Dexmedetomidine versus propofol sedation in reducing delirium among older adults in the ICU: A systematic review and meta-analysis

Comparing Hypothermic and Thermal Neutral Conditions to Induce Metabolic Suppression

Suppressing metabolism in astronauts could decrease CO2 production. It is unknown whether active cooling is required to suppress metabolism in sedated patients. We hypothesized that hypothermia would have an additive effect with dexmedetomidine on suppressing metabolism. This is a randomized crossover trial of healthy subjects receiving sedation with dexmedetomidine and exposure to a cold (20°C) or thermal neutral (31°C) environment for 3 hours. We measured heart rate, blood pressure, core temperature, resting oxygen consumption (VO2), resting carbon dioxide production (VCO2), and resting energy expenditure (REE) at baseline and each hour of exposure to either environment. We also evaluated components of the Defense Automated Neurobehavioral Assessment (DANA) Brief to evaluate the effect of metabolic suppression on cognition. Six subjects completed the study. Heart rate and core temperature were lower during the cold (56 bpm) condition than the thermal neutral condition (67 bpm). VO2, VCO2, and REE decreased between baseline and the 3-hour measurement in the cold condition (Δ = 0.9 mL/min, 56.94 mL/min, 487.9 Kcal/D, respectively). DANA simple response time increased between baseline and start of recovery in both conditions (20°C 136.9 cognitive efficiency [CE] and 31°C 87.83 CE). DANA procedural reaction time increased between baseline and start of recovery in the cold condition (220.6 CE) but not in the thermal neutral condition. DANA Go/No-Go time increased between baseline and start of recovery in both conditions (20°C 222.1 CE and 31°C 122.3 CE). Sedation and cold environments are required for metabolic suppression. Subjects experienced decrements in cognitive performance in both conditions. A significant recovery period may be required after metabolic suppression before completing mission critical tasks.

Co-administration of dexmedetomidine with total intravenous anaesthesia in carotid endarterectomy reduces requirements for propofol and improves haemodynamic stability: A single-centre, prospective, randomised controlled trial

BACKGROUND

Total intravenous anaesthesia guided by electroencephalography and neurophysiological monitoring may be used for carotid endarterectomy. Reduction of brain metabolic demand during cross-clamping of the internal carotid artery with propofol titrated to burst suppression requires effect-site concentrations that may delay emergence and interfere with intraoperative neurophysiological monitoring.

OBJECTIVE

To test the hypothesis that dexmedetomidine decreases the effect-site concentration of propofol required for burst-suppression in patients undergoing carotid endarterectomy.

DESIGN

Randomised controlled trial.

PARTICIPANTS

Patients undergoing carotid endarterectomy.

SETTING

University Hospital of Berne, Switzerland, from October 2018 to September 2024.

INTERVENTIONS

Patients were randomised into a control ( n  = 23) and a dexmedetomidine groups ( n  = 22). Total intravenous anaesthesia was administered to both groups. Patients in the dexmedetomidine group received an intravenous bolus of dexmedetomidine (0.4 μg kg -1 over 10 min) before induction, followed by a continuous intravenous infusion (0.4 μg kg -1  h -1 ). The effect-site concentrations of propofol were titrated against frontal electroencephalography parameters. Burst suppression was induced with propofol during cross-clamping of the internal carotid artery.

OUTCOME MEASURES

The primary outcome was the effect-site concentration of propofol required for burst-suppression. The secondary outcomes were the requirement for vasoactive substances, neurophysiological monitoring parameters, and postoperative delirium.

RESULTS

The effect-site concentration of propofol required for burst suppression was 4.0 μg ml -1 [3.50 to 4.90] (median [interquartile range]) in the dexmedetomidine group compared with 6.0 μg ml -1 [5.5 to 7.3] in the control group ( P  < 0.001). Less norepinephrine was required in the dexmedetomidine group (total 454 μg [246 to 818] compared with 1000 μg [444 to 1326] ( P  = 0.015) in the control group). Dexmedetomidine did not affect intraoperative neurophysiological monitoring.

CONCLUSION

Co-administration of dexmedetomidine to total intravenous anaesthesia for carotid endarterectomy decreased the effect-site concentrations of propofol required for burst suppression by 33%. The propofol-sparing effect and peripheral alpha-agonism of dexmedetomidine may explain the reduced requirement for vasopressors.

TRIAL REGISTRATION

Clinicaltrials.gov identifier: NCT04662177.

Effects of Implementing an Enhanced Recovery After Cardiac Surgery Protocol with On-Table Extubation on Patient Outcome and Satisfaction-A Before-After Study

Background/Objectives: Enhanced recovery after surgery (ERAS) protocols aim to improve clinical outcomes, shorten hospital length of stay (LOS), and reduce costs through a multidisciplinary perioperative approach. Although introduced in colorectal surgery, they are less established in cardiac surgery, especially in combination with on-table extubation (OTE). This study evaluates the impact of a novel ERAS concept with OTE (RERACS) in elective aortic-valve-replacement and coronary bypass surgery. Methods: In a monocentric study, we compared a prospective RERACS-group (n = 114) to a retrospective control group (n = 119) (TRIAL Registration (DRKS00031402). The RERACS concept contained multiple perioperative treatment measures such as respiratory training, short fasting, and OTE. The control group received standard care. Results: Primary endpoint: postoperative LOS. Secondary measurements: length of postoperative vasoactive drug support, duration of mechanical ventilation, complication rate, and patient satisfaction on the second postoperative day. RERACS patients showed significantly shorter postoperative length of stay (ICU: 40 ± 34 h vs. 56 ± 51 h, p = 0.005; hospital: 9 ± 4 d vs. 11 ± 6 d, p = 0.028), lower nosocomial infection rates (24% vs. 40%), fewer cases of postoperative cognitive dysfunction ((subsyndromal) delirium 40% vs. 57%), reduced nausea and vomiting (14.9% vs. 32.8%), and faster weaning from catecholamines (22 ± 30 h vs. 42 ± 48 h, p < 0.001), as well as high patient satisfaction. Conclusions: Our study indicated that an ERAS concept with OTE is safe and associated with faster and improved recovery, including lower catecholamine requirements, reduced LOS, and high patient satisfaction in low-risk cardiac surgery.

Effect of perioperative application of dexmedetomidine on post-operative stress reaction, pain and prognostic adverse effects in patients undergoing gynaecological laparoscopy

INTRODUCTION

The aim of this study was to analyse the effect of perioperative dexmedetomidine (DEX) application on stress response, post-operative pain and prognosis in patients undergoing gynaecologic laparoscopy.

PATIENTS AND METHODS

One hundred and sixty-eight patients admitted for gynaecologic laparoscopic surgery from May 2020 to November 2022 were included in the study. The patients were randomly divided into pre-operative DEX group ( n = 56), intraoperative DEX group ( n = 56) and post-operative DEX group ( n = 56) according to the application of DEX in the perioperative period. The visual analogue scale (VAS), time awake, extubation time, pneumoperitoneum time, post-anaesthesia care unit (PACU) stay time and Richmond agitation-sedation scale score (RASS) were recorded.

RESULTS

Patients in both the pre-operative and intraoperative DEX groups had substantially shorter wakeup and extubation times than those in the post-operative DEX group. Patients in the pre-operative DEX group had considerably shorter wakeup and extubation times than those in the intraoperative DEX group, and their pneumoperitoneum time was significantly shorter than that of the post-operative DEX group ( P < 0.001). The RASS scores of the pre-operative DEX group and intraoperative DEX group were significantly lower than those of the post-operative DEX group at 1 h, 6 h and 12 h after surgery. Meanwhile, at all time periods, the RASS scores of patients in the pre-operative DEX group were considerably lower than those in the intraoperative DEX group ( P < 0.01). The VAS scores of patients in the pre-operative DEX group and intraoperative DEX group were evidently lower than those in the post-operative DEX group at 0.5 h, 2 h and 12 h postoperatively, and the VAS scores of patients in the pre-operative DEX group were markedly lower than those in the intraoperative DEX group ( P < 0.001). The incidence of nausea and vomiting was significantly lower in the pre-operative DEX group than in the intraoperative DEX group and the post-operative DEX group at 0-2 h, >2-12 h and >12-24 h postoperatively ( P < 0.001). The incidence of nausea and vomiting in the intraoperative DEX group was significantly lower than that in the post-operative DEX group from 0 to 2 h after surgery ( P < 0.05). The incidence of adverse reactions was not significantly different amongst the three groups of patients ( P > 0.05).

CONCLUSION

Pre-operative and intraoperative application of DEX can help reduce post-operative pain and stress responses, help patients recover quickly after surgery and improve patient prognosis, especially the pre-operative application of DEX.

The effect of two different modes of anaesthesia maintenance on postoperative delirium in elderly patient with low preoperative mini-cog score

BACKGROUND

Postoperative delirium is a common distressing symptom experienced following laparoscopic cholecystectomy. The study aimed to investigate the influence of a low preoperative Mini-Cog testing score and 2 different anesthesia methods: total intravenous anaesthesia (TIVA) versus sevoflurane, on postoperative delirium in elderly patients undergoing laparoscopic cholecystectomy.

METHODS

A total of 84 patients over 60 years old who underwent laparoscopic cholecystectomy between March 1and - October 1 2023 were included in the study. Patients with a Mini-Cog score of 0-2 were considered to have low and possibly impaired neurocognitive function. We invastigated the effects of preoperative Mini-Cog score and the two anesthesia methods used on the incidence of postoperative delirium.

RESULTS

The proportion of patients with low Mini-Cog score in the preoperative period was 17.9%. Sevoflurane and TIVA was used in 41 and 43 patients respectively. The incidence of postoperative delirium in patients with low preoperative Mini-Cog scores was 66.7% at postoperative 0 h and 33.3% at the 1st hours. Postoperative delirium was found to be statistically higher in patients with low Mini-cog scores than in those with negatively-screened for Mini-cog scores (p: 0.01-0.035). In patients using sevoflurane, the incidence of postoperative delirium was 26.8% and 24.4% at the 0 and 1st hours, respectively. This was found to be statistically higher than in patients receiving TIVA (p: 0.036 - 0.010).

CONCLUSION

Low Mini-Cog score was an indicator of a higher risk of early postoperative delirium. Sevoflurane is more likely to cause postoperative delirium than TIVA.

TRIAL REGISTRATION

The study was registered on ClinicalTrials.gov (Identifier: NCT06597812) .

Propofol Promoted the Cell Growth and Epithelial Mesenchymal Transformation of the HTR-8/SVneo Cells through Targeting the METTL3 Mediated ZEB2

Preeclampsia (PE) belongs to hypertensive disorder complicating pregnancy, which is a serious obstetric complication. Propofol is a new type of fast and short-acting general anesthetic, which has also been demonstrated to promote the cell growth recently. Therefore, this study was carried out to explore the effects of propofol on the cell growth, migration and invasion in the HTR-8/SVneo cells. The cell biological behaviors were analyzed using CCK-8, EdU, transwell assays. The relationship between METTL3 and ZEB2 was confirmed by RIP assay. Western blot and RT-qPCR assays were carried out to detect the protein and mRNA levels. The results showed that propofol enhanced the cell viability, proliferation, migration and invasion of the HTR-8/SVneo cells. Besides, METTL3 overexpression neutralized the propofol role. Furthermore, METTL3 overexpression elevated the m6A levels of ZEB2 and decreased the mRNA levels and stability of ZEB2. ZEB2 overexpression neutralized the role of METTL3 in the propofol treated HTR-8/SVneo cells. In conclusion, this study demonstrated the effects of propofol on promoting the cell growth, migration and invasion of HTR-8/SVneo cells. Mechanistically, propofol indirectly regulated ZEB2 expression by targeting METTL3 mediated m6A methylation modification.

Effect of age and ICU types on mortality in invasive mechanically ventilated patients with sepsis receiving dexmedetomidine: a retrospective cohort study with propensity score matching

Background: Dexmedetomidine is recommended for sedation in patients on mechanical ventilation. Whether age or ICU types could alter mortality in invasive mechanically ventilated patients with sepsis receiving dexmedetomidine is unknown. Methods: We included patients with sepsis receiving invasive mechanical ventilation from the Medical Information Mart for Intensive Care IV database. The exposure was intravenous dexmedetomidine administration during ICU stay. The primary outcome was 28-day mortality. The secondary outcomes were the length of ICU stay and liberation from invasive mechanical ventilation. Propensity score matching (PSM) and Cox proportional hazards regression were used to adjust for confounders and investigate any association. Restricted cubic spline models were used to evaluate potential nonlinear associations. Results: The pre-matched and propensity score-matched cohorts included 5,871 and 2016 patients, respectively. In the PSM cohorts, dexmedetomidine exposure was related to lower 28-day mortality (186 [17.7%] vs. 319 [30.3%]; p < 0.001). Patients receiving dexmedetomidine, regardless of whether they were younger (≤65 years; hazard ratio [HR], 0.31; 95% confidence interval [CI], 0.23-0.42; p < 0.001) or elderly (>65 years; HR, 0.65; 95% CI, 0.52-0.83; p < 0.001), was associated with lower 28-day mortality (61 [10.3%] vs. 168 [28.2%] for younger; 125 [27.2%] vs. 152 [33.0%] for elderly). Patients receiving dexmedetomidine was also associated with lower 28-day mortality (53 [12.6%] vs. 113 [26.5%] for surgical intensive care unit [SICU]; 133 [21.0%] vs. 206 [32.9%] for non-SICU) regardless of whether the first admission to the SICU (HR, 0.36; 95% CI, 0.25-0.50; p < 0.001) or non-SICU (HR, 0.50; 95% CI, 0.40-0.62; p < 0.001). Moreover, both dose and duration of dexmedetomidine administration were related to lower 28-day mortality than no dexmedetomidine in younger patients (p < 0.001), but it not statistically significant in elderly patients. Conclusion: Dexmedetomidine was associated with lower 28-day mortality in critically ill patients with sepsis receiving invasive mechanical ventilation, regardless of whether patients were younger or elderly, the first admission to the SICU or non-SICU.

Different Sedation Strategies in Older Patients Receiving Spinal Anesthesia for Hip Surgery on Postoperative Delirium: A Randomized Clinical Trial

Background

Postoperative delirium (POD) is of great concern as a complication of surgery in older adult patients. Sedation strategies influence the development of POD. This study compared how sedation strategies administered during spinal anesthesia influenced POD in patients aged ≥65 years undergoing elective surgery for hip fracture repair.

Patients and Methods

A randomized clinical trial was conducted from 1 August 2021 to 30 June 2022 at a single academic medical center. Two hundred and twenty-six patients were randomly divided into four groups: lighter sedation with propofol (LP), heavier sedation with propofol (HP), lighter sedation with dexmedetomidine (LD), and heavier sedation with dexmedetomidine (HD). The incidence of delirium was the primary outcome and was assessed daily by the blinded Confusion Assessment Method.

Results

There was a significant association between dexmedetomidine (LD+HD group) and a lower incidence of delirium (11.9% [13/109] vs the propofol group (23.6% [26/110]; Risk ratio, 0.51; 95% CI, 0.274 to 0.929; p=0.024). In the propofol group, heavier sedation had a higher rate of POD (32.7% [18/55] vs the lighter sedation group (14.5% [8/55]; Risk ratio, 2.25; 95% CI, 1.069 to 4.736; p=0.025).

Conclusion

Dexmedetomidine was associated with a lower incidence of delirium than that with propofol among older patients with hip fractures. In patients that received propofol, heavier sedation was associated with high incidence of POD.

Trends in use of antipsychotics and psychoactive drugs in older patients after major surgery

BACKGROUND

Professional society guidelines recommend limiting the use of antipsychotics in older patients with postoperative delirium. How these recommendations affected the use of antipsychotics and other psychoactive drugs in the postoperative period has not been studied.

METHODS

This retrospective cohort study included patients 65 years or older without psychiatric diagnoses who underwent major surgery in community hospitals (CHs) and academic medical centers (AMCs) in the United States. The outcome was the rate of hospital days exposed to antipsychotics, antidepressants, antiepileptics, benzodiazepines, hypnotics, and selective alpha-2 receptor agonist dexmedetomidine in the postoperative period by hospital type.

RESULTS

The study included 4,098,431 surgical admissions from CHs (mean age 75.0 [standard deviation, 7.1] years; 50.8% female) during 2008-2018 and 2,310,529 surgical admissions from AMCs (75.0 [7.4] years; 49.4% female) during 2009-2018. In the intensive care unit (ICU) setting, the number of exposed days per 1000 hospital-days declined for haloperidol (CHs: 33-21 days [p < 0.01]; AMCs: 24-15 days [p < 0.01]) and benzodiazepines (CHs: 261-136 days [p < 0.01]; AMCs: 150-77 days [p < 0.01]). The use of atypical antipsychotics, antidepressants, antiepileptics, and dexmedetomidine increased, while hypnotic use varied by the hospital type. In the non-ICU setting, the rate declined for haloperidol in CHs but not in AMCs (CHs: 10-6 days [p < 0.01]; AMCs: 4-3 days [p = 0.52]) and for benzodiazepines in both settings (CHs: 126-56 days [p < 0.01]; AMCs: 30-27 days [p < 0.01]). The use of antiepileptics and antidepressants increased, while the use of atypical antipsychotics and hypnotics varied by the hospital type.

CONCLUSIONS

The use of haloperidol and benzodiazepines in the postoperative period declined at both CHs and AMCs. These trends coincided with the increasing use of other psychoactive drugs.

Ketamine: A Practical Review for the Consultation-Liaison Psychiatrist

BACKGROUND

Ketamine is a noncompetitive N-methyl-D-aspartate-receptor antagonist often used for sedation and management of acute agitation in general hospital settings. Many hospitals now include ketamine as part of their standard agitation protocol, and consultation-liaison psychiatrists frequently find themselves treating patients who have received ketamine, despite lack of clear recommendations for management.

OBJECTIVE

Conduct a nonsystematic narrative review regarding the use of ketamine for agitation and continuous sedation, including benefits and adverse psychiatric effects. Compare ketamine to more traditional agents of agitation control. Provide consultation-liaison psychiatrists with a summary of available knowledge and recommendations for managing patients receiving ketamine.

METHODS

A literature review was performed using PubMed, querying published articles from inception to March 2023 for articles related to use of ketamine for agitation or continuous sedation and side effects including psychosis and catatonia.

RESULTS

A total of 37 articles were included. Ketamine was found to have multiple benefits, including shorter time to adequate sedation for agitated patients when compared to haloperidol ± benzodiazepines and unique advantages for continuous sedation. However, ketamine carries significant medical risks including high rates of intubation. Ketamine appears to induce a syndrome that mimics schizophrenia in healthy controls, and such effects are more pronounced and longer-lasting in patients with schizophrenia. Evidence regarding rates of delirium with ketamine for continuous sedation is mixed and requires further investigation before the agent is widely adopted for this purpose. Finally, the diagnosis of "excited delirium syndrome" and use of ketamine to treat this controversial syndrome warrants critical evaluation.

CONCLUSIONS

Ketamine carries many potential benefits and can be an appropriate medication for patients with profound undifferentiated agitation. However, intubation rates remain high, and ketamine may worsen underlying psychotic disorders. It is essential that consultation-liaison psychiatrists understand the advantages, disadvantages, biased administration, and areas of limited knowledge regarding ketamine.

Remimazolam tosylate's long-term sedative properties in ICU patients on mechanical ventilation: effectiveness and safety

OBJECTIVE

This study compared remimazolam tosylate with propofol or midazolam to assess its safety and effectiveness for long-term sedation of intensive care unit (ICU) patients requiring mechanical ventilation.

METHODS

Adult patients in the ICU receiving sedation and mechanical ventilation for longer than 24 h were included in this single-center, prospective, observational study. Depending on the sedatives they were given, they were split into two groups (midazolam or propofol group; remimazolam group). ICU mortality was the main result. Laboratory tests, adverse events, and the length of ICU stay were considered secondary outcomes.

RESULTS

A total of 106 patients were involved (46 received propofol or midazolam versus 60 received remimazolam). Age (P = 0.182), gender (P = 0.325), and the amount of time between being admitted to the ICU and receiving medication infusion (P = 0.770) did not substantially differ between the two groups. Multivariate analysis revealed no statistically significant difference in ICU mortality between the two groups. The remimazolam group showed less variability in heart rate (P = 0.0021), pH (P = 0.048), bicarbonate (P = 0.0133), lactate (P = 0.0002), arterial blood gas analyses, liver, and kidney function. The Richmond Agitation and Sedation Scale scores, length of ICU stay, and occurrence of adverse events did not exhibit significant differences between the two groups.

CONCLUSION

Remimazolam tosylate did not increase the total inpatient cost, the incidence of adverse events, and ICU mortality in patients with mechanical ventilation. These findings suggest that remimazolam may represent a promising alternative for sedation in the ICU setting.

The role of dexmedetomidine in ARDS: an approach to non-intensive care sedation

Introduction

Severe COVID-19 is a life-threatening condition characterized by complications such as interstitial pneumonia, hypoxic respiratory failure, and acute respiratory distress syndrome (ARDS). Non-pharmacological intervention with mechanical ventilation plays a key role in treating COVID-19-related ARDS but is influenced by a high risk of failure in more severe patients. Dexmedetomidine is a new generation highly selective α2-adrenergic receptor (α2-AR) agonist that provides sedative effects with preservation of respiratory function. The aim of this study is to assess how dexmedetomidine influences gas exchange during non-invasive ventilation (NIV) and high-flow nasal cannula (HFNC) in moderate to severe ARDS caused by COVID-19 in a non-intensive care setting.

Methods

This is a single center retrospective cohort study. We included patients who showed moderate to severe respiratory distress. All included subjects had indication to NIV and were suitable for a non-intensive setting of care. A total of 170 patients were included, divided in a control group (n = 71) and a treatment group (DEX group, n = 99).

Results

A total of 170 patients were hospitalized for moderate to severe ARDS and COVID-19. The median age was 71 years, 29% females. The median Charlson comorbidity index (CCI) was 2.5. Obesity affected 21% of the study population. The median pO2/FiO2 was 82 mmHg before treatment. After treatment, the increase of pO2/FiO2 ratio was clinically and statistically significant in the DEX group compared to the controls (125 mmHg [97-152] versus 94 mmHg [75-122]; ***p < 0.0001). A significative reduction of NIV duration was observed in DEX group (10 [7-16] days vs. 13 [10-17] days; *p < 0.02). Twenty four patients required IMV in control group (n = 71) and 16 patients in DEX group (n = 99) with a reduction of endotracheal intubation of 62% (OR 0.38; **p < 0.008). A higher incidence of sinus bradycardia was observed in the DEX group.

Conclusion

Dexmedetomidine provides a "calm and arousal" status which allows spontaneous ventilation in awake patients treated with NIV and HFNC. The adjunctive therapy with dexmedetomidine is associated with a higher pO2/FiO2, lower duration of NIV, and a lower risk of NIV failure. A higher incidence of sinus bradycardia needs to be considered.

Comparison Between Dexmedetomidine and Propofol for Sedation on Outcomes After Cardiac Surgery in Patients Requiring Mechanical Ventilation: A Meta-Analysis of Randomized-Control Trials

The aim of this study was to compare outcomes between dexmedetomidine and propofol for sedation after cardiac surgery in patients requiring mechanical ventilation. This meta-analysis was performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Online databases, including EMBASE, PubMed, and the Cochrane Library, were comprehensively searched to identify relevant randomized controlled trials (RCTs) comparing the safety and efficacy of dexmedetomidine and propofol in patients undergoing cardiac surgery and requiring mechanical ventilation. The examined outcomes included the mean length of intensive care unit (ICU) stay in hours, duration of mechanical ventilation in hours, length of hospital stay in days, and number of patients diagnosed with delirium. A total of 14 studies were included in the present meta-analysis while 1360 patients undergoing cardiac surgery were involved in these studies. Pooled results showed that the duration of mechanical ventilation was lower in the dexmedetomidine group compared to the propofol group (mean difference (MD): 0.75, 95% confidence interval (CI): 0.06-1.44, p-value: 0.03). We also found a significantly low length of stay in ICU in the dexmedetomidine group compared to the propofol (MD: 0.89, 95% CI: 0.04-1.74, p-value: 0.04). The length of hospital stay was also significantly lower in patients receiving dexmedetomidine as compared to the propofol group (MD: 0.51, 95% CI: 0.32-0.70, p-value<0.001). Risk of delirium was significantly higher in patients receiving propofol compared to patients receiving dexmedetomidine (RR: 2.02, 95% CI: 1.48-2.74, p-value<0.001). In conclusion, our meta-analysis provides evidence of the beneficial impacts of dexmedetomidine on clinical outcomes in patients undergoing cardiac surgery. Dexmedetomidine was associated with a significant reduction in the duration of mechanical ventilation, length of stay in the intensive care unit (ICU) and hospital, and the risk of delirium.

Postoperative delirium: identifying the patient at risk and altering the course: A narrative review

Postoperative delirium (POD) is a common neurocognitive syndrome seen in older patients after major surgery. POD is linked to longer stays in hospital and intensive care, a greater incidence of postoperative complications, worse functional outcome, and higher mortality. Researchers have not yet fully elucidated the exact pathophysiology of POD. Several risk factors that contribute to the development of POD have been identified, such as advanced age, cardiac or hip surgery, preoperative cognitive decline or delirium, disturbances in brain levels of neurotransmitters and information processing, oxidative stress and neuro-inflammation. Identifying patients at risk for POD enables a more precise and efficient allocation of medical resources and facilitates POD prevention and management. The present review addresses how to identify patients at risk of POD and summarizes the currently available evidence and best-practice recommendations for peri-operative management and prevention of POD.

Dexmedetomidine is safe and effective for reducing intraprocedural pain in colorectal endoscopic submucosal dissection

Objectives

Endoscopic submucosal dissection (ESD) is effective for the resection of colorectal intramucosal lesions. This study was performed to examine the safety and effectiveness of using dexmedetomidine (DEX) in the anesthesia regimen of patients with colorectal lesions undergoing ESD.

Methods

We retrospectively examined 287 consecutive patients who underwent ESD for colorectal lesions in our institution from January 2015 to December 2021. Outcomes including the frequency of intraprocedural pain and adverse events were compared between the DEX and no DEX groups. Moreover, univariate and multivariate analyses were conducted for each clinical factor of intraprocedural pain. Intraprocedural pain was defined as patient-reported abdominal pain or body movement during the procedure.

Results

The incidence of intraprocedural pain was significantly lower in the DEX than in the no DEX group (7% vs. 17%, p = 0.02). The incidence of hypotension was also significantly higher in the DEX group (7% vs. 0%, p = 0.01), but no cerebrovascular or cardiac ischemic events occurred. In the univariate analyses, the diameter of the resected specimen, procedure time, no use of DEX, and total midazolam dose was associated with intraprocedural pain. The midazolam dose and DEX administration were significantly negatively correlated and the diameter of resected specimen and procedure time were significantly positively correlated. Multivariate logistic regression showed that no use of DEX was independently associated with intraprocedural pain (p = 0.02).

Conclusions

Adding DEX to the anesthesia regimen in patients undergoing colorectal ESD appears to be safe and effective for reducing intraprocedural pain.

Delirium in trauma ICUs: a review of incidence, risk factors, outcomes, and management

PURPOSE OF REVIEW

This article reviews the impact and importance of delirium on patients admitted to the ICU after trauma, including the latest work on prevention and treatment of this condition. As the population ages, the incidence of geriatric trauma will continue to increase with a concomitant rise in the patient and healthcare costs of delirium in this population.

RECENT FINDINGS

Recent studies have further defined the risk factors for delirium in the trauma ICU patient population, as well as better demonstrated the poor outcomes associated with the diagnosis of delirium in these patients. Recent trials and meta-analysis offer some new evidence for the use of dexmedetomidine and quetiapine as preferred agents for prevention and treatment of delirium and add music interventions as a promising part of nonpharmacologic bundles.

SUMMARY

Trauma patients requiring admission to the ICU are at significant risk of developing delirium, an acute neuropsychiatric disorder associated with increased healthcare costs and worse outcomes including increased mortality. Ideal methods for prevention and treatment of delirium are not well established, especially in this population, but recent research helps to clarify optimal prevention and treatment strategies.

Modern Sedation and Analgesia Strategies in Neurocritical Care

PURPOSE OF REVIEW

Patients with acute neurologic injury require a specialized approach to critical care, particularly with regard to sedation and analgesia. This article reviews the most recent advances in methodology, pharmacology, and best practices of sedation and analgesia for the neurocritical care population.

RECENT FINDINGS

In addition to established agents such as propofol and midazolam, dexmedetomidine and ketamine are two sedative agents that play an increasingly central role, as they have a favorable side effect profile on cerebral hemodynamics and rapid offset can facilitate repeated neurologic exams. Recent evidence suggests that dexmedetomidine is also an effective component when managing delirium. Combined analgo-sedation with low doses of short-acting opiates is a preferred sedation strategy to facilitate neurologic exams as well as patient-ventilator synchrony. Optimal care for patients in the neurocritical care population requires an adaptation of general ICU strategies that incorporates understanding of neurophysiology and the need for close neuromonitoring. Recent data continues to improve care tailored to this population.

Propofol Inhibits Ferroptotic Cell Death Through the Nrf2/Gpx4 Signaling Pathway in the Mouse Model of Cerebral Ischemia-Reperfusion Injury

Ferroptosis is characterized by excessive accumulation of iron and lipid peroxides, which are involved in ischemia, reperfusion-induced organ injury, and stroke. Propofol, an anesthetic agent, has neuroprotective effects due to its potent antioxidant, anti-ischemic, and anti-inflammatory properties. However, the relationship between propofol and ferroptosis is still unclear. In the current study, we elucidated the role of ferroptosis in the neuroprotective effect of propofol in mouse brains subjected to cerebral ischemia reperfusion injury (CIRI). Ferroptosis was confirmed by Western blotting assays, transmission electron microscopy, and glutathione assays. Propofol regulated Nrf2/Gpx4 signaling, enhanced antioxidant potential, inhibited the accumulation of lipid peroxides in CIRI-affected neurons, and significantly reversed CIRI-induced ferroptosis. Additionally, Gpx4 inhibitor RSL3 and Nrf2 inhibitor ML385 attenuated the effects of propofol on antioxidant capacity, lipid peroxidation, and ferroptosis in CIRI-affected neurons. Our data support a protective role of propofol against ferroptosis as a cause of cell death in mice with CIRI. Propofol protected against CIRI-induced ferroptosis partly by regulating the Nrf2/Gpx4 signaling pathway. These findings may contribute to the development of future therapies targeting ferroptosis induced by CIRI.

Percutaneous Transforaminal Endoscopic Surgery (PTES) for Treatment of Lumbar Degenerative Disease in Patients with Underlying Diseases: A Retrospective Cohort Study of 196 Cases

Objective

To evaluate the postoperative outcomes, safety and feasibility of percutaneous transforaminal endoscopic surgery (PTES) for the treatment of lumbar degenerative disease (LDD) in the patients with underlying diseases.

Methods

From June 2017 to April 2019, PTES was performed to treat 226 patients of single-level LDD. According to clinical background, the patients were divided into two groups. A total of 102 patients with underlying diseases were included in group A. The other 124 LDD patients without underlying diseases were included in group B. The occurrence of postoperative complications was recorded. Leg pain was assessed before, immediately, 1 month, 2 months, 3 months, 6 months, 1 year, and 2 years after PTES using VAS, and ODI before PTES and 2 years after PTES were recorded. The therapeutic quality (Excellent, Good, Moderate or Poor) was defined according to MacNab grade at 2-year follow-up.

Results

No aggravation of underlying diseases or serious complications was observed in all patients within 6 months after the operation. Altogether, 196 patients were followed up for more than 2 years, 89 patients in group A and 107 patients in group B. The VAS score of leg pain and ODI dropped significantly after surgery (P<0.001) in both groups. One case of group B received PTES again due to recurrence 52 months after surgery. According to MacNab, the excellent and good rate was 97.75% (87/89) in group A and 96.26% (103/107) in group B. In operative duration, frequency of intraoperative fluoroscopy, blood loss, incision length, hospital stay, VAS, ODI, and the excellent and good rate, there was no statistical difference between the two groups.

Conclusion

PTES is safe, effective and feasible for the treatment of LDD with underlying diseases, which is comparable to PTES for LDD without underlying diseases. The entrance point of PTES (Gu's Point) is located at the corner of the flat back turning to the lateral side. PTES is not only a minimally invasive surgical technique but also includes a postoperative care system for preventing LDD recurrence.

A randomised controlled trial of dexmedetomidine for delirium in adults undergoing heart valve surgery

Dexmedetomidine might reduce delirium after cardiac surgery. We allocated 326 participants to an infusion of dexmedetomidine at a rate of 0.6 μg kg^-1 for 10 min and then at 0.4 μg.kg^-1 .h^-1 until the end of surgery; 326 control participants received comparable volumes of saline. We detected delirium in 98/652 (15%) participants during the first seven postoperative days: 47/326 after dexmedetomidine vs. 51/326 after placebo, p = 0.62, adjusted relative risk (95%CI) 0.86 (0.56-1.33), p = 0.51. Postoperative renal impairment (Kidney Disease Improving Global Outcomes stages 1, 2 and 3) was detected in 46, 9 and 2 participants after dexmedetomidine and 25, 7 and 4 control participants, p = 0.040. Intra-operative dexmedetomidine infusion did not reduce the incidence of delirium after cardiac valve surgery but might impair renal function.

Perioperative Optimization of the Cardiac Surgical Patient

Perioperative optimization of cardiac surgical patients is imperative to reduce complications, utilize health care resources efficiently, and improve patient recovery and quality of life. Standardized application of evidence-based best practices can lead to better outcomes. Although many practices should be applied universally to all patients, there are also opportunities along the surgical journey to identify patients who will benefit from additional interventions that will further ameliorate their recovery. Enhanced recovery programs aim to bundle several process elements in a standardized fashion to optimize outcomes after cardiac surgery. A foundational concept of enhanced recovery is attaining a better postsurgical end point for patients, in less time, through achievement and maintenance in their greatest possible physiologic, functional, and psychological state. Perioperative optimization is a broad topic, spanning multiple phases of care and involving a variety of medical specialties and nonphysician health care providers. In this review we highlight a variety of perioperative care topics, in which a comprehensive approach to patient care can lead to improved results for patients, providers, and the health care system. A particular focus on patient-centred care is included. Although existing evidence supports all of the elements reviewed, most require further improvements in implementation, as well as additional research, before their full potential and usefulness can be determined.

Postoperative Delirium after Dexmedetomidine versus Propofol Sedation in Healthy Older Adults Undergoing Orthopedic Lower Limb Surgery with Spinal Anesthesia: A Randomized Controlled Trial

BACKGROUND

Delirium is a critical postoperative complication in older patients. Based on the hypothesis that intraoperative dexmedetomidine sedation would lower postoperative delirium than propofol sedation would, the authors compared the incidence of postoperative delirium in older adults, using the mentioned sedatives.

METHODS

This double-blinded, randomized controlled study included 748 patients, aged 65 yr or older, who were scheduled for elective lower extremity orthopedic surgery, between June 2017 and October 2021. Patients were randomized equally into two groups in a 1:1 ratio according to the intraoperative sedative used (dexmedetomidine vs. propofol). The postoperative delirium incidence was considered the primary outcome measure; it was determined using the confusion assessment method, on the first three postoperative days. The mean arterial pressure and heart rate were evaluated as secondary outcomes.

RESULTS

The authors enrolled 732 patients in the intention-to-treat analyses. The delirium incidence was lower in the dexmedetomidine group than in the propofol group (11 [3.0%] vs. 24 [6.6%]; odds ratio, 0.42; 95% CI, 0.201 to 0.86; P = 0.036). During sedation, the mean arterial pressure (median [interquartile range] mmHg) was higher in the dexmedetomidine group (77 [71 to 84]) than in the propofol group (74 [69 to 79]; P < 0.001); however, it significantly fell lower (74 [68 to 80]) than that of the propofol group (80 [74 to 87]) in the postanesthesia care unit (P < 0.001). Lower heart rates (beats/min) were recorded with the use of dexmedetomidine than with propofol, both during sedation (60 [55 to 66] vs. 63 [58 to 70]) and in the postanesthesia care unit (64 [58 to 72] vs. 68 [62-77]; P < 0.001).

CONCLUSIONS

Dexmedetomidine showed a lower incidence of postoperative delirium than propofol in healthy older adults undergoing lower extremity orthopedic surgery.

EDITOR’S PERSPECTIVE

What Is the Role of Dexmedetomidine in Modern Anesthesia and Critical Care?

Dexmedetomidine's unique sedative properties have led to its widespread use. Dexmedetomidine has a beneficial pharmacologic profile including analgesic sparing effects, anxiolysis, sympatholysis, organ-protective effects against ischemic and hypoxic injury, and sedation which parallels natural sleep. An understanding of predictable side effects, effects of age-related physiologic changes, and pharmacokinetic and pharmacodynamic effects of dexmedetomidine is crucial to maximize its safe administration in adults and children. This review focuses on the growing body of literature examining advances in applications of dexmedetomidine in children and adults.

Anti-Inflammatory Action of Dexmedetomidine on Human Microglial Cells

Neuroinflammation, where inflammatory cytokines are produced in excess, contributes to the pathogenesis of delirium. Microglial cells play a central role in neuroinflammation by producing and releasing inflammatory cytokines in response to infection, tissue damage and neurodegeneration. Dexmedetomidine (DEX) is a sedative, which reduces the incidence of delirium. Thus, we hypothesized that DEX may alleviate delirium by exhibiting anti-inflammatory action on microglia. In the present study, we investigated the anti-inflammatory action of DEX on human microglial HMC3 cells. The results indicated that DEX partially suppressed the IL-6 and IL-8 production by lipopolysaccharide (LPS)-stimulated HMC3 cells as well as the phosphorylation of p38 MAPK and IκB and the translocation of NF-κB. Furthermore, DEX substantially suppressed IL-6 and IL-8 production by unstimulated HMC3 cells as wells as the phosphorylation of p38 MAPK and IκB and the translocation of NF-κB. These observations suggest that DEX exhibits anti-inflammatory action on not only LPS-stimulated but also unstimulated microglial cells via the suppression of inflammatory signaling and cytokine production.

Acute kidney injury-associated delirium: a review of clinical and pathophysiological mechanisms

Acute kidney injury is a known clinical risk factor for delirium, an acute cognitive dysfunction that is commonly encountered in the critically ill population. In this comprehensive review of clinical and basic research studies, we detail the epidemiology, clinical implications, pathogenesis, and management strategies of patients with acute kidney injury-associated delirium. Specifically addressed are the pathological roles of endogenous toxin or drug accumulation, acute kidney injury-mediated neuroinflammation, and acute kidney injury-associated volume overload as discrete potential biological mechanisms of the condition. The optimization of clinical contributors and normalization of renal function are reviewed as pragmatic management strategies in addition to potential and emerging therapeutic approaches.

Outcomes of dexmedetomidine versus propofol sedation in critically ill adults requiring mechanical ventilation: a systematic review and meta-analysis of randomised controlled trials

BACKGROUND

Guidelines have recommended the use of dexmedetomidine or propofol for sedation after cardiac surgery, and propofol monotherapy for other patients. Further outcome data are required for these drugs.

METHODS

This systematic review and meta-analysis was prospectively registered on PROSPERO. The primary outcome was ICU length of stay. Secondary outcomes included duration of mechanical ventilation, ICU delirium, all-cause mortality, and haemodynamic effects. Intensive care patients were analysed separately as cardiac surgical, medical/noncardiac surgical, those with sepsis, and patients in neurocritical care. Subgroup analyses based on age and dosage were conducted.

RESULTS

Forty-one trials (N=3948) were included. Dexmedetomidine did not significantly affect ICU length of stay across any ICU patient subtype when compared with propofol, but it reduced the duration of mechanical ventilation (mean difference -0.67 h; 95% confidence interval: -1.31 to -0.03 h; P=0.041; low certainty) and the risk of ICU delirium (risk ratio 0.49; 95% confidence interval: 0.29-0.87; P=0.019; high certainty) across cardiac surgical patients. Dexmedetomidine was also associated with a greater risk of bradycardia across a variety of ICU patients. Subgroup analyses revealed that age might affect the incidence of haemodynamic side-effects and mortality among cardiac surgical and medical/other surgical patients.

CONCLUSION

Dexmedetomidine did not significantly impact ICU length of stay compared with propofol, but it significantly reduced the duration of mechanical ventilation and the risk of delirium in cardiac surgical patients. It also significantly increased the risk of bradycardia across ICU patient subsets.

Delirium in elderly patients with COPD combined with respiratory failure undergoing mechanical ventilation: a prospective cohort study

Background

COPD combined with respiratory failure is very common in intensive care unit (ICU). We aimed to evaluate the current status and influencing factors of delirium in elderly COPD patients with undergoing mechanical ventilation.

Methods

Patients with COPD combined with respiratory failure and mechanically ventilated who were admitted to the ICU of our hospital were selected. The characteristics of included patients were assessed. Pearson correlation analysis was performed to evaluate the characteristics of patients and delirium. Logistic regression analysis was conducted to identify the risk factors of delirium in elderly patients with COPD combined with respiratory failure undergoing mechanical ventilation.

Results

A total of 237 COPD combined with respiratory failure patients were included, the incidence of delirium was 21.94%. Pearson correlation analysis indicated that age (r = 0.784), BMI (r = 0.709), hypertension (r = 0.696), APACHE II score (r = 0.801), CPOT (r = 0.513), sedation(r = 0.626) and PaO₂ (r = 0.611) were all correlated with the occurrence of delirium (all p < 0.05). Logistic regression analysis indicated that age ≥ 75y (OR 3.112, 95% CI 2.144–4.602), BMI ≤ 19 kg/m² (OR 2.742, 95% CI 1.801–3.355), hypertension(OR 1.909, 95% CI 1.415–2.421), APACHE II score ≥ 15 (OR 2.087, 95% CI 1.724–2.615), CPOT ≥ 5 (OR 1.778, 95% CI 1.206–2.641), sedation(OR 3.147, 95% CI 2.714–3.758), PaO₂ ≤ 75 mmHg(OR 2.196, 95%CI 1.875–3.088) were the risk factors of delirium in elderly patients with COPD combined with respiratory failure undergoing mechanical ventilation (all p < 0.05).

Conclusions

Delirium is common in patients with COPD and respiratory failure undergoing mechanical ventilation, and there are many related influencing factors. Medical staff should pay more attention to patients with risk factors and take intervention measures as soon as possible to reduce the incidence of delirium.

Effect of Programmed Comprehensive Nursing for Postoperative Delirium in Intensive Care Unit Patients

Background

This study is to evaluate the effect of programmed comprehensive nursing for postoperative delirium in intensive care unit (ICU) patients.

Methods

A total of 90 cases of ICU surgery patients admitted to our hospital from July 2019 to July 2020 were recruited and assigned via the random number table method (1 : 1) to receive either conventional nursing (control group) or programmed comprehensive nursing (experimental group). The delirium assessment method was used to record the incidence of delirium events at different time points after the intervention. Outcome measures included delirium events, the Visual Analogue Scale (VAS) scores, the Pittsburgh sleep quality index (PSQI) scores, the activities of daily living (ADL) scale scores, nursing satisfaction, and total nursing efficiency.

Results

Programmed comprehensive nursing was associated with significantly better nursing satisfaction, ADL scores, VAS scores, PSQI scores, and nursing efficiency than conventional nursing (all P < 0.05). Programmed comprehensive nursing resulted in a significantly lower incidence of postoperative delirium than conventional nursing (P < 0.05).

Conclusion

The application of programmed comprehensive nursing for postoperative delirium in ICU patients shows a promising efficiency, effectively alleviates the clinical symptoms of patients, and optimizes various clinical indicators of patients; hence, it is worthy of further application and promotion.

The Effects of Dexmedetomidine on Perioperative Neurocognitive Outcomes After Cardiac Surgery: A Systematic Review and Meta-analysis of Randomized Controlled Trials

OBJECTIVE

The purpose of this systematic review and meta-analysis is to examine the effect of DEX on delayed dNCR (cognitive dysfunction ≥ 1 week postoperative) after cardiac surgery.

BACKGROUND

DEX has salutary effects on cognitive outcomes following cardiac surgery, however, studies are limited by inconsistent assessment tools, timing, and definitions of dysfunction. It is imperative to identify accurate point estimates of effect of DEX on clinically relevant changes in cognitive function.

METHODS

Randomized trials of adults undergoing cardiac surgery comparing perioperative DEX to placebo or alternate sedation and assessing cognitive function ≥ 1 week postoperative were included. Data was abstracted by three reviewers independently and in parallel according to PRISMA guidelines. The primary outcome is dNCR. To classify as dNCR, cognitive function must decrease by at least the minimal clinically important difference or accepted alternate measure (eg, Reliable Change Index ≥1.96). Bias was assessed with the Cochrane Collaboration tool. Data was pooled using a random effects model.

RESULTS

Nine trials (942 participants) were included in qualitative analysis, of which seven were included in the meta-analysis of dNCR. DEX reduced the incidence of dNCR (OR 0.39, 95% CI 0.25-0.61, P < 0.0001) compared to placebo/no DEX. There was no difference in the incidence of delirium (OR 0.69, 95% CI 0.35-1.34, P = 0.27) or incidence of hemodynamic instability (OR 1.14, 95% CI 0.59-2.18, P = 0.70) associated with perioperative DEX.

CONCLUSIONS

DEX reduced the incidence of dNCR 1 week after cardiac surgery. Although this meta-analysis demonstrates short term cognitive outcomes are improved after cardiac surgery with perioperative DEX, future trials examining long term cognitive outcomes, using robust cognitive assessments, and new perioperative neurocognitive disorders nomenclature with objective diagnostic criteria are necessary.

The Effects of Dexmedetomidine on Perioperative Neurocognitive Outcomes After Noncardiac Surgery: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Objective

The purpose of this review is to examine the effect of dexmedetomidine on delayed neurocognitive recovery (dNCR; cognitive dysfunction ≥1 week postoperative) after major noncardiac surgery.

Background

Dexmedetomidine (DEX) effectively reduces delirium in the intensive care unit and reportedly attenuates cognitive decline following major noncardiac surgery. Ascertaining the true effect on postoperative cognition is difficult because studies are limited by suboptimal selection of cognitive assessment tools, timing of testing, and criteria for defining significant cognitive decline.

Methods

Prospective randomized trials comparing perioperative DEX to placebo for major noncardiac surgery assessing cognitive function ≥1 week postoperative were included. Pediatric, nonhuman, and non-English trials, and those where executive function was not assessed were excluded. Data were abstracted by 3 reviewers independently and in parallel according to PRISMA guidelines. The a priori binary primary outcome is dNCR defined as cognitive function declining by the minimal clinically important difference or accepted alternate measure (eg, Reliable Change Index ≥1.96). Bias was assessed with the Cochrane Collaboration tool. Data were pooled using a random effects model.

Results

Among 287 citations identified, 26 (9%) met criteria for full-text retrieval. Eleven randomized trials (1233 participants) were included for qualitative analysis, and 7 trials (616 participants) were included for meta-analysis of dNCR. Dexmedetomidine did not reduce the incidence of dNCR significantly (OR 0.57, 95% CI 0.30-1.10, P = 0.09) compared with placebo. There was no difference in the incidence of delirium (OR 0.94, 95% CI 0.55-1.63, P = 0.83) and a higher incidence of hemodynamic instability (OR 2.11, 95% CI 1.22-3.65, P = 0.008).

Conclusions

Dexmedetomidine does not reduce dNCR 1 week after major noncardiac surgery. This meta-analysis does not yet support the use of perioperative DEX to improve short term cognitive outcomes at this time; trials underway may yet change this conclusion while larger trials are needed to refine the point estimate of effect and examine long-term cognitive outcomes.

Perioperative Low Dose Dexmedetomidine and Its Effect on the Visibility of the Surgical Field for Middle Ear Microsurgery: A Randomised Controlled Trial

Background and Purpose: There are many benefits of administering dexmedetomidine perioperatively. The pharmacokinetics (PK) and pharmacodynamics (PD) of intravenous, intranasal and oral dexmedetomidine that was administered before anesthesia were compared in this study, and the effects of dexmedetomidine on the surgical field visibility in tympanoplasty was evaluated. Methods: A single-blind, randomized controlled trial was conducted in a university-affiliated hospital where 45 patients who underwent tympanoplasty under general anesthesia were randomly allocated into three groups. Dexmedetomidine was administered by intravenous infusion at 0.8 μg.kg^-1 for 10 min, intranasal instillation at a drop rate of 1 μg.kg^-1 and oral intake at 4 μg.kg^-1 ten minutes before the induction of anesthesia. The PK and PD of dexmedetomidine after a single low dose administration and its effect on the surgical field in tympanoplasty were analysed. Results: A plasma concentration of dexmedetomidine of 220 pg/ml was achieved immediately after intravenous infusion and at 13.2 and 70.3 min for intranasal and oral administration, respectively. Dexmedetomidine decreased the heart rate (HR) and mean arterial pressure (MAP) in all three groups, although these values remained higher in the oral dexmedetomidine group at all eight time points. Intravenous dexmedetomidine provided the best visualization of the surgical field for opening of the tympanic sinus, 30 min after the start of the infusion (p < 0.05). Intranasal dexmedetomidine provided a significantly better visual field than oral dexmedetomidine for the repair of a tympanic membrane perforation using the fascia temporal muscle (p < 0.05). Conclusion: A single low dose of dexmedetomidine administered intravenously or intranasally could decrease HR and MAP, improve surgical field visibility and be appropriate for deliberate hypotension for surgical procedures of 1-2 h in length. Trial registration: Clinicaltrials.gov identifier: NCT03800641.

Effect of dexmedetomidine and propofol sedation on the prognosis of children with severe respiratory failure: a systematic review and meta-analysis

BACKGROUND

During treatment of acute respiratory failure (ARF) in children, sedation can reduce pain, improve tolerance, and reduce the incidence of adverse events, so selecting an appropriate sedation strategy is very important for improving prognosis and quality of life. Both dexmedetomidine and propofol have good sedative effects, so we investigated the application of these drugs in critically ill children with ARF by literature search and meta-analysis.

METHODS

We searched Embase, The Cochrane Library, PubMed, Ovid, Clinicaltrials.org, and Google Scholar for randomized controlled trials (RCTs) preferentially but not exclusively, and used RevMan 5.4 to analyze the screened literature.

RESULTS

Seven studies were included in the quantitative meta-analysis, with a total of 1,188 patients. There was no significant difference in the effect of dexmedetomidine and propofol on the duration of tracheal intubation in children with ARF [mean difference (MD) =-0.05; 95% confidence interval (CI): (-0.42, 0.32); Z=0.26; P=0.79], but dexmedetomidine sedation could reduce the intensive care unit (ICU) stay in children with ARF [MD =-0.62; 95% CI: (-1.08, -0.16); Z=2.65; P=0.008], and shorten the total hospital stay [MD =-1.94; 95% CI: (-2.63, -1.25); Z=5.48; P<0.00001]. There was no significant effect on mortality between the two groups [odds ratio (OR) =0.48; 95% CI: (0.19, 1.25); Z=1.50; P=0.13]. The incidence rate of bradycardia with dexmedetomidine sedation was higher than with propofol [OR =12.30; 95% CI: (2.28, 66.47); Z=2.92; P=0.004], and the incidence of hypotension was also higher [OR =6.99, 95% CI: (1.22, 39.86); Z=2.19; P=0.03].

DISCUSSION

Compared with propofol, dexmedetomidine can significantly reduce the ICU stay and hospital stay. However, bradycardia and hypotension may occur during the use of dexmedetomidine, which requires close attention and timely intervention.

Development and validation of prediction models for neurocognitive disorders in adult patients admitted to the ICU with sleep disturbance

BACKGROUND

Neurocognitive disorders (NCDs) and sleep disturbance are highly prevalent in the perioperative period and intensive care unit (ICU). There has been a lack of individualized evaluation tools designed for the high-risk NCDs in critically ill patients with sleep disturbance.

OBJECTIVES

The aim of this study was to develop and validate prediction models for NCDs among adult patients with sleep disturbance.

METHODS

The R software was used to analyze the dataset of adult patients admitted to the ICU with sleep disturbance, who were diagnosed following the codes of the International Classification of Diseases, 9th Revision (ICD-9) and 10th Revision (ICD-10) using the MIMIC-IV database. We used logistic regression and LASSO analyses to identify important risk factors associated with NCDs and develop nomograms for NCDs predictions. We measured the performances of the nomograms using the bootstrap resampling procedure, sensitivity, specificity of the receiver operating characteristic (ROC), area under the ROC curves (AUC), and decision curve analysis (DCA).

RESULTS

The prediction models shared the 10 risk factors (age, gender, midazolam, morphine, glucose, diabetes diseases, potassium, international normalized ratio, partial thromboplastin time, and respiratory rate). Cardiovascular diseases were included in the logistic regression, the sensitivity was 74.1%, and specificity was 64.6%. When platelet and Glasgow Coma Score (GCS) were included and cardiovascular diseases were removed in the LASSO prediction model, the sensitivity was 86.1% and specificity was 82.8%. Discriminative abilities of the logistic prediction and LASSO prediction models for NCDs in the validation set were evaluated as the AUC scores, which were 0.730 (95% CI 0.716-0.743) and 0.920 (95% CI 0.912-0.927). Net benefits of the prediction models were observed at threshold probabilities of 0.567 and 0.914.

CONCLUSIONS

The LASSO prediction model showed better performance than the logistic prediction model and should be preferred for nomogram-assisted decisions on clinical risk management of NCDs among adult patients with sleep disturbance in the ICU.

Influence of Dexmedetomidine on Diaphragm Function and Postoperative Outcomes in ICU Patients with Mechanical Ventilation

Objective

To probe into the influence of dexmedetomidine (DEX) on diaphragm function and postoperative outcomes of mechanically ventilated patients in the intensive care unit (ICU).

Methods

84 patients with mechanical ventilation (MV) in the ICU of our hospital were selected as the research participants, including 38 patients in the control group (CG) sedated with midazolam (MZ) and 46 patients in the research group (RG) with DEX sedation. Ramsay sedation score, visual analogue scale (VAS), and restlessness score (RS) were used to evaluate their state before sedation (T0), as well as 2 h (T1), 6 h (T2), and 24 h (T3) after sedation, and the alterations of mean arterial pressure (MAP) and heart rate (HR) were recorded. Serum cortisol (Cor), adrenocorticotropic hormone (ACTH), superoxide dismutase (SOD), malondialdehyde (MDA), interleukin- (IL-) 1β, IL-6, and tumor necrosis factor-α (TNF-α) were measured before and 24 h after sedation. The end-inspiratory diaphragm thickness (DTei) and end-expiratory diaphragm thickness (DTee) were measured within 2 h after the initiation of MV and 5 min after the spontaneous breathing test (SBT), and the diaphragm thickening fraction (DTF) was calculated. Finally, the ventilator weaning, MV time, and the incidence of adverse reactions (ADs) of the two groups were counted.

Results

T0 and T3 witnessed no distinct difference in Ramsay, VAS, and RS scores between the two arms (P > 0.05), but at T1 and T2, RG had better sedation state and lower VAS and RS scores than CG (P < 0.05), with more stable vital signs (P < 0.05). After sedation, the contents of oxidative stress and inflammatory factors in RG were lower, while DTee, DTei, and DTF were higher, versus CG (P < 0.05). Moreover, RG presented higher success rate of first ventilator weaning, less MV time, and lower incidence of ADs than CG (P < 0.05).

Conclusions

DEX is effective in mechanically ventilated patients in the ICU, which can protect patients against diaphragm function damage, improve the success rate of ventilator weaning, and benefit the postoperative outcome, with excellent and rapid sedation effect and less stress damage to patients.

Propofol Ameliorates Microglia Activation by Targeting MicroRNA-221/222-IRF2 Axis

Background

Propofol is a widely used intravenous anesthetic drug with potential neuroprotective effect in diverse diseases of neuronal injuries such as traumatic brain injury and ischemic stroke. However, the underlying molecular mechanism remains largely unknown.

Methods

Real-time qPCR, enzyme-linked immunosorbent assay, and Western blotting were used to identify the expression pattern of miR-221/222, inflammatory genes, cytokines, and IRF2. The biological roles and mechanisms of propofol in microglia activation were determined in BV2 cells and primary microglia. Bioinformatic analysis and luciferase reporter assay were used to confirm the regulatory role of miR-221/222 in Irf2 expression.

Results

We found that miR-221 and miR-222 were downstream targets of propofol and were consistently upregulated in lipopolysaccharide- (LPS-) primed BV2 cells. Gain- and loss-of-function studies revealed that miR-221 and miR-222 were profoundly implicated in microglia activation. Then, interferon regulatory factor 2 (Irf2) was identified as a direct target gene of miR-221/222. IRF2 protein levels were reduced by miR-221/222 and increased by propofol treatment. Ectopic expression of IRF2 attenuated the proinflammatory roles induced by LPS in BV2 cells. More importantly, the suppressive effects of propofol on LPS-primed activation of BV2 cells or primary mouse microglia involved the inhibition of miR-221/222-IRF2 axis.

Conclusions

Our study highlights the critical function of miR-221/222, which inhibited Irf2 translation, in the anti-inflammatory effects of propofol, and provides a new perspective for the molecular mechanism of propofol-mediated neuroprotective effect.

Comparison of clinical efficacy and safety between dexmedetomidine and propofol among patients undergoing gastrointestinal endoscopy: a meta-analysis

OBJECTIVE

To compare the clinical efficacy and safety of dexmedetomidine and propofol in patients who underwent gastrointestinal endoscopy.

METHODS

Relevant studies comparing dexmedetomidine and propofol among patients who underwent gastrointestinal endoscopy were retrieved from databases such as PubMed, Embase, and Cochrane Library.

RESULTS

Seven relevant studies (dexmedetomidine group, n = 238; propofol group, n = 239) met the inclusion criteria. There were no significant differences in the induction time (weighted mean difference [WMD] = 3.46, 95% confidence interval [CI] = -0.95-7.88, I2 = 99%) and recovery time (WMD = 2.74, 95% CI = -2.72-8.19, I2 = 98%). Subgroup analysis revealed no significant differences in the risks of hypotension (risk ratio [RR] = 0.56, 95% CI = 0.25-1.22) and nausea and vomiting (RR = 1.00, 95% CI = 0.46-2.22) between the drugs, whereas dexmedetomidine carried a lower risk of hypoxia (RR = 0.26, 95% CI = 0.11-0.63) and higher risk of bradycardia (RR = 3.01, 95% CI = 1.38-6.54).

CONCLUSIONS

Dexmedetomidine had similar efficacy and safety profiles as propofol in patients undergoing gastrointestinal endoscopy.

Assessment and Management of Delirium in the Pediatric Intensive Care Unit: A Review

Many critically ill patients suffer from delirium which is associated with significant morbidity and mortality. There is a paucity of data about the incidence, symptoms, or treatment of delirium in the pediatric intensive care unit (PICU). Risk factors for delirium are common in the PICU including central nervous system immaturity, developmental delay, mechanical ventilation, and use of anticholinergic agents, corticosteroids, vasopressors, opioids, or benzodiazepines. Hypoactive delirium is the most common subtype in pediatric patients; however, hyperactive delirium has also been reported. Various screening tools are validated in the pediatric population, with the Cornell Assessment of Pediatric Delirium (CAPD) applicable to the largest age range and able to detect signs and symptoms consistent with both hypo- and hyperactive delirium. Treatment of delirium should always include identification and reversal of the underlying etiology, reserving pharmacologic management for those patients without symptom resolution, or with significant impact to medical care. Atypical antipsychotics (olanzapine, quetiapine, and risperidone) should be used first-line in patients requiring pharmacologic treatment owing to their apparent efficacy and low incidence of reported adverse effects. The choice of atypical antipsychotic should be based on adverse effect profile, available dosage forms, and consideration of medication interactions. Intravenous haloperidol may be a potential treatment option in patients unable to tolerate oral medications and with significant symptoms. However, given the high incidence of serious adverse effects with intravenous haloperidol, routine use should be avoided. Dexmedetomidine should be used when sedation is needed and when clinically appropriate, given the positive impact on delirium. Additional well-designed trials assessing screening and treatment of PICU delirium are needed.

Effect of dexmedetomidine on delirium during sedation in adult patients in intensive care units: A systematic review and meta-analysis

STUDY OBJECTIVE

To compare the effect of sedation protocols with and without dexmedetomidine on delirium risk and duration in adult patients in intensive care units (ICUs).

DESIGN

A meta-analysis of randomized controlled trials.

REVIEW METHODS

We searched the Cochrane Central Register of Controlled Trials, PubMed, EMBASE, and ISI Web of Science from inception to September 3, 2020. We included studies comparing the effect of dexmedetomidine-based sedation on delirium risk with non-dexmedetomidine-based sedation in adult patients in ICUs. We pooled the data using a random-effects model using Review Manager 5.2, and assessed publication bias using Stata 11.0. The quality of evidence was rated using the Grading of Recommendations, Assessment, Development and Evaluation system.

MAIN RESULTS

We included 36 studies involving 9623 participants. The use of dexmedetomidine was associated with reduced risk of delirium (risk ratio [RR], 0.63; 95% confidence interval [CI], 0.54-0.75; very low-quality evidence), but higher incidences of hypotension and bradycardia during hospital stay. Dexmedetomidine was also associated with shorter durations of ICU stay, hospital stay and mechanical ventilation. Dexmedetomidine did not affect ICU mortality (RR, 1.01; 95% CI, 0.89-1.14; low-quality evidence), hospital mortality (RR, 1.01; 95% CI, 0.91-1.12; very low-quality evidence), or 30-day mortality (RR, 0.77; 95% CI, 0.58-1.01; moderate-quality evidence), or duration of delirium (mean difference, -0.74 days; 95% CI, -1.83 to 0.36 days; very low-quality evidence). We identified publication bias for risk and duration of delirium, length of ICU stay, and hospital stay.

CONCLUSIONS

Low- or very low-quality evidence suggests that dexmedetomidine was associated with a clinically-small reduction of delirium risk, ICU/hospital stay and mechanical ventilation duration, but were not associated with improved mortality or shorter delirium duration in ICU patients. These findings were inconclusive because of publication bias, heterogeneity, and limited sample size. Significant adverse effects of dexmedetomidine include hypotension and bradycardia. PROSPERO registration number: CRD42018095358.

The Safety and Efficacy Evaluation of Dexmedetomidine for Procedural Sedation and Postoperative Behaviors in Pediatric Populations: A Systematic Review and Meta-analysis

BACKGROUND

This study systematically evaluated the safety and efficacy of dexmedetomidine for procedural sedation and postoperative behaviors in a pediatric population as well as whether the results met the information required to draw conclusions.

OBJECTIVE

To evaluate the safety and efficacy evaluation of dexmedetomidine for procedural sedation and postoperative behaviors in a pediatric population.

METHODS

PubMed, Cochrane library, Web of Science and Ovid MEDLINE were searched to obtain randomized controlled trials (RCTs) comparing dexmedetomidine with control medicine and comparing different doses of dexmedetomidine.

RESULTS

There were a total of 16 RCTs for a total of 3240 patients. Dexmedetomidine slowed down the heart rate (HR; mean difference: -13.27; 95% CI: -16.41 to 10.14; P < 0.001) and reduced postoperative delirium (risk ratio [RR]: 0.31; 95% CI: 0.20-0.50; P < 0.001), the number of pain patients (RR: 0.48; 95% CI: 0.30-0.75; P = 0.002), and desaturation (RR: 0.34; 95% CI: 0.13-0.89; P = 0.03) compared with the control group. The limitation was that it was difficult to determine the range of low- and high-dose dexmedetomidine.

CONCLUSION AND RELEVANCE

Dexmedetomidine slowed down intraoperative HR within the normal range, which might reduce myocardial oxygen consumption. It reduced postoperative pain and postoperative complications: delirium and desaturation. Dexmedetomidine showed no dose-dependent increase in the procedural sedation time of pediatric patients. Clinically, dexmedetomidine can improve pediatric procedural sedation and postoperative behavior, and it can be considered as a related medicine for safety in pediatric surgery.

Dexmedetomidine for prevention of postoperative delirium in older adults undergoing oesophagectomy with total intravenous anaesthesia: A double-blind, randomised clinical trial

BACKGROUND

Dexmedetomidine is known to be a sedative. Recent studies suggest that administration of dexmedetomidine can prevent postoperative delirium (POD) which has been confirmed as a common complication after major surgery. However, its effects in patients undergoing oesophagectomy are scarce.

OBJECTIVE

To investigate the efficacy and safety of dexmedetomidine in reducing POD in elderly patients after transthoracic oesophagectomy with total intravenous anaesthesia (TIVA).

DESIGN

A randomised, double-blind, placebo-controlled trial.

SETTING

Single-centre, tertiary care hospital, November 2016 to September 2018.

PATIENTS

Eligible patients (n = 177) undergoing transthoracic oesophagectomy were randomly assigned to receive total intravenous anaesthesia (TIVA, n = 87) or dexmedetomidine with TIVA (DEX-TIVA, n = 90).

INTERVENTIONS

Patients receiving DEX-TIVA received a loading dose of dexmedetomidine (0.4 μg kg-1), over 15 min, followed by a continuous infusion at a rate of 0.1 μg kg-1 h-1 until 1 h before the end of surgery. Patients receiving TIVA received physiological saline with a similar infusion rate protocol.

OUTCOME MEASURES

The primary outcome was the incidence of POD. The secondary endpoints were the incidence of emergence agitation, serum interleukin-6 (IL-6) levels and haemodynamic profile.

RESULTS

All randomised patients were included with planned intention-to-treat analyses for POD. Delirium occurred in 15 (16.7%) of 90 cases given dexmedetomidine, and in 32 (36.8%) of 87 cases given saline (P = 0.0036). The DEX-TIVA group showed less frequent emergence agitation than the TIVA group (22.1 vs. 48.0%, P = 0.0058). The incremental change in surgery-induced IL-6 levels was greater in the TIVA group than DEX-TIVA group (P < 0.0001).

CONCLUSION

Adding peri-operative dexmedetomidine to a total intravenous anaesthetic safely reduces POD and emergence agitation in elderly patients undergoing open transthoracic oesophagectomy. These benefits were associated with a postoperative reduction in circulating levels of the pro-inflammatory cytokine IL-6 and stabilisation of the haemodynamic profile.

TRIAL REGISTRATION

Chinese Clinical Trials Register Identifier: ChiCTR-IPR-17010881.

Diagnosis, prevention, and management of delirium in the intensive cardiac care unit

Delirium is a frequent complication in patients admitted to intensive cardiac care units (ICCU) with potentially severe consequences including increased risks of mortality, cognitive impairment and dependence at discharge, and longer times on mechanical ventilation and hospital stay. Delirium has been widely documented and studied in general intensive care units and in patients after cardiac surgery, but it has barely been studied in acute nonsurgical cardiac patients. Moreover, delirium (especially in its hypoactive form) is commonly misdiagnosed. We propose a protocol for delirium prevention and management in ICCUs. A daily comprehensive assessment to improve detection should be done using validated scales (ie, confusion assessment method). Preventive measures are particularly relevance and constitute the basis of treatment as well, acting on reversible risk factors, including environmental interventions, such as quiet time, sleep promotion, family support, communication, and adequate treatment of pain and dyspnea. Pharmacological prophylaxis is not indicated with the exception of patients at risk of withdrawal syndrome but should only be used in patients with confirmed delirium. Dexmedetomidine is the drug of choice in patients with severe agitation, and those weaning from invasive mechanical ventilation. As the complexity of ICCUs increases, clinical scenarios posing challenges for the management of delirium become more frequent. Efforts should be done to improve the identification of patients at risk during admission in order to establish preventive interventions to avoid this complication. Patient-centered protocols will increase the awareness of the healthcare professionals for better prevention and earlier diagnosis and will positively impact on prognosis.

Neuroanesthesiology Update

This review summarizes the literature published in 2020 that is relevant to the perioperative care of neurosurgical patients and patients with neurological diseases as well as critically ill patients with neurological diseases. Broad topics include general perioperative neuroscientific considerations, stroke, traumatic brain injury, monitoring, anesthetic neurotoxicity, and perioperative disorders of cognitive function.

Dexmedetomidine Attenuates LPS-Induced Monocyte-Endothelial Adherence via Inhibiting Cx43/PKC-α/NOX2/ROS Signaling Pathway in Monocytes

Dexmedetomidine is widely used for sedating patients in operation rooms or intensive care units. Its protective functions against oxidative stress, inflammation reaction, and apoptosis have been widely reported. In present study, we explored the effects of dexmedetomidine on monocyte-endothelial adherence. We built lipopolysaccharide- (LPS-) induced monocyte-endothelial adherence models with U937 monocytes and human umbilical vein endothelial cells (HUVECs) and observed the effects of dexmedetomidine on U937-HUVEC adhesion. Specific siRNA was designed to knock-down Connexin43 (Cx43) expression in U937 monocytes. Gö6976, GSK2795039, and NAC were used to inhibit PKC-α, NOX2, and ROS, respectively. Then, we detected whether dexmedetomidine could downregulate Cx43 expression and its downstream PKC-α/NOX2/ROS signaling pathway activation and ultimately result in the decrease of U937-HUVEC adhesion. The results showed that dexmedetomidine, at its clinically relevant concentrations (0.1 nM and 1 nM), could inhibit adhesion of molecule expression (VLA-4 and LFA-1) and U937-HUVEC adhesion. Simultaneously, it also attenuated Cx43 expression in U937 monocytes. With the downregulation of Cx43 expression, the activity of PKC-α and its related NOX2/ROS signaling pathway were reduced. Inhibiting PKC-α/NOX2/ROS signaling pathway with Gö6976, GSK2795039, and NAC, respectively, VLA-4, LFA-1 expression, and U937-HUVEC adhesion were all decreased. In summary, we concluded that dexmedetomidine, at its clinically relevant concentrations (0.1 nM and 1 nM), decreased Cx43 expression in U937 monocytes and PKC-α associated with carboxyl-terminal domain of Cx43 protein. With the downregulation of PKC-α, the NOX2/ROS signaling pathway was inhibited, resulting in the decrease of VLA-4 and LFA-1 expression. Ultimately, U937-HUVEC adhesion was reduced.

Effect of intraoperative dexmedetomidine infusion on delirium in adult patients following cardiac valve surgery: a protocol of a randomized, double-blinded, and placebo-controlled study

Background

Delirium is an acute status of brain dysfunction that commonly occurs in patients who have undergone cardiac surgery, and increases morbidity and mortality. It is associated with risk factors, such as older age, use of narcotics, cardiopulmonary bypass, and hypothermia. Dexmedetomidine infusion might exert a neuroprotective effect. However, the effect of perioperative administration of dexmedetomidine on the incidence of postoperative delirium (POD) in patients undergoing cardiac or non-cardiac surgery is yet controversial. The present study aimed to reveal the effect of intraoperative dexmedetomidine administration on the incidence of delirium in adult patients following cardiac surgery.

Methods

This single-center, randomized, double-blinded, and placebo-controlled trial consisted of 652 patients randomly divided into two groups: dexmedetomidine and placebo. 0.6 μg/kg dexmedetomidine will be infused 10 min after central vein catheterization, followed by a continuous infusion at a speed of 0.4 μg/kg/h until the end of surgery in the dexmedetomidine group, while normal saline will be administered at the same rate in the placebo group. The primary outcome is the incidence of POD during the first 7 days post-surgery. The secondary outcomes include duration of mechanical ventilation after surgery, duration of stay in the intensive care unit and the hospital after surgery, incidence of hypotension during or after dexmedetomidine infusion, acute kidney injury and sudden arrhythmia during the hospital stay postoperatively, and all-cause mortality in 30 and 90 days after surgery, respectively.

Discussion

This study was approved by the Ethics Committee of the Chinese Academy of Medical Sciences Fuwai Hospital on 6 March 2019 (2019-1180). The results will be disseminated at academic conferences and submitted to peer-reviewed publications. Either positive or negative results will provide guidance for clinical practice.

Trial registration

The Chinese Clinical Trial Registry (http://www.chictr.org.cn) ChiCTR1900022583. Registered on 17 April 2019.

Protective effects of dexmedetomidine on the survival of random flaps

BACKGROUND

Random flaps can be used to repair wounds and improve shape and functional reconstruction, but inflammation and necrosis limit their application. Modified McFarlane flap models were constructed on the backs of rats. We hypothesized that dexmedetomidine (DEX) could improve the survival rate of ischemic random flaps.

METHODS

Sixty rats were randomly divided into three groups: a low-dose DEX group (DEX-L group, 10 μg/kg/D), a high-dose DEX group (DEX-H group, 20 μg/kg/D) and a control group (0.9 % saline equivalent). On day 7 after flap construction, the survival percentage of the flap model was calculated. Hematoxylin and eosin staining (H&E) was used to evaluate the histopathological status of the flaps and microvessel density (MVD). Lead oxide/gelatin angiography was used to detect angiogenesis, and laser Doppler flow imaging (LDF) was used to detect blood perfusion. The levels of superoxide dismutase (SOD) and malondialdehyde (MDA) in the middle areas of the flaps were measured to show the level of oxidative stress. The expressions of Toll-like receptor (TLR4), nuclear factor-kappa B (NF-κB), interleukin (IL)-1β, IL-6, tumor necrosis factor-α (TNF-α) and vascular endothelial growth factor (VEGF) were detected by immunohistochemistry.

RESULTS

DEX significantly increased the average survival percentage of the flaps and reduced ischemia and necrosis of the distal end of the flaps. SOD activity significantly increased, while MDA significantly decreased, indicating that DEX reduces oxidative damage. The expression of inflammatory immunoregulatory proteins (TLR4, NF-κB) was downregulated, and the levels of inflammatory factors (IL-1β, IL-6 and TNF-α) were lower. In addition, DEX upregulated VEGF expression, promoted angiogenesis, and increased blood perfusion.

CONCLUSION

In random flap transplantation, a high dose of DEX is beneficial to flap survival.