State of the clinical science of perioperative brain health: report from the American Society of Anesthesiologists Brain Health Initiative Summit 2018

Influencing factors and risk prediction model for emergence agitation after general anesthesia for primary liver cancer

BACKGROUND

General anesthesia is commonly used in the surgical management of gastrointestinal tumors; however, it can lead to emergence agitation (EA). EA is a common complication associated with general anesthesia, often characterized by behaviors, such as crying, struggling, and involuntary limb movements in patients. If treatment is delayed, there is a risk of incision cracking and bleeding, which can significantly affect surgical outcomes. Therefore, having a proper understanding of the factors influencing the occurrence of EA and implementing early preventive measures may reduce the incidence of agitation during the recovery phase from general anesthesia, which is beneficial for improving patient prognosis.

AIM

To analyze influencing factors and develop a risk prediction model for EA occurrence following general anesthesia for primary liver cancer.

METHODS

Retrospective analysis of clinical data from 200 patients who underwent hepatoma resection under general anesthesia at Wenzhou Central Hospital (January 2020 to December 2023) was conducted. Post-surgery, the Richmond Agitation-Sedation Scale was used to evaluate EA presence, noting EA incidence after general anesthesia. Patients were categorized by EA presence postoperatively, and the influencing factors were analyzed using logistic regression. A nomogram-based risk prediction model was constructed and evaluated for differentiation and fit using receiver operating characteristics and calibration curves.

RESULTS

EA occurred in 51 (25.5%) patients. Multivariate analysis identified advanced age, American Society of Anesthesiologists (ASA) grade III, indwelling catheter use, and postoperative pain as risk factors for EA (P < 0.05). Conversely, postoperative analgesia was a protective factor against EA (P < 0.05). The area under the curve of the nomogram was 0.972 [95% confidence interval (CI): 0.947-0.997] for the training set and 0.979 (95%CI: 0.951-1.000) for the test set. Hosmer-Lemeshow test showed a good fit (χ² = 5.483, P = 0.705), and calibration curves showed agreement between predicted and actual EA incidence.

CONCLUSION

Age, ASA grade, catheter use, postoperative pain, and analgesia significantly influence EA occurrence. A nomogram constructed using these factors demonstrates strong predictive accuracy.

The utility of remote cognitive screening tools in identifying cognitive impairment in older surgical patients: An observational cohort study

STUDY OBJECTIVES

To determine the prevalence of suspected cognitive impairment using the Centers for Disease Control and Prevention (CDC) cognitive question, Ascertain Dementia Eight-item Questionnaire (AD8), Modified Telephone Interview for Cognitive Status (TICS-M), and Telephone Montreal Cognitive Assessment (T-MoCA), the agreement between each tool beyond chance, and the risk factors associated with a positive screen.

DESIGN

Multicenter prospective study.

SETTING

Remote preoperative assessments.

PATIENTS

307 non-cardiac surgical patients aged ≥65 years.

MEASUREMENTS

Prevalence, Cohen's kappa (κ).

MAIN RESULTS

The T-MoCA detected the highest prevalence of suspected cognitive impairment (28%), followed by the AD8 (17%), CDC cognitive question (9%), and TICS-M (6%). The four screening tools showed poor agreement beyond chance with one another, with the CDC cognitive question and AD8 approaching the threshold for weak agreement (κ = 0.39). Depression was associated with screening positive on the CDC cognitive question (OR: 2.81; 95% CI: 1.04, 7.68). Obstructive sleep apnea (OSA) (OR: 3.10; 95% CI: 1.26, 7.71) and functional disability (OR: 3.74; 95% CI: 1.34, 11.11) were associated with a positive AD8 screen. Older age (OR: 1.56; 95% CI: 1.01, 2.41), male sex (OR: 3.08; 95% CI: 1.09, 9.40), and higher pain level (OR: 1.21; 95% CI: 1.01, 1.47) were associated with a positive TICS-M screen. Similarly, older age (OR: 1.33; 95% CI: 1.03, 1.73), male sex (OR: 2.02; 95% CI: 1.09, 3.83), and higher pain level (OR: 1.15; 95% CI: 1.02, 1.30) were associated with a positive T-MoCA screen.

CONCLUSIONS

The CDC cognitive question, AD8, TICS-M, and T-MoCA were easily implemented during preoperative assessment among older surgical patients. OSA, functional disability, and depression were associated with complaints on the CDC cognitive question and AD8. Older age, male sex, and higher pain level were associated with screening positive on the TICS-M and T-MoCA. Early remote cognitive screening may enhance risk stratification of vulnerable patients.

Summary of the Clinical Evidence for Non-Pharmacological Management of Postoperative Delirium in Adults: An Evidence Synthesis

Objective

To retrieve, evaluate, and summarise the clinical evidence for non-pharmacological interventions in adult postoperative delirium (POD), encompassing the preoperative, intraoperative, and postoperative phases.

Methods

The methods included conducting searches on UpToDate Clinical Consultants, the Scottish Intercollegiate Guidelines Network, the National Institute for Health and Care Excellence, the Registered Nurses' Association of Ontario, BMJ Best Practice, the Cochrane Library, Web of Science, PubMed, China National Knowledge Infrastructure, Wanfang, VIP, and the Chinese Biomedical Literature Service System. Clinical practice guidelines, clinical decision-making, evidence summaries, evidence synthesis, expert consensus, systematic reviews, and meta-analyses on non-pharmacological interventions for adult POD were examined, and the search period spanned between the establishment of each database and 30 October 2023.

Results

A total of 17 documents were included, comprising three guidelines, one expert consensus, one clinical decision-making article, four evidence summaries, three systematic reviews, and five meta-analyses. These documents primarily focused on the following three aspects: preoperative, intraoperative, and postoperative care. In total, 30 "best evidence" instances were compiled.

Conclusion

Considering the complexity and potential harm of adult POD, an accurate and timely evaluation of high-risk factors, alongside effective medical nursing strategies, is vital in its prevention and treatment. Non-pharmacological interventions remain the preferred choice for preventing and treating POD. Medical institutions should establish standardised processes for non-pharmacological intervention in adult POD, based on evidence-based medicine, to enhance the level of clinical care in this field.

Prevalence of neurocognitive disorders 5 years after elective orthopaedic surgery

BACKGROUND

Peri-operative neurocognitive disorders are one of the most common complications affecting older adults after anaesthesia and surgery. It is not clear how exposure to surgery and anaesthesia contributes to the prevalence of long-term neurocognitive disorders. This study aimed to report the prevalence of neurocognitive disorders, and explore pre-operative factors associated with neurocognitive disorders 5 years after elective orthopaedic surgery.

METHODS

A prospective, 5-year longitudinal, cohort study was performed recruiting patients (aged ≥ 60 y) undergoing elective orthopaedic surgery and a contemporaneous non-surgical control group. Neurocognitive disorder was evaluated and classified at baseline and 5-year review incorporating: self- and informant-reported cognition; functional participation; and performance on neuropsychological tests.

RESULTS

Recruitment at 5-year follow-up included 195 patients and 21 control participants. In the patient cohort the prevalence of neurocognitive disorder was 38.1% (n = 75), with 61 (30.1%) meeting the criteria for mild neurocognitive disorder and 14 (7.1%) for major neurocognitive disorder. At 5-year follow-up, 121 (61.4%) patients were classified with a neurocognitive disorder, with 88 (44.7%) characterised with mild neurocognitive disorder and 33 (16.8%) with major neurocognitive disorder. Age (odds ratio (95%CI) 1.07 (1.02-1.13); p = 0.01) and baseline cognitive impairment (odds ratio (95%CI) 2.1 (1.06-4.15); p = 0.03) were significant predictors of neurocognitive disorder 5 years after surgery.

CONCLUSION

More than half of older adult patients had some form of neurocognitive disorder 5 years after elective orthopaedic surgery. Surgery and anaesthesia may be associated with the trajectory of cognitive decline in at-risk older adults, including those with pre-operative cognitive impairment. Cognitive screening should be factored into pre-operative assessments of older adults to inform subsequent care.

National survey on perioperative cognitive dysfunction

BACKGROUND

Perioperative cognitive dysfunction (PCD) is a very prevalent clinical syndrome due to the progressive aging of the surgical population.The aim of our study is to evaluate the clinical practice of Spanish anesthesiologists surveyed regarding this entity.

MATERIAL AND METHODS

Prospective online survey conducted by the Neurosciences Section and distributed by SEDAR.

RESULTS

544 responses were obtained, with a participation rate of 17%. 54.4% of respondents never make a preoperative assessment of cognitive impairment, only 7.5% always do it. 79.6% lack an intraoperative management protocol for the patient at risk of PCD. In the anesthetic planning, only 23.3% of the patients was kept in mind. Eighty-nine percent considered regional anesthesia with or without sedation preferable to general anesthesia for the prevention of PCD. 88.8% considered benzodiazepines to present a high risk of PCD. 71.7% considered that anesthetic depth monitoring could prevent postoperative cognitive deficit. Routine evaluation of postoperative delirium is low, only 14%. More than 80% recognize that PCD is underdiagnosed.

CONCLUSIONS

Among Spanish anesthesiologists surveyed, PCD is still a little known and underappreciated entity. It is necessary to raise awareness of the need to detect risk factors for PCD, as well as postoperative assessment and diagnosis. Therefore, the development of guidelines and protocols and the implementation of continuing education programs in which anesthesiologists should be key members of multidisciplinary teams in charge of perioperative care are suggested.

Postoperative Delirium and the Older Adult: Untangling the Confusion

Postoperative delirium is one of the most prevalent postoperative complications, affecting mostly older adults. Its incidence is expected to rise because of surgical advances, shifting demographics, and increased life expectancy. Although an acute alteration in brain function, postoperative delirium is associated with adverse outcomes, including progressive cognitive decline and dementia, that place significant burdens on patients' lives and healthcare systems. This has prompted efforts to understand the mechanisms of postoperative delirium to provide effective prevention and treatment. There are multiple mechanisms involved in the etiology of postoperative delirium that share similarities with the physiological changes associated with the aging brain. In addition, older patients often have multiple comorbidities including increased cognitive impairment that is also implicated in the genesis of delirium. These tangled connections pinpointed a shift toward creation of a holistic model of the pathophysiology of postoperative delirium. Scientific advancements integrating clinical risk factors, possible postoperative delirium biomarkers, genetic features, digital platforms, and other biotechnical and information technological innovations, will become available in the near future. Advances in artificial intelligence, for example, will aggregate cognitive testing platforms with patient-specific postoperative delirium risk stratification studies, panels of serum and cerebrospinal fluid molecules, electroencephalogram signatures, and gut microbiome features, along with the integration of novel polygenetic variants of sleep and cognition. These advances will allow for the enrollment of high-risk patients into prevention programs and help uncover new pharmacologic targets.

Comparison of the frailty index and frailty phenotype and their associations with postoperative delirium incidence and severity

BACKGROUND

Recent studies have reported an association between presurgical frailty and postoperative delirium. However, it remains unclear whether the frailty-delirium relationship differs by measurement tool (e.g., frailty index vs. frailty phenotype) and whether frailty is associated with delirium, independent of preoperative cognition.

METHODS

We used the successful aging after elective surgery (SAGES) study, a prospective cohort of older adults age ≥70 undergoing major non-cardiac surgery (N = 505). Preoperative measurement of the modified mini-mental (3MS) test, frailty index and frailty phenotype were obtained. The confusion assessment method (CAM), supplemented by chart review, identified postoperative delirium. Delirium feature severity was measured by the sum of CAM-severity (CAM-S) scores. Generalized linear models were used to determine the relative risk of each frailty measure with delirium incidence and severity. Subsequent models adjusted for age, sex, surgery type, Charlson comorbidity index, and 3MS.

RESULTS

On average, patients were 76.7 years old (standard deviation 5.22), 58.8% of women. For the frailty index, the incidence of delirium was 14% in robust, 17% in prefrail, and 31% in frail patients (p < 0.001). For the frailty phenotype, delirium incidence was 13% in robust, 21% in prefrail, and 27% in frail patients (p = 0.016). Frailty index, but not phenotype, was independently associated with delirium after adjustment for comorbidities (relative risk [RR] 2.13, 95% confidence interval [CI] 1.23-3.70; RR 1.61, 95% CI 0.77-3.37, respectively). Both frailty measures were associated with delirium feature severity. After adjustment for preoperative cognition, only the frailty index was associated with delirium incidence; neither index nor phenotype was associated with delirium feature severity.

CONCLUSION

Both the frailty index and phenotype were associated with the development of postoperative delirium. The index showed stronger associations that remained significant after adjusting for baseline comorbidities and preoperative cognition. Measuring frailty prior to surgery can assist in identifying patients at risk for postoperative delirium.

Effect of prophylactic corticosteroids on postoperative neurocognitive dysfunction in the adult population: An updated systematic review, meta-analysis, and trial sequential analysis of randomised controlled trials

Background and Aims

Postoperative neurocognitive dysfunction (PNCD) commonly occurs after surgery and prolongs hospital stays. Both direct noxious stimuli to the central nervous system and systemic inflammation have been implicated. Due to their potent anti-inflammatory effects, corticosteroids have been utilised to attenuate the incidence and severity of PNCD. This systematic review and meta-analysis strived to evaluate the prophylactic role of perioperative corticosteroids for PNCD.

Methods

A search was run in pre-defined databases for randomised controlled trials (RCTs) assessing the role of corticosteroids in preventing PNCD. The incidence of PNCD within 1 month was the primary outcome. Secondary outcomes included the use of antipsychotic medications for the treatment, postoperative infection, and hospital length of stay. The results are exhibited as odds ratio (OR) and the mean difference (MD) with 95% confidence interval (CI).

Results

Fifteen RCTs comprising 15,398 patients were included. The incidence of PNCD was significantly lower in the corticosteroid group than in the control group, with a pooled OR of 0.75 (95% CI 0.58, 0.96; P = 0.02; I2 = 66%). Trial sequential analysis showed the clinical benefit of corticosteroids in preventing PNCD; however, the requisite information size is still inadequate. The sub-group analysis supported the prophylactic effect of corticosteroids on delirium prevention but not on delayed neurocognitive recovery.

Conclusions

Our meta-analysis revealed statistically significant protective effects of corticosteroids on the incidence of PNCD. However, further studies are still needed to confirm the protective role of this commonly used and relatively safe strategy for preventing PNCD.

Emerging Insights into Postoperative Neurocognitive Disorders: The Role of Signaling Across the Gut-Brain Axis

The pathophysiological regulatory mechanisms in postoperative neurocognitive disorders (PNCDs) are intricately complex. Currently, the pathogenesis of PNCDs has not been fully elucidated. The mechanism involved may include a variety of factors, such as neuroinflammation, oxidative stress, and neuroendocrine dysregulation. Research into the gut microbiota-induced regulations on brain functions is increasingly becoming a focal point of exploration. Emerging evidence has shown that intestinal bacteria may play an essential role in maintaining the homeostasis of various physiological systems and regulating disease occurrence. Recent studies have confirmed the association of the gut-brain axis with central nervous system diseases. However, the regulatory effects of this axis in the pathogenesis of PNCDs remain unclear. Therefore, this paper intends to review the bidirectional signaling and mechanism of the gut-brain axis in PNCDs, summarize the latest research progress, and discuss the possible mechanism of intestinal bacteria affecting nervous system diseases. This review is aimed at providing a scientific reference for predicting the clinical risk of PNCD patients and identifying early diagnostic markers and prevention targets.

Crosstalk between GABAA receptors in astrocytes and neurons triggered by general anesthetic drugs

General anesthetic drugs cause cognitive deficits that persist after the drugs have been eliminated. Astrocytes may contribute to such cognition-impairing effects through the release of one or more paracrine factors that increase a tonic inhibitory conductance generated by extrasynaptic γ-aminobutyric acid type A (GABAA) receptors in hippocampal neurons. The mechanisms underlying this astrocyte-to-neuron crosstalk remain unknown. Interestingly, astrocytes express anesthetic-sensitive GABAA receptors. Here, we tested the hypothesis that anesthetic drugs activate astrocytic GABAA receptors to initiate crosstalk leading to a persistent increase in extrasynaptic GABAA receptor function in neurons. We also investigated the signaling pathways in neurons and aimed to identify the paracrine factors released from astrocytes. Astrocytes and neurons from mice were grown in primary cell cultures and studied using in vitro electrophysiological and biochemical assays. We discovered that the commonly used anesthetics etomidate (injectable) and sevoflurane (inhaled) stimulated astrocytic GABAA receptors, which in turn promoted the release paracrine factors, that increased the tonic current in neurons via a p38 MAPK-dependent signaling pathway. The increase in tonic current was mimicked by exogenous IL-1β and abolished by blocking IL-1 receptors; however, unexpectedly, IL-1β and other cytokines were not detected in astrocyte-conditioned media. In summary, we have identified a novel form of crosstalk between GABAA receptors in astrocytes and neurons that engages a p38 MAPK-dependent pathway. Brief commentary BACKGROUND: Many older patients experience cognitive deficits after surgery. Anesthetic drugs may be a contributing factor as they cause a sustained increase in the function of "memory blocking" extrasynaptic GABAA receptors in neurons. Interestingly, astrocytes are required for this increase; however, the mechanisms underlying the astrocyte-to-neuron crosstalk remain unknown. TRANSLATIONAL SIGNIFICANCE: We discovered that commonly used general anesthetic drugs stimulate GABAA receptors in astrocytes, which in turn release paracrine factors that trigger a persistent increase in extrasynaptic GABAA receptor function in neurons via p38 MAPK. This novel form of crosstalk may contribute to persistent cognitive deficits after general anesthesia and surgery.

Two-lung ventilation with artificial pneumothorax on cerebral desaturation and early postoperative cognitive outcome: a randomized controlled trial

BACKGROUND

The effect of two lung ventilation (TLV) with carbon dioxide artificial pneumothorax on cerebral desaturation and postoperative neurocognitive changes in elderly patients undergoing elective minimally invasive esophagectomy (MIE) is unclear.

OBJECTIVES

The first aim of this study was to compare the effect of TLV and one lung ventilation (OLV) on cerebral desaturation. The second aim was to assess changes in early postoperative cognitive outcomes of two ventilation methods.

METHODS

This prospective, randomized, controlled trial enrolled patients 65 and older scheduled for MIE. Patients were randomly assigned (1:1) to TLV group or OLV group. The primary outcome was the incidence of cerebral desaturation events (CDE). Secondary outcomes were the cumulative area under the curve of desaturation for decreases in regional cerebral oxygen saturation (rSO2) values below 20% relative to the baseline value (AUC.20) and the incidence of delayed neurocognitive recovery.

RESULTS

Fifty-six patients were recruited between November 2019 and August 2020. TLV group had a lower incidence of CDE than OLV group [3 (10.71%) vs. 13 (48.14%), P = 0.002]. TLV group had a lower AUC.20 [0 (0-35.86) % min vs. 0 (0-0) % min, P = 0.007], and the incidence of delayed neurocognitive recovery [2 (7.4%) vs. 11 (40.7%), P = 0.009] than OLV group. Predictors of delayed neurocognitive recovery on postoperative day 7 were age (OR 1.676, 95% CI 1.122 to 2.505, P = 0.006) and AUC.20 (OR 1.059, 95% CI 1.025 to 1.094, P < 0.001).

CONCLUSION

Compared to OLV, TLV had a lower incidence of CDE and delayed neurocognitive recovery in elderly patients undergoing MIE. The method of TLV combined with carbon dioxide artificial pneumothorax may be an option for these elderly patients. Chinese Clinical Trial Registry (identifier: ChiCTR1900027454).

Itaconate alleviates anesthesia/surgery-induced cognitive impairment by activating a Nrf2-dependent anti-neuroinflammation and neurogenesis via gut-brain axis

BACKGROUND

Postoperative cognitive dysfunction (POCD) is a common neurological complication of anesthesia and surgery in aging individuals. Neuroinflammation has been identified as a hallmark of POCD. However, safe and effective treatments of POCD are still lacking. Itaconate is an immunoregulatory metabolite derived from the tricarboxylic acid cycle that exerts anti-inflammatory effects by activating the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway. In this study, we investigated the effects and underlying mechanism of 4-octyl itaconate (OI), a cell-permeable itaconate derivative, on POCD in aged mice.

METHODS

A POCD animal model was established by performing aseptic laparotomy in 18-month-old male C57BL/6 mice under isoflurane anesthesia while maintaining spontaneous ventilation. OI was intraperitoneally injected into the mice after surgery. Primary microglia and neurons were isolated and treated to lipopolysaccharide (LPS), isoflurane, and OI. Cognitive function, neuroinflammatory responses, as well as levels of gut microbiota and their metabolites were evaluated. To determine the mechanisms underlying the therapeutic effects of OI in POCD, ML385, an antagonist of Nrf2, was administered intraperitoneally. Cognitive function, neuroinflammatory responses, endogenous neurogenesis, neuronal apoptosis, and Nrf2/extracellular signal-related kinases (ERK) signaling pathway were evaluated.

RESULTS

Our findings revealed that OI treatment significantly alleviated anesthesia/surgery-induced cognitive impairment, concomitant with reduced levels of the neuroinflammatory cytokines IL-1β and IL-6, as well as suppressed activation of microglia and astrocytes in the hippocampus. Similarly, OI treatment inhibited the expression of IL-1β and IL-6 in LPS and isoflurane-induced primary microglia in vitro. Intraperitoneal administration of OI led to alterations in the gut microbiota and promoted the production of microbiota-derived metabolites associated with neurogenesis. We further confirmed that OI promoted endogenous neurogenesis and inhibited neuronal apoptosis in the hippocampal dentate gyrus of aged mice. Mechanistically, we observed a decrease in Nrf2 expression in hippocampal neurons both in vitro and in vivo, which was reversed by OI treatment. We found that Nrf2 was required for OI treatment to inhibit neuroinflammation in POCD. The enhanced POCD recovery and promotion of neurogenesis triggered by OI exposure were, at least partially, mediated by the activation of the Nrf2/ERK signaling pathway.

CONCLUSIONS

Our findings demonstrate that OI can attenuate anesthesia/surgery-induced cognitive impairment by stabilizing the gut microbiota and activating Nrf2 signaling to restrict neuroinflammation and promote neurogenesis. Boosting endogenous itaconate or supplementation with exogenous itaconate derivatives may represent novel strategies for the treatment of POCD.

Structural disconnectivity in postoperative delirium: A perioperative two-center cohort study in older patients

BACKGROUND

Structural disconnectivity was found to precede dementia. Global white matter abnormalities might also be associated with postoperative delirium (POD).

METHODS

We recruited older patients (≥65 years) without dementia that were scheduled for major surgery. Diffusion kurtosis imaging metrics were obtained preoperatively, after 3 and 12 months postoperatively. We calculated fractional anisotropy (FA), mean diffusivity (MD), mean kurtosis (MK), and free water (FW). A structured and validated delirium assessment was performed twice daily.

RESULTS

Of 325 patients, 53 patients developed POD (16.3%). Preoperative global MD (standardized beta 0.27 [95% confidence interval [CI] 0.21-0.32] p < 0.001) was higher in patients with POD. Preoperative global MK (-0.07 [95% CI -0.11 to (-0.04)] p < 0.001) and FA (0.07 [95% CI -0.10 to (-0.04)] p < 0.001) were lower. When correcting for baseline diffusion, postoperative MD was lower after 3 months (0.05 [95% CI -0.08 to (-0.03)] p < 0.001; n = 183) and higher after 12 months (0.28 [95% CI 0.20-0.35] p < 0.001; n = 45) among patients with POD.

DISCUSSION

Preoperative structural disconnectivity was associated with POD. POD might lead to white matter depletion 3 and 12 months after surgery.

An immune signature of postoperative cognitive decline in elderly patients

Postoperative cognitive decline (POCD) is the predominant complication affecting elderly patients following major surgery, yet its prediction and prevention remain challenging. Understanding biological processes underlying the pathogenesis of POCD is essential for identifying mechanistic biomarkers to advance diagnostics and therapeutics. This longitudinal study involving 26 elderly patients undergoing orthopedic surgery aimed to characterize the impact of peripheral immune cell responses to surgical trauma on POCD. Trajectory analyses of single-cell mass cytometry data highlighted early JAK/STAT signaling exacerbation and diminished MyD88 signaling post-surgery in patients who developed POCD. Further analyses integrating single-cell and plasma proteomic data collected before surgery with clinical variables yielded a sparse predictive model that accurately identified patients who would develop POCD (AUC = 0.80). The resulting POCD immune signature included one plasma protein and ten immune cell features, offering a concise list of biomarker candidates for developing point-of-care prognostic tests to personalize perioperative management of at-risk patients. The code and the data are documented and available at https://github.com/gregbellan/POCD .

Teaser

Modeling immune cell responses and plasma proteomic data predicts postoperative cognitive decline.

Long-term cognitive outcomes after surgery and anesthesia: what we find depends on where we look

Purpose of review

To review how anecdote and narrative medicine, primary cohort studies, epidemiological studies, and the dementia literature can be bridged to understand long-term postoperative cognitive decline.

Recent findings

Primary cohort studies have measured recoverable declines in memory and executive function after major surgery, but less-appreciated sources also offer critical insights. Anecdote reveals that functionally-impactful cognitive decline may persist after physical recovery in some patients despite modern medications and monitoring, and that physicians are unprepared to address patients' cognitive concerns. However, epidemiological studies reproducibly demonstrate that elective surgery has no, or a negligible, average impact on cognition in older patients. Cognitively provocative factors - like medical hospital admissions or health factors like diabetes and smoking - are common in late life, and surgery likely contributes minimally to long-term cognitive change for most patients.

Summary

Patients should be reassured that, while anecdotes of durable cognitive change after surgery are easily accessible, most patients experience cognitive recovery after major surgery. However, those who do not recover deserve characterization of their symptoms and investigation of modifiable causes to facilitate cognitive recovery.

Complement C3 From Astrocytes Plays Significant Roles in Sustained Activation of Microglia and Cognitive Dysfunctions Triggered by Systemic Inflammation After Laparotomy in Adult Male Mice

Aberrant activation of complement cascades plays an important role in the progress of neurological disorders. Complement C3, the central complement component, has been implicated in synaptic loss and cognitive impairment. Recent study has shown that wound injury-induced systemic inflammation can trigger the increase of C3 in the brain. Our previous studies have demonstrated that laparotomy-triggered systemic inflammation could induce neuroinflammation and cognitive dysfunctions. Furthermore, sustained activation of microglia was observed even 14 days after laparotomy, while most of cytokines had returned to basal levels rapidly at the earlier time point. Although we have demonstrated that anti-inflammatory intervention successfully attenuated cognitive dysfunction by preventing increase of cytokines and activation of microglia, how sustained activation of microglia and cognitive dysfunction occur is still a mystery. In this study, we investigated the role of C3 in mediating activation of microglia and cognitive dysfunction by using laparotomy in adult male mouse only as the experimental model of systemic inflammation and AAV9-C3shRNA. Our data observed that laparotomy induced neurotoxic reactive astrocytes with an increase of C3 in the hippocampus. Furthermore, inhibition of C3 by AAV9-C3shRNA prevented synaptic engulfment by microglia and attenuated cognitive dysfunctions after laparotomy. Inhibition of C3 did not modulate activation of astrocytes and expression of various cytokines. Current findings demonstrated that C3 plays significant roles in sustained activation of microglia and cognitive dysfunctions, which suggests that C3 is the valuable molecule target to attenuate in neurological conditions characterised by neuroinflammation and cognitive dysfunction.

Post-operative cognitive dysfunction is exacerbated by high-fat diet via TLR4 and prevented by dietary DHA supplementation

Post-operative cognitive dysfunction (POCD) is an abrupt decline in neurocognitive function arising shortly after surgery and persisting for weeks to months, increasing the risk of dementia diagnosis. Advanced age, obesity, and comorbidities linked to high-fat diet (HFD) consumption such as diabetes and hypertension have been identified as risk factors for POCD, although underlying mechanisms remain unclear. We have previously shown that surgery alone, or 3-days of HFD can each evoke sufficient neuroinflammation to cause memory deficits in aged, but not young rats. The aim of the present study was to determine if HFD consumption before surgery would potentiate and prolong the subsequent neuroinflammatory response and memory deficits, and if so, to determine the extent to which these effects depend on activation of the innate immune receptor TLR4, which both insults are known to stimulate. Young-adult (3mo) & aged (24mo) male F344xBN F1 rats were fed standard chow or HFD for 3-days immediately before sham surgery or laparotomy. In aged rats, the combination of HFD and surgery caused persistent deficits in contextual memory and cued-fear memory, though it was determined that HFD alone was sufficient to cause the long-lasting cued-fear memory deficits. In young adult rats, HFD + surgery caused only cued-fear memory deficits. Elevated proinflammatory gene expression in the hippocampus of both young and aged rats that received HFD + surgery persisted for at least 3-weeks after surgery. In a separate experiment, rats were administered the TLR4-specific antagonist, LPS-RS, immediately before HFD onset, which ameliorated the HFD + surgery-associated neuroinflammation and memory deficits. Similarly, dietary DHA supplementation for 4 weeks prior to HFD onset blunted the neuroinflammatory response to surgery and prevented development of persistent memory deficits. These results suggest that HFD 1) increases risk of persistent POCD-associated memory impairments following surgery in male rats in 2) a TLR4-dependent manner, which 3) can be targeted by DHA supplementation to mitigate development of persistent POCD.

Preparing for and Not Waiting for Surgery

Cancer surgery is an essential treatment strategy but can disrupt patients' physical and psychological health. With worldwide demand for surgery expected to increase, this review aims to raise awareness of this global public health concern, present a stepwise framework for preoperative risk evaluation, and propose the adoption of personalised prehabilitation to mitigate risk. Perioperative medicine is a growing speciality that aims to improve clinical outcome by preparing patients for the stress associated with surgery. Preparation should begin at contemplation of surgery, with universal screening for established risk factors, physical fitness, nutritional status, psychological health, and, where applicable, frailty and cognitive function. Patients at risk should undergo a formal assessment with a qualified healthcare professional which informs meaningful shared decision-making discussion and personalised prehabilitation prescription incorporating, where indicated, exercise, nutrition, psychological support, 'surgery schools', and referral to existing local services. The foundational principles of prehabilitation can be adapted to local context, culture, and population. Clinical services should be co-designed with all stakeholders, including patient representatives, and require careful mapping of patient pathways and use of multi-disciplinary professional input. Future research should optimise prehabilitation interventions, adopting standardised outcome measures and robust health economic evaluation.

Role of supplemental regional blocks on postoperative neurocognitive dysfunction after major non-cardiac surgeries: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND/IMPORTANCE

Postoperative neurocognitive dysfunction (PNCD) is a frequent and preventable complication after surgery. The large high-quality evidence for the efficacy of supplemental regional analgesia blocks (RAB) for preventing PNCD is still elusive.

OBJECTIVE

The objective of this meta-analysis was to evaluate the effect of RAB versus standard anesthesia care on the incidence of PNCD in adult patients undergoing major non-cardiac surgery.

EVIDENCE REVIEW

PubMed, EMBASE, Scopus, and the Cochrane Central Registers of Controlled Trials (CENTRAL) were searched for randomized controlled trials (RCTs) from 2017 until June 2022. The primary outcome was the incidence of PNCD within 1 month of surgery. A random-effects model with an inverse variance method was used to pool results, and OR and mean differences were calculated for dichotomous and continuous outcomes. Various exploratory subgroup analyses were performed to explore the possibility of the association between the various patient, technique, and surgery-related factors. Grading of Recommendation, Assessment, Development, and Evaluation guidelines were used to determine the certainty of evidence.

FINDINGS

Twenty-six RCTs comprizing 4414 patients were included. The RAB group was associated with a significant reduction in the incidence of PNCD with an OR of 0.46 (95% CI 0.35 to 0.59; p<0.00001; I2=28%) compared with the control group (moderate certainty). Subgroup analysis exhibited that the prophylactic efficacy of RAB persisted for both delirium and delayed neurocognitive recovery.

CONCLUSIONS

Current evidence suggests that supplemental RAB are beneficial in preventing PNCD in patients after major non-cardiac surgery.

PROSPERO REGISTRATION NUMBER

CRD42022338820.

Comparing analog and digital neurocognitive tests with older adults: a study of the ISPOCD battery vs. a digital test battery from Mindmore

BACKGROUND

Delayed neurocognitive recovery and neurocognitive disorder are common postoperative complications among older adults. The assessment of these complications traditionally relies on analog neurocognitive tests, predominantly using the test battery from the ISPOCD-study as the standard approach. However, analog tests are time-consuming and necessitate trained staff which poses limitations. The potential availability of a digital neurocognitive test as an alternative to the ISPOCD remains unknown. We conducted a comparative study between the analog test battery from ISPOCD and the self-administrated digital test battery developed by Mindmore.

METHODS

We conducted a crossover study with 50 cognitively healthy older adults ≥ 60 years of age recruited in Stockholm Sweden, between February and April 2022. The primary outcome focused on measuring comparability between the two test batteries. Our secondary outcomes included assessing participants' perceptions and attitudes about the tests with qualitative interviews and their usability experiences.

RESULTS

Fifty older adults, mean age 76, female 56%, with a university or college degree 48% participated in the study. The sub tests in two test batteries demonstrated a medium-large correlation (r = 0.3-0.5), except for one measure. For four out of six measures, significant differences were found with medium to large effect sizes, ranging from 0.57-1.43. Two categories were recognized in the qualitative analysis: self-competing in a safe environment, and experience with technology. Participants expressed feeling safe and at ease during the assessment, with some preferring the digital test over the analog. Participants reported a high level of usability with the digital test and a majority participants (n = 47) reported they would undergo the digital test for a potential future surgery.

CONCLUSIONS

The digital test battery developed by Mindmore offers several advantages, including rapid access to test results, easy comprehension, and use for participants, thereby increased accessibility of cognitive screening.

TRIAL REGISTRATION NUMBER

NCT05253612; ClinicalTrials.gov, 24/02/2022.

Necroptosis involved in sevoflurane-induced cognitive dysfunction in aged mice by activating NMDA receptors increasing intracellular calcium

Perioperative neurocognitive disorders are a common surgical and postanesthesia complication. Necroptosis contributes to the emergence of various neurological disorders. We conjecture that cognitive impairment is associated with necroptosis of hippocampal neurons, which is mediated by NMDA receptors leading to cytoplasmic calcium imbalance. C57BL/6 J male mice ( 18 months) were randomly divided into the C ( control group), S ( sevoflurane group), S+M ( sevoflurane plus the NMDA receptor antagonist memantine group) and S+N ( sevoflurane plus necrostatin-1) group. We exposed the mice to 3% sevoflurane for 2 h a day for three consecutive days in the S, S+M and S+N groups. Memantine ( 20 mg/kg) or Nec-1 ( 10 mg/kg) was injected intraperitoneally 1 h before sevoflurane anesthesia in the S+M or S+N group. We used the animal behavior tests to evaluate the cognitive function. Pathological damage, the rate of necroptosis, [Ca2+]i, and the expression of necroptosis-related proteins were evaluated. The cognitive function tests, pathological damage, the rate of necroptosis, the expression of necroptosis-related proteins, NMDAR2A and NMDAR2B were significantly different in the S group ( P < 0.05). Alleviated pathological damage, decreased the rate of necroptosis and down-regulated the expression of necroptosis-related proteins occurred in the S+M and S+N group ( P < 0.05). The lower elevated [Ca2+]i, expression of NMDAR2A and NMDAR2B were found in the S+M group. Our findings highlighted sevoflurane-induced cognitive dysfunction is associated with an imbalance in cytoplasmic calcium homeostasis by activating NMDA receptors, which causes hippocampus neurons to undergo necroptosis and ultimately affects cognitive performance in aged mice.

Risk factors of post-anaesthesia care unit delirium in patients undergoing non-cardiac surgery in Singapore

Introduction

Post-anaesthesia care unit (PACU) delirium affects 5%-45% of patients after surgery and is associated with postoperative delirium and increased mortality. Up to 40% of PACU delirium is preventable, but it remains under-recognised due to a lack of awareness of its diagnosis. The nursing delirium screening scale (Nu-DESC) has been validated for diagnosing PACU delirium, but is not routinely used locally. This study aimed to use Nu-DESC to establish the incidence and risk factors of PACU delirium in patients undergoing non-cardiac surgery in the surgical population.

Methods

We conducted an audit of eligible patients undergoing major surgery in three public hospitals in Singapore over 1 week. Patients were assessed for delirium 30-60 min following their arrival in PACU using Nu-DESC, with a total score of ≥2 indicative of delirium.

Results

A total of 478 patients were assessed. The overall incidence rate of PACU delirium was 18/478 (3.8%), and the incidence was 9/146 (6.2%) in patients aged > 65 years. Post-anaesthesia care unit delirium was more common in females, patients with malignancy and those who underwent longer operations. Logistic regression analysis showed that the use of bispectral index (P < 0.001) and the presence of malignancy (P < 0.001) were significantly associated with a higher incidence of PACU delirium.

Conclusion

In this first local study, the incidence of PACU delirium was 3.8%, increasing to 6.2% in those aged > 65 years. Understanding these risk factors will form the basis for which protocols can be established to optimise resource management and prevent long-term morbidities and mortality in PACU delirium.

Trail making test B in postoperative delirium: a replication study

Background

The Trail Making Test B (TMT-B) is indicative of cognitive flexibility and several other cognitive domains. Previous studies suggest that it might be associated with the risk of developing postoperative delirium, but evidence is limited and conflicting. We therefore aimed to replicate the association of preoperative TMT-B results with postoperative delirium.

Methods

We included older adults (≥65 yr) scheduled for major surgery and without signs of dementia to participate in this binational two-centre longitudinal observational cohort study. Presurgical TMT-B scores were obtained. Delirium was assessed twice daily using validated instruments. Logistic regression was applied and the area under the receiver operating characteristic curve calculated to determine the predictive performance of TMT-B. We subsequently included covariates used in previous studies for consecutive sensitivity analyses. We further analysed the impact of outliers, missing or impaired data.

Results

Data from 841 patients were included and of those, 151 (18%) developed postoperative delirium. TMT-B scores were statistically significantly associated with the incidence of postoperative delirium {odds ratio per 10-s increment 1.06 (95% confidence interval [CI] 1.02-1.09), P=0.001}. The area under the receiver operating characteristic curve was 0.60 ([95% CI 0.55-0.64], P<0.001). The association persisted after removing 21 outliers (1.07 [95% CI 1.03-1.07], P<0.001). Impaired or missing TMT-B data (n=88) were also associated with postoperative delirium (odds ratio 2.74 [95% CI 1.71-4.35], P<0.001).

Conclusions

The TMT-B was associated with postoperative delirium, but its predictive performance as a stand-alone test was low. The TMT-B alone is not suitable to predict delirium in a clinical setting.

Clinical trial registration

NCT02265263. (https://clinicaltrials.gov/ct2/show/results/NCT02265263).

α5GABAA receptor: A potential therapeutic target for perioperative neurocognitive disorders, a review of preclinical studies

Perioperative neurocognitive disorders (PND) are a common complication in elderly patients following surgery, which not only prolongs the recovery period but also affects their future quality of life and imposes a significant burden on their family and society. Multiple factors, including aging, vulnerability, anesthetic drugs, cerebral oxygen desaturation, and severe pain, have been associated with PND. Unfortunately, no effective drug is currently available to prevent PND. α5 γ-aminobutyric acid subtype A (α5GABAA) receptors have been implicated in cognitive function modulation. Positive or negative allosteric modulators of α5GABAA receptors have been found to improve cognitive impairment under different conditions. Therefore, targeting α5GABAA receptors may represent a promising treatment strategy for PND. This review focuses on preclinical studies of α5GABAA receptors and the risk factors associated with PND, primarily including aging, anesthetics, and neuroinflammation. Specifically, positive allosteric modulators of α5GABAA receptors have improved cognitive function in aged experimental animals. In contrast, negative allosteric modulators of α5GABAA receptors have been found to facilitate cognitive recovery in aged or adult experimental animals undergoing anesthesia and surgery but not in aged experimental animals under anesthesia alone. The reasons for the discordant findings have yet to be elucidated. In preclinical studies, different strategies of drug administration, as well as various behavioral tests, may influence the stability of the results. These issues need to be carefully considered in future studies.

Downregulation of the glucose transporter GLUT 1 in the cerebral microvasculature contributes to postoperative neurocognitive disorders in aged mice

INTRODUCTION

Glucose transporter 1 (GLUT1) is essential for glucose transport into the brain and is predominantly expressed in the cerebral microvasculature. Downregulation of GLUT1 precedes the development of cognitive impairment in neurodegenerative conditions. Surgical trauma induces blood-brain barrier (BBB) disruption, neuroinflammation, neuronal mitochondria dysfunction, and acute cognitive impairment. We hypothesized that surgery reduces the expression of GLUT1 in the BBB that in turn disrupts its integrity and contributes to metabolic dysregulation in the brain that culminates in postoperative cognitive impairment.

METHODOLOGY

Using an abdominal surgery model in aged WT mice, we assessed the perioperative changes in cognitive performance, tight junction proteins expression, GLUT1 expression, and the associated metabolic effects in the hippocampus. Thereafter, we evaluated the effects of these parameters in aged mice with conditional overexpression of GLUT1, and then again in aged mice with conditional overexpression of GLUT1 with or without prior exposure to the GLUT1 inhibitor ST-31.

RESULTS

We showed a significant decline in cognitive performance, along with GLUT1 reduction and diminished glucose metabolism, especially in the ATP level in the postoperative mice compared with controls. Overexpression of GLUT1 expression alleviated postoperative cognitive decline and improved metabolic profiles, especially in adenosine, but did not directly restore ATP generation to control levels. GLUT1 inhibition ameliorated the postoperative beneficial effects of GLUT1 overexpression.

CONCLUSIONS

Surgery-induced GLUT1 reduction significantly contributes to postoperative cognitive deficits in aged mice by affecting glucose metabolism in the brain. It indicates the potential of targeting GLUT1 to ameliorate perioperative neurocognitive disorders.

Diagnosing delirium in perioperative and intensive care medicine

PURPOSE OF REVIEW

This article reviews the current literature on instruments used for screening and diagnosing delirium in perioperative and intensive care medicine. It summarizes recent findings to guide clinicians and researchers in choosing the most appropriate tools.

RECENT FINDINGS

The incidence of delirium in hospitalized patients ranges from 5% to over 50%, depending on the population of patients studied. Failure to diagnose delirium in a timely manner is associated with serious adverse outcomes, including death and institutionalization. Valid assessment tests are needed for delirium detection, as early identification and treatment of delirium may help to prevent complications. Currently, there are more than 30 available instruments, which have been developed to assist with the screening and diagnosis of delirium. However, these tools vary greatly in sensitivity, specificity, and administration time, and their overabundance challenges the selection of specific tool as well as direct comparisons and interpretation of results across studies.

SUMMARY

Overlooking or misdiagnosing delirium may result in poor patient outcomes. Familiarizing healthcare workers with the variety of delirium assessments and selecting the most appropriate tool to their needs is an important step toward improving awareness and recognition of delirium.

The Thalamus in Perioperative Neurocognitive Disorders

Thalamus function and structure are known predictors of individual differences in the risk of age-related neurocognitive disorders (NCD), such as dementia. However, to date, little is known about their role in the perioperative setting. Here, we provide a narrative review of brain-imaging studies of preoperative and postoperative thalamus scanning parameters associated with risks of developing perioperative NCD, such as postoperative delirium (POD) and postoperative cognitive dysfunction (POCD) during the postoperative phase. These findings are discussed in light of the concept of reserve capacity.

Human umbilical cord-derived mesenchymal stem cells ameliorate perioperative neurocognitive disorder by inhibiting inflammatory responses and activating BDNF/TrkB/CREB signaling pathway in aged mice

BACKGROUND

Perioperative neurocognitive disorder (PND) is a key complication affecting older individuals after anesthesia and surgery. Failure to translate multiple pharmacological therapies for PND from preclinical studies to clinical settings has necessitated the exploration of novel therapeutic strategies. Human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) treatment has emerged as a promising therapeutic strategy for treating neurodegenerative diseases and has the potential to translate basic science into clinical practice. In this study, we investigated the effects and underlying mechanism of hUC-MSCs on PND in aged mice.

METHODS

hUC-MSCs were isolated from an infant umbilical cord and identified using flow cytometry and differentiation assays. We established PND model by undergoing aseptic laparotomy under isoflurane anesthesia maintaining spontaneous ventilation in eighteen-month-old male C57BL/6 mice. hUC-MSCs were slowly injected into mice by coccygeal vein before anesthesia. Cognitive function, systemic and neuroinflammatory responses, neuroplasticity, endogenous neurogenesis, and brain-derived neurotrophic factor (BDNF) were assessed. To determine the brain mechanisms underlying by which hUC-MSCs mediate their neuroprotective effects in PND, K252a, an antagonist of BDNF receptor, was administered intraperitoneally before surgery. Hippocampal BDNF/TrkB/CREB signaling pathway and metabolomic signatures were evaluated.

RESULTS

hUC-MSC treatment ameliorated the learning and memory impairment in aged mice with PND. The downstream effects were the suppression of systemic and hippocampal inflammation and restoration of neurogenesis and neuroplasticity dysregulation. Interestingly, the level of mature BDNF, but not that of proBDNF, was increased in the hippocampus after hUC-MSC treatment. Further analysis revealed that the improved cognitive recovery and the restoration of neurogenesis and neuroplasticity dysregulation elicited by exposure to hUC-MSCs were, at least partially, mediated by the activation of the BDNF/TrkB/CREB signaling pathway. Untargeted metabolomic further identified lipid metabolism dysfunction as potential downstream of the BDNF/TrkB/CREB signaling pathway in hUC-MSC-mediated neuroprotection for PND.

CONCLUSIONS

Our study highlights the beneficial effects of hUC-MSC treatment on PND and provides a justification to consider the potential use of hUC-MSCs in the perioperative period.

Investigation on Awareness of Cognitive Impairment Diseases Among Surgical Practitioners

Objective

In this study, we assessed the awareness of cognitive dysfunction and the reasons for the lack of awareness among surgical practitioners in Jiaxing.

Methods

Questionnaires were distributed to surgical practitioners covering all Class III and Class II hospitals in Jiaxing. Respondents were asked to make selections regarding the demographic data, clinical attitudes and practices of cognitive dysfunction based on Alzheimer's Disease Assessment Scale (ADKS) of the Chinese version.

Results

A total of 180 questionnaires were distributed, 12 of which were incomplete, with 168 being included for analysis. The respondents were generally under 50 years of age (150, 89.3%), predominantly males (146, 86.9%), and surgeons (153, 91.1%). They generally had a bachelor's or master's degrees (165, 98.2%), and served in Class III hospitals (127, 75.6%). The title of the practitioner was found to impact their attention toward their patients' cognitive status during preoperative preparation (P<0.05). Titles and hospital levels were found to influence decisions of surgical practitioners to invite specialist physicians for consultation and assessment when a patient was identified to have cognitive dysfunction (P<0.05). Most surgical practitioners had little knowledge or training about Alzheimer's disease and cognitive dysfunction. Among the 168 respondents, the mean ADKS score was 20.14±2.40, and the awareness rate was 67.1%, indicating that the surgical practitioner's title influenced ADKS score (P<0.001).

Conclusion

Surgical practitioners, especially young physicians and those in Class II hospitals, had lower awareness of cognitive dysfunction, with low ADKS scores; therefore, they needed to be further trained to recognize cognitive dysfunction.

General anesthesia versus regional anesthesia in patients undergoing obliterative vaginal procedures for pelvic organ prolapse

INTRODUCTION AND HYPOTHESIS

The objective was to compare outcomes in patients receiving general versus regional anesthesia when undergoing obliterative vaginal surgery for pelvic organ prolapse.

METHODS

Obliterative vaginal procedures performed from 2010 to 2020 were identified in the American College of Surgeons National Surgical Quality Improvement Program database using Current Procedural Terminology codes. Surgeries were categorized into general anesthesia (GA) or regional anesthesia (RA). Rates of reoperation, readmission, operative time, and length of stay were determined. A composite adverse outcome was calculated including any of the following: nonserious or serious adverse events, 30-day readmission, or reoperation. Propensity score-weighted analysis of perioperative outcomes was performed.

RESULTS

The cohort included 6,951 patients, of whom 6,537 (94%) underwent obliterative vaginal surgery under GA and 414 (6%) received RA. When comparing outcomes under the propensity score-weighted analysis, operative times were shorter (median 96 vs 104 min, p<0.01) in the RA group versus GA. There were no significant differences between composite adverse outcomes (10% vs 12%, p=0.06), or readmission (5% vs 5%, p=0.83) and reoperation rates (1% vs 2%, p=0.12) between the RA and GA groups. Length of stay was shorter in patients receiving GA than in those receiving RA, especially when undergoing concomitant hysterectomy (67% discharged within 1 day in GA vs 45% in RA, p<0.01).

CONCLUSIONS

Composite adverse outcomes, reoperation rates, and readmission rates were similar in patients who received RA for obliterative vaginal procedures compared with GA. Operative times were shorter in patients receiving RA than in those receiving GA, and length of stay was shorter in patients receiving GA than in those receiving RA.

Pro-Con Debate: Judicious Benzodiazepine Administration for Preoperative Anxiolysis in Older Patients

In this Pro-Con commentary article, we discuss the risks and benefits of administering preoperative benzodiazepines to older patients to decrease preoperative anxiety. The Pro side first focuses on the critical importance of treating preoperative anxiety and that benzodiazepines are the best tool to achieve that goal. The competing argument presented by the Con side is that myriad options exist to treat preoperative anxiety without simultaneously increasing the risk for devastating complications such as postoperative delirium. Both sides call for more high-quality investigations to determine the most effective strategies for decreasing preoperative anxiety in older adults while improving outcomes and reducing morbidity.

Plasma lipidomics reveals potential lipid markers for the prediction of delayed neurocognitive recovery after cardiac surgery with cardiopulmonary bypass

BACKGROUND

Delayed neurocognitive recovery (DNR) is a cognitive change that affects patients after anesthesia and surgery, with a high incidence, severely impairing their quality of life. We identified relevant metabolic pathways to determine predictive lipid markers and understand the pathogenesis of DNR.

METHODS

A non-targeted lipidomic strategy using Waters Acquity I Class UPLC-Xevo G2-S QTOF UPLC-MS was employed to identify different lipids in the 24 h postoperative plasma of patients whose cognitive function was assessed 7-14 days after surgery. Principal component analysis, orthogonal partial least squares discriminant analysis, and receiver operating characteristic (ROC) curves were used to identify potential biomarkers for predicting DNR. Metabolic pathway analysis was performed using the online platform MetaboAnalyst 5.0.

RESULTS

Pre-operative hemoglobin was identified as an independent risk factor for DNR. The individual areas under the ROC curves (AUC) of the 5 representative lipids were all > 0.6, and the AUC of the combined predictor was 0.912. Glycerophospholipid metabolic pathway was dysregulated in patients with subsequent DNR.

CONCLUSION

This study identified a series of potential predictive biomarkers for DNR. These data suggested that glycerophospholipid metabolism may be the mechanism underlying the occurrence and progression of DNR.

Usability and feasibility of a digital cognitive screening tool measuring older adults' early postoperative neurocognitive recovery: a protocol for a pilot study

INTRODUCTION

Delayed neurocognitive recovery, also identified as early postoperative cognitive decline (POCD), is a common complication after surgery, with advanced age being the most important risk factor. As the geriatric population is increasing worldwide, and number of older adults undergoing surgery continues to rise, so will the incidence of POCD. Only a small proportion use digital cognitive tests for measuring postoperative neurocognitive performance compared with analogue tests. This study aims to evaluate a digital cognitive screening tool, Mindmore Postoperative version (Mindmore-P), in a perioperative setting to determine its feasibility and usability, and to compare preoperative cognition with early postoperative neurocognitive performance. Further, to determine associations between neurocognitive performance and perioperative factors as well as to explore patients' experiences of early neurocognitive recovery.

METHODS AND ANALYSIS

We will include 50 patients (aged ≥60 years) undergoing elective abdominal surgery under general anaesthesia. Cognitive functions will be measured with Mindmore-P preoperatively and on postoperative day (POD) 1 or 2 as well as 2-3 weeks after surgery. Preoperatively, frailty, (Clinical Frailty Scale), depression (Geriatric Depression Scale-15), functional status (12-item WHO Disability Assessment Schedule 2.0) and pre-recovery status (Swedish web version Quality of Recovery Scale, SwQoR) will be measured. Delirium will be assessed by Nu-DESC (Nursing Delirium Screening Scale) twice a day, with start on POD 1 and until the patient is discharged from the hospital. Outcomes at 2-3 weeks postoperatively are postoperative recovery (SwQoR), depression, functional status and usability (System Usability Scale) of Mindmore-P. Postoperative recovery will also be measured POD 1 or 2. We will also explore feasibility and experience of early postoperative neurocognitive recovery with interviews approximately 1 month after surgery.

ETHICS AND DISSEMINATION

This study is approved by the Swedish Ethical Review Authority (REC Reference: 2022-03593-01) and will follow the principles outlined in the 1964 Helsinki Declaration and its later amendments. Results from this study will be disseminated in peer-reviewed journals, scientific conferences and in social media.

TRIAL REGISTRATION NUMBER

NCT05564195.

A Real-Time Neurophysiologic Stress Test for the Aging Brain: Novel Perioperative and ICU Applications of EEG in Older Surgical Patients

As of 2022, individuals age 65 and older represent approximately 10% of the global population [1], and older adults make up more than one third of anesthesia and surgical cases in developed countries [2, 3]. With approximately > 234 million major surgical procedures performed annually worldwide [4], this suggests that > 70 million surgeries are performed on older adults across the globe each year. The most common postoperative complications seen in these older surgical patients are perioperative neurocognitive disorders including postoperative delirium, which are associated with an increased risk for mortality [5], greater economic burden [6, 7], and greater risk for developing long-term cognitive decline [8] such as Alzheimer's disease and/or related dementias (ADRD). Thus, anesthesia, surgery, and postoperative hospitalization have been viewed as a biological "stress test" for the aging brain, in which postoperative delirium indicates a failed stress test and consequent risk for later cognitive decline (see Fig. 3). Further, it has been hypothesized that interventions that prevent postoperative delirium might reduce the risk of long-term cognitive decline. Recent advances suggest that rather than waiting for the development of postoperative delirium to indicate whether a patient "passed" or "failed" this stress test, the status of the brain can be monitored in real-time via electroencephalography (EEG) in the perioperative period. Beyond the traditional intraoperative use of EEG monitoring for anesthetic titration, perioperative EEG may be a viable tool for identifying waveforms indicative of reduced brain integrity and potential risk for postoperative delirium and long-term cognitive decline. In principle, research incorporating routine perioperative EEG monitoring may provide insight into neuronal patterns of dysfunction associated with risk of postoperative delirium, long-term cognitive decline, or even specific types of aging-related neurodegenerative disease pathology. This research would accelerate our understanding of which waveforms or neuronal patterns necessitate diagnostic workup and intervention in the perioperative period, which could potentially reduce postoperative delirium and/or dementia risk. Thus, here we present recommendations for the use of perioperative EEG as a "predictor" of delirium and perioperative cognitive decline in older surgical patients.

Serum Biomarkers of a Pro-Neuroinflammatory State May Define the Pre-Operative Risk for Postoperative Delirium in Spine Surgery

Advances in spine surgery enable technically safe interventions in older patients with disabling spine disease, yet postoperative delirium (POD) poses a serious risk for postoperative recovery. This study investigates biomarkers of pro-neuroinflammatory states that may help objectively define the pre-operative risk for POD. This study enrolled patients aged ≥60 scheduled for elective spine surgery under general anesthesia. Biomarkers for a pro-neuroinflammatory state included S100 calcium-binding protein β (S100β), brain-derived neurotrophic factor (BDNF), Gasdermin D, and the soluble ectodomain of the triggering receptor expressed on myeloid cells 2 (sTREM2). Postoperative changes of Interleukin-6 (IL-6), Interleukin-1β (IL-1β), and C-reactive protein (CRP) were assessed as markers of systemic inflammation preoperatively, intraoperatively, and early postoperatively (up to 48 h). Patients with POD (n = 19, 75.7 ± 5.8 years) had higher pre-operative levels of sTREM2 (128.2 ± 69.4 pg/mL vs. 97.2 ± 52.0 pg/mL, p = 0.049) and Gasdermin D (2.9 ± 1.6 pg/mL vs. 2.1 ± 1.4 pg/mL, p = 0.29) than those without POD (n = 25, 75.6 ± 5.1 years). STREM2 was additionally a predictor for POD (OR = 1.01/(pg/mL) [1.00-1.03], p = 0.05), moderated by IL-6 (Wald-χ² = 4.06, p = 0.04). Patients with POD additionally showed a significant increase in IL-6, IL-1β, and S100β levels on the first postoperative day. This study identified higher levels of sTREM2 and Gasdermin D as potential markers of a pro-neuroinflammatory state that predisposes to the development of POD. Future studies should confirm these results in a larger cohort and determine their potential as an objective biomarker to inform delirium prevention strategies.

Preoperative characterization of baseline EEG recordings for risk stratification of post-anesthesia care unit delirium

STUDY OBJECTIVE

Delirium in the post-anesthesia care unit (PACU-D) presents a serious condition with a high medical and socioeconomic impact. In particular, PACU-D is among common postoperative complications of elderly patients. As PACU-D may be associated with postoperative delirium, early detection of at-risk patients and strategies to prevent PACU-D are important. We characterized EEG baseline signatures of patients who developed PACU-D following surgery and general anesthesia and patients who did not.

DESIGN AND SETTING

We conducted a post-hoc analysis of preoperative EEG recordings between patients with and without PACU-D, as indicated by positive bCAM scores post general anesthesia and surgery.

PATIENTS AND MEASUREMENTS

Preoperative baseline EEG recordings from 89 patients were recorded at controlled eyes-open (focused wakefulness) and eyes-closed (relaxed wakefulness) conditions. We computed power spectral densities, permutation entropy, spectral entropy and spectral edge frequency to see if these parameters can reflect potential baseline EEG differences between PACU-D (31.5%) and noPACU-D (68.5%) patients. Wilcoxon's Rank Sum Test as well as AUC values were used to determine statistical significance.

MAIN RESULTS

Baseline EEG recordings showed significant differences between PACU-D and noPACU-D patients preoperatively. Compared to the noPACU-D group, PACU-D patients presented with lower power in higher frequencies during relaxed and focused wakefulness alike. These differences in power led to AUC values of 0.73 [0.59;0.85] (permutation entropy) and 0.72 [0.61;0.83] (spectral edge frequency) indicative of a "fair" performance to separate patients with and without PACU-D.

CONCLUSIONS

The baseline EEG of relaxed wakefulness as well as focused wakefulness may be used to assess the risk of developing PACU-D following surgery under general anesthesia. Moreover, routinely used monitoring parameters capture these differences as well, potentially allowing an easy transfer to clinical settings.

CLINICAL TRIAL NUMBER

NCT03775356.

Reduced excitatory neurotransmission in the hippocampus after inflammation and sevoflurane anaesthesia

Background

Inflammation and general anaesthesia likely contribute to perioperative neurocognitive disorders, possibly by causing a neuronal imbalance of excitation and inhibition. We showed previously that treatment with lipopolysaccharide (LPS) and sevoflurane causes a sustained increase in a tonic inhibitory conductance in the hippocampus; however, whether excitatory neurotransmission is also altered remains unknown. The goal of this study was to examine excitatory synaptic currents in the hippocampus after treatment with LPS and sevoflurane. Synaptic plasticity in the hippocampus, a cellular correlate of learning and memory, was also studied.

Methods

Mice were injected with vehicle or LPS (1 mg kg-1 i.p.), and after 24 h they were then exposed to vehicle or sevoflurane (2.3%; 2 h). Hippocampal slices were prepared 48 h later. Excitatory synaptic currents were recorded from pyramidal neurones. Long-term potentiation (LTP) and long-term depression (LTD) were studied in the Schaffer collateral-cornu ammonis 1 pathway.

Results

The amplitude of miniature excitatory postsynaptic currents (EPSCs) was reduced after LPS+sevoflurane (P<0.001), whereas that of spontaneous EPSCs was unaltered, as evidenced by cumulative distribution plots. The frequency, area, and kinetics of both miniature and spontaneous EPSCs were unchanged, as were LTP and LTD.

Conclusions

The reduced amplitude of miniature EPSCs, coupled with the previously reported increase in tonic inhibition, indicates that the combination of LPS and sevoflurane markedly disrupts the balance of excitation and inhibition. Restoring this balance by pharmacologically enhancing excitatory neurotransmission and inhibiting the tonic current may represent an effective therapeutic option for perioperative neurocognitive disorders.

Depth of anesthesia, temperature, and postoperative delirium in children and adolescents undergoing cardiac surgery

BACKGROUND

After pediatric cardiosurgical interventions, postoperative delirium can occur, which can be associated with undesirable consequences during and after the hospital stay. It is therefore important to avoid any factors causing delirium as far as possible. Electroencephalogram (EEG) monitoring can be used during anesthesia to individually adjust dosages of hypnotically acting drugs. It is necessary to gain knowledge about the relationship between intraoperative EEG and postoperative delirium in children.

METHODS

In a dataset comprising 89 children (53 male, 36 female; median age: 0.99 (interquartile range: 0.51, 4.89) years) undergoing cardiac surgery involving use of a heart-lung machine, relationships between depth of anesthesia as measured by EEG (EEG index: Narcotrend Index (NI)), sevoflurane dosage, and body temperature were analyzed. A Cornell Assessment of Pediatric Delirium (CAP-D) score ≥ 9 indicated delirium.

RESULTS

The EEG could be used in patients of all age groups for patient monitoring during anesthesia. In the context of induced hypothermia, EEG monitoring supported individually adjusted sevoflurane dosing. The NI was significantly correlated with the body temperature; decreasing temperature was accompanied by a decreasing NI. A CAP-D score ≥ 9 was documented in 61 patients (68.5%); 28 patients (31.5%) had a CAP-D < 9. Delirious patients with an intubation time ≤ 24 h showed a moderate negative correlation between minimum NI (NImin) and CAP-D (rho = -0.41, 95% CI: -0.70 - -0.01, p = 0.046), i.e., CAP-D decreased with increasing NImin. In the analysis of all patients' data, NImin and CAP-D showed a weak negative correlation (rho = -0.21, 95% CI: -0.40 - 0.01, p = 0.064). On average, the youngest patients had the highest CAP-D scores (p = 0.002). Patients with burst suppression / suppression EEG had a longer median intubation time in the intensive care unit than patients without such EEG (p = 0.023). There was no relationship between minimum temperature and CAP-D score.

CONCLUSIONS

The EEG can be used to individually adjust sevoflurane dosing during hypothermia. Of the patients extubated within 24 h and classified as delirious, patients with deeper levels of anesthesia had more severe delirium symptoms than patients with lighter levels of anesthesia.

Low-Intensity Pulsed Ultrasound Attenuates Postoperative Neurocognitive Impairment and Salvages Hippocampal Synaptogenesis in Aged Mice

Postoperative neurocognitive impairment is an urgent problem with global aging accelerating. The prevention and treatment of postoperative neurocognitive impairment have been widely investigated but lack effective strategies. Low-intensity pulsed ultrasound (LIPUS), a non-invasive tool, has shown an effect on neuroprotection, but whether it could attenuate the postoperative neurocognitive impairment and the underlying mechanisms remains unknown. An experimental setup for LIPUS stimulation of the hippocampus was well established. A laparotomy model in aged mice was applied, and a Morris water maze was used to assess cognitive function. RT-qPCR and western blotting were used to detect levels of Piezo1, synapse-associated proteins in the hippocampus, respectively. Immunofluorescent staining was also used to determine the neural activation and Piezo1 expression. The results showed that LIPUS increased synapse-related proteins of the hippocampus and attenuated cognitive impairment in aged mice. Meanwhile, LIPUS suppressed the overexpression of Piezo1 in the hippocampus. We further found that LIPUS promoted Calpain1 activity and increased extracellular regulated protein kinases (Erk) phosphorylation. Our results suggested that LIPUS could improve cognitive impairment and increase hippocampal synaptogenesis through the Piezo1-mediated Calpain1/ Erk pathway. LIPUS could be used as an effective physical intervention to alleviate postoperative cognitive dysfunction in the aged population.

Advancing our understanding of postoperative cognitive trajectories in older adults

The use of large amounts of uniform electronic data over long periods provides a step toward understanding and ultimately shaping the perioperative cognitive trajectory of older patients. With the improvements in the quality, uniformity, and amount of data contained within the electronic health record, along with developments in machine learning and big data analysis, we can look forward to enhanced studies that will help advance clinical practice and scientific understanding of perioperative brain health, including the severe and debilitating risk of dementia.

Processed electroencephalography-guided general anaesthesia to reduce postoperative delirium: a systematic review and meta-analysis

BACKGROUND

Postoperative delirium (POD) is the most common serious postoperative complication in older adults. It has uncertain aetiology, limited preventative strategies, and poor long-term outcomes. This updated systematic review and meta-analysis aimed to estimate the effect of processed electroencephalography (pEEG)-guided general anaesthesia during surgery on POD incidence.

METHODS

We performed a systematic review and meta-analysis by searching OVID MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials (CENTRAL) electronic databases. Studies of adult patients having general anaesthesia for any surgery where pEEG was used and POD was an outcome measure were included. Full-text reports of RCTs published from database inception until August 28, 2021, were included. Trials were excluded if sedation rather than general anaesthesia was administered, or the setting was intensive care. The primary outcome was POD assessed by validated tools. The study was prospectively registered with PROSPERO.

RESULTS

Nine studies, which included 4648 eligible subjects, were identified. The incidence of POD in the pEEG-guided general anaesthesia or lighter pEEG target group was 19.0% (440/2310) compared with 23.3% (545/2338) in the usual care or deeper pEEG target group (pooled odds ratio=0.78; 95% confidence interval, 0.60-1.00; P=0.054). Significant heterogeneity was detected (I²=53%).

CONCLUSIONS

Our primary analysis demonstrated a highly sensitive result with a pooled analysis of trials in which the intervention group adhered to manufacturer's recommended guidelines, showing reduced incidence of POD with pEEG guidance. High clinical heterogeneity limits inferences from this and any future meta-analyses.

CLINICAL TRIAL REGISTRATION

CRD42020199404 (PROSPERO).

Cognitive deficits after general anaesthesia in animal models: a scoping review

BACKGROUND

It remains controversial whether general anaesthetic drugs contribute to perioperative neurocognitive disorders in adult patients. Preclinical studies have generated conflicting results, likely because of differing animal models, study protocols, and measured outcomes. This scoping review of preclinical studies addressed the question: 'Do general anaesthetic drugs cause cognitive deficits in adult animals that persist after the drugs have been eliminated from the brain?'

METHODS

Reports of preclinical studies in the MEDLINE database published from 1953 to 2021 were examined. A structured review process was used to assess original studies of cognitive behaviours, which were measured after treatment (≥24 h) with commonly used general anaesthetic drugs in adult animals.

RESULTS

The initial search yielded 380 articles, of which 106 were fully analysed. The most frequently studied animal model was male (81%; n=86/106) rodents (n=106/106) between 2-3 months or 18-20 months of age. Volatile anaesthetic drugs were more frequently studied than injected drugs, and common outcomes were memory behaviours assessed using the Morris water maze and fear conditioning assays. Cognitive deficits were detected in 77% of studies (n=82/106) and were more frequent in studies of older animals (89%), after inhaled anaesthetics, and longer drug treatments. Limitations of the studies included a lack of physiological monitoring, mortality data, and risk of bias attributable to the absence of randomisation and blinding.

CONCLUSIONS

Most studies reported cognitive deficits after general anaesthesia, with age, use of volatile anaesthetic drugs, and duration of anaesthesia as risk factors. Recommendations to improve study design and guide future research are presented.

Selective TLR4 Antagonism Prevents and Reverses Morphine-Induced Persistent Postoperative Cognitive Dysfunction, Dysregulation of Synaptic Elements, and Impaired BDNF Signaling in Aged Male Rats

Perioperative neurocognitive disorders (PNDs) are characterized by confusion, difficulty with executive function, and episodic memory impairment in the hours to months following a surgical procedure. Postoperative cognitive dysfunction (POCD) represents such impairments that last beyond 30 d postsurgery and is associated with increased risk of comorbidities, progression to dementia, and higher mortality. While it is clear that neuroinflammation plays a key role in PND development, what factors underlie shorter self-resolving versus persistent PNDs remains unclear. We have previously shown that postoperative morphine treatment extends POCD from 4 d (without morphine) to at least 8 weeks (with morphine) in aged male rats, and that this effect is likely dependent on the proinflammatory capabilities of morphine via activation of toll-like receptor 4 (TLR4). Here, we extend these findings to show that TLR4 blockade, using the selective TLR4 antagonist lipopolysaccharide from the bacterium Rhodobacter sphaeroides (LPS-RS Ultrapure), ameliorates morphine-induced POCD in aged male rats. Using either a single central preoperative treatment or a 1 week postoperative central treatment regimen, we demonstrate that TLR4 antagonism (1) prevents and reverses the long-term memory impairment associated with surgery and morphine treatment, (2) ameliorates morphine-induced dysregulation of the postsynaptic proteins postsynaptic density 95 and synaptopodin, (3) mitigates reductions in mature BDNF, and (4) prevents decreased activation of the BDNF receptor TrkB (tropomyosin-related kinase B), all at 4 weeks postsurgery. We also reveal that LPS-RS Ultrapure likely exerts its beneficial effects by preventing endogenous danger signal HMGB1 (high-mobility group box 1) from activating TLR4, rather than by blocking continuous activation by morphine or its metabolites. These findings suggest TLR4 as a promising therapeutic target to prevent or treat PNDs.SIGNIFICANCE STATEMENT With humans living longer than ever, it is crucial that we identify mechanisms that contribute to aging-related vulnerability to cognitive impairment. Here, we show that the innate immune receptor toll-like receptor 4 (TLR4) is a key mediator of cognitive dysfunction in aged rodents following surgery and postoperative morphine treatment. Inhibition of TLR4 both prevented and reversed surgery plus morphine-associated memory impairment, dysregulation of synaptic elements, and reduced BDNF signaling. Together, these findings implicate TLR4 in the development of postoperative cognitive dysfunction, providing mechanistic insight and novel therapeutic targets for the treatment of cognitive impairments following immune challenges such as surgery in older individuals.

Preoperative Factors Predict Memory Decline After Coronary Artery Bypass Grafting or Percutaneous Coronary Intervention in an Epidemiological Cohort of Older Adults

Background Durable memory decline may occur in older adults after surgical (coronary artery bypass grafting [CABG]) or nonsurgical (percutaneous coronary intervention) coronary revascularization. However, it is unknown whether individual memory risk can be predicted. We reanalyzed an epidemiological cohort of older adults to predict memory decline at ≈1 year after revascularization. Methods and Results We studied Health and Retirement Study participants who underwent CABG or percutaneous coronary intervention at age ≥65 years between 1998 and 2015 and participated in ≥1 biennial postprocedure assessment. Using a memory score based on direct and proxy cognitive tests, we identified participants whose actual postprocedure memory score was 1-2 ("mild") or >2 ("major") SDs below expected postprocedure performance. We modeled probability of memory decline using logistic regression on preoperatively known factors and evaluated model discrimination and calibration. A total of 1390 participants (551 CABG, 839 percutaneous coronary intervention) underwent CABG/percutaneous coronary intervention at 75±6 years old; 40% were women. The cohort was 83% non-Hispanic White, 8.4% non-Hispanic Black, 6.4% Hispanic ethnicity, and 1.7% from other groups masked by the HRS (Health and Retirement Study) to preserve participant confidentiality. At a median of 1.1 (interquartile range, 0.6-1.6) years after procedure, 267 (19%) had mild memory decline and 88 (6.3%) had major memory decline. Factors predicting memory decline included older age, frailty, and off-pump CABG; obesity was protective. The optimism-corrected area under the receiver operator characteristic curve was 0.73 (95% CI, 0.71-0.77). A cutoff of 50% probability of memory decline identified 14% of the cohort as high risk, and was 94% specific and 30% sensitive for late memory decline. Conclusions Preoperative factors can be used to predict late memory decline after coronary revascularization in an epidemiological cohort with high specificity.

Current Recommendations for Perioperative Brain Health: A Scoping Review

Perioperative complications such as stroke, delirium, and neurocognitive dysfunction are common and responsible for increased morbidity and mortality. Our objective was to characterize and synthesize the contemporary guidelines on perioperative brain health for noncardiac, non-neurologic surgery in a scoping review. We performed a structured search for articles providing recommendations on brain health published between 2016 and 2021 and included the following complications: perioperative stroke and perioperative neurocognitive disorders, the latter of which encompasses postoperative delirium and a spectrum of postoperative cognitive dysfunction. We categorized recommendations by subtopic (stroke, postoperative delirium, postoperative cognitive dysfunction), type (disclosure/ethics/policies, prevention, risk stratification, screening/diagnosis, and management), and pharmacological versus nonpharmacological strategies. We noted country of origin, specialty of the authors, evidence grade (if available), and concordance/discordance between recommendations. Eight publications provided 129 recommendations, originating from the United States (n=5), Europe (n=1), United Kingdom (n=1), and China (n=1). Three publications (37%) applied grading of evidence as follows: Grading of Recommendations, Assessment, Development, and Evaluations (GRADE): A, 30%; B, 36%; C, 30%; D, 4%. We identified 42 instances of concordant recommendations (≥2 publications) on 15 themes, including risk factor identification, risk disclosure, baseline neurocognitive testing, nonpharmacological perioperative neurocognitive disorder prevention, intraoperative monitoring to prevent perioperative neurocognitive disorders, avoidance of benzodiazepines, delaying elective surgery after stroke, and emergency imaging and rapid restoration of cerebral perfusion after perioperative stroke. We identified 19 instances of discordant recommendations on 7 themes, including the use of regional anesthesia and monitoring for perioperative stroke prevention, pharmacological perioperative neurocognitive disorder management, and postoperative stroke screening. We synthesized recommendations for clinical practice and highlighted areas where high-quality evidence is required to inform best practices in perioperative brain health.

Frailty Assessment and Prehabilitation Before Complex Spine Surgery in Patients With Degenerative Spine Disease: A Narrative Review

Degenerative spine disease increases in prevalence and may become debilitating as people age. Complex spine surgery may offer relief but becomes riskier with age. Efforts to lessen the physiological impact of surgery through minimally invasive techniques and enhanced recovery programs mitigate risk only after the decision for surgery. Frailty assessments outperform traditional tools of perioperative risk stratification. The extent of frailty predicts complications after spine surgery such as reoperation for infection and 30-day mortality, as well as elements of social cost such as hospital length of stay and discharge to an advanced care facility. Symptoms of spine disease overlap with phenotypic markers of frailty; therefore, different frailty assessment tools may perform differently in patients with degenerative spine disease. Beyond frailty, however, cognitive decline and psychosocial isolation may interact with frailty and affect achievable surgical outcomes. Prehabilitation, which has reduced perioperative risk in colorectal and cardiac surgery, may benefit potential complex spine surgery patients. Typical prehabilitation includes physical exercise, nutrition supplementation, and behavioral measures that may offer symptomatic relief even in the absence of surgery. Nonetheless, the data on the efficacy of prehabilitation for spine surgery remains sparse and barriers to prehabilitation are poorly defined. This narrative review concludes that a frailty assessment-potentially supplemented by an assessment of cognition and psychosocial resources-should be part of shared decision-making for patients considering complex spine surgery. Such an assessment may suffice to prompt interventions that form a prehabilitation program. Formal prehabilitation programs will require further study to better define their place in complex spine care.