In-depth characterization of the neuroinflammatory reaction induced by peripheral surgery in an animal model

Update of the European Society of Anaesthesiology and Intensive Care Medicine evidence-based and consensus-based guideline on postoperative delirium in adult patients

Postoperative delirium (POD) remains a common, dangerous and resource-consuming adverse event but is often preventable. The whole peri-operative team can play a key role in its management. This update to the 2017 ESAIC Guideline on the prevention of POD is evidence-based and consensus-based and considers the literature between 01 April 2015, and 28 February 2022. The search terms of the broad literature search were identical to those used in the first version of the guideline published in 2017. POD was defined in accordance with the DSM-5 criteria. POD had to be measured with a validated POD screening tool, at least once per day for at least 3 days starting in the recovery room or postanaesthesia care unit on the day of surgery or, at latest, on postoperative day 1. Recent literature confirmed the pathogenic role of surgery-induced inflammation, and this concept reinforces the positive role of multicomponent strategies aimed to reduce the surgical stress response. Although some putative precipitating risk factors are not modifiable (length of surgery, surgical site), others (such as depth of anaesthesia, appropriate analgesia and haemodynamic stability) are under the control of the anaesthesiologists. Multicomponent preoperative, intra-operative and postoperative preventive measures showed potential to reduce the incidence and duration of POD, confirming the pivotal role of a comprehensive and team-based approach to improve patients' clinical and functional status.

Association between cholinesterase activity and critical illness brain dysfunction

BACKGROUND

Delirium is a frequent manifestation of acute brain dysfunction and is associated with cognitive impairment. The hypothesized mechanism of brain dysfunction during critical illness is centered on neuroinflammation, regulated in part by the cholinergic system. Point-of-care serum cholinesterase enzyme activity measurements serve as a real-time index of cholinergic activity. We hypothesized that cholinesterase activity during critical illness would be associated with delirium in the intensive care unit (ICU) and cognitive impairment after discharge.

METHODS

We enrolled adults with respiratory failure and/or shock and measured plasma acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activity on days 1, 3, 5, and 7 after enrollment. AChE values were also normalized per gram of hemoglobin (AChE/Hgb). We assessed for coma and delirium twice daily using the Richmond Agitation Sedation Scale and the Confusion Assessment Method for the ICU to evaluate daily mental status (delirium, coma, normal) and days alive without delirium or coma. Cognitive impairment, disability, and health-related quality of life were assessed at up to 6 months post-discharge. We used multivariable regression to determine whether AChE, AChE/Hgb, and BChE activity were associated with outcomes after adjusting for relevant covariates.

RESULTS

We included 272 critically ill patients who were a median (IQR) age 56 (39-67) years and had a median Sequential Organ Failure Assessment score at enrollment of 8 (5-11). Higher daily AChE levels were associated with increased odds of being delirious versus normal mental status on the same day (Odds Ratio [95% Confidence Interval] 1.64 [1.11, 2.43]; P = 0.045). AChE/Hgb and BChE activity levels were not associated with delirious mental status. Lower enrollment BChE was associated with fewer days alive without delirium or coma (P = 0.048). AChE, AChE/Hgb, and BChE levels were not significantly associated with cognitive impairment, disability, or quality of life after discharge.

CONCLUSION

Cholinesterase activity during critical illness is associated with delirium but not with outcomes after discharge, findings that may reflect mechanisms of acute brain organ dysfunction.

TRIAL REGISTRATION

NCT03098472. Registered 31 March 2017.

Goal-directed therapy based on rScO2 monitoring in elderly patients with one-lung ventilation: a randomized trial on perioperative inflammation and postoperative delirium

Background

The incidence of postoperative delirium (POD) is high in elderly patients with one-lung ventilation, which is mostly related to the impairment of cerebral oxygen supply/demand balance during operation. (Surgical) stress can cause changes to normal physiological function and increase oxygen supply to the brain. When cerebral oxygen supply/demand is unbalanced, other organs may have already suffered from hypoperfusion or even hypoxic damages leading to increased release of inflammatory factors. Regional saturation of cerebral oxygenation (rScO₂) monitoring can noninvasively monitor the variation of regional cerebral oxygen supply/demand balance in real time, and it has a good correlation with the occurrence of POD. S-100β is one of the markers commonly used to predict and diagnose POD, and lactate is one of the important indicators for the quality of tissue perfusion. The study explores whether the goal-directed therapy based on rScO₂ monitoring can reduce perioperative inflammatory factor levels and POD incidence in elderly patients with one-lung ventilation and improve tissue perfusion.

Methods

The study is registered on Chinese Clinical Trial Registry (ChiCTR2100054888). A total of 159 patients scheduled for thoracoscopic lobectomy under general anesthesia were divided into the control group (n = 81) and the goal-directed therapy group (GDT group, n = 78). On the basis of the conventional management in the control group, the GDT group applied goal-directed rScO₂ monitoring to maintain rScO₂ at ±20% baseline level during one-lung ventilation. The levels of interleukin-1β, interleukin-6, tumor necrosis factor-α, and lactate; the intensity of postoperative pain; and the incidence of POD before anesthesia (T1), at the end of operation (T2), on day 1 after operation (T3), on day 3 after operation (T4), and on day 7 after operation or before discharge (T5) were compared respectively between the two groups.

Results

The incidence of POD at T3 and the awakening time in the GDT group were lower than those in the control group (P < 0.05). During T2 to T4, the levels of inflammatory factors and lactate concentration in the control group were higher than those in the GDT group (P < 0.05). During T3 to T4, the levels of C-reactive protein and lactate in the control group were higher than those in the GDT group (P < 0.05). During T2 to T3, the levels of S-100β in the control group were higher than those in the GDT group (P < 0.05). The levels of inflammatory factors and lactate concentration in both groups during T2 to T4 were higher than those at T1 and T5 (P < 0.05), and there was no statistical difference at T1 versus T5 (P > 0.05). There was no significant difference in postoperative pain intensity, the incidence of agitation during awakening, and postoperative hospital stays between the two groups.

Conclusion

Goal-directed therapy based on rScO₂ monitoring can reduce perioperative inflammatory factor levels, postoperative delirium incidence, and postoperative awakening time and improve tissue perfusion in elderly patients with one-lung ventilation.

Trial registration

The Chinese Clinical Trial Registry ChiCTR2100054888. Registered on 28 December 2021

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-022-06654-6.

Physostigmine for prevention of postoperative delirium and long-term cognitive dysfunction in liver surgery: A double-blinded randomised controlled trial

BACKGROUND

Anecdotally, cholinergic stimulation has been used to treat delirium and reduce cognitive dysfunction.

OBJECTIVE

The aim of this investigation was to evaluate whether physostigmine reduced the incidence of postoperative delirium (POD) and postoperative cognitive dysfunction (POCD) in patients undergoing liver resection.

DESIGN

This was a double-blind, randomised, placebo-controlled trial. Between 11 August 2009 and 3 March 2016, patients were recruited at the Charité - Universitätsmedizin Berlin in Germany. Follow-ups took place at 1 week (T1), 90 days (T2) and 365 days (T3) after surgery.

SETTING

This single-centre study was conducted at an academic medical centre.

PARTICIPANTS

In total, 261 participants aged at least 18 years scheduled for elective liver surgery were randomised. The protocol also included 45 non-surgical matched controls to provide normative data for POCD and neurocognitive deficit (NCD).

INTERVENTION

Participants were allocated to receive either intravenous physostigmine, as a bolus of 0.02 mg kg-1 body weight followed by 0.01 mg kg-1 body weight per hour (n = 130), or placebo (n = 131), for 24 h after induction of anaesthesia.

MAIN OUTCOMES AND MEASURES

Primary outcomes were POD, assessed using the Diagnostic and Statistical Manual of Mental Disorders (DSM-4-TR) twice daily up to day 7 after surgery, and POCD assessed via the CANTAB neuropsychological test battery, and two paper pencil tests on the day before surgery, and on postoperative days 7, 90 and 365.

RESULTS

In total, 261 patients were randomised, 130 to the physostigmine and 131 to the placebo group. The incidence of POD did not differ significantly between the physostigmine and placebo groups (20 versus 15%; P = 0.334). Preoperative cognitive impairment and POCD frequencies did not differ significantly between the physostigmine and placebo groups at any time. Lower mortality rates were found in the physostigmine group compared with placebo at 3 months [2% (95% confidence interval (CI), 0 to 4) versus 11% (95% CI, 6 to 16), P = 0.002], and 6 months [7% (95% CI, 3 to 12) versus 16% (95% CI, 10 to 23), P = 0.012] after surgery.

CONCLUSION

Physostigmine had no effect on POD and POCD when applied after induction of anaesthesia up to 24 h.

TRIAL REGISTRATION

DOI 10.1186/ISRCTN18978802, EudraCT 2008-007237-47, Ethics approval ZS EK 11 618/08 (15 January 2009).

Proinflammatory Extracellular Vesicle-Mediated Signaling Contributes to the Induction of Neuroinflammation in Animal Models of Endotoxemia and Peripheral Surgical Stress

Peripheral inflammation induced by endotoxemia or surgical stress induces neuroinflammation thereby causing neurological symptoms ranging from sickness behavior to delirium. Thus, proinflammatory signaling must be operative between the periphery and the central nervous system (CNS). In the present study, we tested whether nanometer-sized extracellular vesicles (EVs) that were produced during the peripheral inflammatory process have the capacity to induce neuroinflammation. Conditions of endotoxemia or surgical intervention were simulated in rats by lipopolysaccharide (LPS) injection or partial hepatectomy (HpX). EVs were concentrated from these animals and tested for their proinflammatory action (I) in a microglial cell line and (II) by intracerebroventricular and (III) by intravenous injections into healthy rats. EVs from both conditions induced the secretion of cytokines from the glial cell line. Intracerebroventricular injection of the EVs caused the release of inflammatory cytokines to the cerebrospinal fluid indicating their pro-neuroinflammatory capacity. Finally, proinflammatory EVs were shown to pass the blood-brain barrier and induce neuroinflammation after their intravenous injection. Based on these data, we suggest that EV-associated proinflammatory signaling contributes to the induction of neuroinflammation in endotoxemia and peripheral surgical stress. Preliminary results suggest that peripheral cholinergic signals might be involved in the control of proinflammatory EV-mediated signaling from the periphery to the brain.

The Potential Protective Effect of Mesencephalic Astrocyte-Derived Neurotrophic Factor on Post-Operative Delirium via Inhibiting Inflammation and Microglia Activation

Background

The increased inflammation is closely correlated with post-operative delirium (POD). Mesencephalic astrocyte-derived neurotrophic factor (MANF) shows protective effect on inflammatory diseases. However, the relationship between MANF and POD is still undefined. This study aimed to explore the potential effect of MANF on POD.

Methods

Pre- and post-operative levels of MANF and inflammatory cytokines were measured in serum from POD and non-POD patients by ELISA, as well as endogenous MANF in serum from healthy individuals with different ages. Endogenous MANF in mice brain from different ages was also measured. Abdominal surgery was performed for POD mice model. POD-like behavior changes in mice were evaluated using buried food test, open field test and Y maze test.

Results

Endogenous MANF was decreased in age-dependent manner in both humans and mice. The pre-operative level of MANF in serum from POD patients was lower compared with that in non-POD patients (p=0.016). MANF increase in serum after surgery was less in POD patients than that in non-POD patients (p<0.001). In mice, recombinant human MANF reversed the surgery-induced elongation of latency to eat food, increase in latency to center and increase in time in center in open field test, and also increase in duration in novel arm in Y maze test. In addition, MANF inhibited surgery-induced inflammation, microglial activation and M1 polarization in mice.

Conclusion

The relative low MANF level may contribute to POD in the elderly. MANF has a protective role against POD-like behavior changes in mice.

Immunomodulatory lipid mediator profiling of cerebrospinal fluid following surgery in older adults

Arachidonic acid (AA), docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA) derived lipids play key roles in initiating and resolving inflammation. Neuro-inflammation is thought to play a causal role in perioperative neurocognitive disorders, yet the role of these lipids in the human central nervous system in such disorders is unclear. Here we used liquid chromatography–mass spectrometry to quantify AA, DHA, and EPA derived lipid levels in non-centrifuged cerebrospinal fluid (CSF), centrifuged CSF pellets, and centrifuged CSF supernatants of older adults obtained before, 24 h and 6 weeks after surgery. GAGE analysis was used to determine AA, DHA and EPA metabolite pathway changes over time. Lipid mediators derived from AA, DHA and EPA were detected in all sample types. Postoperative lipid mediator changes were not significant in non-centrifuged CSF (p > 0.05 for all three pathways). The AA metabolite pathway showed significant changes in centrifuged CSF pellets and supernatants from before to 24 h after surgery (p = 0.0000247, p = 0.0155 respectively), from before to 6 weeks after surgery (p = 0.0000497, p = 0.0155, respectively), and from 24 h to 6 weeks after surgery (p = 0.0000499, p = 0.00363, respectively). These findings indicate that AA, DHA, and EPA derived lipids are detectable in human CSF, and the AA metabolite pathway shows postoperative changes in centrifuged CSF pellets and supernatants.

Surgery, neuroinflammation and cognitive impairment

Trauma experienced during surgery can contribute to the development of a systemic inflammatory response that can cause multi-organ dysfunction or even failure. Post-surgical neuroinflammation is a documented phenomenon that results in synaptic impairment, neuronal dysfunction and death, and impaired neurogenesis. Various pro-inflammatory cytokines, such as TNFα, maintain a state of chronic neuroinflammation, manifesting as post-operative cognitive dysfunction and post-operative delirium. Furthermore, elderly patients with post-operative cognitive dysfunction or delirium are three times more likely to experience permanent cognitive impairment or dementia. We conducted a narrative review, considering evidence extracted from various databases including Pubmed, MEDLINE and EMBASE, as well as journals and book reference lists. We found that further pre-clinical and well-powered clinical studies are required to delineate the precise pathogenesis of post-operative delirium and cognitive dysfunction. Despite the burden of post-operative neurological sequelae, clinical studies investigating therapeutic agents, such as dexmedetomidine, ibuprofen and statins, have yielded conflicting results. In addition, evidence supporting novel therapeutic avenues, such as nicotinic and HMGB-1 targeting and remote ischaemic pre-conditioning, is limited and necessitates further investigation.