Pathomechanisms of Non-Traumatic Acute Brain Injury in Critically Ill Patients

The possible role of gut microbiota dysbiosis in the pathophysiology of delirium in older persons

Delirium is a clinical syndrome characterized by an acute change in attention, awareness and cognition with fluctuating course, frequently observed in older patients during hospitalization for acute medical illness or after surgery. Its pathogenesis is multifactorial and still not completely understood, but there is general consensus on the fact that it results from the interaction between an underlying predisposition, such as neurodegenerative diseases, and an acute stressor acting as a trigger, such as infection or anesthesia. Alterations in brain insulin sensitivity and metabolic function, increased blood-brain barrier permeability, neurotransmitter imbalances, abnormal microglial activation and neuroinflammation have all been involved in the pathophysiology of delirium. Interestingly, all these mechanisms can be regulated by the gut microbiota, as demonstrated in experimental studies investigating the microbiota-gut-brain axis in dementia. Aging is also associated with profound changes in gut microbiota composition and functions, which can influence several aspects of disease pathophysiology in the host. This review provides an overview of the emerging evidence linking age-related gut microbiota dysbiosis with delirium, opening new perspectives for the microbiota as a possible target of interventions aimed at delirium prevention and treatment.

Cytokine profiles in intensive care unit delirium

Background

Neuroinflammation causing disruption of the blood-brain barrier and immune cell extravasation into the brain parenchyma may cause delirium; however, knowledge of the exact pathophysiologic mechanism remains incomplete. The purpose of our study was to determine whether cytokine profiles differ depending on whether delirium occurs in the setting of sepsis, coronavirus disease 2019 (COVID-19), or recent surgery.

Methods

This prospective observational cohort study involved 119 critically ill patients admitted to a multidisciplinary intensive care unit (ICU) during 2019 and 2020. Delirium was identified using the validated confusion assessment method for the ICU. Multiple delirium risk factors were collected daily including clinical characteristics, hospital course, lab values, vital signs, surgical exposure, drug exposure, and COVID-19 characteristics. Serums samples were collected within 12 hours of ICU admission and cytokine levels were measured.

Results:

The following proinflammatory cytokines were elevated in our delirium population: tumor necrosis factor (TNF)-α, interleukin (IL)-6, IL-18, C-C motif ligand (CCL) 2, CCL3, C-X-C motif chemokine ligand (CXCL)1, CXCL10, IL-8, IL-1 receptor antagonist, and IL-10. Analysis of relative cytokine levels in those patients that developed delirium in the setting of sepsis, COVID-19, and recent surgery showed elevations of CCL2, CXCL10, and TNF-α in both the sepsis and COVID-19 group in comparison to the postsurgical population. In the postsurgical group, granulocyte colony-stimulating factor was elevated and CXCL10 was decreased relative to the opposing groups.

Conclusions

We identify several cytokines and precipitating factors known to be associated with delirium. However, our study suggests that the cytokine profile associated with delirium is variable and contingent upon delirium precipitating factors.

Potential Usefulness of Blood Urea Nitrogen to Creatinine Ratio in the Prediction and Early Detection of Delirium Motor Subtype in the Intensive Care Unit

Prediction and early detection of delirium can improve patient outcomes. A high blood urea nitrogen to creatinine ratio (BCR), which reflects dehydration, has been reported as a risk factor for delirium. Additionally, BCR represents skeletal muscle loss in intensive care unit (ICU) patients, which can have critical implications for clinical outcomes. We investigated whether BCR could be used to predict the occurrence and motor subtype of delirium in ICU patients through a retrospective cohort study that included 7167 patients (50 years or older) admitted to the ICU. Patients were assessed daily using the Richmond Agitation-Sedation Scale and the Confusion Assessment Method for ICU and categorized according to the delirium subtype. Participants were split into 10 groups according to BCR at ICU admission and the prevalence of each delirium subtype was compared. Multivariable logistic regression was then used for analysis. A higher BCR at ICU admission was associated with the development of hypoactive delirium. Moreover, BCR > 24.9 was associated with higher rates of hypoactive delirium. Our findings showed that a high BCR at ICU admission was associated with the development of hypoactive delirium, which suggested that BCR could be a potential biomarker for hypoactive delirium in ICU patients.

The future of intensive care: delirium should no longer be an issue

In the ideal intensive care unit (ICU) of the future, all patients are free from delirium, a syndrome of brain dysfunction frequently observed in critical illness and associated with worse ICU-related outcomes and long-term cognitive impairment. Although screening for delirium requires limited time and effort, this devastating disorder remains underestimated during routine ICU care. The COVID-19 pandemic brought a catastrophic reduction in delirium monitoring, prevention, and patient care due to organizational issues, lack of personnel, increased use of benzodiazepines and restricted family visitation. These limitations led to increases in delirium incidence, a situation that should never be repeated. Good sedation practices should be complemented by novel ICU design and connectivity, which will facilitate non-pharmacological sedation, anxiolysis and comfort that can be supplemented by balanced pharmacological interventions when necessary. Improvements in the ICU sound, light control, floor planning, and room arrangement can facilitate a healing environment that minimizes stressors and aids delirium prevention and management. The fundamental prerequisite to realize the delirium-free ICU, is an awake non-sedated, pain-free comfortable patient whose management follows the A to F (A-F) bundle. Moreover, the bundle should be expanded with three additional letters, incorporating humanitarian care: gaining (G) insight into patient needs, delivering holistic care with a 'home-like' (H) environment, and redefining ICU architectural design (I). Above all, the delirium-free world relies upon people, with personal challenges for critical care teams to optimize design, environmental factors, management, time spent with the patient and family and to humanize ICU care.

Intensive care unit delirium in patients with severe COVID-19: A prospective observational cohort study

Background:

Delirium is common in patients with severe coronavirus disease-19 (COVID-19). The purpose of our study was to determine whether severe COVID-19 is an independent risk factor for the development of delirium in patients treated in the intensive care unit (ICU).

Methods:

This prospective observational cohort study involved 162 critically ill patients admitted to a multidisciplinary ICU during 2019 and 2020. A validated screening tool was used to diagnose delirium. Multiple delirium risk factors were collected daily including clinical characteristics, hospital course, lab values, vital signs, surgical exposure, drug exposure, and COVID-19 characteristics. After univariate analysis, a multivariate logistic regression analysis was performed to determine independent risk factors associated with the development of delirium.

Results:

In our study population, 50 (31%) patients developed delirium. A total of 39 (24.1%) tested positive for COVID-19. Initial analysis showed COVID-19 to be more prevalent in those patients that developed delirium (40% vs. 17%; P = 0.003). Multivariate analysis showed opioid use (odds ratio [OR]: 24 [95% confidence intervals (CI): 16–27]; P ≤ 0.001), benzodiazepine use (OR: 23 [95% CI: 16–63] P = 0.001), and estimated mortality based on acute physiology and chronic health evaluation IV score (OR: 1.04 [95% CI: 1.01–1.07] P = 0.002) to be independently associated with delirium development. COVID-19 (OR: 1.44 [95% CI: 0.13–10.6]; P = 0.7) was not found to be associated with delirium.

Conclusion:

Delirium is prevalent in critically ill patients admitted to the ICU, including those with COVID-19. However, after adjustment for important covariates, we found in this cohort that COVID-19 was not an independent risk factor for delirium.

Postoperative delirium and neurocognitive disorders

PURPOSE OF REVIEW

Postoperative neurocognitive disorders (NCD) are significant causes of morbidity and mortality. In this paper, we will review our understanding and potential management of postoperative NCD.

RECENT FINDINGS

Postoperative delirium, delayed neurocognitive recovery and postoperative cognitive dysfunction (POCD) are recognized as a part of the continuous spectrum of postoperative NCD. Although the pathophysiology is still poorly understood, there is renewed focus on improving neurocognitive outcomes of aging surgical population. Novel methods of neurocognitive screening are developed and research in the prevention and management of NCD has gained traction.

SUMMARY

A spectrum of NCD exists in surgical patients ranging from postoperative delirium, delayed neurocognitive recovery, and POCD. Identification of patients at-risk for developing NCD can help target appropriate perioperative intervention. Also, specialized care teams and the implementation of standardized protocols are crucial for the successful management perioperative NCD. Finally, large, randomized, multicenter studies are needed to confirm benefits of preventive and treatment strategies.

Efficacy of Bifidobacterium Triple Viable Enteric-Coated Capsules Combined with Enteral Nutrition on Patients with Chronic Critical Illness and Influence on Immune and Coagulation Function

OBJECTIVE

To investigate the efficacy of enteric-coated Bifidobacterium triple viable capsules combined with enteral nutrition in the treatment of patients with chronic critical illness (CCI) and their effects on the immune and coagulation function of patients.

METHODS

106 CCI patients admitted to the intensive care unit of our hospital from December 2018 to March 2020 were selected as the research objects, and they were randomly divided into the control group (n = 53) and the observation group (n = 53). The control group was given symptomatic treatment, etiological treatment, clinical nursing, enteral nutrition support, and other conventional treatment methods according to the patient's condition. On this basis, the observation group was treated with enteric-coated Bifidobacterium triple viable capsules, and both groups were treated for 14 days. All patients were followed up for 3 months after treatment, and their death/cure prognosis was recorded. The acute physiological and chronic health (APACHE II) scoring system was used to evaluate the acute physiological and chronic health status of the two groups before and after treatment, and the organs of the patients were scored with sepsis-related organ failure assessment (SOFA) score. T lymphocyte subsets (CD3+, CD4+, CD8+, and CD4+/CD8+), prothrombin time (PT), activated partial thrombin time (APTT), fibrinogen (FIB), and D-dimer (DD) were measured before and after treatment.

RESULTS

The cure rate of the observation group was slightly higher than that of the control group, and the mortality rate was slightly lower than that of the control group, but the difference was not statistically significant (P < 0.05). After treatment, the APACHE II and SOFA scores of the two groups were lower than before treatment, and the APACHE II and SOFA scores of the observation group were lower than those of the control group, and the differences were both statistically significant (P < 0.05). After treatment, the levels of CD3+, CD4+, and CD4+/CD8+ in the two groups were higher than those before treatment, and the levels of CD8+ were lower than before treatment. The CD3+, CD4+, and CD4+/CD8+ levels of the observation group were higher than those of the control group, and the CD8+ levels were lower than the control group, and the differences were both statistically significant (P < 0.05). After treatment, the PT and APTT levels of the two groups of patients were higher than those before treatment, and the levels of FIB and DD were lower than those before treatment. The PT and APTT levels of the observation group were higher than those of the control group, and the FIB and DD levels were lower than those of the control group, and the differences were both statistically significant (P < 0.05).

CONCLUSION

The combination of enteric-coated Bifidobacterium triple viable capsules and enteral nutrition for CCI has high cure rate, which can not only improve the patients' physiological health status and organ dysfunction but also effectively improve the patients' immune and coagulation function, which is worthy of promotion.

Neutrophil-to-Lymphocyte Ratios and Infections after Traumatic Brain Injury: Associations with Hospital Resource Utilization and Long-Term Outcome

Traumatic brain injury (TBI) induces immune dysfunction that can be captured clinically by an increase in the neutrophil-to-lymphocyte ratio (NLR). However, few studies have characterized the temporal dynamics of NLR post-TBI and its relationship with hospital-acquired infections (HAI), resource utilization, or outcome. We assessed NLR and HAI over the first 21 days post-injury in adults with moderate-to-severe TBI (n = 196) using group-based trajectory (TRAJ), changepoint, and mixed-effects multivariable regression analysis to characterize temporal dynamics. We identified two groups with unique NLR profiles: a high (n = 67) versus a low (n = 129) TRAJ group. High NLR TRAJ had higher rates (76.12% vs. 55.04%, p = 0.004) and earlier time to infection (p = 0.003). In changepoint-derived day 0–5 and 6–20 epochs, low lymphocyte TRAJ, early in recovery, resulted in more frequent HAIs (p = 0.042), subsequently increasing later NLR levels (p ≤ 0.0001). Both high NLR TRAJ and HAIs increased hospital length of stay (LOS) and days on ventilation (p ≤ 0.05 all), while only high NLR TRAJ significantly increased odds of unfavorable six-month outcome as measured by the Glasgow Outcome Scale (GOS) (p = 0.046) in multivariable regression. These findings provide insight into the temporal dynamics and interrelatedness of immune factors which collectively impact susceptibility to infection and greater hospital resource utilization, as well as influence recovery.

Theory: Treatments for Prolonged ICU Patients May Provide New Therapeutic Avenues for Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS)

We here provide an overview of treatment trials for prolonged intensive care unit (ICU) patients and theorize about their relevance for potential treatment of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). Specifically, these treatment trials generally target: (a) the correction of suppressed endocrine axes, notably through a "reactivation" of the pituitary gland's pulsatile secretion of tropic hormones, or (b) the interruption of the "vicious circle" between inflammation, oxidative and nitrosative stress (O&NS), and low thyroid hormone function. There are significant parallels in the treatment trials for prolonged critical illness and ME/CFS; this is consistent with the hypothesis of an overlap in the mechanisms that prevent recovery in both conditions. Early successes in the simultaneous reactivation of pulsatile pituitary secretions in ICU patients-and the resulting positive metabolic effects-could indicate an avenue for treating ME/CFS. The therapeutic effects of thyroid hormones-including in mitigating O&NS and inflammation and in stimulating the adreno-cortical axis-also merit further studies. Collaborative research projects should further investigate the lessons from treatment trials for prolonged critical illness for solving ME/CFS.