Severe sepsis in older adults

Prediction of prognosis in elderly patients with sepsis based on machine learning (random survival forest)

Background

Elderly patients with sepsis have many comorbidities, and the clinical reaction is not obvious. Thus, clinical treatment is difficult. We planned to use the laboratory test results and comorbidities of elderly patients with sepsis from a large-scale public database Medical Information Mart for Intensive Care (MIMIC) IV to build a random survival forest (RSF) model and to evaluate the model’s predictive value for these patients.

Methods

Clinical information of elderly patients with sepsis in MIMIC IV database was collected retrospectively. Machine learning (RSF) was used to select the top 30 variables in the training cohort to build the final RSF model. The model was compared with the traditional scoring systems SOFA, SAPSII, and APSIII. The performance of the model was evaluated by C index and calibration curve.

Results

A total of 6,503 patients were enrolled in the study. The top 30 important variables screened by RSF were used to construct the final RSF model. The new model provided a better C-index (0.731 in the validation cohort). The calibration curve described the agreement between the predicted probability of RSF model and the observed 30-day survival.

Conclusions

We constructed a prognostic model to predict a 30-day mortality risk in elderly patients with sepsis based on machine learning (RSF algorithm), and it proved superior to the traditional scoring systems. The risk factors affecting the patients were also ranked. In addition to the common risk factors of vasopressors, ventilator use, and urine output. Newly added factors such as RDW, type of ICU unit, malignant cancer, and metastatic solid tumor also significantly influence prognosis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12873-022-00582-z.

Long-term Renal Outcomes in Adults With Sepsis-Induced Acute Kidney Injury: A Systematic Review

BACKGROUND

Despite advances in medical technologies and intervention occurrences, acute kidney injury (AKI) incidence continues to rise. Early interventions after sepsis are essential to prevent AKI and its long-term consequences. Acute kidney injury is the leading cause of organ failure in sepsis; therefore, more research is needed on its long-term consequences and progression to kidney injury.

OBJECTIVES

The aim of this study was to review the state of the science on long-term renal outcomes after sepsis-induced AKI and long-term renal consequences.

METHODS

We identified research articles from PubMed and CINAHL databases using relevant key words for sepsis-induced AKI within 5 years delimited to full-text articles in English.

RESULTS

Among 1280 abstracts identified, we ultimately analyzed 12 full-text articles, identifying four common themes in the literature: (1) AKI determination criteria, (2) severity/prognosis-related factors, (3) time frame for long-term outcome measures, and (4) chronic kidney disease (CKD) and renal related exclusions. Researchers primarily used KDIGO (Kidney Disease: Improving Global Outcomes) guidelines to define AKI. All of these studies excluded patients with CKD. The range of time for long-term renal outcomes was 28 days to 3 years, with the majority being 1 year. Renal outcomes ranged from recovery to renal replacement therapy to death.

CONCLUSIONS

To better understand the long-term renal outcomes after sepsis-induced AKI, more consistent measures are needed across all studies regarding the time frame and specific renal outcomes. Because all of these articles excluded patients with CKD, a gap exists on long-term renal outcome in acute on CKD.

Early Recognition and Management of Sepsis in the Elderly: A Case Study

Sepsis is a life-threatening and debilitating sickness in the elderly. This case study explores the importance of adequate assessment of patients on their initial presentation to the emergency department, during hospitalization, and before discharge. The clinical evaluation, recognition, and management of sepsis continue to be essential for patient survival to prevent and decrease the mortality rate. Some changes go on in the elderly organ systems and can lead to delay in identifying and treatment implementation. The use of the Third International Consensus Definition for Sepsis and Septic Shock (Sepsis-3) to anticipate outcomes in septic patients and the use of the Survival Sepsis Campaign for treatment guidelines promptly to improve outcomes are crucial. This article aims to inform clinicians and nurses of the importance of early recognition of subtle signs and symptoms and the management of sepsis in the elderly.

Sepsis-induced selective loss of NMDA receptors modulates hippocampal neuropathology in surviving septic mice

Background

Sepsis-induced neuroinflammation plays an important role in sepsis-related brain dysfunction. However, the molecules that are targeted during neuroinflammation resulting from sepsis-induced brain dysfunction remain unclear. Herein, we tried to investigate the expression and roles of NMDA receptor subunits during sepsis-related brain dysfunction.

Methods

Sepsis was induced by cecal ligation and perforation (CLP) or by a single intraperitoneal injection of lipopolysaccharide (LPS, 8 mg/kg) in C57BL/6J mice. The NMDA receptor co-agonist D-serine was injected intraperitoneally for 3 days (500 mg/kg/day) to compensate for the loss of NMDA receptors. The behaviors of mice were tested in the Barnes maze and in the open field test. The mice were euthanized at the indicated time points. The brains were collected to detect the following: the levels of synaptophysin and NMDA receptor subunits GluN2A, GluN2B and GluN1 (by Western blot and RT-PCR); the number of CA1 neurons (by Nissl staining); neuronal activity (by p-CREB staining); neuroinflammation (by staining of Iba-1 and inflammatory factors IL-1β, TNF-α, NLRP3); and the levels of oxidative stress [by dihydroethidium (DHE)].

Results

Sepsis selectively decreased the protein and mRNA levels of GluN2A, GluN2B and GluN1 but not the levels of synaptophysin or the neuronal number in the hippocampus of mice in either of the classic CLP-induced or LPS-induced sepsis models during the first 7 days after sepsis. Intraperitoneal injection of D-serine obviously limited the lipopolysaccharide-induced changes, including the impairment of learning and memory, the loss of NMDA receptor subunits, robust neuroinflammation, the levels of ROS stress and the decrease of p-CREB in the hippocampus of mice.

Conclusion

These data suggest that the sepsis-induced selective loss of NMDA receptors modulates hippocampal neuropathology in the mice that survived sepsis, and the data show that NMDA receptors are potential targets for the improvement of brain dysfunction in sepsis survivors.

Role of TFEB Mediated Autophagy, Oxidative Stress, Inflammation, and Cell Death in Endotoxin Induced Myocardial Toxicity of Young and Aged Mice

Elderly patients are susceptible to sepsis. LPS induced myocardial injury is a widely used animal model to assess sepsis induced cardiac dysfunction. The age dependent mechanisms behind sepsis susceptibility were not studied. We analyzed age associated changes to cardiac function, cell death, inflammation, oxidative stress, and autophagy in LPS induced myocardial injury. Both young and aged C57BL/6 mice were used for LPS administration. The results demonstrated that LPS induced more cardiac injury (creatine kinase, lactate dehydrogenase, troponin I, and cardiac myosin-light chains 1), cardiac dysfunction (left ventricular inner dimension, LVID, and ejection fraction (EF)), cell death, inflammation, and oxidative stress in aged mice compared to young mice. However, a significant age dependent decline in autophagy was observed. Translocation of Transcription Factor EB (TFEB) to nucleus and formation of LC3-II were significantly reduced in LPS administered aged mice compared to young ones. In addition to that, downstream effector of TFEB, LAMP-1, was induced in response to LPS challenge in young mice. The present study newly demonstrates that TFEB mediated autophagy is crucial for protection against LPS induced myocardial injury particularly in aging senescent heart. Targeting this autophagy-oxidative stress-inflammation-cell death axis may provide a novel therapeutic strategy for cardioprotection in the elderly.