Intraoperative ketamine administration to prevent delirium or postoperative cognitive dysfunction: A systematic review and meta-analysis

Postoperative cognitive dysfunction: a concept analysis

BACKGROUND

Post-operative cognitive dysfunction (POCD) is a concern for clinicians that often presents post-surgery where generalized anesthesia has been used. Its prevalence ranges from 36.6% in young adults to 42.4% in older individuals. Conceptual clarity for POCD is lacking in the currently body literature. Our two-fold purpose of this concept analysis was to (1) critically appraise the various definitions, while also providing the best definition, of POCD and (2) narratively synthesize the attributes, surrogate or related terms, antecedents (risk factors), and consequences of the concept.

METHOD

The reporting of our review was guided by the PRISMA statement and the 6-step evolutionary approach to concept analysis developed by Rodgers. Three databases, including Medline, CINAHL, and Web of Science, were searched to retrieve relevant literature on the concept of POCD. Two independent reviewers conducted abstract and full-text screening, data extraction, and appraisal. The review process yielded a final set of 86 eligible articles.

RESULT

POCD was defined with varying severities ranging from subtle-to-extensive cognitive changes (1) affecting single or multiple cognitive domains that manifest following major surgery (2), is transient and reversible, and (3) may last for several weeks to years. The consequences of POCD may include impaired quality of life, resulting from withdrawal from the labor force, increased patients' dependencies, cognitive decline, an elevated risk of dementia, rising healthcare costs, and eventual mortality.

CONCLUSION

This review resulted in a refined definition and comprehensive analysis of POCD that can be useful to both researchers and clinicians. Future research is needed to refine the operational definitions of POCD so that they better represent the defining attributes of the concept.

The impact of perioperative ketamine or esketamine on the subjective quality of recovery after surgery: a meta-analysis of randomised controlled trials

BACKGROUND

This meta-analysis aimed to evaluate the impact of ketamine/esketamine on postoperative subjective quality of recovery (QoR).

METHODS

MEDLINE, Embase, Cochrane library, and Google Scholar were searched for randomised controlled trials (RCTs) that examined the impacts of perioperative ketamine/esketamine use and postoperative QoR. The primary outcome was subjective QoR (QoR-9, QoR-15, QoR-40) on postoperative day (POD) 1-3, whereas the secondary outcomes included pain severity, anxiety scores, depression scores, risk of adverse events (i.e. nausea, vomiting, dizziness, drowsiness), and length of stay.

RESULTS

The analysis included 18 RCTs (1554 participants; ketamine: seven trials, esketamine: 11 trials), of which 15 were conducted in China. Ketamine/esketamine improved the QoR scores on PODs 1 and 2 compared with the control (standardised mean difference [SMD]: 0.63, P<0.0001 for POD 1; SMD: 0.56, P=0.04 for POD 2), without beneficial effect on POD 3. Subgroup analyses revealed significant differences in QoR scores on POD 1 by regimen (SMD: esketamine 1.14, ketamine 0.01) and country (SMD: China 0.82, other countries -0.21). The emotional domain of QoR was improved from PODs 1 to 3, whereas the other domains were only improved on POD 1. Lower postoperative anxiety (SMD: -0.48, P=0.003) and depression (SMD: -0.72, P=0.001) scores were also observed with ketamine/esketamine use. Furthermore, pain severity was reduced on PODs 1 and 2, with no difference in the risk of adverse events or length of stay.

CONCLUSIONS

This meta-analysis demonstrated that ketamine/esketamine use in the perioperative period is associated with improved early subjective QoR, pain severity, and psychological symptoms without an increase in the likelihood of adverse events.

SYSTEMATIC REVIEW PROTOCOL

PROSPERO (CRD42023477580).

Cognitive trajectories after surgery: Guideline hints for assessment and treatment

Elderly patients who undergo major surgery (not-neurosurgical) under general anaesthesia frequently complain about cognitive difficulties, especially during the first weeks after surgical "trauma". Although recovery usually occurs within a month, about one out of four patients develops full-blown postoperative Neurocognitive disorders (NCD) which compromise quality of life or daily autonomy. Mild/Major NCD affect approximately 10% of patients from three months to one year after major surgery. Neuroinflammation has emerged to have a critical role in the postoperative NCDs pathogenesis, through microglial activation and the release of pro-inflammatory cytokines which increase blood-brain-barrier permeability, enhance movement of leukocytes into the central nervous system (CNS) and favour the neuronal damage. Moreover, pre-existing Mild Cognitive Impairment, alcohol or drugs consumption, depression and other factors, together with several intraoperative and post-operative sequelae, can exacerbate the severity and duration of NCDs. In this context it is crucial rely on current progresses in serum and CSF biomarker analysis to frame neuroinflammation levels, along with establishing standard protocol for neuropsychological assessment (with specific set of tools) and to apply cognitive training or neuromodulation techniques to reduce the incidence of postoperative NCDs when required. It is recommended to identify those patients who would need such preventive intervention early, by including them in pre-operative and post-operative comprehensive evaluation and prevent the development of a full-blown dementia after surgery. This contribution reports all the recent progresses in the NCDs diagnostic classification, pathogenesis discoveries and possible treatments, with the aim to systematize current evidences and provide guidelines for multidisciplinary care.

Effect of Esketamine on Postoperative Delirium in Patients Undergoing Cardiac Valve Replacement with Cardiopulmonary Bypass: A Randomized Controlled Trial

BACKGROUND

The aim of this study was to investigate the effects of esketamine on the risk of postoperative delirium (POD) in adults undergoing on-pump cardiac valve surgery.

METHODS

In this randomized, triple-blind, controlled trial, 116 adult patients with an American Society of Anesthesiologists (ASA) grade Ⅱ or Ⅲ and a New York Heart Association (NYHA) grade Ⅱ or Ⅲ who underwent cardiac valve surgery with cardiopulmonary bypass were included. Esketamine (0.25 mg/kg) or normal saline was administered intravenously before anesthesia induction. The primary outcome was POD, defined as a positive delirium assessment according to the 3-minute confusion assessment method (CAM) or the confusion assessment method for the intensive care unit (CAM-ICU) on a twice-daily basis for 7 days after surgery. Delirium duration and the delirium subtype were also recorded. The cognitive status of patients was measured according to the Mini-Mental State Examination at baseline, discharge, 30 days postoperatively and 3 months postoperatively.

RESULTS

A total of 112 patients (mean age, 52 years; 53.6% female) were enrolled; 56 were assigned to receive esketamine, and 56 were assigned to receive placebo. POD occurred in 13 (23.2%) patients in the esketamine group and in 25 (44.6%) patients in the placebo group (relative risk [RR], 0.52, 95% confidence interval [CI], 0.28-0.91; P = .018). Thirteen patients (23.2%) in the esketamine group and 24 (42.9%) patients in the placebo group had multiple episodes of delirium (RR, 0.54, 95% CI, 0.28-0.92), and 13 (23.2%) vs 22 (39.3%) patients exhibited the hyperactive subtype.

CONCLUSIONS

A single dose of esketamine (0.25 mg/kg) injected intravenously before anesthesia induction reduced the incidence of delirium in relatively young patients with ASA grade Ⅱ or Ⅲ who underwent on-pump cardiac surgery.

Effects of S-ketamine added to patient-controlled analgesia on early postoperative pain and recovery in patients undergoing thoracoscopic lung surgery: A randomized double-blinded controlled trial

STUDY OBJECTIVE

To investigate whether the addition of S-ketamine to patient-controlled hydromorphone analgesia decreases postoperative moderate-to-severe pain and improves the quality of recovery (QoR) in patients undergoing thoracoscopic lung surgery.

DESIGN

Single-center prospective randomized double-blinded controlled trial.

SETTING

Tertiary university hospital.

PATIENTS

242 patients undergoing thoracoscopic lung surgery.

INTERVENTIONS

Patients were randomized to receive intravenous patient-controlled analgesia (IV-PCA) with hydromorphone alone or hydromorphone combined with S-ketamine (0.5 mg/kg/48 h, 1 mg/kg/48 h, or 2 mg/kg/48 h).

MEASUREMENTS

Primary outcome was proportion of patients with moderate-to-severe pain. (numerical rating scale [NRS] pain scores ≥4 when coughing) within 2 days after surgery. Postoperative QoR scores and other prespecified outcomes were also recorded.

MAIN RESULTS

Of 242 enrolled patients, 220 were included in the final analysis. The results demonstrated that the incidence of postoperative moderate-to-severe pain was significantly different between the hydromorphone group and combined S-ketamine group (absolute difference, 27.9%; 95% confidence interval [CI], 11.7% to 42.1%; P < 0.001). Patients who received S-ketamine had lower NRS pain scores at rest and when coughing on postoperative day 1 (POD1; median difference 1 and 1, P < 0.001) and postoperative day 2 (POD2; median difference 1 and 1, P < 0.001). The QoR-15 scores were higher in the combined S-ketamine group on POD1 (mean difference 6, P < 0.001) and POD2 (mean difference 6, P < 0.001) than in the hydromorphone group. A higher dose of S-ketamine was associated with deeper sedation. No differences were detected in the other safety outcomes.

CONCLUSIONS

Addition of S-ketamine to IV-PCA hydromorphone significantly reduced the incidence of postoperative moderate-to-severe pain and improved the QoR in patients undergoing thoracoscopic lung surgery.

TRIAL REGISTRATION

Chinese Clinical Trail Register (identifier: ChiCTR2200058890).

Postoperative neurocognitive disorders: A clinical guide

For years, postoperative cognitive outcomes have steadily garnered attention, and in the past decade, they have remained at the forefront. This prominence is primarily due to empirical research emphasizing their potential to compromise patient autonomy, reduce quality of life, and extend hospital stays, and increase morbidity and mortality rates, especially impacting elderly patients. The underlying pathophysiological process might be attributed to surgical and anaesthesiological-induced stress, leading to subsequent neuroinflammation, neurotoxicity, burst suppression and the development of hypercoagulopathy. The beneficial impact of multi-faceted strategies designed to mitigate the surgical and perioperative stress response has been suggested. While certain potential risk factors are difficult to modify (e.g., invasiveness of surgery), others - including a more personalized depth of anaesthesia (EEG-guided), suitable analgesia, and haemodynamic stability - fall under the purview of anaesthesiologists. The ESAIC Safe Brain Initiative research group recommends implementing a bundle of non-invasive preventive measures as a standard for achieving more patient-centred care. Implementing multi-faceted preoperative, intraoperative, and postoperative preventive initiatives has demonstrated the potential to decrease the incidence and duration of postoperative delirium. This further validates the importance of a holistic, team-based approach in enhancing patients' clinical and functional outcomes. This review aims to present evidence-based recommendations for preventing, diagnosing, and treating postoperative neurocognitive disorders with the Safe Brain Initiative approach.

The impact of ketamine on outcomes in critically ill patients: a systematic review with meta-analysis and trial sequential analysis of randomized controlled trials

BACKGROUND

This meta-analysis aims to evaluate the effects of ketamine in critically ill intensive care unit (ICU) patients.

METHODS

We searched for randomized controlled trials (RCTs) in PubMed, Scopus, and the Cochrane Library; the search was performed initially in January but was repeated in December of 2023. We focused on ICU patients of any age. We included studies that compared ketamine with other traditional agents used in the ICU. We synthesized evidence using RevMan v5.4 and presented the results as forest plots. We also used trial sequential analysis (TSA) software v. 0.9.5.10 Beta and presented results as TSA plots. For synthesizing results, we used a random-effects model and reported differences in outcomes of two groups in terms of mean difference (MD), standardized MD, and risk ratio with 95% confidence interval. We assessed the risk of bias using the Cochrane RoB tool for RCTs. Our outcomes were mortality, pain, opioid and midazolam requirements, delirium rates, and ICU length of stay.

RESULTS

Twelve RCTs involving 805 ICU patients (ketamine group, n=398; control group, n=407) were included in the meta-analysis. The ketamine group was not superior to the control group in terms of mortality (in five studies with 318 patients), pain (two studies with 129 patients), mean and cumulative opioid consumption (six studies with 494 patients), midazolam consumption (six studies with 304 patients), and ICU length of stay (three studies with 270 patients). However, the model favored the ketamine group over the control group in delirium rate (four studies with 358 patients). This result is significant in terms of conventional boundaries (alpha=5%) but is not robust in sequential analysis. The applicability of the findings is limited by the small number of patients pooled for each outcome.

CONCLUSIONS

Our meta-analysis did not demonstrate differences between ketamine and control groups regarding any outcome except delirium rate, where the model favored the ketamine group over the control group. However, this result is not robust as sensitivity analysis and trial sequential analysis suggest that more RCTs should be conducted in the future.

Ketofol versus Dexmedetomidine for preventing postoperative delirium in elderly patients undergoing intestinal obstruction surgeries: a randomized controlled study

PURPOSE

Postoperative delirium (POD) is considered the most common postoperative neurological complication in elderly patients. The aim of this study was to evaluate the efficacy of the administration of ketofol versus dexmedetomidine (DEX) for minimizing POD in elderly patients undergoing urgent exploration for intestinal obstruction.

METHODS

This prospective double-blinded randomized clinical trial was conducted on 120 elderly patients undergoing urgent exploration for intestinal obstruction. Patients were randomly allocated to one of the three groups: Group C (control group) patients received normal saline 0.9%, group D received dexmedetomidine, and group K received ketofol (ketamine: propofol was 1:4). The primary outcome was the incidence of POD. Secondary outcomes were incidence of emergence agitation, postoperative pain, consumption of rescue opioids, hemodynamics, and any side effects.

RESULTS

The incidence of POD was statistically significantly lower in ketofol and DEX groups than in the control group at all postoperative time recordings. Additionally, VAS scores were statistically significantly decreased in the ketofol and DEX groups compared to the control group at all time recordings except at 48 and 72 h postoperatively, where the values of the three studied groups were comparable. The occurrence of emergence agitation and high-dose opioid consumption postoperatively were found to be significant predictors for the occurrence of POD at 2 h and on the evening of the 1st postoperative day.

CONCLUSION

The administration of ketofol provides a promising alternative option that is as effective as DEX in reducing the incidence of POD in elderly patients undergoing urgent exploration for intestinal obstruction.

TRIAL REGISTRATION

This clinical trial was approved by the Institutional Review Board (IRB) at Zagazig University (ZU-IRB# 6704// 3/03/2021) and ClinicalTrials.gov (NCT04816162, registration date 22/03/ 2021). The first research participant was enrolled on 25/03/2021).

Prevalence of Delirium After Abdominal Surgery and Association With Ketamine: A Retrospective, Propensity-Matched Cohort Study

IMPORTANCE

Delirium is a common postoperative complication for older patients in the ICU. Ketamine, used primarily as an analgesic, has been thought to prevent delirium.

OBJECTIVE

Determine the prevalence and association of delirium with low-dose ketamine use in ICU patients after abdominal surgery.

DESIGN

Single-center, retrospective, propensity-matched cohort study.

SETTING

Eight hospital academic medical center.

PATIENTS

Cohort comprising 1836 patients admitted to the ICU after abdominal surgery between June 23, 2018 and September 1, 2022.

MAIN OUTCOMES AND MEASURES

Propensity score matching (PSM) with a 3:1 ratio between no-ketamine use and ketamine use was performed through a greedy algorithm (caliper of 0.005). Outcomes of interest included: delirium (assessed by Confusion Assessment Method-ICU), mean pain score (Numeric Pain Scale or Critical Care Pain Observation Tool score as available), mean opioid consumption (morphine milligram equivalents), length of stay (d), and mortality.

RESULTS

Prevalence of delirium was 47.71% (95% CI, 45.41-50.03%) in the cohort. Of 1836 patients, 120 (6.54%) used low-dose ketamine infusion. After PSM, the prevalence of delirium was 56.02% (95% CI, 51.05-60.91%) in all abdominal surgery patients. The ketamine group had 41% less odds of delirium (odds ratio [OR] = 0.59; 95% CI, 0.37-0.94; p = 0.026) than patients with no-ketamine use. Patients with ketamine use had higher mean pain scores (3.57 ± 2.86 vs. 2.21 ± 2.09, p < 0.001). In the subgroup analysis, patients in the ketamine-use group 60 years old or younger had 64% less odds of delirium (OR = 0.36; 95% CI, 0.13-0.95; p = 0.039). The mean pain scores were higher in the ketamine group for patients 60 years old or older. There was no significant difference in mortality and opioid consumption.

CONCLUSIONS AND RELEVANCE

Low-dose ketamine infusion was associated with lower prevalence of delirium in ICU patients following abdominal surgery. Prospective studies should further evaluate ketamine use and delirium.

Association between intraoperative ketamine and the incidence of emergence delirium in laparoscopic surgeries: an observational study

BACKGROUND

Emergence Delirium (ED) is an essential condition in the immediate postoperative period. Systematic review and meta-analysis of randomized controlled trials have concluded that the effect of ketamine on postoperative delirium remains unclear. The present study sought to evaluate if the intraoperative use of ketamine for postoperative analgesia is associated with postoperative ED in laparoscopic surgeries.

METHODS

A prospective observational study was performed in the PostAnesthetic Care Unit (PACU) to evaluate patients who had undergone laparoscopic surgery under a rigid intraoperative anesthesia protocol from July 2018 to January 2019. Patients submitted to laparoscopic surgery for cholecystectomy, oophorectomy, or salpingectomy with a score ≥1 on the Richmond Assessment Sedation Scale (RASS) or ≥2 on the Nursing Delirium Screening Scale (Nu-DESC) were considered to have ED. t-test, Chi-Square test or Fisher's exact tests were used for comparison.

RESULTS

One hundred and fifteen patients were studied after laparoscopic surgery. Seventeen patients (14.8%) developed ED, and the incidence of ED in patients who received ketamine was not different from that of other patients (18.3% vs. 10.6%, p = 0.262). Patients with ED had more postoperative pain and morphine requirement at the PACU (p = 0.005 and p = 0.025, respectively). Type of surgery (general surgery, OR = 6.4, 95% CI 1.2‒35.2) and postoperative pain (OR = 3.7, 95% CI 1.2‒11.4) were risk factors for ED.

CONCLUSION

In this study, no association was found between ED and intraoperative administration of ketamine in laparoscopic surgeries. Type of surgery and postoperative pain were risk factors for ED.

A pre-anesthetic bolus of ketamine versus dexmedetomidine for prevention of postoperative delirium in elderly patients undergoing emergency surgery: a randomized, double-blinded, placebo-controlled study

BACKGROUND

We aimed to evaluate whether a single dose of ketamine or dexmedetomidine before induction of general anesthesia could reduce the incidence of postoperative delirium (primary outcome) or cognitive dysfunction (secondary outcome) in elderly patients undergoing emergency surgery.

PATIENTS AND METHODS

This randomized, double-blinded, placebo-controlled trial included 60 elderly patients who were scheduled for emergency surgery. The patients were randomly assigned into one of three groups (n = 20): group I received 0.9% normal saline, group II received 1 µg/kg dexmedetomidine, and group III received 1 mg/kg ketamine right before anesthesia induction. Patients were observed for three days after surgery and tested for postoperative delirium and cognitive dysfunction using the delirium observation screening scale and the mini-mental state examination score, respectively.

RESULTS

The dexmedetomidine group had the lowest incidence of delirium (p = 0.001) and cognitive dysfunction (p = 0.006) compared to the ketamine and placebo groups. The multivariate logistic regression model revealed that dexmedetomidine reduced the incidence of postoperative delirium by 32% compared to placebo (reference) (OR = 0.684, 95% CI: 0.240-0.971, p = 0.025), whereas ketamine increased the risk by threefold (OR = 3.012, 95% CI: 1.185-9.681, p = 0.013). Furthermore, dexmedetomidine reduced the incidence of postoperative cognitive dysfunction by 62% (OR = 0.375, 95% CI: 0.091-0.543, p = 0.012), whereas ketamine increased the risk by 4.5 times (OR = 4.501, 95% CI: 1.161-8.817, p = 0.006).

CONCLUSION

A single pre-anesthetic bolus of dexmedetomidine is a practical choice for preventing postoperative delirium in elderly patients undergoing emergency surgery.

TRIAL REGISTRATION

This study was approved by the Ethics Committee of Aswan University Hospital (approval number: aswu/548/7/2021; registration date: 06/07/2021) and registered on ClinicalTrials.gov (NCT05341154) (22/04/2022).

Evaluating the effects of S-ketamine on postoperative delirium in elderly patients following total hip or knee arthroplasty under intraspinal anesthesia: a single-center randomized, double-blind, placebo-controlled, pragmatic study protocol

Introduction

Postoperative delirium (POD) is an acute, transient brain disorder associated with decreased postoperative quality of life, dementia, neurocognitive changes, and mortality. A small number of trials have explored the role of S-ketamine in the treatment of POD due to its neuroprotective effects. Surprisingly, these trials have failed to yield supportive results. However, heterogeneity in delirium assessment methodologies, sample sizes, and outcome settings as well as deficiencies in S-ketamine use methods make the evidence provided by these studies less persuasive. Given the severe impact of POD on the health of elderly patients and the potential for S-ketamine to prevent it, we believe that designing a large sample size, and rigorous randomized controlled trial for further evaluation is necessary.

Methods

This is a single-center, randomized, double-blind, placebo-controlled, pragmatic study. Subjects undergoing total hip or knee arthroplasty will be randomized in a 1:1 ratio to intervention (n = 186) and placebo (n = 186) groups. This trial aims to explore the potential role of S-ketamine in the prevention of POD. Its primary outcome is the incidence of POD within 3 postoperative days. Secondary outcomes include the number of POD episodes, the onset and duration of POD, the severity and subtype of POD, pain scores and opioid consumption, sleep quality, clinical outcomes, and safety outcomes.

Discussion

To our knowledge, this is the first pragmatic study that proposes to use S-ketamine to prevent POD. We reviewed a large body of literature to identify potential preoperative confounding variables that may bias associations between the intervention and primary outcome. We will use advanced statistical methods to correct potential confounding variables, improving the test's power and external validity of test results. Of note, the patient population included in this trial will undergo intraspinal anesthesia. Although large, multicenter, randomized controlled studies have found no considerable difference in the effects of regional and general anesthesia on POD, patients receiving intraspinal anesthesia have less exposure to at-risk drugs, such as sevoflurane, propofol, and benzodiazepines, than patients receiving general anesthesia. At-risk drugs have been shown to negatively interfere with the neuroprotective effects of S-ketamine, which may be the reason for the failure of a large number of previous studies. There is currently a lack of randomized controlled studies evaluating S-ketamine for POD prevention, and our trial helps to fill a gap in this area.Trial registration: http://www.chictr.org.cn, identifier ChiCTR2300075796.

Efficacy of intraoperative subanesthetic dose of ketamine/esketamine in preventing postoperative cognitive dysfunction: a systematic review and meta-analysis

Background

Postoperative cognitive dysfunction (POCD) is a common complication after anesthesia surgery, especially in older people, that can persist weeks or months after surgery as a short-term impairment of cognitive abilities, or even for a prolonged duration over years, potentially progressing into permanent cognitive dysfunction. However, the pathogenesis of POCD is not fully understood, and therefore an optimal solution for preventing POCD has yet to be established. Some studies have shown that intraoperative ketamine/esketamine reduces the incidence of POCD, but this remains controversial.

Objectives

We evaluated the effect of intraoperative subanesthetic doses of ketamine/esketamine versus no intervention in adults undergoing general anesthesia surgery on the incidence of POCD.

Data Sources

We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and searched the PubMed, Embase, Ovid, Cochrane, Scopus, and Web of Science databases for the MeSH terms 'ketamine', 'esketamine', and 'Postoperative Cognitive Complications' from database inception to 25 June 2023.

Results

We found no statistically significant difference in the incidence of POCD within 7 days for intraoperative subanesthetic dose of ketamine/esketamine compared with the control group [relative risk (RR) = 0.57, 95% confidence interval (CI): 0.32, 1.01], and the results from the subgroup analysis based on age (>60 years) also revealed that the difference was not statistically significant (RR = 0.49, 95% CI: 0.23, 1.04).

Conclusion

Compared with controls, intraoperative subanesthetic dose of ketamine/esketamine has no advantage in preventing POCD in patients, or in elderly patients. This study provides reference data for POCD research and clinical drug intervention strategies.

Registration

Prospective Register of Systematic Reviews (PROSPERO; registration number CRD42023401159).

Perioperative analgesia in the elderly

The administration of analgesic drugs in elderly patients should take into account age-related physiological changes, loss of efficiency of homeostatic mechanisms, and pharmacological interactions with chronic therapies. Underestimation of pain in patients with impaired cognition is often linked to difficulties in pain assessment. In the preoperative phase, it is essential to assess the physical status, cognitive reserve, and previous chronic pain conditions to plan effective analgesia. Furthermore, an accurate pharmacological history of the patient must be collected to establish any possible interaction with the whole perioperative analgesic plan. The use of analgesic drugs with different mechanisms of action for pain relief in the intraoperative phase is a crucial step to achieve adequate postoperative pain control in older adults. The combined multimodal and opioid-sparing strategy is strongly recommended to reduce side effects. The use of various adjuvants is also preferable. Moreover, the implementation of non-pharmacological approaches may lead to faster recovery. High-quality postoperative analgesia in older patients can be achieved only with a collaborative interdisciplinary team. The aim of this review is to highlight the perioperative pain management strategies in the elderly with a special focus on intraoperative pharmacological interventions.

Postoperative cognitive recovery and prevention of postoperative cognitive complications in the elderly patient

Elderly patients undergoing surgery are at higher risk of life-altering and costly complications. This challenge is increasingly recognized with the growing geriatric surgical population. Advanced age and comorbid conditions, such as disability and frailty that often develop with age, are all independent risk factors of postoperative morbidity and mortality. A common factor in this age group is cognitive impairment, which poses a challenge for the patient and clinician in the perioperative setting. It affects the capacity for informed consent and limits optimization before surgery; furthermore, an existing impairment may progress in severity during the perioperative period, and new onset of signs of delirium or postoperative cognitive dysfunction may arise during postoperative recovery. In this article, we aim to review the current literature examining the latest definitions, diagnostic criteria, and preventive strategies that may ameliorate postoperative cognitive complications.

The effect of intravenous lidocaine on postoperative cognitive dysfunction: a systematic review and meta-analysis

BACKGROUND

Postoperative cognitive dysfunction (POCD) has been reported as a significant complication in elderly patients. Various methods have been proposed for reducing the incidence and severity of POCD. Intravenous lidocaine administration has been reported in the literature to reduce POCD, but the effect of lidocaine remains controversial.

METHODS

We screened Medline, Embase, Cochrane Library, and China National Knowledge Infrastructure (up to April 2022) databases following a search strategy for intravenous lidocaine on POCD. We also screened related bibliographies on lidocaine for POCD. Ten articles comprising 1517 patients were selected and analyzed. We divided the postoperative follow-up period as follows: short term (<30 days), medium term (30-90 days), and long term (>90 days).

OUTCOMES

We found that lidocaine could attenuate the overall incidence of POCD, especially in the short term. There were no differences between lidocaine and placebo on the overall severity of POCD.

CONCLUSION

Lidocaine administered intravenously could attenuate the overall incidence of POCD and its severity in the short term.

Effects of anesthetic adjunctive agents on postoperative cognitive dysfunction in elderly patients undergoing noncardiac surgery: A Bayesian network meta-analysis

BACKGROUND

Elderly patients are prone to postoperative cognitive dysfunction (POCD). The comparison of the effects of anesthetic adjuvant drugs on POCD in elderly patients undergoing noncardiac surgery remains controversial.

METHODS

The final search took place on June 10, 2023. Randomized controlled trials including ketamine, ulinastatin, dexmedetomidine, parecoxib, and midazolam on the prevention and treatment of POCD in elderly undergoing noncardiac surgery were collected. A Bayesian network meta-analysis was performed to quantitatively combine the evidence.

RESULTS

A total of 35 randomized trials were finally included in this systematic review, and the overall risk of bias is Allocation concealment. These anesthetic adjuvant drugs did not show significant differences in preventing POCD on postoperative days 1 and 7 compared with each other, but ulinastatin may be more effective in preventing POCD than dexmedetomidine [odds ratio (OR) = 0.28, 95% confidence interval (CI) = (0.10, 0.71)] and parecoxib [OR = 0.3, 95% CI = (0.10, 0.82 on postoperative day 3. The efficiency ranking results also find that ulinastatin and ketamine might provide better effects regarding POCD prevention.

CONCLUSIONS

Ketamine and ulinastatin might have better effects in preventing POCD in elderly patients undergoing noncardiac surgery. Our meta-analysis provided evidence for the use of ulinastatin and ketamine in the prevention of POCD in elderly patients undergoing noncardiac surgery.

Frailty: the perioperative and anesthesia challenges of an emerging pandemic

Frailty is a complex and multisystem biological process characterized by reductions in physiological reserve. It is an increasingly common phenomena in the surgical population, and significantly impacts postoperative recovery. In this review, we will discuss the pathophysiology of frailty, as well as preoperative, intraoperative, and postoperative considerations for frailty care. We will also discuss the different models of postoperative care, including enhanced recovery pathways, as well as elective critical care admission. With discoveries of new effective interventions, and advances in healthcare information technology, optimized pathways could be developed to provide the best care possible that meets the challenges of perioperative frailty.

Effects of intra-operative administration of subanesthetic s-ketamine on emergence from sevoflurane anesthesia: a randomized double-blind placebo-controlled study

BACKGROUND

Ketamine is administered in the perioperative period for its benefits in analgesia, anti-agitation and anti-depression when administered at a small dose. However, it is not clear whether the intra-operative administration of ketamine would affect emergence under sevoflurane anesthesia. To investigate this effect, we designed this trial.

METHODS

In this randomized, double-blind, placebo-controlled study, we enrolled 44 female patients aged 18-60 who were scheduled to elective laparoscopic gynecological surgeries. All patients were randomly assigned to saline or s-ketamine group. In s-ketamine group, patients received 0.125 mg/kg s-ketamine 30 min after the start of surgery. In saline group, patients were administered the same volume of saline. Sevoflurane and remifentanil were used to maintain general anesthesia. The primary outcome was emergence time. We also assessed postoperative agitation, cognitive function, and delirium. In addition, we collected and analyzed prefrontal electroencephalogram (EEG) during and after general anesthesia.

RESULTS

There were no significant differences in emergence time between s-ketamine group and saline group (10.80 ± 3.77 min vs. 10.00 ± 2.78 min, P = 0.457). Neither postoperative agitation (4 [3, 4] vs. 4 [3, 4], P = 0.835) nor cognitive function (25.84 ± 2.69 vs. 25.55 ± 2.19, P = 0.412) differed between groups. No postoperative delirium was observed in either group. Subanesthetic s-ketamine resulted in active EEG with decreased power of slow (-0.35 ± 1.13 dB vs. -1.63 ± 1.03 dB, P = 0.003), delta (-0.22 ± 1.11 dB vs. -1.32 ± 1.09 dB, P = 0.011) and alpha (-0.31 ± 0.71 dB vs. -1.71 ± 1.34 dB, P = 0.0003) waves and increased power of beta-gamma bands (-0.30 ± 0.89 dB vs. 4.20 ± 2.08 dB, P < 0.0001) during sevoflurane anesthesia, as well as an increased alpha peak frequency (-0.16 ± 0.48 Hz vs. 0.31 ± 0.73 Hz, P = 0.026). EEG patterns did not differ during the recovery period after emergence between groups.

CONCLUSION

Ketamine administered during sevoflurane anesthesia had no apparent influence on emergence time in young and middle-aged female patients undergoing laparoscopic surgery. Subanesthetic s-ketamine induced an active prefrontal EEG pattern during sevoflurane anesthesia but did not raise neurological side effects after surgery.

TRIAL REGISTRATION

Chinese Clinical Trial Registry, ChiCTR2100046479 (date: 16/05/2021).

Several reasons why ketamine as a neuroplastic agent may have failed to prevent postoperative delirium: Implications for future protocols

Ketamine exerts anti-inflammatory, neuroprotective and neuroplastic activity, therefore it may counteract the neurotoxic processes underlying postoperative delirium. However, the majority of studies in this field failed. We identified several pharmacological reasons why these studies may have failed, together with suggestions of how to remediate them. Among them, the interaction with intravenous general anesthetics exerting the opposite effect on GABA interneurons than ketamine may be of principal importance. We suggest biomarkers which may elucidate the influence of this interaction on the different steps of neuroplastic pathways. We hypothesize that administering ketamine before or after general anesthesia could both prevent the interactions and strengthen the effect of ketamine by timing surgery within the climax of ketamine-induced neuroplastic changes or by stabilizing AMPA receptors. It is vital to deal with these questions because the protocols of ongoing studies are based again on the administration of ketamine during general anesthesia (the major identified pitfall).

The Management of Postoperative Cognitive Dysfunction in Cirrhotic Patients: An Overview of the Literature

Background and objectives: Postoperative cognitive dysfunction (POCD) represents a decreased cognitive performance in patients undergoing general anesthesia for major surgery. Since liver cirrhosis is associated with high mortality and morbidity rates, cirrhotic patients also assemble many risk factors for POCD. Therefore, preserving cognition after major surgery is a priority, especially in this group of patients. The purpose of this review is to summarize the current knowledge regarding the effectiveness of perioperative therapeutic strategies in terms of cognitive dysfunction reduction. Data Collection: Using medical search engines such as PubMed, Google Scholar, and Cochrane library, we analyzed articles on topics such as: POCD, perioperative management in patients with cirrhosis, hepatic encephalopathy, general anesthesia in patients with liver cirrhosis, depth of anesthesia, virtual reality in perioperative settings. We included 115 relevant original articles, reviews and meta-analyses, and other article types such as case reports, guidelines, editorials, and medical books. Results: According to the reviewed literature, the predictive capacity of the common clinical tools used to quantify cognitive dysfunction in cirrhotic settings is reduced in perioperative settings; however, novel neuropsychological tools could manage to better identify the subclinical forms of perioperative cognitive impairments in cirrhotic patients. Moreover, patients with preoperative hepatic encephalopathy could benefit from specific preventive strategies aimed to reduce the risk of further neurocognitive deterioration. Intraoperatively, the adequate monitoring of the anesthesia depth, appropriate anesthetics use, and an opioid-sparing technique have shown favorable results in terms of POCD. Early recovery after surgery (ERAS) protocols should be implemented in the postoperative setting. Other pharmacological strategies provided conflicting results in reducing POCD in cirrhotic patients. Conclusions: The perioperative management of the cognitive function of cirrhotic patients is challenging for anesthesia providers, with specific and targeted therapies for POCD still sparse. Therefore, the implementation of preventive strategies appears to remain the optimal attitude. Further research is needed for a better understanding of POCD, especially in cirrhotic patients.

Impact of Ketamine on Quality of Recovery after Laparoscopic Surgery: A Single-Centre Single-Blinded Trial Using the QoR-15 Questionnaire

Background

The quality of recovery is a cluster of patient-related outcomes that emphasise not only pain but different physical and emotional dimensions. Traditionally, ketamine is used to improve postoperative analgesia and avoid opioid consumption and opioid-related side effects.

Objective

The present study sought to evaluate if intraoperative ketamine administration (as a part of multimodal analgesia) influences the quality of recovery after laparoscopic surgery.

Design

A prospective two-armed, single-blinded trial. Settings. Tertiary single-centre trial between July 2021 and January 2022. Patients. From the 146 patients initially admitted to the study, 127 patients were enrolled, 60 in the ketamine group (group K) and 67 in the control group (group NK). Intervention. Both groups received a rigid intraoperative anaesthesia protocol; furthermore, in group K, 0.5 mg/kg of the ideal body weight of ketamine was administered. Main Outcome Measures. The primary outcome was to evaluate the effect of ketamine administration on the postoperative quality of recovery using the Portuguese version of the Quality of Recovery-15 (QoR-15) Questionnaire 24 h after surgery. The total score and minimal clinically significant difference (MCID) of the QoR-15 were compared. Other variables were also assessed such as the presence of emergence delirium (ED), the Numeric Rating Scale (NRS) for pain, and the presence of postoperative nausea and vomiting (PONV).

Results

A total of 127 patients were allocated to the study groups, 60 in group K and 67 in group NK. Regarding the primary outcome, no differences were found in individual categories (15 items) and in the total score of QoR-15 (p=0.214). Concerning improvement (MCID ≥ 8) or worsening (MCID ≤ 8) in quality of recovery, no difference was found between the groups (24 vs. 32 and 6 vs. 6; p=0.776). Finally, no difference was found in secondary postoperative outcomes including ED (p=0.55), NRS (p=0.401), and PONV (p=0.55).

Conclusion

In this study, the administration of ketamine in laparoscopic surgery had no impact on the quality of recovery 24 h after surgery. This trial is registered with NCT03724019.

Effect of Subanesthetic Dose of Esketamine on Perioperative Neurocognitive Disorders in Elderly Undergoing Gastrointestinal Surgery: A Randomized Controlled Trial

Background

Perioperative neurocognitive disorders (PND), including delayed neurocognitive recovery (dNCR) and postoperative cognitive dysfunction (POCD), are common postoperative complications in elderly patients and adversely affect their prognosis. The study was designed to explore the effects of esketamine on postoperative cognitive function in elderly patients who underwent gastrointestinal surgery under general anesthesia and its potential mechanism.

Methods

Eighty-four patients aged 65 and above undergoing gastrointestinal surgery were randomly divided into 2 groups: the esketamine group (group S) and the control group (group C). Group S received intravenous sub-anesthetic doses of esketamine (0.15 mg/kg) 5 minutes before the initiation of surgery, while group C received the same volume of saline. A battery of neuropsychological tests was used to assess cognitive function before surgery, 7 days, and 3 months after surgery. The primary outcome was the incidence of dNCR at 7 days postoperatively and POCD at 3 months postoperatively in both groups. The secondary outcome measures included changes in the levels of serum interleukin-6 (IL-6) and calcium-binding protein β (S100β) before and 1 day after surgery.

Results

The incidence of dNCR in group S was lower than that of group C (18.15% vs 38.24% P=0.033). Contrarily, there was no difference in both groups regarding POCD 3 months postoperatively (6.06% vs 14.37% P=0.247). Plasma IL-6 and S100β levels were significantly elevated in both groups on postoperative day 1 (p<0.05), but esketamine pretreatment reduced these levels to some extent compared with group C (p<0.05).

Conclusion

Sub-anesthetic doses of esketamine might reduce the incidence of dNCR and improve early postoperative cognitive function in elderly patients undergoing gastrointestinal surgery, which might be related to the anti-neuroinflammation effects of esketamine.

Preventing postoperative cognitive dysfunction using anesthetic drugs in elderly patients undergoing noncardiac surgery: a systematic review and meta-analysis

Postoperative cognitive dysfunction (POCD) is a common neurological system disorder in surgical patients. The choice of anesthetic can potentially reduce POCD. The authors performed this network meta-analysis to compare different anesthetic drugs in reducing the incidence of POCD for elderly people undergoing noncardiac surgery. We searched MEDLINE, EMBASE, the Cochrane Library, and the Web of Science for randomized controlled trials comparing the different anesthetic drugs for noncardiac surgery in elderly from inception until July, 2022. The protocol was registered on the PROSPERO database (CRD#42020183014). A total of 34 trials involving 4314 patients undergoing noncardiac surgery in elderly were included. The incidence of POCD for each anesthetic drug was placebo (27.7%), dexmedetomidine (12.9%), ketamine (15.2%), propofol (16.8%), fentanyl (23.9%), midazolam (11.3%), sufentanil (6.3%), sevoflurane (24.0%), and desflurane (28.3%). Pairwise and network meta-analysis showed dexmedetomidine was significantly reducing the incidence of POCD when compared with placebo. Network meta-analysis also suggested dexmedetomidine was significantly reducing the incidence of POCD when compared with sevoflurane. Sufentanil and dexmedetomidine ranked the first and second in reducing the incidence of POCD with the surface under the cumulative ranking curve value of 87.4 and 81.5%. Sufentanil and dexmedetomidine had the greatest possibility to reduce the incidence of POCD for elderly people undergoing noncardiac surgery.

Tau protein plays a role in the mechanism of cognitive disorders induced by anesthetic drugs

Cognitive disorders are mental health disorders that can affect cognitive ability. Surgery and anesthesia have been proposed to increase the incidence of cognitive dysfunction, including declines in memory, learning, attention and executive function. Tau protein is a microtubule-associated protein located in the axons of neurons and is important for microtubule assembly and stability; its biological function is mainly regulated by phosphorylation. Phosphorylated tau protein has been associated with cognitive dysfunction mediated by disrupting the stability of the microtubule structure. There is an increasing consensus that anesthetic drugs can cause cognitive impairment. Herein, we reviewed the latest literature and compared the relationship between tau protein and cognitive impairment caused by different anesthetics. Our results substantiated that tau protein phosphorylation is essential in cognitive dysfunction caused by anesthetic drugs, and the possible mechanism can be summarized as "anesthetic drugs-kinase/phosphatase-p-Tau-cognitive impairment".

Is ketamine infusion effective and safe as an adjuvant of sedation in the PICU? Results from the Ketamine Infusion Sedation Study (KISS)

STUDY OBJECTIVE

We aimed to evaluate the efficacy and safety of ketamine in ensuring comfort and sparing conventional drugs when used as an adjuvant for analgesia and sedation in the Pediatric Intensive Care Unit (PICU) as a continuous infusion (≥12 h).

DESIGN

Observational prospective study.

SETTING

Tertiary-care-center PICU.

PATIENTS

All consecutive patients <18 years who received ketamine for ≥12 h between January 2019 and July 2021.

INTERVENTIONS

ketamine infusion for ≥12 h.

MEASUREMENTS AND MAIN RESULTS

Seventy-seven patients (median age 16 months, Interquartile Range (IQR) 7-43) were enrolled. Twenty-six percent of patients (n = 20) were paralyzed, while 74% (n = 57) were not. The median infusion duration was 90 h (IQR 39-193), with doses between 15 (IQR 15-20) and 30 μg/kg/min (IQR 20-50). At 24 h of ketamine infusion, values of COMFORT-B-Scale (CBS) were significantly lower compared with values pre-ketamine (p < 0.001). Simultaneously, doses/kg/h of opioids and benzodiazepines significantly decreased at 24 h (p < 0.001 and p = 0.002, respectively), while doses/kg/h of propofol (p = 0.500) and dexmedetomidine (p = 0.072) did not significantly change. Seventy-four percent of non-paralyzed patients (42/57) had a decrease in CBS ≥2 points with no increase of concomitant analgosedation drugs. Among paralyzed patients (n = 20), 13 (65%) had no increase of concomitant analgosedation within 24 h after ketamine initiation. Overall, 55/77 (71%) of patients responded to ketamine. The mean and maximum ketamine infusion dosages were significantly higher in the non-responders (p = 0.021 and 0.028, respectively). Eleven patients had adverse events potentially related to ketamine (hypersalivation, systemic hypertension, dystonia/dyskinesia, tachycardia, and agitation) and six patients required intervention (dose reduction, suspension, or pharmacologic therapy). None of the patients developed delirium during ketamine infusion.

CONCLUSIONS

Ketamine used as a continuous infusion in the PICU might represent a valid strategy to ensure comfort and spare opioids and benzodiazepines in difficult-to-sedate PICU patients. Adverse events are minor and easily reversible. Future study will be needed to investigate long-term outcomes.

Prone positioning reduces frontal and hippocampal neuronal dysfunction in a murine model of ventilator-induced lung injury

Prone positioning is an established treatment for severe acute lung injury conditions. Neuronal dysfunction frequently occurs with mechanical ventilation-induced acute lung injury (VILI) and clinically manifests as delirium. We previously reported a pathological role for systemic interleukin 6 (IL-6) in mediating neuronal injury. However, currently no studies have investigated the relationship between prone or supine positioning and IL-6 mediated neuronal dysfunction. Here, we hypothesize that prone positioning mitigates neuronal injury, via decreased IL-6, in a model of VILI. VILI was induced by subjecting C57BL/6J mice to high tidal volume (35 cc/kg) mechanical ventilation. Neuronal injury markers [cleaved caspase-3 (CC3), c-fos, heat shock protein 90 (Hsp90)] and inflammatory cytokines (IL-6, IL-1β, TNF-α) were measured in the frontal cortex and hippocampus. We found statistically significantly less neuronal injury (CC3, c-Fos, Hsp90) and inflammatory cytokines (IL-6, IL-1β, TNF-α) in the frontal cortex and hippocampus with prone compared to supine positioning (p < 0.001) despite no significant group differences in oxygen saturation or inflammatory infiltrates in the bronchoalveolar fluid (p > 0.05). Although there were no group differences in plasma IL-6 concentrations, there was significantly less cortical and hippocampal IL-6 in the prone position (p < 0.0001), indicating supine positioning may enhance brain susceptibility to systemic IL-6 during VILI via the IL-6 trans-signaling pathway. These findings call for future clinical studies to assess the relationship between prone positioning and delirium and for investigations into novel diagnostic or therapeutic paradigms to mitigate delirium by reducing expression of systemic and cerebral IL-6.

Nonopioid Analgesics for the Perioperative Geriatric Patient: A Narrative Review

Management of acute perioperative pain in the geriatric patient can be challenging as the physiologic and pharmacokinetic changes associated with aging may predispose older patients to opioid-related side effects. Furthermore, elderly adults are more susceptible to postoperative delirium and postoperative cognitive dysfunction, which may be exacerbated by both poorly controlled postoperative pain and commonly used pain medications. This narrative review summarizes the literature published in the past 10 years for several nonopioid analgesics commonly prescribed to the geriatric patient in the perioperative period. Nonopioid analgesics are broken down as follows: medications prescribed throughout the perioperative period (acetaminophen and nonsteroidal anti-inflammatory drugs), medications limited to the acute perioperative setting (N-methyl-D-aspartate receptor antagonists, dexmedetomidine, dexamethasone, and local anesthetics), and medications to be used with caution in the geriatric patient population (gabapentinoids and muscle relaxants). Our search identified 1757 citations, but only 33 specifically focused on geriatric analgesia. Of these, only 21 were randomized clinical trials' and 1 was a systematic review. While guidance in tailoring pain regimens that focus on the use of nonopioid medications in the geriatric patient is lacking, we summarize the current literature and highlight that some nonopioid medications may extend benefits to the geriatric patient beyond analgesia.

Inflammatory markers in postoperative cognitive dysfunction for patients undergoing total hip arthroplasty: a meta-analysis

BACKGROUND

Postoperative cognitive dysfunction (POCD) is a poorly understood disorder, very common even after total hip arthroplasty (THA). It is widely considered that inflammation response play a role in the pathogenesis of POCD.

AIMS

The aim of the present study was to investigate whether inflammation cytokine concentrations could serve as biomarkers for POCD in patients undergoing THA.

METHODS

A systematic search of databases was conducted to retrieve publications measuring circulating inflammatory markers of patients with and without POCD after THA. Inflammatory markers identified in more than two studies were pooled. The standardized mean difference (SMD) and the 95% confidence interval (95% CI) were calculated for each outcome. Fail-safe N statistics was calculated to estimate possible publication bias.

RESULTS

The pooled incidence rate of POCD after THA by combining 11 cohort studies was 31%. A total of five inflammatory markers, CRP, S-100B, IL-1β, IL-6 and TNF-α, were assessed. Significantly higher pre-operative CRP (P = 0.012) and S-100B (P < 0.0001) as well as post-operative CPR (P = 0.005) and IL-6 (P < 0.0001) at 6 h were found in POCD compared with non-POCD patients undergoing THA. Fail-safe N statistics revealed that these results are robust.

DISCUSSION

The current evidence suggests that some of the inflammatory markers, including CRP, S-100B, and IL-6, were correlated with the occurrence of POCD after THA.

CONCLUSION

Monitor of inflammatory markers might help early diagnosis of POCD after THA and development of preventive strategies.

Mechanism of Mongolian Medicine Eerdun Wurile in Improving Postoperative Cognitive Dysfunction Through Activation of the PI3K Signaling Pathway

Objective

To study the effect of Eerdun Wurile (EW), a traditional Mongolian medicine, on the cognitive function of rats by activating the IRS-PI3K-AKT-GLUT4 pathway in an animal model of postoperative cognitive dysfunction (POCD).

Methods

Fifty clean-grade adults Sprague Dawley (SD) male rats were assigned to one of five groups: (1) a control group with no anesthesia (Group C), (2) a POCD model group with anesthesia only (Group P), (3) POCD group with low-dose EW treated (Group L), (4) a POCD group with high-dose EW treated (Group H), and (5) a POCD model group with dexmedetomidine treated (Group D) for positive control. The study started 7 days after all rats had acclimated to housing. Rats were trained in the Morris Water Maze navigation 5 days before surgery. All rats underwent the same maze for navigation and spatial exploration experiments on the preoperative day 1 and postoperative days 1, 3, 5, and their learning and memory abilities were assessed. At the end of the water maze experiment, rats were sacrificed to obtain hippocampal tissue. The mRNA levels of IRS-2, PI3K, AKT, and GLUT4 were measured in the hippocampus by real-time PCR, and the expression of IRS-2, PI3K, AKT, and GLUT4 protein in the hippocampus was determined by Western blotting to investigate the potential mechanisms at the molecular level.

Results

Compared to control Group C, Group P, L, H, and D showed prolonged escape latency (P < 0.05) and decreased number of times to cross the platform (P < 0.05) at 1, 3 and 5 days after surgery. Compared to Group P, Group L, H, and D showed a decrease in escape latency with an increased number of crossing the platform at all-time points after surgery (P < 0.05). Within individual P, L, H, and D groups, escape latencies decreased (P < 0.05) and the number of times that the platform was crossed increased (P < 0.05) between postoperative days 3 and 5 compared to postoperative 1 day. Compared to Group C, the mRNA expression of IRS-2, PI3K, AKT and GLUT4 in the hippocampus of P, L, H, and D groups were decreased (P < 0.05). Compared to Group P, IRS-2, PI3K, AKT, and GLUT4 in the hippocampus of L, H, and D groups were increased (P < 0.05). Compared with Group D, the expression levels of IRS-2 and AKT in both L and H groups were higher. The expression level of PI3K in Group L was also higher (P < 0.05) vs Group D. The expression of AKT mRNA in Group H was higher than in Group L (P < 0.05). Compared to Group C, the p-IRS-2/IRS-2 ratio in the hippocampus of Group P was higher than that of Group C (P < 0.05). Compared to Group P, the ratios of p-IRS-2/IRS-2 in Group L, Group H, and Group D were lower, and the ratios of the p-PI3K/PI3K, p-AKT/AKT, and p-GLUT4/GLUT4 were higher (P < 0.05).

Conclusion

Administration of EW showed the effect on the signaling pathway in rats with POCD. The therapeutic effect was better in the low-dose group. This could be related to the insulin downstream signal molecule PI3K and the IRS-PI3K-AKT-GLUT4 signaling pathway.

Perioperative Pain Management Issues Unique to Older Adults Undergoing Surgery: A Narrative Review

INTRODUCTION

The older population is growing and with this growth there is a parallel rise in the operations performed on this vulnerable group. The perioperative pain management strategy for older adults is unique and requires a team-based approach for provision of high-quality surgical care.

METHODS

Literature search was performed using PubMed in addition to review of relevant protocols and guidelines from geriatric, surgical, and anesthesia societies. Systematic reviews and meta-analyses, randomized trials, observational studies, and society guidelines were summarized in this review.

MANAGEMENT

The optimal approach to a pain management strategy for older adults undergoing surgery involves addressing all phases of perioperative care. For example, preoperative assessment of a patient's cognitive function and presence of chronic pain may impact the pain management plan. Consideration should be also given to intraoperative strategies to improve pain control and minimize both the dose and side effects from opioids (e.g. regional anesthetic techniques). Postoperative pain control (e.g. under or over treatment of pain) may impact the development of elderly-specific complications such as postoperative delirium and functional decline. Finally, pain management does not stop after the older adult patient leaves the hospital. Both discharge planning and post-operative clinic follow-up provide important opportunities for collaboration and intervention.

CONCLUSIONS

An opioid-sparing pain management strategy for older adults can be accomplished with a comprehensive and collaborative interdisciplinary strategy addressing all phases of perioperative care.

Cognitive Outcomes after DEXmedetomidine sedation in cardiac surgery: CODEX randomised controlled trial protocol

INTRODUCTION

Older patients undergoing cardiac surgery carry the highest risk for developing major postoperative neurocognitive disorder (postoperative NCD or P-NCD) with up to 25% incidence 3 months after surgery. P-NCD is associated with significant morbidity, mortality, loss of independence, premature retirement and increased healthcare costs. This multicentre randomised trial is investigating the efficacy of postoperative dexmedetomidine sedation in reducing the incidence of major P-NCD after cardiac surgery compared with standard protocols. CODEX will be the largest interventional trial with major P-NCD as the primary outcome.

METHODS AND ANALYSIS

CODEX is recruiting patients ≥60 years old, undergoing elective cardiac surgery and without pre-existing major cognitive dysfunction or dementia. Eligible participants are randomised to receive postoperative dexmedetomidine or standard institutional sedation protocols in the intensive care unit. Baseline preoperative cognitive function is assessed with the computer-based Cogstate Brief Battery. The primary outcome, major P-NCD, 3 months after surgery is defined as a decrease in cognitive function ≥1.96 SD below age-matched, non-operative controls. Secondary outcomes include delirium, major P-NCD at 6/12 months, depressive symptoms, mild P-NCD and quality of surgical recovery at 3/6/12 months. The specific diagnostic criteria used in this protocol are consistent with the recommendations for clinical assessment and management of NCD from the Nomenclature Consensus Working Group on perioperative cognitive changes. Intention-to-treat analysis will compare major P-NCD at 3 months between study groups.

ETHICS AND DISSEMINATION

CODEX was approved by Sunnybrook Health Sciences Centre Research Ethics Board (REB) (Project ID 1743). This will be the first multicentre, randomised controlled trial to assess the efficacy of a pharmacological intervention to reduce the incidence of major P-NCD after cardiac surgery in patients ≥60 years old. Dissemination of the study results will include briefings of key findings and interpretation, conference presentations and peer-reviewed publications.

TRIAL REGISTRATION NUMBER

NCT04289142.

Methodology of measuring postoperative cognitive dysfunction: a systematic review

BACKGROUND

Postoperative cognitive dysfunction (POCD) is an adverse outcome that impacts patients' quality of life. Its diagnosis relies on formal cognitive testing performed before and after surgery. The substantial heterogeneity in methodology limits comparability and meta-analysis of studies. This systematic review critically appraises the methodology of studies on POCD published since the 1995 Consensus Statement and aims to provide guidance to future authors by providing recommendations that may improve comparability between future studies.

METHODS

This systematic review of literature published between 1995 and 2019 included studies that used baseline cognitive testing and a structured cognitive test battery, and had a minimal follow-up of 1 month. For cohorts with multiple publications, data from the primary publication were supplemented with available data from later follow-up studies.

RESULTS

A total of 274 unique studies were included in the analysis. In the included studies, 259 different cognitive tests were used. Studies varied considerably in timing of assessment, follow-up duration, definition of POCD, and use of control groups. Of the 274 included studies, 70 reported POCD as a dichotomous outcome at 1 to <3 months, with a pooled incidence of 2998/10 335 patients (29.0%).

CONCLUSIONS

We found an overwhelming heterogeneity in methodology used to study POCD since the publication of the 1995 Consensus Statement. Future authors could improve study quality and comparability through optimal timing of assessment, the use of commonly used cognitive tests including the Consensus Statement 'core battery', application of appropriate cut-offs and diagnostic rules, and detailed reporting of the methods used.

PROSPERO REGISTRY NUMBER

CRD42016039293.

Safety of treatment options available for postoperative pain

IntroductionPostoperative pain is one of the most common adverse events after surgery and has been shown to increase the risk of other complications. On the other hand, liberal opioid use in the perioperative period is also associated with risk of adverse events. The current consensus is therefore to provide multimodal, opioid minimizing analgesia after surgery.Areas CoveredIn this review, we will discuss the benefits and risks associated with non-opioid analgesics, including non-steroidal anti-inflammatory drugs, gabapentinoids, ketamine, α-2 agonists, and corticosteroids. In addition, we will discuss the general and block-specific risks associated with regional anesthestic techniques.Expert OpinionAdverse events associated with non-opioid analgesics are rare outside their specific contraindicated patient groups, especially when dosed appropriately. α-2 agonists can cause transient hypotension and bradycardia, and gabapentinoids may cause sedation in higher risk patient populations. Regional anesthesia techniques are generally safe when done by an experienced practitioner. We therefore encourage the development of standardized multimodal analgesic protocols, which may facilitate opioid minimization and lead to better patient outcomes.

Ketamine vs. haloperidol for prevention of cognitive dysfunction and postoperative delirium: A phase IV multicentre randomised placebo-controlled double-blind clinical trial

STUDY OBJECTIVE

Delirium is frequently observed in the postoperative and intensive care unit (ICU) population. Due to the multifactorial origin of delirium and according to international guidelines (e.g., American Geriatrics Society; Prevention and Management of Pain, Agitation/Sedation, Delirium, Immobility, and Sleep Disruption (PADIS) guideline), there are several but no incontestable options for prevention and symptomatic treatment. The purpose of the Baden PRIDe (Prevention and Reduction of Incidence of postoperative Delirium) trial was to determine whether postoperative cognitive dysfunction and delirium could be prevented by the combination of possible preventive agents such as haloperidol and ketamine. In addition, pre- and postoperative levels of the biomarkers cortisol, neuron specific enolase (NSE) and S100β were measured to investigate their dynamics in delirious and non-delirious patients after surgery.

DESIGN

The Baden PRIDe Trial was an investigator-initiated, phase IV, two-centre, randomised, placebo-controlled, double-blind clinical trial.

SETTING

Perioperative care.

PATIENTS

182 adult patients that underwent elective or emergency surgery under general or combined (i.e., general and regional) anaesthesia.

INTERVENTIONS

Pre-anaesthetic, pharmacologic prevention of postoperative brain dysfunction with haloperidol, ketamine, and the combination of both vs. placebo.

MEASUREMENTS

Assessment of cognitive performance pre- and postoperatively with the MMSE, the DOS, the Nursing Delirium Screening Scale (Nu-DESC) or the Intensive Care Delirium Screening Checklist (ICDSC) during ICU stay.

MAIN RESULTS

None of the three study arms - haloperidol, ketamine, or both drugs combined - was significantly superior to placebo for prevention of postoperative brain dysfunction and delirium (P = 0.39). Measured levels of postoperative cortisol were significantly higher in delirious patients. S-100β levels were significantly higher in all postoperative outcome groups (cognitive impairment, delirium, no cognitive decline), whereas postoperative NSE levels declined in all groups.

CONCLUSIONS

The study results offer no possibility for a novel recommendation for prevention of postoperative cognitive decline including delirium. Perioperative S-100β trajectories in patients with cognitive deterioration suggest affection of glial cells in particular.

TRIAL REGISTRATION

ClinicalTrials.govNCT02433041; registered on April 7, 2015.

The Effects of Anesthesia on Adult Hippocampal Neurogenesis

In animal studies, prolonged sedation with general anesthetics has resulted in cognitive impairments that can last for days to weeks after exposure. One mechanism by which anesthesia may impair cognition is by decreasing adult hippocampal neurogenesis. Several studies have seen a reduction in cell survival after anesthesia in rodents with most studies focusing on two particularly vulnerable age windows: the neonatal period and old age. However, the extent to which sedation affects neurogenesis in young adults remains unclear. Adult neurogenesis in the dentate gyrus (DG) was analyzed in male and female rats 24 h after a 4-h period of sedation with isoflurane, propofol, midazolam, or dexmedetomidine. Three different cell populations were quantified: cells that were 1 week or 1 month old, labeled with the permanent birthdate markers EdU or BrdU, respectively, and precursor cells, identified by their expression of the endogenous dividing cell marker proliferating cell nuclear antigen (PCNA) at the time of sacrifice. Midazolam and dexmedetomidine reduced cell proliferation in the adult DG in both sexes but had no effect on postmitotic cells. Propofol reduced the number of relatively mature, 28-day old, neurons specifically in female rats and had no effects on younger cells. Isoflurane had no detectable effects on any of the cell populations examined. These findings show no general effect of sedation on adult-born neurons but demonstrate that certain sedatives do have drug-specific and sex-specific effects. The impacts observed on different cell populations predict that any cognitive effects of these sedatives would likely occur at different times, with propofol producing a rapid but short-lived impairment and midazolam and dexmedetomidine altering cognition after a several week delay. Taken together, these studies lend support to the hypothesis that decreased neurogenesis in the young adult DG may mediate the effects of sedation on cognitive function.

Pharmacological Agents That Prevent Postoperative Cognitive Dysfunction in Patients With General Anesthesia: A Network Meta-analysis

BACKGROUND

Postoperative cognitive dysfunction (POCD) is associated with prolonged hospital stays, increased mortality, and negative socioeconomic consequences. Dexmedetomidine, ketamine, dexamethasone, and lidocaine have previously been reported to be effective for preventing POCD.

STUDY QUESTION

In this network meta-analysis, we apply direct and indirect comparisons to rank these pharmacological agents in terms of their effect on POCD, through which we seek to provide evidence for future clinical medication.

DATA SOURCES

A comprehensive literature search of PubMed, EMBASE, the Cochrane Library, and Web of Science was conducted to identify randomized controlled trials that examined the effects of dexmedetomidine, ketamine, dexamethasone, or lidocaine on POCD induced by general anesthesia.

STUDY DESIGN

For eligible studies, 2 reviewers independently extracted data and assessed the respective risk of bias. Bayesian network meta-analysis was conducted using R-3.4.1 software. A total of 30 articles were included in this meta-analysis.

RESULTS

Direct comparison showed that dexmedetomidine [odds ratio (OR) = 0.42, 95% confidence interval (CI): 0.32-0.55] may decrease the incidence of POCD for noncardiac surgery; dexmedetomidine (OR = 0.08, 95% CI: 0.01-0.63) and ketamine (OR = 0.09, 95% CI: 0.02-0.32) were found to decrease POCD for cardiac surgery. The R-software ranking result for prevention of POCD was dexmedetomidine, lidocaine, ketamine, placebo, and dexamethasone, respectively, in noncardiac surgery, and dexmedetomidine, ketamine, lidocaine, placebo, and dexamethasone in cardiac surgery.

CONCLUSION

Dexmedetomidine exhibited obvious superiority to other agents for noncardiac surgery; dexmedetomidine and ketamine exhibited a significantly better performance than other agents for cardiac surgery. Dexamethasone did not show better efficacy than the placebo. However, more rigorously designed studies comprising larger sample sizes are needed to confirm our findings.

A randomized controlled trial for measuring effects on cognitive functions of adding ketamine to propofol during sedation for colonoscopy

BACKGROUND

The purpose of this study was to evaluate the effects of adding ketamine to propofol on cognitive functions in patients undergoing sedation for colonoscopy.

METHODS

In this randomized, double-blinded, and controlled study, 200 patients were randomly allocated to ketamine/propofol admixture group (Group KP, n = 100), and propofol group (Group P, n = 100). Patients in Group KP received 0.25 mg/kg of ketamine and 0.5 mg/kg of propofol. Patients in Group P received 0.5 mg/kg propofol. Cognitive functions were measured using CogState battery before and after the colonoscopy procedure. Ninety five patients in Group KP and 92 patients in Group P had completed the CogStates tests and were included in the data analysis.

RESULTS

Compared with before procedure baseline, the performance on detection and identification tasks were significantly impaired after the procedure in both Group KP (P = .004, P = .001) and Group P patients (P = .005, P < .001). However, one-card learning accuracy and One-back memory was only impaired in Group KP patients (P = .006, P = .040) after the endoscopy but left intact in Group P patients. Group KP patients showed more severe impairment in one-card learning accuracy compared with Group P patients (P = .044). Group KP patients have better 5 minutes MAP (P = .005) and were also less likely to suffer from complications such as respiratory depression (P = .023) and hypotension (P = .015). OAA/S scores, BIS, MAP, complications, recovery times, and endoscopist and patient satisfaction were similar between the 2 groups.

CONCLUSION

Although adding ketamine to propofol for sedation in colonoscopy provided fewer complications such as respiratory depression and hypotension, it also causes more impairment in cognitive functions.

Postoperative cognitive dysfunction in elderly patients undergoing hip arthroplasty

Even after successful hip arthroplasty, elderly patients who have undergone this procedure remain subject to cognitive decline and may collectively develop postoperative cognitive dysfunction (POCD). However, no consensus exists as to the risk factors resulting in a higher likelihood that a patient may present with this complication, and the aetiology of POCD is not well understood. We conducted a systematic review of papers concerning the influence of POCD-related risk factors in patients undergoing hip arthroplasty but limited the literature search to papers in English. A systematic and electronic search for manuscripts in the PubMed database was performed in order to identify all studies in which the risk factors for POCD were investigated. Articles were also obtained from the authors' files. Keywords for the search were postoperative cognitive dysfunction/change/impairment/decline/deficit, elderly/older/aged patients, and hip arthroplasty/replacement surgery. The evidence published to date suggests that POCD is a multifactorial disease, which includes an individual patient's characteristics, surgery, type of anaesthesia, and pain levels. All of these factors can increase the risk of POCD incidence. There are a number of factors that appear to influence the risk of early cognitive dysfunction after hip arthroplasty. Nevertheless, the specific mechanism and explicit risk factors associated with this cognitive dysfunction are not completely understood. Hip arthroplasty has made it possible for older patients to find relief from pain and improve their function, whereas it also increases the risk for suffering POCD that may affect these patients' quality of life and increase their mortality. Therefore, it is worthwhile investigating the mechanism of POCD in future studies in order to prevent and treat this condition.

Ketamine promotes the neural differentiation of mouse embryonic stem cells by activating mTOR

Ketamine is a widely used general anesthetic and has been reported to demonstrate neurotoxicity and neuroprotection. Investigation into the regulatory mechanism of ketamine on influencing neural development is of importance for a better and safer way of relieving pain. Reverse transcription‑quantitative polymerase chain reaction and western blotting were used to detect the critical neural associated gene expression, and flow cytometry to detect the neural differentiation effect. Hence, in the present study the underlying mechanism of ketamine (50 nM) on neural differentiation of the mouse embryonic stem cell (mESC) line 46C was investigated. The results demonstrated that a low dose of ketamine (50 nM) promoted the differentiation of mESCs to neural stem cells (NSCs) and activated mammalian target of rapamycin (mTOR) by upregulating the expression levels of phosphorylated (p)‑mTOR. Furthermore, inhibition of the mTOR signaling pathway by rapamycin or knockdown of mTOR suppressed neural differentiation. A rescue experiment further confirmed that downregulation of mTOR inhibited the promotion of neural differentiation induced by ketamine. Taken together, the present study indicated that a low level of ketamine upregulated p‑mTOR expression levels, promoting neural differentiation.