Intraoperative xenon for prevention of delirium after on-pump cardiac surgery: a randomised, observer-blind, controlled clinical trial

Characteristics associated with effectiveness in postoperative delirium research: a systematic review of randomised controlled trials with meta-regression and meta-analysis

BACKGROUND

Postoperative delirium remains prevalent despite extensive research through randomised trials aimed at reducing its incidence. Understanding trial characteristics associated with interventions' effectiveness facilitates data interpretation.

METHODS

Trial characteristics were extracted from eligible trials identified through two systematic literature searches. Multivariable meta-regression was used to investigate trial characteristics associated with effectiveness estimated using odds ratios. Meta-analysis was used to investigate pooled effectiveness.

RESULTS

We identified 201 eligible trials. Compared with China, trials from the USA/Canada (ratio of odds ratio, 1.89; 95% confidence interval, 1.45-2.45) and Europe/Australia/New Zealand (1.67; 1.29-2.18) had an 89% and 67% higher odds ratio, respectively, suggesting reduced effectiveness. The effectiveness was enhanced when the incidence of postoperative delirium increased (0.85; 0.79-0.92, per 10% increase). Trials with concerns related to deviations from intended interventions reported increased effectiveness compared with those at low risk (0.69; 0.53-0.90). Compared with usual care, certain interventions appeared to have reduced the incidence of postoperative delirium in low-risk trials with low-to-moderate certainty of evidence. However, these findings should be considered inconclusive because of challenges in grouping heterogeneous interventions, the limited number of eligible trials, the prevalence of small-scale studies, and potential publication bias.

CONCLUSIONS

The effectiveness of postoperative delirium trials varied based on the region of trial origin, the incidence of delirium, and the risk of bias. The limitations caution against drawing definitive conclusions from different bodies of evidence. These findings highlight the imperative need to improve the quality of research on a global scale.

SYSTEMATIC REVIEW PROTOCOL

PROSPERO (CRD42023413984).

The role of perioperative sedative anesthetics in preventing postoperative delirium: a systematic review and network-meta analysis including 6679 patients

OBJECTIVE

Postoperative delirium is a common and debilitating complication that significantly affects patients and their families. The purpose of this study is to investigate whether there is an effective sedative that can prevent postoperative delirium while also examining the safety of using sedatives during the perioperative period.

METHODS

The net-meta analysis was used to compare the incidence of postoperative delirium among four sedatives: sevoflurane, propofol, dexmedetomidine, and midazolam. Interventions were ranked according to their surface under the cumulative ranking curve (SUCRA).

RESULTS

A total of 41 RCT studies involving 6679 patients were analyzed. Dexmedetomidine can effectively reduce the incidence of postoperative delirium than propofol (OR 0.47 95% CI 0.25-0.90), midazolam (OR 0.42 95% CI 0.17-1.00), normal saline (OR 0.42 95% CI 0.33-0.54) and sevoflurane (OR 0.39 95% CI 0.18-0.82). The saline group showed a significantly lower incidence of bradycardia compared to the group receiving dexmedetomidine (OR 0.55 95% CI 0.37-0.80). In cardiac surgery, midazolam (OR 3.34 95%CI 2.04-5.48) and normal saline (OR 2.27 95%CI 1.17-4.39) had a higher rate of postoperative delirium than dexmedetomidine, while in non-cardiac surgery, normal saline (OR 1.98 95%CI 1.44-2.71) was more susceptible to postoperative delirium than dexmedetomidine.

CONCLUSION

Our analysis suggests that dexmedetomidine is an effective sedative in preventing postoperative delirium whether in cardiac surgery or non-cardiac surgery. The preventive effect of dexmedetomidine on postoperative delirium becomes more apparent with longer surgical and extubation times. However, it should be administered with caution as it was found to be associated with bradycardia.

Effects of xenon anesthesia on postoperative neurocognitive disorders: a systematic review and meta-analysis

The latest clinical trials have reported conflicting outcomes regarding the effectiveness of xenon anesthesia in preventing postoperative neurocognitive dysfunction; thus, this study assessed the existing evidence. We searched the PubMed, Embase, Cochrane Library, and Web of Science databases from inception to April 9, 2023, for randomized controlled trials of xenon anesthesia in postoperative patients. We included English-language randomized controlled studies of adult patients undergoing surgery with xenon anesthesia that compared its effects to those of other anesthetics. Duplicate studies, pediatric studies, and ongoing clinical trials were excluded. Nine studies with 754 participants were identified. A forest plot revealed that the incidence of postoperative neurocognitive dysfunction did not differ between the xenon anesthesia and control groups (P = 0.43). Additionally, xenon anesthesia significantly shortened the emergence time for time to opening eyes (P < 0.001), time to extubation (P < 0.001), time to react on demand (P = 0.01), and time to time and spatial orientation (P = 0.04). However, the Aldrete score significantly increased with xenon anesthesia (P = 0.005). Postoperative complications did not differ between the anesthesia groups. Egger's test for bias showed no small-study effect, and a trim-and-fill analysis showed no apparent publication bias. In conclusion, xenon anesthesia probably did not affect the occurrence of postoperative neurocognitive dysfunction. However, xenon anesthesia may effectively shorten the emergence time of certain parameters without adverse effects.

Appraisal of Postoperative Outcomes of Volatile and Intravenous Anesthetics: A Network Meta-Analysis of Patients Undergoing Cardiac Surgery

OBJECTIVES

To determine the relative efficacy of specific regimens used as primary anesthetics, as well as the potential combination of volatile and intravenous anesthetics among patients undergoing cardiac, thoracic, and vascular surgery.

DESIGN

This frequentist, random-effects network meta-analysis was registered prospectively (CRD42022316328) and conducted according to the PRISMA-NMA framework. Literature searches were conducted up to April 1, 2022 across relevant databases. Risk of bias (RoB) and confidence of evidence were assessed by RoB-2 and CINeMA, respectively. Pooled treatment effects were compared with propofol monotherapy.

SETTING

Fifty-three randomized controlled trials (N = 8,085) were included, of which 46 trials (N = 6,604) enrolled patients undergoing cardiac surgery.

PARTICIPANTS

Trials enrolling adults (≥18) undergoing cardiac, thoracic, and vascular surgery, using the same induction regimens, and comparing volatile and/or total intravenous anesthesia for the maintenance of anesthesia. Given that the majority of trials focused on those undergoing cardiac surgery and the heterogeneity, analyses were restricted to this population.

MEASUREMENT AND MAIN RESULTS

Outcomes of interest included intensive care unit (ICU) length of stay (LOS), myocardial infarction, in-hospital and 30-day mortality, stroke, and delirium. Across 19 trials (N = 1,821; 9 arms; I2 = 64.5%), sevoflurane combined with propofol decreased ICU LOS (mean difference [MD] -18.26 hours; 95% CI -34.78 to -1.73 hours), whereas midazolam with propofol (MD 17.51 hours; 95% CI 2.78-32.25 hours) was associated with a significant increase in ICU LOS, when compared with propofol monotherapy. Among 27 trials (N = 4,080; 10 arms; I2 = 0%), midazolam was associated with significantly greater risk of myocardial infarction versus propofol (risk ratio 1.94; 95% CI 1.01-3.71). There were no significant differences across other outcomes.

CONCLUSION

In patients undergoing cardiac surgery, sevoflurane with propofol was associated with decreased ICU LOS compared with propofol monotherapy. Midazolam with propofol increased ICU LOS compared with propofol alone. The combined use of intravenous and volatile anesthetics should be explored further. Future trials in thoracic and vascular surgery are warranted.

Noble gas and neuroprotection: From bench to bedside

In recent years, inert gases such as helium, argon, and xenon have gained considerable attention for their medical value. Noble gases present an intriguing scientific paradox: although extremely chemically inert, they display a remarkable spectrum of clinically useful biological properties. Despite a relative paucity of knowledge about their mechanisms of action, some noble gases have been used successfully in clinical practice. The neuroprotection elicited by these noble gases has been investigated in experimental animal models of various types of brain injuries, such as traumatic brain injury, stroke, subarachnoid hemorrhage, cerebral ischemic/reperfusion injury, and neurodegenerative diseases. Collectively, these central nervous system injuries are a leading cause of morbidity and mortality every year worldwide. Treatment options are presently limited to thrombolytic drugs and clot removal for ischemic stroke, or therapeutic cooling for other brain injuries before the application of noble gas. Currently, there is increasing interest in noble gases as novel treatments for various brain injuries. In recent years, neuroprotection elicited by particular noble gases, xenon, for example, has been reported under different conditions. In this article, we have reviewed the latest in vitro and in vivo experimental and clinical studies of the actions of xenon, argon, and helium, and discuss their potential use as neuroprotective agents.

The effects of anesthesia methods and anesthetics on postoperative delirium in the elderly patients: A systematic review and network meta-analysis

Study objective

Postoperative delirium (POD) is one of the serious postoperative complications in elderly patients, which is always related to long-term mortality. Anesthesia is often considered a risk factor for POD. This systematic review and network meta-analysis (NMA) aimed to assess the impact of different anesthesia methods and anesthetics on POD.

Measurements

We searched for studies published in PubMed, Embase, Web of Science, Scopus, and Cochrane Library (CENTRAL) from inception to 18 March 2022. RevMan 5.3 and CINeMA 2.0.0 were used to assess the risk of bias and confidence. Data analysis using STATA 17.0 and R 4.1.2. STATA 17.0 was used to calculate the surface under the cumulative ranking curve (SUCRA) and provide network plots with CINeMA 2.0.0. NMA was performed with R 4.1.2 software gemtc packages in RStudio.

Main results

This NMA included 19 RCTs with 5,406 patients. In the pairwise meta-analysis results, only regional anesthesia (RA) with general anesthesia (GA) vs. GA (Log OR: –1.08; 95% CI: –1.54, –0.63) were statistically different in POD incidence. In the NMA results, there was no statistical difference between anesthesia methods, and psoas compartment block (PCB) with bupivacaine was superior to the desflurane, propofol, sevoflurane, and spinal anesthesia with bupivacaine of POD occurrence.

Conclusion

Our study indicated that RA and GA had no significant effect on POD, and there was no difference between anesthesia methods. Pairwise meta-analysis showed that, except for RA with GA vs. GA, the rest of the results were not statistically different. Besides, PCB with bupivacaine may benefit to reduce POD incidence.

Systematic review registration

https://www.crd.york.ac.uk/prospero/dis play_record.php?ID=CRD42022319499, identifier PROSPERO 2022 CRD42022319499.

Perioperative neurocognitive disorders: A narrative review focusing on diagnosis, prevention, and treatment

Perioperative neurocognitive disorders (NCDs) refer to neurocognitive abnormalities detected during the perioperative periods, including preexisting cognitive impairment, preoperative delirium, delirium occurring up to 7 days after surgery, delayed neurocognitive recovery, and postoperative NCD. The Diagnostic and Statistical Manual of Mental Disorders‐5th edition (DSM‐5) is the golden standard for diagnosing perioperative NCDs. Given the impracticality of using the DSM‐5 by non‐psychiatric practitioners, many diagnostic tools have been developed and validated for different clinical scenarios. The etiology of perioperative NCDs is multifactorial and includes predisposing and precipitating factors. Identifying these risk factors is conducive to preoperative risk stratification and perioperative risk reduction. Prevention for perioperative NCDs should include avoiding possible contributors and implementing nonpharmacologic and pharmacological interventions. The former generally includes avoiding benzodiazepines, anticholinergics, prolonged liquid fasting, deep anesthesia, cerebral oxygen desaturation, and intraoperative hypothermia. Nonpharmacologic measures include preoperative cognitive prehabilitation, comprehensive geriatric assessment, implementing fast‐track surgery, combined use of regional block, and sleep promotion. Pharmacological measures including dexmedetomidine, nonsteroidal anti‐inflammatory drugs, and acetaminophen are found to have beneficial effects. Nonpharmacological treatments are the first‐line measures for established perioperative NCDs. Pharmacological treatments are still limited to severely agitated or distressed patients.

A systematic review of strategies for preventing delirium in patients undergoing vascular surgery

OBJECTIVES

Elderly patients undergoing vascular surgery are at risk of developing postoperative delirium, which is associated with a high mortality. Delirium prevention is difficult and is investigated in surgical patients from various specialisms, but little is known about delirium prevention in vascular surgery. For this reason we performed a systematic review on strategies for delirium prevention in patients undergoing elective surgery for peripheral arterial disease or for an aneurysm of the abdominal aorta.

METHODS

This systematic review included studies describing strategies for preventing delirium in patients undergoing elective surgery for peripheral arterial disease or for an aneurysm of the abdominal aorta. The search was conducted using the keywords 'vascular surgery', 'prevention' and 'delirium', and was last run on October 21st, 2021 in the electronic databases Pubmed, MEDLINE, Embase, Web of Science, the Cochrane library and Emcare. Risk of bias was assessed using the Cochrane Risk of Bias tool for randomized controlled trials and the ROBINS-1 tool for observational studies.

RESULTS

Four studies including 565 patients were included in the systematic review. A significant decrease in the incidence of delirium was reported by a study investigating the effect of comprehensive geriatric assessments within patients undergoing surgery for an aneurysm of the abdominal aorta or lower limb bypass surgery (24% in the control group versus 11% in the intervention group, p = 0.018), and in the total group of a study evaluating the effect of outpatient clinic multimodal prehabilitation for patients with an aneurysm of the abdominal aorta (11.7% in the control group versus 8.2% in the intervention group, p = 0.043, OR = 0.56). A non-significant decrease in delirium incidence was described for patients receiving a multidisciplinary quality improvement at the vascular surgical ward (21.4% in the control group versus 14.6% in the intervention group, p = 0.17). The study concerning the impact of the type of anaesthesia on delirium in eleven older vascular surgical patients, of which three developed delirium, did not differentiate between the different types of anaesthesia the patients received.

CONCLUSION

Despite the high and continuous increasing incidence of delirium in the growing elderly vascular population, little is known about effective preventive strategies. An approach to address multiple risk factors simultaneously seems to be promising in delirium prevention, whether through multimodal prehabilitation or comprehensive geriatric assessments. Several strategies including prehabilitation programs have been proven to be successful in other types of surgery and more research is required to evaluate effective preventive strategies and prehabilitation programs in vascular surgical patients.

Effects of Atorvastatin Therapy on Postoperative Delirium After Malignant Tumor Surgeries in Older Adults

INTRODUCTION

Postoperative delirium (POD) is one of the prevalent and potentially fatal clinical conditions, leading to high disability and mortality in older patients, as well as increased duration of hospital stay and more hospitalization expenses. There were no effective drugs in the clinical management of POD, and an absence of evidence-based medicine concerning the treatment of POD.

MATERIALS AND METHODS

The present study explored whether atorvastatin (Ato) can decrease the occurrence rate of POD. The present research included patients over the age of 60 who were hospitalized to critical care units (ICUs) following surgery for malignant tumors. Patients received Ato (40mg/day) or placebos utilizing a computer-based random sequencing (in a 1:1 ratio). The primary outcome measure was the occurrence of delirium within the first seven days following surgery.

RESULTS

A total of 230 individuals were classified into two groups, namely the placebo group (n=123) and the Ato group (n=107). Patients belonging to two groups had similar baseline clinical data, and there were no statistically significant differences between them. The occurrence of delirium in the Ato group was remarkably reduced unlike the case in the placebo group. 30-day all-cause mortality did not vary significantly between the two groups. Pulmonary infection and Bedsore were significantly decreased in the Ato group than the placebo group, there were no statistically significant differences between the two groups in rhabdomyolysis and abnormal liver enzymes. In terms of medication responses, there were no statistically significant differences between the two groups. Ato patients had remarkably shortened hospital stays and spent remarkably less on hospitalization expenditures in comparison with those in the placebo group.

CONCLUSION

The findings from the present research indicated that Ato can decrease the occurrence of delirium following surgical operation of malignant tumors among elderly patients, it also can reduce the duration of hospitalization, hospital cost, and post-surgical complications, but not improve 30-day all-cause mortality.

REGISTRATION NUMBER

ChiCTR-IPR-17011984.

Postoperative delirium and quality of life after transcatheter and surgical aortic valve replacement: A prospective observational study

OBJECTIVE

In older patients, postoperative delirium is a frequently occurring complication after surgical aortic valve replacement, leading to an excess in postoperative morbidity and mortality. It remains controversial whether transcatheter aortic valve implantation and minimally invasive surgical aortic valve replacement can reduce the risk of postoperative delirium. This study aimed to compare the incidence of postoperative delirium after transcatheter aortic valve implantation and surgical aortic valve replacement and the impact on long-term outcomes.

METHODS

Between September 2018 and January 2020, we conducted an observational, prospective cohort study in patients aged 70 years or more undergoing transcatheter aortic valve implantation or surgical aortic valve replacement. The primary end point was the incidence of in-hospital postoperative delirium during 5 postoperative days assessed with the Confusion Assessment Method. Secondary end points included perioperative inflammation, postoperative complications, health status (EuroQol 5-dimensional questionnaire 5 levels), and mortality up to 6 months. Transcatheter aortic valve implantation and surgical aortic valve replacement were compared using propensity weighting to account for important baseline differences (European System for Cardiac Operative Risk Evaluation II, age, and frailty).

RESULTS

We included 250 patients with a mean (standard deviation) age of 80 (±5.8) years and a European System for Cardiac Operative Risk Evaluation score of 5 (±4.7). In the propensity-weighted analysis, those undergoing surgical aortic valve replacement (N = 166) had a higher incidence of postoperative delirium compared with transcatheter aortic valve implantation (N = 84) (51% vs 15%: P < .0001). Furthermore, patients undergoing surgical aortic valve replacement experienced more inflammation, a greater depth of anesthesia, and more intraoperative hypotension. After surgical aortic valve replacement, 41% of patients experienced an improved health status compared with 12% after transcatheter aortic valve implantation (P < .0001). No outcome differences were noted within the surgical aortic valve replacement groups.

CONCLUSIONS

Transcatheter aortic valve implantation is associated with a lower risk for postoperative delirium. Nevertheless, patients undergoing surgical aortic valve replacement experience the greatest improvement in quality of life. Heart teams should consider these outcomes in shared decision-making in the choice of transcatheter aortic valve implantation or surgical aortic valve replacement.

Noble gases and neuroprotection: summary of current evidence

PURPOSE OF REVIEW

To summarize the current data on neuroprotection derived by noble gas treatment focusing on xenon and argon.

RECENT FINDINGS

Both xenon and argon have demonstrated neuroprotective properties in an array of disease models. However, current data for argon after traumatic brain injury (TBI) is conflicting. Recent human data is only available for xenon showing some beneficial aspects (fewer adverse events) but no effect on outcomes, such as incidence of postoperative delirium.

SUMMARY

Promising results are available for neuroprotection derived by noble gas treatment. Results for xenon are more consistent than those for argon. The mechanism of action of xenon (noncompetitive NMDA-receptor inhibition) is also better understood compared with that of argon. The evidence for argon's neuroprotective actions (particularly after TBI) remains uncertain.

Comparing the effect of xenon and sevoflurane anesthesia on postoperative neural injury biomarkers: a randomized controlled trial

General anesthesia and surgery are associated with an increase in neural injury biomarkers. Elevations of these neural injury biomarkers in the perioperative period are associated with postoperative delirium. Xenon has been shown to be protective against a range of neurological insults in animal models. It remains to be seen if xenon anesthesia is neuroprotective in the perioperative setting in humans. Twenty-four participants scheduled for lithotripsy were randomized to receive either xenon or sevoflurane general anesthesia. There was no statistically significant difference in the concentrations of postoperative neural injury biomarkers between the xenon and sevoflurane group. Following the procedure there was a significant increase in the concentration from baseline of all three biomarkers at 1 hour post-induction with a return to baseline at 5 hours. General anesthesia for lithotripsy was associated with a significant increase at 1 hour post-induction in the neural injury biomarkers total tau, neurofilament light and tau phosphorylated at threonine 181, a marker of tau phosphorylation. The protocol was approved by the St. Vincent’s Hospital Melbourne Ethics Committee (approval No. HREC/18/SVHM/221) on July 20, 2018 and was registered with the Australia New Zealand Clinical Trials Registry (registration No. ACTRN12618000916246) on May 31, 2018.

Pharmacological strategies to prevent postoperative delirium: a systematic review and network meta-analysis

Background

Postoperative delirium (POD) is a condition of cerebral dysfunction and a common complication after surgery. This study aimed to compare and determine the relative efficacy of pharmacological interventions for preventing POD using a network meta-analysis.

Methods

We performed a systematic and comprehensive search to identify and analyze all randomized controlled trials until June 29, 2020, comparing two or more pharmacological interventions, including placebo, to prevent or reduce POD. The primary outcome was the incidence of POD. We performed a network meta-analysis and used the surface under the cumulative ranking curve (SUCRA) values and rankograms to present the hierarchy of the pharmacological interventions evaluated.

Results

According to the SUCRA value, the incidence of POD decreased in the following order: the combination of propofol and acetaminophen (86.1%), combination of ketamine and dexmedetomidine (86.0%), combination of diazepam, flunitrazepam, and pethidine (84.8%), and olanzapine (75.6%) after all types of anesthesia; combination of propofol and acetaminophen (85.9%), combination of ketamine and dexmedetomidine (83.2%), gabapentin (82.2%), and combination of diazepam, flunitrazepam, and pethidine (79.7%) after general anesthesia; and ketamine (87.1%), combination of propofol and acetaminophen (86.0%), and combination of dexmedetomidine and acetaminophen (66.3%) after cardiac surgery. However, only the dexmedetomidine group showed a lower incidence of POD than the control group after all types of anesthesia and after general anesthesia.

Conclusions

Dexmedetomidine reduced POD compared with the control group. The combination of propofol and acetaminophen and the combination of ketamine and dexmedetomidine seemed to be effective in preventing POD. However, further studies are needed to determine the optimal pharmacological intervention to prevent POD.

Efficacy of xenon anesthesia in preventing postoperative cognitive dysfunction after cardiac and major non-cardiac surgeries in elderly patients: a topical review

Elderly patients undergoing major cardiac and non-cardiac surgeries have a high propensity (up to 40–60%) of developing postoperative cognitive dysfunction, which are caused by patient’s factors, type of surgery, intraoperative and postoperative factors. All these pose a challenge to the clinicians. The noble gas xenon does not undergo metabolism or any kind of biotransformation in the body owing to its inert nature. Xenon confers excellent hemodynamic stability and provides excellent recovery at the end of surgery. This topical review discusses advantages of xenon anesthesia in elderly patients undergoing major cardiac and non-cardiac surgeries and whether it is worth using a costly anesthetic in elderly patients for preventing postoperative cognitive dysfunction.

Propofol plus low-dose dexmedetomidine infusion and postoperative delirium in older patients undergoing cardiac surgery

BACKGROUND

Postoperative delirium (POD) is a frequent complication in older patients. Dexmedetomidine might be effective in decreasing the incidence of POD. We hypothesised that adding low-dose rate dexmedetomidine infusion to a propofol sedation regimen would have fewer side-effects and would counteract the possible delirium producing properties of propofol, resulting in a lower risk of POD than propofol with placebo.

METHODS

In this double-blind placebo-controlled trial, patients ≥60 yr old undergoing on-pump cardiac surgery were randomised 1:1 to the following postoperative sedative regimens: a propofol infusion and dexmedetomidine (0.4 μg kg^-1 h^-1) or a propofol infusion and saline 0.9% (placebo group). The study drug was started at chest closure and continued for 10 h. The primary endpoint was in-hospital POD, assessed using the Confusion Assessment Method and chart review method.

RESULTS

POD over the course of hospital stay occurred in 31/177 (18%) and 33/172 (19%) patients in the dexmedetomidine and placebo arm, respectively (P=0.687; odds ratio=0.89; 95% confidence interval, 0.52-1.54). The incidence of POD in the intensive care alone, or on the ward alone, was also not significantly different between the groups. Subjects in the dexmedetomidine group spent less median time in a delirious state (P=0.026). Median administered postoperative norepinephrine was significantly higher in the dexmedetomidine group (P<0.001). One patient in the dexmedetomidine group and 10 patients in the placebo group died in the hospital.

CONCLUSIONS

Adding low-dose rate dexmedetomidine to a sedative regimen based on propofol did not result in a different risk of in-hospital delirium in older patients undergoing cardiac surgery. With a suggestion of both harm and benefit in secondary outcomes, supplementing postoperative propofol with dexmedetomidine cannot be recommended based on this study.

CLINICAL TRIAL REGISTRATION

NCT03388541.