does it have a future?

Sepsis is characterized by high mortality and poor prognosis and is one of the leading causes of death among patients in the intensive care unit (ICU). In the past, drugs that block early inflammatory responses have done little to reverse the progression of sepsis. Programmed cell death receptor 1 (PD-1) and its two ligands, programmed cell death receptor ligand 1(PD-L1) and programmed cell death receptor ligand 2 (PD-L2), are negative regulatory factors of the immune response of the body. Recently, the role of the PD-1 signaling pathway in sepsis has been widely studied. Studies showed that the PD-1 signaling pathways are closely related to the mortality and prognosis of sepsis patients. In the immunotherapy of sepsis, whether in animal experiments or clinical trials, anti-PD-1/PD-L1 antibodies have shown good promise. In this review, firstly, we focus on the immunosuppressive mechanism of sepsis and the structure and function of the PD-1 signaling pathway. The variety of the PD-1 signaling pathways in sepsis is introduced. Then, the relationship between the PD-1 signaling pathway and immune cells and organ dysfunction and the regulatory factors of the PD-1 signaling pathway in sepsis is discussed. Finally, the application of the PD-1 signaling pathway in sepsis is specifically emphasized.

Inflammation and Coagulation during Critical Illness and Long-Term Cognitive Impairment and Disability

Rationale: The biological mechanisms of long-term cognitive impairment and disability after critical illness are unclear.Objectives: To test the hypothesis that markers of acute inflammation and coagulation are associated with subsequent long-term cognitive impairment and disability.Methods: We obtained plasma samples from adults with respiratory failure or shock on Study Days 1, 3, and 5 and measured concentrations of CRP (C-reactive protein), IFN-γ, IL-1β, IL-6, IL-8, IL-10, IL-12, MMP-9 (matrix metalloproteinase-9), TNF-α (tumor necrosis factor-α), soluble TNF receptor 1, and protein C. At 3 and 12 months after discharge, we assessed global cognition, executive function, and activities of daily living. We analyzed associations between markers and outcomes using multivariable regression, adjusting for age, sex, education, comorbidities, baseline cognition, doses of sedatives and opioids, stroke risk (in cognitive models), and baseline disability scores (in disability models).Measurements and Main Results: We included 548 participants who were a median (interquartile range) of 62 (53-72) years old, 88% of whom were mechanically ventilated, and who had an enrollment Sequential Organ Failure Assessment score of 9 (7-11). After adjusting for covariates, no markers were associated with long-term cognitive function. Two markers, CRP and MMP-9, were associated with greater disability in basic and instrumental activities of daily living at 3 and 12 months. No other markers were consistently associated with disability outcomes.Conclusions: Markers of systemic inflammation and coagulation measured early during critical illness are not associated with long-term cognitive outcomes and demonstrate inconsistent associations with disability outcomes. Future studies that pair longitudinal measurement of inflammation and related pathways throughout the course of critical illness and during recovery with long-term outcomes are needed.

Systemic inflammation is negatively associated with early post discharge growth following acute illness among severely malnourished children - a pilot study

Background: Rapid growth should occur among children with severe malnutrition (SM) with medical and nutritional management. Systemic inflammation (SI) is associated with death among children with SM and is negatively associated with linear growth. However, the relationship between SI and weight gain during therapeutic feeding following acute illness is unknown. We hypothesised that growth post-hospital discharge is associated with SI among children with SM. Methods: We conducted secondary analysis of data from HIV-uninfected children with SM (n=98) who survived and were not readmitted to hospital during one year of follow-up. We examined the relationship between changes in absolute deficits in weight and mid-upper-arm circumference (MUAC) from enrolment at stabilisation to 60 days and one year later, and untargeted plasma proteome, targeted cytokines/chemokines, leptin, and soluble CD14 using multivariate regularized linear regression. Results: The mean change in absolute deficit in weight and MUAC was -0.50kg (standard deviation; SD±0.69) and -1.20cm (SD±0.89), respectively, from enrolment to 60 days later. During the same period, mean weight and MUAC gain was 3.3g/kg/day (SD±2.4) and 0.22mm/day (SD±0.2), respectively. Enrolment interleukins; IL17-alpha and IL-2, and serum amyloid P were negatively associated with weight and MUAC gain during 60 days. Lipopolysaccharide binding protein and complement component 2 were negatively associated with weight gain only. Leptin was positively associated with weight gain. Soluble CD14, beta-2 microglobulin, and macrophage inflammatory protein 1 beta were negatively associated with MUAC gain only. Glutathione peroxidase 3 was positively associated with weight and MUAC gain during one year. Conclusions: Early post-hospital discharge weight and MUAC gain were rapid and comparable to children with uncomplicated SM treated in the community. Higher concentrations of SI markers were associated with less weight and MUAC gain, suggesting inflammation negatively impacts recovery from wasting. This finding warrants further research on reducing inflammation on growth among children with SM.

Older adults demonstrate biomarker evidence of the persistent inflammation, immunosuppression and catabolism syndrome (PICS) after sepsis

BACKGROUND

Hospital deaths after sepsis have decreased substantially and most young adult survivors rapidly recover (RAP). However, many older survivors develop chronic critical illness (CCI) with poor long-term outcomes. The etiology of CCI is multifactorial and the relative importance remains unclear. Sepsis is caused by a dysregulated immune response and biomarkers reflecting a persistent inflammation, immunosuppression and catabolism syndrome (PICS) have been observed in CCI after sepsis. Therefore, the purpose of this study was to compare serial PICS biomarkers in a) older (versus young) adults and b) older CCI (versus older RAP) patients to gain insight into underlying pathobiology of CCI in older adults.

METHODS

Prospective longitudinal study with young (≤ 45 years) and older (≥ 65 years) septic adults who were characterized by a) baseline predisposition, b) hospital outcomes, c) serial SOFA organ dysfunction scores over 14 days, d) Zubrod Performance status at three, six and 12-month follow-up and e) mortality over 12 months. Serial blood samples over 14 days were analyzed for selected biomarkers reflecting PICS.

RESULTS

Compared to the young, more older adults developed CCI (20% vs 42%) and had markedly worse serial SOFA scores, performance status and mortality over 12 months. Additionally, older (versus young) and older CCI (versus older RAP) patients had more persistent aberrations in biomarkers reflecting inflammation, immunosuppression, stress metabolism, lack of anabolism and anti-angiogenesis over 14 days after sepsis.

CONCLUSION

Older (versus young) and older CCI (versus older RAP) patient subgroups demonstrate early biomarker evidence of the underlying pathobiology of PICS.

Machine Learning Identifies Complicated Sepsis Course and Subsequent Mortality Based on 20 Genes in Peripheral Blood Immune Cells at 24 H Post-ICU Admission

A complicated clinical course for critically ill patients admitted to the intensive care unit (ICU) usually includes multiorgan dysfunction and subsequent death. Owing to the heterogeneity, complexity, and unpredictability of the disease progression, ICU patient care is challenging. Identifying the predictors of complicated courses and subsequent mortality at the early stages of the disease and recognizing the trajectory of the disease from the vast array of longitudinal quantitative clinical data is difficult. Therefore, we attempted to perform a meta-analysis of previously published gene expression datasets to identify novel early biomarkers and train the artificial intelligence systems to recognize the disease trajectories and subsequent clinical outcomes. Using the gene expression profile of peripheral blood cells obtained within 24 h of pediatric ICU (PICU) admission and numerous clinical data from 228 septic patients from pediatric ICU, we identified 20 differentially expressed genes predictive of complicated course outcomes and developed a new machine learning model. After 5-fold cross-validation with 10 iterations, the overall mean area under the curve reached 0.82. Using a subset of the same set of genes, we further achieved an overall area under the curve of 0.72, 0.96, 0.83, and 0.82, respectively, on four independent external validation sets. This model was highly effective in identifying the clinical trajectories of the patients and mortality. Artificial intelligence systems identified eight out of twenty novel genetic markers (SDC4, CLEC5A, TCN1, MS4A3, HCAR3, OLAH, PLCB1, and NLRP1) that help predict sepsis severity or mortality. While these genes have been previously associated with sepsis mortality, in this work, we show that these genes are also implicated in complex disease courses, even among survivors. The discovery of eight novel genetic biomarkers related to the overactive innate immune system, including neutrophil function, and a new predictive machine learning method provides options to effectively recognize sepsis trajectories, modify real-time treatment options, improve prognosis, and patient survival.

Why Septic Patients Remain Sick After Hospital Discharge?

Sepsis is well known to cause a high patient death rate (up to 50%) during the intensive care unit (ICU) stay. In addition, sepsis survival patients also exhibit a very high death rate after hospital discharge compared to patients with any other disease. The addressed question is then: why septic patients remain ill after hospital discharge? The cellular and molecular mechanisms involved in the high rate of septic patient deaths are still unknown. We described herein the studies that investigated the percentage of septic patients that died after hospital discharge ranging from 90 days up to 5 years. We also reported the symptoms of septic patients after hospital discharge and the development of the recently called post-sepsis syndrome (PSS). The most common symptoms of the PSS are cognitive disabilities, physical functioning decline, difficulties in performing routine daily activities, and poor life quality. The PSS also associates with quite often reinfection and re-hospitalization. This condition is the cause of the high rate of death mentioned above. We reported the proportion of patients dying after hospital discharge up to 5 years of followed up and the PSS symptoms associated. The authors also discuss the possible cellular and metabolic reprogramming mechanisms related with the low survival of septic patients and the occurrence of PSS.

Procalcitonin as a Marker of Comorbid Atrial Fibrillation in Chronic Kidney Disease and History of Sepsis

Cardiovascular disease and infection are the leading causes of mortality in patients with stage 5 chronic kidney disease on hemodialysis (CKD5-HD). Inflammation is a large component in the pathogenesis of both atrial fibrillation (AF) and sepsis and may link these conditions in CKD5-HD. Procalcitonin (PCT) is an inflammatory biomarker elevated in systemic infection and CKD5-HD, yet its value with regard to comorbid AF has not been thoroughly investigated. The aim of this study sought to evaluate circulating inflammatory markers, including PCT, Angiopoietin-1, Angiopoetin-2, CD40-L, C-reactive protein, d-dimer, and von Willebrand factor in relation to these conditions. Plasma levels of inflammatory markers were measured by enzyme linked immunosorbent assay method in CKD5-HD (n = 97) patients and controls (n = 50). Procalcitonin levels were significantly elevated (P = .0270) in CKD5-HD with comorbid AF compared to those without AF. Further analysis of patients with a history of sepsis demonstrated significantly elevated levels of PCT (P = .0405) in those with comorbid AF (160.7 ± 39.5 pg/mL) compared to those without AF (117.4 ± 25.3 pg/mL). This study demonstrates that the inflammatory biomarker PCT is further elevated in the presence of both AF and a history of sepsis in hemodialysis patients and suggests that underlying chronic inflammation following sepsis resolution may place these patients at greater risk of developing AF.

In-Hospital Death after Septic Shock Reversal: A Retrospective Analysis of In-Hospital Death among Septic Shock Survivors at Thailand's Largest National Tertiary Referral Center

Advances in sepsis resuscitation have significantly improved shock control; however, many patients still die after septic shock reversal. We conducted a retrospective review to examine in-hospital death in whom shock was reversed and vasopressor was discontinued for 72 hours or longer. Factors independently associated with death were determined. Medical records of septic shock survivors from the medical intensive care unit of the Department of Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand, during January 2012-January 2019 were analyzed. A total of 350 septic shock patients were enrolled. Of these, 280 survived initial resuscitation. Eighty of 280 patients died, 45 died by 28 days (16.1%), and 35 (12.5%) died thereafter during their hospital stay. Multi-organ failure and hospital-acquired pneumonia (HAP) were the leading causes of death, followed by other infection and noninfectious complication. Although the death group had more laboratory derangement and required more organ support, there were four factors associated with mortality from multivariate analysis. Hospital-acquired pneumonia was the leading factor, followed by sequential organ failure assessment score and serum albumin at 72 hours after discontinuation of vasopressors, and total intravenous fluid during 72 hours after discontinuation of vasopressors. In-hospital mortality after hemodynamic restoration in patients with septic shock was substantial. Causes and contributing factors were identified. Measures to mitigate these risks would be beneficial for rendering more favorable patient outcomes.

Risk and clinical outcomes of acute myocardial infarction and acute ischemic stroke following gram-negative bloodstream infection

Objectives

This retrospective cohort study examines incidence, risk factors, and clinical outcomes of acute myocardial infarction (AMI) and acute ischemic stroke (AIS) within one year of gram-negative bloodstream infection (GN-BSI) based on predefined clinical criteria.

Methods

Hospitalized adults with GN-BSI at Prisma Health-Midlands hospitals in South Carolina, USA from 2010 through 2015 were identified. Kaplan-Meier analysis was used to determine incidence of AMI and AIS within one year after GN-BSI. Multivariate Cox proportional hazards regression models were used to examine risk factors for AMI or AIS and impact on 1-year mortality.

Results

Among 1292 patients with GN-BSI, 263 and 17 developed AMI and AIS within 1-year with incidences of 23.4% and 1.9%, respectively. Majority of AMI were type 2 (164; 62%); 99 patients had type 1 AMI with incidence of 8.9%. Age >65 years (hazard ratio [HR] 1.52, 95% CI: 1.17-1.99), prior coronary artery disease or stroke (HR 1.74, 95% CI: 1.34-2.25), hypertension (HR 1.55, 95% CI: 1.13-2.15), end-stage renal disease (HR 1.52, 95% CI: 1.09-2.08), and quick Pitt bacteremia score (HR 1.55 per point, 95% CI: 1.40-1.72) were predictors of AMI/AIS. Development of type 1 AMI or AIS after GN-BSI was independently associated with increased 1-year mortality (HR 1.47, 95% CI: 1.03-2.07).

Conclusions

AMI and AIS occur frequently within one year of GN-BSI and have negative impact on 1-year survival. Future randomized clinical trials are needed to determine the most effective clinical interventions for prevention of AMI/AIS following BSI in high risk patients and improve survival after these events.

Prognosis-related classification and dynamic monitoring of immune status in patients with sepsis: A prospective observational study

BACKGROUND

The dynamic monitoring of immune status is crucial to the precise and individualized treatment of sepsis. In this study, we aim to introduce a model to describe and monitor the immune status of sepsis and to explore its prognostic value.

METHODS

A prospective observational study was carried out in Zhongshan Hospital, Fudan University, enrolling septic patients admitted between July 2016 and December 2018. Blood samples were collected at days 1 and 3. Serum cytokine levels (e.g., tumor necrosis factor-α [TNF-α], interleukin-10 [IL-10]) and CD14⁺ monocyte human leukocyte antigen-D-related (HLA-DR) expression were measured to serve as immune markers. Classification of each immune status, namely systemic inflammatory response syndrome (SIRS), compensatory anti-inflammatory response syndrome (CARS), and mixed antagonistic response syndrome (MARS), was defined based on levels of immune markers. Changes of immune status were classified into four groups which were stabilization (SB), deterioration (DT), remission (RM), and non-remission (NR).

RESULTS

A total of 174 septic patients were enrolled including 50 non-survivors. Multivariate analysis discovered that IL-10 and HLA-DR expression levels at day 3 were independent prognostic factors. Patients with MARS had the highest mortality rate. Immune status of 46.1% patients changed from day 1 to day 3. Among four groups of immune status changes, DT had the highest mortality rate, followed by NR, RM, and SB with mortality rates of 64.7%, 42.9%, and 11.2%, respectively.

CONCLUSIONS

Severe immune disorder defined as MARS or deterioration of immune status defined as DT lead to the worst outcomes. The preliminary model of the classification and dynamic monitoring of immune status based on immune markers has prognostic values and is worthy of further investigation.

Sepsis and Cancer: An Interplay of Friends and Foes

Sepsis and cancer share a number of pathophysiological features, and both result from the inability of the host's immune system to cope with the initial insult (tissue invasion by pathogens and malignant cell transformation, respectively). The common coexistence of both disorders and the profound related alterations in immune homeostasis raise the question of their mutual impact on each other's course. This translational review aims to discuss the interactions between cancer and sepsis supported by clinical data and the translation to experimental models. The dramatic improvement in cancer has come at a cost of increased risks of life-threatening infectious complications. Investigating the long-term outcomes of sepsis survivors has revealed an unexpected susceptibility to cancer long after discharge from the ICU. Nonetheless, it is noteworthy that an acute septic episode may harbor antitumoral properties under particular circumstances. Relevant double-hit animal models have provided clues to whether and how bacterial sepsis may impact malignant tumor growth. In sequential sepsis-then-cancer models, postseptic mice exhibited accelerated tumor growth. When using reverse cancer-then-sepsis models, bacterial sepsis applied to mice with cancer conversely resulted in inhibition or even regression of tumor growth. Experimental models thus highlight dual effects of sepsis on tumor growth, mostly depending on the sequence of insults, and allow deciphering the immune mechanisms and their relation with microorganisms.

Systemic inflammation is negatively associated with early post discharge growth following acute illness among severely malnourished children - a pilot study

Background: Rapid growth should occur among children with severe malnutrition (SM) when medically and nutritionally treated. Systemic inflammation (SI) is associated with death among children with SM and is negatively associated with linear growth. However, the relationship between SI and weight gain during therapeutic feeding following acute illness is unknown. We hypothesised that growth in the first 60 days post-hospital discharge is associated with SI among children with SM. Methods: We conducted secondary analysis of data from HIV-uninfected children with SM (n=98) who survived and were not readmitted to hospital during one year of follow up. We examined the relationship between changes in absolute deficits in weight and mid-upper-arm circumference (MUAC) from enrolment at stabilisation to 60 days later and untargeted plasma proteome, targeted cytokines/chemokines, leptin, and soluble CD14 (sCD14) using multivariate regularized linear regression. Results: The mean change in absolute deficit in weight and MUAC was -0.50kg (standard deviation; SD±0.69) and -1.20cm (SD±0.89), respectively, from enrolment to 60 days later. During the same period, mean weight and MUAC gain was 3.3g/kg/day (SD±2.4) and 0.22mm/day (SD±0.2), respectively. Enrolment inflammatory cytokines interleukin 17 alpha (IL17α), interleukin 2 (IL2), and serum amyloid P (SAP) were negatively associated with weight and MUAC gain. Lipopolysaccharide binding protein (LBP) and complement component 2 were negatively associated with weight gain only. Leptin was positively associated with weight gain. sCD14, beta-2 microglobulin (β2M), and macrophage inflammatory protein 1 beta (MIP1β) were negatively associated with MUAC gain only. Conclusions: Early post-hospital discharge weight and MUAC gain were rapid and comparable to children with uncomplicated SM treated with similar diet in the community. Higher concentrations of SI markers were associated with less weight and MUAC gain, suggesting inflammation negatively impacts recovery from wasting. This finding warrants further research on the role of inflammation on growth among children with SM.

Best-practice IgM- and IgA-enriched immunoglobulin use in patients with sepsis

Background

Sepsis is a life-threatening organ dysfunction caused by a dysregulated host response to infection. Despite treatment being in line with current guidelines, mortality remains high in those with septic shock. Intravenous immunoglobulins represent a promising therapy to modulate both the pro- and anti-inflammatory processes and can contribute to the elimination of pathogens. In this context, there is evidence of the benefits of immunoglobulin M (IgM)- and immunoglobulin A (IgA)-enriched immunoglobulin therapy for sepsis. This manuscript aims to summarize current relevant data to provide expert opinions on best practice for the use of an IgM- and IgA-enriched immunoglobulin (Pentaglobin) in adult patients with sepsis.

Main text

Sepsis patients with hyperinflammation and patients with immunosuppression may benefit most from treatment with IgM- and IgA-enriched immunoglobulin (Pentaglobin). Patients with hyperinflammation present with phenotypes that manifest throughout the body, whilst the clinical characteristics of immunosuppression are less clear. Potential biomarkers for hyperinflammation include elevated procalcitonin, interleukin-6, endotoxin activity and C-reactive protein, although thresholds for these are not well-defined. Convenient biomarkers for identifying patients in a stage of immune-paralysis are still matter of debate, though human leukocyte antigen–antigen D related expression on monocytes, lymphocyte count and viral reactivation have been proposed. The timing of treatment is potentially more critical for treatment efficacy in patients with hyperinflammation compared with patients who are in an immunosuppressed stage. Due to the lack of evidence, definitive dosage recommendations for either population cannot be made, though we suggest that patients with hyperinflammation should receive an initial bolus at a rate of up to 0.6 mL (30 mg)/kg/h for 6 h followed by a continuous maintenance rate of 0.2 mL (10 mg)/kg/hour for ≥ 72 h (total dose ≥ 0.9 g/kg). For immunosuppressed patients, dosage is more conservative (0.2 mL [10 mg]/kg/h) for ≥ 72 h, without an initial bolus (total dose ≥ 0.72 g/kg).

Conclusions

Two distinct populations that may benefit most from Pentaglobin therapy are described in this review. However, further clinical evidence is required to strengthen support for the recommendations given here regarding timing, duration and dosage of treatment.

Postcritical illness vulnerability

PURPOSE OF REVIEW

Critical illness survivorship is associated with new and worsening physical, cognitive, and emotional status. Survivors are vulnerable to further health set-backs, most commonly because of infection and exacerbation of chronic medical conditions. Awareness of survivors' challenges are important given the anticipated rise in critical illness survivors because of SARS-CoV-2 viral sepsis.

RECENT FINDINGS

Studies continue to document challenges of critical illness survivorship. Beyond the cognitive, physical, and mental health sequelae encompassed by postintensive case syndrome, patients commonly experience persistent immunosuppression, re-hospitalization, inability to resume prior employment, and reduced quality of life. Although recommended practices for enhancing recovery from sepsis are associated with better outcomes, only a minority of patients receive all recommended practices. ICU follow-up programs or peer support groups remain important interventions to learn about and address the multifaceted challenges of critical illness survivorship, but there is little evidence of benefit to date.

SUMMARY

Survivors of sepsis and critical illness commonly experience impaired health status, reduced quality of life, and inability to return to prior employment. Although the challenges of critical illness survivorship are increasingly well documented, there are relatively few studies on enhancing recovery. Future studies must focus on identifying best practices for optimizing recovery and strategies to promote their implementation.

Development, Validation, and Clinical Utility Assessment of a Prognostic Score for 1-Year Unplanned Rehospitalization or Death of Adult Sepsis Survivors

IMPORTANCE

The longer-term risk of rehospitalizations and death of adult sepsis survivors is associated with index sepsis illness characteristics.

OBJECTIVE

To derive and validate a parsimonious prognostic score for unplanned rehospitalizations or death in the first year after hospital discharge of adult sepsis survivors.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study used data from the Intensive Care National Audit & Research Centre Case Mix Programme database on adult sepsis survivors identified from consecutive critical care admissions to 192 adult general critical care units in England, United Kingdom, between April 1, 2009, and March 31, 2014 (94 748 patients in the derivation cohort), and between April 1, 2014, and March 31, 2015 (24 669 patients in the validation cohort). Statistical analysis was performed from July 5 to October 31, 2019. Generic characteristics (age, sex, race/ethnicity, 2015 Index of Multiple Deprivation [IMD2015] in England quintiles, preadmission dependence, previous hospitalizations in the year preceding index sepsis admission, comorbidity, admission type, Acute Physiology and Chronic Health Evaluation II physiology score, hospital length of stay, worst blood lactate and blood hemoglobin concentrations, and type of hospital) and sepsis-specific characteristics (site of infection, numbers of organ dysfunctions, and organ support) at the index sepsis admission were used as predictors.

MAIN OUTCOMES AND MEASURES

Prognostic score derived and validated using multivariable logistic regression for the outcome of unplanned rehospitalization or death in the first year after hospital discharge of adult sepsis survivors, as well as clinical usefulness assessed using decision curve analysis. Prognostic score validation was performed for internal validation with bootstrapping and temporal cohort external validation.

RESULTS

This cohort study included 94 748 patients (51 164 men [54.0%]; mean [SD] age, 61.3 [17.0] years) in the derivation cohort and 24 669 patients (13 255 men [53.7%]; mean [SD] age, 62.1 [16.8%]) in the validation cohort. Unplanned rehospitalization or death in the first year after hospital discharge occurred for 48 594 patients (51.3%) in the derivation cohort and 13 129 patients (53.2%) in the validation cohort. Eight independent predictors were identified and weighted to generate a prognostic score for every patient: previous hospitalizations, age in 10-year increments, IMD2015 in England quintiles, preadmission dependence, comorbidities, admission type, blood hemoglobin level, and site of infection. The total prognostic score ranged from 0 to 22 points, with lower scores indicating a lower risk of the outcome. The derivation and validation cohorts had similar rates of prognostic scores of 0 to 4 points (5088 of 16 684 patients [30.5%] and 471 of 1725 patients [27.3%]) and prognostic scores of 11 points or more (15 732 of 21 641 patients [72.7%] and 5753 of 7952 patients [72.3%]). The area under the receiver operating characteristic curve for the prognostic score was 0.675 (95% CI, 0.672-0.679). The decision curve analysis highlighted an optimal score cutoff of 7 points or more.

CONCLUSIONS AND RELEVANCE

The prognostic score reported in this study uses 8 internationally feasible predictors measured during the index sepsis admission and provides clinically useful information on sepsis survivors' risk of unplanned rehospitalization or death in the first year after hospital discharge.

Abdominal sepsis patients have a high incidence of chronic critical illness with dismal long-term outcomes

BACKGROUND

As hospital sepsis mortality has decreased, more surgical ICU survivors are progressing into chronic critical illness (CCI). This study documents the incidence of CCI and long-term outcomes of patients with abdominal sepsis. We hypothesized that patients developing CCI would have biomarker evidence of immune and metabolic derangement, with a high incidence of poor 1-year outcomes.

METHODS

Review of abdominal sepsis patients entered in a prospective longitudinal study of surgical ICU sepsis.

RESULTS

Of the 144 study patients, only 6% died early, 37% developed CCI (defined as ICU days ≥14 with organ dysfunction) and 57% were classified rapid recovery (RAP). Compared to RAP, CCI patients a) were older (66 vs 58), males who were sicker at baseline (Charlson Comorbidity Index 4 vs 2), b) had persistently elevated biomarkers of dysregulated immunity/metabolism (IL-6, IL-8, sPDL-1, GLP1), c) experienced more secondary infections (4.9 vs 2.3) and organ failure (Denver MOF frequency 40 vs 1%), d) were much more likely to have poor dispositions (85 vs 22%) with severe persistent disabilities by Zubrod Score and e) had a notably higher 1-year mortality of 42% (all p < 0.05).

CONCLUSION

Over 1/3rd surgical ICU patients treated for abdominal sepsis progress into CCI and experience dismal long-term outcomes.

The role of serum cystatin C in estimation of renal function in survivors of critical illness

PURPOSE

Estimating renal function by serum creatinine after critical illness is a challenging problem. However, the role of cystatin C for estimation of the renal function in survivors of critical illness is unknown. We aimed to compare the performance of serum cystatin C- and serum creatinine-based eGFR against a reference GFR using ^99mTc-diethylenetriaminepentaacetic acid (^99mTc-DTPA) in survivors of critical illness.

MATERIAL AND METHODS

Survivors of critical illness with stable hemodynamics and renal functions were recruited. Their serum creatinine and cystatin C levels were measured. eGFR were calculated by using various equations: 1)CKD-EPI SCysC; 2) Thai eGFR SCysC; 3)CKD-EPI SCr; 4)Thai eGFR SCr; 5)MDRD Caucasian SCr; 6)CKD-EPI SCr-SCysC. The ^99mTc-DTPA plasma clearance was used as a standard eGFR.

RESULTS

Forty-two patients were included. The bias (median percentage difference) between standard GFR and SCysC-based eGFR were 41.97% (95%CI 33.1% to 48.5%) for CKD-EPI SCysC and 31.72% (95%CI 21.1% to 34.9%) for Thai eGFR SCysC. While, the bias between standard GFR and SCr-based eGFR were -11.37 (95%CI -20.9 to 1.6) for CKD-EPI SCr, -18.30 (95%CI -26.3 to -10.6) for Thai eGFR SCr, and -27.17 (-43.7 to -19.1) for MDRD Caucasian SCr.

CONCLUSION

In survivors of critical illness, we demonstrated limitations of estimating GFR by both currently available SCysC and SCr-based equations. Therefore, further studies are still needed to develop better eGFR equations.

Critical Illness and the Frailty Syndrome: Mechanisms and Potential Therapeutic Targets

Frailty is a syndrome characterized by decreased reserves across multiple physiologic systems resulting in functional limitations and vulnerability to new stressors. Physical frailty develops over years in community-dwelling older adults but presents or worsens within days in the intensive care unit (ICU) because common mechanisms governing age-related physical frailty are often exacerbated by critical illness. The hallmark of physical frailty is a combined loss of muscle mass, force, and endurance. About one-third of ICU patients have frailty before hospitalization, which increases their risk for both short- and long-term disability and mortality. While there are several valid ways to measure clinical frailty in patients before or after an ICU admission, the mechanistic underpinnings of frailty in critically ill patients and ICU survivors have not been thoroughly investigated. Furthermore, therapeutic interventions to treat frailty during and after time in the ICU are lacking. In this narrative review, we examine studies that identify potential biological mechanisms underlying the development and propagation of physical frailty in both aging and critical illness (eg, inflammation, mitochondrial myopathy, and neuroendocrinopathy). We discuss specific aspects of these frailty mechanisms in older adults, critically ill patients, and ICU survivors that may represent therapeutic targets. Consistent with complexity underlying frailty, this syndrome is unlikely to result from an excess of a single harmful mediator or deficit of a single protective mediator. Rather, frailty occurs in the presence of an incompletely understood state of multisystem dysregulation. We further describe knowledge gaps that warrant clinical and translational research in frailty and critical care with an overall goal of developing effective frailty treatments in critically ill patients and ICU survivors.

Antibody Production in Murine Polymicrobial Sepsis-Kinetics and Key Players

Although antigen-specific priming of antibody responses is impaired during sepsis, there is nevertheless a strong increase in IgM and IgG serum concentrations. Using colon ascendens stent peritonitis (CASP), a mouse model of polymicrobial abdominal sepsis, we observed substantial increases in IgM as well as IgG of all subclasses, starting at day 3 and peaking 2 weeks after sepsis induction. The dominant source of antibody-secreting cells was by far the spleen, with a minor contribution of the mesenteric lymph nodes. Remarkably, sepsis induction in splenectomized mice did not change the dynamics of the serum IgM/IgG reaction, indicating that the marginal zone B cells, which almost exclusively reside in the spleen, are dispensable in such a setting. Hence, in systemic bacterial infection, the function of the spleen as dominant niche of antibody-producing cells can be compensated by extra-splenic B cell populations as well as other lymphoid organs. Depletion of CD4+ T cells did not affect the IgM response, while it impaired IgG generation of all subclasses with the exception of IgG3. Taken together, our data demonstrate that the robust class-switched antibody response in sepsis encompasses both T cell-dependent and -independent components.

Phenotypic heterogeneity by site of infection in surgical sepsis: a prospective longitudinal study

Background

The role of site of infection in sepsis has been poorly characterized. Additionally, sepsis epidemiology has evolved. Early mortality has decreased, but many survivors now progress into chronic critical illness (CCI). This study sought to determine if there were significant differences in the host response and current epidemiology of surgical sepsis categorized by site of infection.

Study design

This is a longitudinal study of surgical sepsis patients characterized by baseline predisposition, insult characteristics, serial biomarkers, hospital outcomes, and long-term outcomes. Patients were categorized into five anatomic sites of infection.

Results

The 316 study patients were predominantly Caucasian; half were male, with a mean age of 62 years, high comorbidity burden, and low 30-day mortality (10%). The primary sites were abdominal (44%), pulmonary (19%), skin/soft tissue (S/ST, 17%), genitourinary (GU, 12%), and vascular (7%). Most abdominal infections were present on admission and required source control. Comparatively, they had more prolonged proinflammation, immunosuppression, and persistent organ dysfunction. Their long-term outcome was poor with 37% CCI (defined as > 14 in ICU with organ dysfunction), 49% poor discharge dispositions, and 30% 1-year mortality. Most pulmonary infections were hospital-acquired pneumonia. They had similar protracted proinflammation and organ dysfunction, but immunosuppression normalized. Long-term outcomes are similarly poor (54% CCI, 47% poor disposition, 32% 1-year mortality). S/ST and GU infections occurred in younger patients with fewer comorbidities, less perturbed immune responses, and faster resolution of organ dysfunction. Comparatively, S/ST had better long-term outcomes (23% CCI, 39% poor disposition, 13% 1-year mortality) and GU had the best (10% CCI, 20% poor disposition, 10% 1-year mortality). Vascular sepsis patients were older males, with more comorbidities. Proinflammation was blunted with baseline immunosuppression and organ dysfunction that persisted. They had the worst long-term outcomes (38% CCI, 67% poor disposition, 57% 1-year mortality).

Conclusion

There are notable differences in baseline predisposition, host responses, and clinical outcomes by site of infection in surgical sepsis. While previous studies have focused on differences in hospital mortality, this study provides unique insights into the host response and long-term outcomes associated with different sites of infection.

General Adaptation in Critical Illness: Glucocorticoid Receptor-alpha Master Regulator of Homeostatic Corrections

In critical illness, homeostatic corrections representing the culmination of hundreds of millions of years of evolution, are modulated by the activated glucocorticoid receptor alpha (GRα) and are associated with an enormous bioenergetic and metabolic cost. Appreciation of how homeostatic corrections work and how they evolved provides a conceptual framework to understand the complex pathobiology of critical illness. Emerging literature place the activated GRα at the center of all phases of disease development and resolution, including activation and re-enforcement of innate immunity, downregulation of pro-inflammatory transcription factors, and restoration of anatomy and function. By the time critically ill patients necessitate vital organ support for survival, they have reached near exhaustion or exhaustion of neuroendocrine homeostatic compensation, cell bio-energetic and adaptation functions, and reserves of vital micronutrients. We review how critical illness-related corticosteroid insufficiency, mitochondrial dysfunction/damage, and hypovitaminosis collectively interact to accelerate an anti-homeostatic active process of natural selection. Importantly, the allostatic overload imposed by these homeostatic corrections impacts negatively on both acute and long-term morbidity and mortality. Since the bioenergetic and metabolic reserves to support homeostatic corrections are time-limited, early interventions should be directed at increasing GRα and mitochondria number and function. Present understanding of the activated GC-GRα's role in immunomodulation and disease resolution should be taken into account when re-evaluating how to administer glucocorticoid treatment and co-interventions to improve cellular responsiveness. The activated GRα interdependence with functional mitochondria and three vitamin reserves (B1, C, and D) provides a rationale for co-interventions that include prolonged glucocorticoid treatment in association with rapid correction of hypovitaminosis.

Older Sepsis Survivors Suffer Persistent Disability Burden and Poor Long-Term Survival

OBJECTIVES

Sepsis has been called a "disease of the elderly," and as in-hospital mortality has decreased, more sepsis survivors are progressing into poorly characterized long-term outcomes. The purpose of this study was to describe the current epidemiology of sepsis in older adults compared with middle-aged and young adults.

DESIGN

Prospective longitudinal study with young (≤45 years), middle-aged (46-64 years), and older (≥65 years) patient groups.

SETTING

University tertiary medical center.

PARTICIPANTS

A total of 328 adult surgical intensive care unit (ICU) sepsis patients.

MEASUREMENTS

Patients were characterized by (1) baseline demographics and predisposition, (2) septic event, (3) hospital outcomes and discharge disposition, (4) 12-month mortality, and (5) Zubrod Performance Status, physical function (Short Physical Performance Battery and handgrip strength), and cognitive function (Hopkins Verbal Learning Test, Controlled Oral Word Association, and Mini-Mental Status Examination) at 3-, 6-, and 12-month follow-up. Loss to follow-up was due to death (in 68), consent withdrawal (in 32), and illness and scheduling difficulties: month 3 (in 51), month 6 (in 29), and month 12 (in 20).

RESULTS

Compared with young and middle-aged patients, older patients had (1) significantly more comorbidities at presentation (eg, chronic renal disease 6% vs 12% vs 21%), intra-abdominal infections (14% vs 25% vs 37%), septic shock (12% vs 25% vs 36%), and organ dysfunctions; (2) higher 30-day mortality (6% vs 4% vs 17%) and fewer ICU-free days (median = 25 vs 23 vs 20); (3) more progression into chronic critical illness (22% vs 34% vs 42%) with higher poor disposition discharge to non-home destinations (19% vs 40% vs 62%); (4) worse 12-month mortality (11% vs 14% vs 33%); and (5) poorer Zubrod Performance Status and objectively measured physical and cognitive functions with only slight improvement over 12-month follow-up.

CONCLUSION

Compared with younger patients, older sepsis survivors suffer both a higher persistent disability burden and 12-month mortality.

C-reactive protein and albumin kinetics after antibiotic therapy in community-acquired bloodstream infection

OBJECTIVES

We assessed C-reactive protein (CRP) and plasma albumin (PA) kinetics to evaluate community-acquired bloodstream infection (CA-BSI) patients' 1-year outcomes.

METHODS

Population-based study, with CRP and PA measurements on day 1 (D1) and D4. Relative CRP variations in relation to D1 CRP value were evaluated (CRP-ratio). Patients were classified as fast response, slow response, non-response, and biphasic response.

RESULTS

A total of 935 patients were included. At D4, the CRP-ratio was lower in survivors on D365 in comparison with D4-D30 non-survivors and D30-D365 non-survivors (p<0.001). In comparison with fast response patients, non-response and biphasic response patients had 2.74 and 5.29 increased risk, respectively, of death in D4-D30 and 2.77 and 3.16 increased risk, respectively, of death in D31-D365. PA levels remained roughly unchanged from D1-D4, but lower D1 PA predicted higher short and long-term mortality (p<0.001). The discriminative performance of the CRP-ratio and D1 PA to identify patients with poor short and long-term mortality after adjustments was acceptable (AUROC=0.79).

CONCLUSIONS

Serial CRP measurements at D1 and D4 after CA-BSI is clinically useful to identify patients with poor outcome. Individual patterns of CRP-ratio response with PA at D1 further refine our ability of predicting short or long-term mortality.

Rate and risk factors for rehospitalisation in sepsis survivors: systematic review and meta-analysis

PURPOSE

Sepsis survivors have a higher risk of rehospitalisation and of long-term mortality. We assessed the rate, diagnosis, and independent predictors for rehospitalisation in adult sepsis survivors.

METHODS

We searched for non-randomized studies and randomized clinical trials in MEDLINE, Cochrane Library, Web of Science, and EMBASE (OVID interface, 1992-October 2019). The search strategy used controlled vocabulary terms and text words for sepsis and hospital readmission, limited to humans, and English language. Two authors independently selected studies and extracted data using predefined criteria and data extraction forms.

RESULTS

The literature search identified 12,544 records. Among 56 studies (36 full and 20 conference abstracts) that met our inclusion criteria, all were non-randomised studies. Studies most often report 30-day rehospitalisation rate (mean 21.4%, 95% confidence interval [CI] 17.6-25.4%; N = 36 studies reporting 6,729,617 patients). The mean (95%CI) rehospitalisation rates increased from 9.3% (8.3-10.3%) by 7 days to 39.0% (22.0-59.4%) by 365 days. Infection was the most common rehospitalisation diagnosis. Risk factors that increased the rehospitalisation risk in sepsis survivors were generic characteristics such as older age, male, comorbidities, non-elective admissions, hospitalisation prior to index sepsis admission, and sepsis characteristics such as infection and illness severity, with hospital characteristics showing inconsistent associations. The overall certainty of evidence was moderate for rehospitalisation rates and low for risk factors.

CONCLUSIONS

Rehospitalisation events are common in sepsis survivors, with one in five rehospitalisation events occurring within 30 days of hospital discharge following an index sepsis admission. The generic and sepsis-specific characteristics at index sepsis admission are commonly reported risk factors for rehospitalisation.

REGISTRATION

PROSPERO CRD 42016039257, registered on 14-06-2016.

Risk Factors for Long-term Mortality and Patterns of End-of-Life Care Among Medicare Sepsis Survivors Discharged to Home Health Care

IMPORTANCE

Despite a growing recognition of the increased mortality risk among sepsis survivors, little is known about the patterns of end-of-life care among this population.

OBJECTIVE

To describe patterns of end-of-life care among a national sample of sepsis survivors and identify factors associated with long-term mortality risk and hospice use.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study assessed sepsis survivors who were Medicare fee-for-service beneficiaries discharged to home health care using national Medicare administrative, claims, and home health assessment data from 2013 to 2014. The initial and final primary analyses were conducted in July 2017 and from July to August 2019, respectively.

EXPOSURES

Sepsis hospital discharge and 1 or more home health assessments within 1 week.

MAIN OUTCOMES AND MEASURES

Outcomes were 1-year mortality among all sepsis survivors and hospitalization in the last 30 days of life, death in an acute care hospital, and hospice use among decedents. Multivariate logistic regression was used to identify factors associated with 1-year mortality and hospice use.

RESULTS

Among 87 581 sepsis survivors who were Medicare fee-for-service beneficiaries discharged to home health care, 49 323 (56.3%) were aged 75 years or older, 69 499 (79.4%) were non-Hispanic white, and 48 472 (55.3%) were female. Among the total survivors, 24 423 (27.9%) people died within 1 year of discharge, with a median (interquartile range) survival time of 119 (51-220) days. Among these decedents, 16 684 (68.2%) were hospitalized in the last 30 days of life, 6560 (26.8%) died in an acute care hospital, and 12 573 (51.4%) were enrolled in hospice, with 5729 (45.6%) using hospice for 7 or fewer days. Several factors were associated with 1-year mortality, including a cancer diagnosis (odds ratio [OR], 3.66; 95% CI, 3.50-3.83; P < .001), multiple dependencies of activities of daily living or instrumental activities of daily living (OR, 2.80; 95% CI, 2.57-3.05; P < .001), and an overall poor health status (OR, 2.21; 95% CI, 2.01-2.44; P < .001) documented on home health assessment. Among the decedents, cancer was associated with hospice use (OR, 2.25; 95% CI, 2.11-2.41; P < .001), patients aged 85 years or older (OR, 1.49; 95% CI, 1.37-1.61; P < .001), and living in an assisted living setting (OR, 1.93; 95% CI, 1.69-2.19; P < .001).

CONCLUSIONS AND RELEVANCE

The findings of this study suggest that death within 1 year after sepsis discharge may be common among Medicare beneficiaries discharged to home health care. Although 1 in 2 decedents used hospice, aggressive care near the end of life and late hospice referral were common. Readily identifiable risk factors suggest opportunities to target efforts to improve palliative and end-of-life care among high-risk sepsis survivors.