Dose- and time-related effects of dexmedetomidine on mortality and inflammatory responses to endotoxin-induced shock in rats

The effect of the concurrent use of Dexmedetomidine (DEX) during the perioperative period on the renal function of patients following craniocerebral interventional surgery

BACKGROUND

Craniocerebral interventional surgery is a common and essential treatment for cerebrovascular diseases. Despite continuous progress in interventional diagnosis and treatment technology, there is no effective method to alleviate contrast-induced kidney injuries. In this retrospective cohort study, we investigated the effect of the concurrent use of Dexmedetomidine (DEX) during the perioperative period on the renal function of patients following craniocerebral interventional surgery.

METHODS

We identified 228 cases of patients underwent craniocerebral interventional surgery from January 2018 to March 2022. Patients who used DEX during general anesthesia were in the DEX group (DEX group) or that did not use dexmedetomidine as the control group (CON group). The markers of kidney injury were recorded before and within 48 h after surgery.

RESULTS

Compared with CON group, the urea nitrogen (BUN) of the DEX group decreased significantly on the first day and the second day after surgery (p < 0.05). The serum cystatin-C and the blood urea nitrogen/creatinine ratio (BUN/Cr) was significantly lower than that in CON group on the second day (p < 0.05). The urine output in the DEX group increased significantly, and the mean arterial pressure (MAP) was higher than the CON group (p < 0.01). There was no difference in postoperative complications, ICU stay time and hospitalization time between the two groups.

CONCLUSION

The combined use of dexmedetomidine in general anesthesia for craniocerebral interventional surgery can reduce BUN levels within 48 h after surgery, significantly increase intraoperative urine volume, maintain intraoperative circulation stability.

Efficacy and safety of dexmedetomidine for analgesia and sedation in neonates: a systematic review

Opioids and benzodiazepines have historically been employed for pain relief; however, they are associated with detrimental long-term neurodevelopmental consequences. Dexmedetomidine, a highly selective alpha-2-adrenoreceptor agonist, has piqued interest as a viable alternative for neonates, owing to its potential analgesic and neuroprotective attributes. We conducted a systematic review to assess the efficacy and safety of dexmedetomidine utilization in neonates. We conducted a comprehensive search of Ovid, MEDLINE, EMBASE, PubMed, Cochrane, and CINAHL, spanning from January 2010 to September 2022. Our review encompassed six studies involving 252 neonates. Overall, dexmedetomidine may be effective in achieving sedation and analgesia. Furthermore, it may reduce the need for adjunctive sedation or analgesia, shorten the time to extubation, decrease the duration of mechanical ventilation, and accelerate the attainment of full enteral feeds. Notably, no significant adverse effects associated with dexmedetomidine were reported. Nevertheless, additional well-designed studies to establish both the efficacy and safety of dexmedetomidine in neonatal care are needed.

Dexmedetomidine post-treatment exacerbates metabolic disturbances in septic cardiomyopathy via α2A-adrenoceptor

Cardiomyopathy is a common complication and significantly increases the risk of death in septic patients. Our previous study demonstrated that post-treatment with dexmedetomidine (DEX) aggravates septic cardiomyopathy. However, the mechanisms for the side effect of DEX post-treatment on septic cardiomyopathy are not well-defined. Here we employed a cecal ligation and puncture (CLP) model and α2A-adrenoceptor deficient (Adra2a-/-) mice to observe the effects of DEX post-treatment on myocardial metabolic disturbances in sepsis. CLP mice displayed significant cardiac dysfunction, altered mitochondrial dynamics, reduced cardiac lipid and glucose uptake, impaired fatty acid and glucose oxidation, enhanced glycolysis and decreased ATP production in the myocardium, almost all of which were dramatically enhanced by DEX post-treatment in septic mice. In Adra2a-/- mice, DEX post-treatment did not affect cardiac dysfunction and metabolic disruptions in CLP-induced sepsis. Additionally, Adra2a-/- mice exhibited impaired cardiac function, damaged myocardial mitochondrial structures, and disturbed fatty acid metabolism and glucose oxidation. In sum, DEX post-treatment exacerbates metabolic disturbances in septic cardiomyopathy in a α2A-adrenoceptor dependent manner.

Posttreatment with dexmedetomidine aggravates LPS-induced myocardial dysfunction partly via activating cardiac endothelial α2A-AR in mice

BACKGROUND

Dexmedetomidine (DEX) administered before or at 30 min after sepsis induction was reported to alleviate septic cardiomyopathy in experimental models. However, sepsis is a life-threatening organ dysfunction due to infection-induced dysregulated host response, whether DEX treatment in the presence of organ dysfunction affects septic cardiomyopathy is unknown. This study investigated the effect of DEX posttreatment on septic cardiomyopathy.

METHODS

Male wild-type and α_2A-adrenergic receptor (AR) knockout mice were exposed to lipopolysaccharide (LPS) or cecal ligation puncture (CLP), and cultured cardiac endothelial cells were used. Mouse survival, myocardial function, inflammatory response and related signaling pathways were determined.

RESULTS

DEX treatment at 6, 9 h after LPS challenge significantly reduced survival rate of LPS-challenged mice, especially at 9 h. DEX administered at 9 h after LPS injection or CLP significantly reduced survival in LPS or CLP-induced sepsis in wild-type mice, but not in α_2A-AR knockout mice. LPS treatment for 20 h decreased the left ventricle + dp/dt, increased myocardial interleukin (IL)-1β and IL-6 concentrations as well as cardiac endothelial tumor necrosis factor (TNF)-α, vascular cell adhesion molecule-1 (VCAM-1) and ICAM-1 expression, which were enhanced by DEX treated at 9 h after LPS injection in wild-type mice, but not in α_2A-AR knockout mice. Furthermore, DEX posttreatment increased p38 phosphorylation, c-Fos nuclear translocation and VCAM-1 expression in LPS-treated cardiac endothelial cells, which were eliminated by α_2A-AR knockout or PKC inhibitor.

CONCLUSIONS

DEX posttreatment aggravates LPS-induced cardiac inflammation and myocardial dysfunction, at least in part, via activating cardiac endothelial α_2A-AR-mediated PKC signal pathway.

Dexmedetomidine versus fentanyl for sedation in extremely preterm infants

BACKGROUND

Few studies have compared the efficacy and complications of dexmedetomidine (DEX) and fentanyl (FEN) in extremely preterm infants.

METHODS

We conducted a single-institution, retrospective controlled before and after study of preterm infants before 28 weeks of gestation admitted between April 2010 and December 2018 to compare the complications and efficacy of DEX and FEN for preterm infants. Patients were administered FEN prior to 2015 and DEX after 2015 as the first-line sedative. A composite outcome of death during hospitalization and developmental quotient (DQ) < 70 at a corrected age of 3 years was compared as the primary outcome. Secondary outcomes including postmenstrual weeks at extubation, days of age when full enteral feeding was achieved and additional sedation by phenobarbital (PB) were compared.

RESULTS

Sixty-six infants were enrolled into the study. The only perinatal factor that differed between the FEN (n = 33) and DEX (n = 33) groups was weeks of gestation. The composite outcome of death and DQ < 70 at a corrected age of 3 years were not significantly different. Postmenstrual weeks at extubation did not significantly differ between groups after adjustment for weeks of gestation and being small for gestational age. On the other hand, full feeding was significantly prolonged by DEX (p = 0.031). Additional sedation was less common in the DEX group (p = 0.044).

CONCLUSION

The composite outcome of death and DQ < 70 at a corrected age of 3 years were not significantly different by DEX or FEN for primary sedation. Prospective randomized controlled trials should examine the long-term effects on development.

A comprehensive evaluation between dexmedetomidine and midazolam for intraoperative sedation in the elderly: protocol for a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

The sedative effect of intraoperative sedation in elderly surgery exerts critical influence on the prognosis. Comparison on the safety and efficacy between dexmedetomidine and midazolam in many clinical randomized controlled trials (RCTs) was inconsistent and suspicious. We aim to comprehensively evaluate the safety and efficacy between dexmedetomidine and midazolam for intraoperative sedation in the elderly via meta-analysis and systematic reviews.

METHODS

RCTs regarding to the comparison of sedative effects and safety between dexmedetomidine and midazolam in elderly patients (aged ≥ 60 years) will be comprehensively searched from 2000 October to 2022 May through 4 English databases and 4 Chinese databases. After extraction in duplicate, the systematic review and meta-analysis will be performed on the primary outcomes (hemodynamic changes, sedative effect, cognitive function) and secondary outcomes (analgesic effect, surgical characteristics, complications, or adverse reactions) for assessing the two therapy methods using Review Manager software (Version 5.3). Sensitivity analysis will be conducted to evaluate the heterogeneity of the results; funnel plot and Egger's trial will be performed to analyze publication bias of the included studies, and trial sequential analysis will be applied to assess the robustness and reliability of preliminary meta-analysis results. Finally, rating quality of evidence and strength of recommendations on the meta results will be summarized by Grading of Recommendations, Assessment, Development and Evaluations (GRADE) approach.

DISCUSSION

This systematic review and meta-analysis will evaluate the safety and efficacy between dexmedetomidine and midazolam for intraoperative sedation in the elderly; it will give an insight on the application of dexmedetomidine and midazolam and will provide evidence-based reference for clinical decision-making.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42021221897.

Association between dexmedetomidine administration and outcomes in critically ill patients with sepsis-associated acute kidney injury

STUDY OBJECTIVE

To investigate the association between dexmedetomidine administration and outcomes in critically ill patients with sepsis-associated acute kidney injury (SA-AKI).

DESIGN

A single-center, retrospective, cohort study.

SETTING

Intensive care unit (ICU).

PATIENTS

A total of 2192 critically ill patients with SA-AKI were included in the analysis, which identified from the Medical Information Mart for Intensive Care (MIMIC-IV) database between 2008 and 2019.

INTERVENTIONS

Intravenous infusion of dexmedetomidine.

MEASUREMENTS

The primary outcome was recovery of renal function. In-hospital mortality, vasopressor requirements, length of ICU and hospital stay were considered secondary outcomes. The Cox proportional hazards, logistic regression, and linear regression models were used to assess the association between dexmedetomidine and outcomes. Propensity score matching (PSM) analysis was used to match patients receiving dexmedetomidine to those without treatment.

MAIN RESULTS

After PSM, 719 matched patient pairs were derived from patients who received dexmedetomidine and those who did not. The administration of dexmedetomidine was associated with a higher rate of renal recovery [61.8% vs. 55.8%, hazard ratio (HR) 1.35; P = 0.01], reduced in-hospital mortality [28.3% vs. 41.3%, HR 0.56; P < 0.001], and prolonged intensive care unit (ICU) stay [15.8d vs 12.6d, HR 2.34; P < 0.001] and hospital stay [23.7d vs 19.7d, HR 4.47; P < 0.001]. No significant difference was found in vasopressor requirements in patients with SA-AKI. Nevertheless, results illustrated that dose receiving between 0.30 and 1.00 μg/kg/h and duration using under 48 h of dexmedetomidine was associated with improvements in renal function recovery in SA-AKI patients.

CONCLUSION

Dexmedetomidine administration was associated with improvements in renal function recovery and in-hospital survival in critically ill patients with SA-AKI. The results need to be verified in further randomized controlled trials.

Effects of dexmedetomidine on hemodynamic, oxygenation, microcirculation, and inflammatory markers in a porcine model of sepsis

PURPOSE

To determine whether dexmedetomidine aggravates hemodynamic, metabolic variables, inflammatory markers, and microcirculation in experimental septic shock.

METHODS

Twenty-four pigs randomized into: Sham group (n = 8), received saline; Shock group (n = 8), received an intravenous infusion of Escherichia coli O55 (3 × 109 cells/mL, 0.75 mL/kg, 1 hour); Dex-Shock group (n = 8), received bacteria and intravenous dexmedetomidine (bolus 0.5 mcg/kg followed by 0.7 mcg/kg/h). Fluid therapy and/ornorepinephrine were administered to maintain a mean arterial pressure > 65 mmHg. Hemodynamic, metabolic, oxygenation, inflammatory markers, and microcirculation were assessed at baseline, at the end of bacterial infusion, and after 60, 120, 180, and 240 minutes.

RESULTS

Compared to Shock group, Dex-Shock group presented a significantly increased oxygen extraction ratio at T180 (23.1 ± 9.7 vs. 32.5 ± 9.2%, P = 0.0220), decreased central venous pressure at T120 (11.6 ± 1 vs. 9.61 ± 1.2 mmHg, P = 0.0214), mixed-venous oxygen saturation at T180 (72.9 ± 9.6 vs. 63.5 ± 9.2%, P = 0.026), and increased plasma lactate (3.7 ± 0.5 vs. 5.5 ± 1 mmol/L, P = 0.003). Despite the Dex-Shock group having a better sublingual vessel density at T240 (12.5 ± 0.4 vs. 14.4 ± 0.3 mL/m2; P = 0.0003), sublingual blood flow was not different from that in the Shock group (2.4 ± 0.2 vs. 2.4 ± 0.1 mL/kg, P = 0.4418).

CONCLUSIONS

Dexmedetomidine did not worsen the hemodynamic, metabolic, inflammatory, or sublingual blood flow disorders resulting from septic shock. Despite inducing a better sublingual vessel density, dexmedetomidine initially and transitorily increased the mismatch between oxygen supply and demand.

Dexmedetomidine to reduce vasopressor resistance in refractory septic shock: Protocol for a double-blind randomized controlled pilot trial (ADRESS Pilot study)

Introduction

Refractory septic shock (RSS) is characterized by high vasopressor requirements, as a consequence of vasopressor resistance, which may be caused or enhanced by sympathetic hyperactivation. Experimental models and clinical trials show a reduction in vasopressor requirements and improved microcirculation compared to conventional sedation. Dexmedetomidine did not reduce mortality in clinical trials, but few septic shock patients were enrolled. This pilot trial aims to evaluate vasopressor re-sensitization with dexmedetomidine and assess the effect size, in order to design a larger trial.

Methods

This is an investigator-initiated, multicenter, randomized, double-blind, placebo-controlled trial, comparing dexmedetomidine versus placebo in RSS patients with norepinephrine dose ≥0.5μg/kg/min. The primary outcome is blood pressure response to phenylephrine challenge, 6 hours after completion of a first challenge, after study treatment initiation. Secondary outcomes include feasibility and safety outcomes (bradycardia), mortality, vasopressor requirements, heart rate variability, plasma and urine catecholamines levels. The sample size is estimated at 32 patients to show a 20% improvement in blood pressure response to phenylephrine. Randomization (1:1) will be stratified by center, sedation type and presence of liver cirrhosis. Blood pressure and ECG will be continuously recorded for the first 24 h, enabling high-quality data collection for the primary and secondary endpoints. The study was approved by the ethics committee “Sud-Est VI” (2019-000726-22) and patients will be included after informed consent.

Discussion

The present study will be the first randomized trial to specifically address the hemodynamic effects of dexmedetomidine in patients with septic shock. We implement a high-quality process for data acquisition and recording in the first 24 h, ensuring maximal quality for the evaluation of both efficacy and safety outcomes, as well as transparency of results. The results of the study will be used to elaborate a full-scale randomized controlled trial with mortality as primary outcome in RSS patients.

Trial registration

Registered with ClinicalTrials.gov (NCT03953677). Registered 16 May 2019, https://clinicaltrials.gov/ct2/show/NCT03953677.

Effects of propofol and dexmedetomidine on carnitine metabolism in normal human bronchial epithelial cells

Propofol and dexmedetomidine (DEX) are widely used for anesthesia and sedation. We investigated the effects of propofol and DEX separately and in combination on the metabolic profile of carnitine in cultured normal human bronchial epithelial cells (BEAS-2B). Cells of the propofol group were cultured with 2 µg/ml propofol in RPMI-1640 medium. Cells of the DEX group were cultured with 0.2 ng/m DEX in RPMI-1640 medium. Cells of the propofol + DEX group were cultured with 2 μg/ml propofol + 0.2 ng/ml DEX in RPMI-1640 medium. The control group was untreated. Cells were incubated for 3 h following treatments. The effects of the drugs on cell viability were assessed using the MTT method and by microscopic examination following staining with acridine orange/ethidium bromide. The effects of drugs on carnitine, acetyl carnitine and 25 acylcarnitine derivative profiles were analyzed using liquid chromatography-tandem mass spectrophotometry. Neither propofol nor DEX affected cell viability. Administration of propofol, DEX or propofol + DEX to BEAS-2B cells caused no significant change in the concentrations of carnitine and acylcarnitine derivatives compared to the control group. We found that propofol and DEX exhibit no negative effects on the carnitine metabolism by BEAS-2B cells in vitro at clinically relevant concentrations. Our findings establish a baseline for clinical studies of the effects of propofol and DEX on carnitine metabolism.

Dexmedetomidine attenuates lipopolysaccharide-induced inflammation through macrophageal IL-10 expression following α7 nAchR activation

Dexmedetomidine, a highly selective α₂-adrenoceptor agonist, has been recently reported to alleviate systemic inflammatory response induced by lipopolysaccharide (LPS), in addition to its sedative, analgesic, bradycardic and hypotensive properties. This study aimed to illustrate the molecular mechanisms underlying dexmedetomidine-induced anti-inflammation. In the LPS-pretreated mice, subcutaneous injection of dexmedetomidine reduced the spleen weight as well as serum and spleen expression of proinflammatory cytokines, tumor necrosis factor-α (TNF-α), interleukin (IL)-6 and IL-1β, and increased serum and spleen expression of IL-10, a known anti-inflammatory cytokine. In addition, dexmedetomidine-attenuated proinflammatory cytokine reduction was entirely inhibited by selective α7 nicotinic acetylcholine receptor (nAChR) antagonist methyllycaconitine but not α₂-adrenoceptor antagonist yohimbine. Dexmedetomidine also increased macrophageal IL-10 expression in the presence and absence of LPS, which was also attenuated by methyllycaconitine but not yohimbine. Furthermore, the stimulatory effect of dexmedetomidine on the expression of IL-10 was also reduced by the α7 nAChR gene silencer siRNA/α7 nAChR. Lastly, pretreatment with the IL-10 neutralizing antibody reversed dexmedetomidine-supressed expression of proinflammatory cytokines. Our findings illustrate that dexmedetomidine-induced anti-inflammation is through macrophageal expression of IL-10 following activation of α7 nAchRs but not α₂-adrenoceptors.

Effects of dexmedetomidine on surgery for type A acute aortic dissection outcome

No study has evaluated the effect of dexmedetomidine in patients who received surgery for type A aortic dissection. This is the first study to evaluate the effect of dexmedetomidine in aortic dissection patients. This study was executed using data from the Chang Gung Research Database in Taiwan. The CGRD contains the multi‐institutional standardized electronic medical records from seven Chang Gung Memorial hospitals, the largest medical system in Taiwan. We retrospectively evaluate patients who received surgery for acute type A aortic dissection between January 2014 and December 2018. Overall, 511 patients were included, of whom 104 has received dexmedetomidine infusion in the postoperative period. One-to-two propensity score-matching yielded 86 cases in the dexmedetomidine group and 158 cases in the non-dexmedetomidine group. The in-hospital mortality and composite outcome including all-cause mortality, acute kidney injury, delirium, postoperative atrial fibrillation, and respiratory failure, were considered primary outcomes. The in-hospital mortality and composite outcome were similar between groups. The risk of Acute Kidney Injury Network stage 3 acute kidney injury was significantly lower in the dexmedetomidine group than in the non-dexmedetomidine group (8.1% vs 19.0%; OR, 0.38; 95% CI, 0.17–0.86; p = 0.020. The risk of newly-onset dialysis was also significantly lower in the dexmedetomidine group than in the non-dexmedetomidine group (4.7% vs 13.3%; OR, 0.32; 95% CI, 0.11–0.90; p = 0.031). Post-operative dexmedetomidine infusion significantly reduced the rate of severe acute kidney injury and newly-onset dialysis in patients who received surgery for acute type A aortic dissection.

Global Research and Scientific Publications on Dexmedetomidine Use in Adults for Anesthesia Care between 2001 and 2021: A Bibliometric Analysis

Background

An increasing number of studies on dexmedetomidine use in adults have been published, but the effectiveness of dexmedetomidine remains contentious.

Objective

This study aimed to describe the changing trends and structural relationships of scientific achievements regarding dexmedetomidine over the past 2 decades and provide researchers with information to help them explore better research opportunities.

Methods

Quantitative data of publications were retrieved from the Scopus database. Analyses of co-occurrence and collaboration among authors, countries, and key words were conducted using VOSviewer 1.6.17 software. Weighted occurrence and average publications per year were calculated.

Results

The 1868 publications retrieved showed an increasing trend of annual publications on dexmedetomidine use in adults between 2001 and 2021. China accounted for the largest contribution to publications in the world (n = 577 [30.89%]). Four key word clusters indicating research hotspots were identified using VOSviewer. The number of articles published in the top 10% of journals in the United States was the highest among all publications from the country (97 out of 201 [48.26%]). Journals from the United Kingdom obtained the highest CiteScore (16.56). Journal of Anaesthesiology Clinical Pharmacology published the highest number of articles on this topic (n = 56). Wang authored the highest number of published articles (n = 42). Recent publications focused on the theme of cytokines and immunomodulation. Sufentanil attracted particular interest as a drug-related key word. Moreover, meta-analysis is becoming an increasingly popular research method in this field.

Conclusions

The increasing number of publications on dexmedetomidine use reflects growing interest in this topic. Future research should focus on meta-analyses to identify the most effective therapeutic methods. The immunomodulatory effect of dexmedetomidine on health and disease is of particular interest.

Dexmedetomidine Restores Autophagic Flux, Modulates Associated microRNAs and the Cholinergic Anti-inflammatory Pathway upon LPS-Treatment in Rats

Infections and perioperative stress can lead to neuroinflammation, which in turn is linked to cognitive impairments such as postoperative delirium or postoperative cognitive dysfunctions. The α2-adrenoceptor agonist dexmedetomidine (DEX) prevents cognitive impairments and has organo-protective and anti-inflammatory properties. Macroautophagy (autophagy) regulates many biological processes, but its role in DEX-mediated anti-inflammation and the underlying mechanism of DEX remains largely unclear. We were interested how a pretreatment with DEX protects against lipopolysaccharide (LPS)-induced inflammation in adult male Wistar rats. We used Western blot and activity assays to study how DEX modulated autophagy- and apoptosis-associated proteins as well as molecules of the cholinergic anti-inflammatory pathway, and qPCR to analyse the expression of autophagy and inflammation-associated microRNAs (miRNA) in the spleen, cortex and hippocampus at different time points (6 h, 24 h, 7 d). We showed that a DEX pretreatment prevents LPS-induced impairments in autophagic flux and attenuates the LPS-induced increase in the apoptosis-associated protein cleaved poly(ADP-ribose)-polymerase (PARP) in the spleen. Both, DEX and LPS altered miRNA expression and molecules of the cholinergic anti-inflammatory pathway in the spleen and brain. While only a certain set of miRNAs was up- and/or downregulated by LPS in each tissue, which was prevented or attenuated by a DEX pretreatment in the spleen and hippocampus, all miRNAs were up- and/or downregulated by DEX itself - independent of whether or not they were altered by LPS. Our results indicate that the organo-protective effect of DEX may be mediated by autophagy, possibly by acting on associated miRNAs, and the cholinergic anti-inflammatory pathway. Preventive effects of DEX on LPS-induced inflammation. DEX restores the LPS-induced impairments in autophagic flux, attenuates PARP cleavage and alters molecules of the cholinergic system in the spleen. Furthermore, DEX alters and prevents LPS-induced miRNA expression changes in the spleen and brain along with LPS.

Dexmedetomidine modulates mitochondrial dynamics to protect against endotoxin-induced lung injury via the protein kinase C-ɑ/heme oxygenase-1 signaling pathway

BACKGROUND

Endotoxin-induced acute lung injury (ALI) has a high mortality rate, and there are limited effective treatment options available. The aim of the present study was to identify if dexmedetomidine could regulate mitochondrial fusion and fission through the protein kinase C (PKC)-α/heme oxygenase (HO)-1 pathway to protect against endotoxin-induced ALI.

MATERIALS AND METHODS

Dexmedetomidine was administered by intraperitoneal injection once daily for 3 days prior to induction of lung injury to mice. Mice in the PKC-α inhibitor group received dexmedetomidine by intraperitoneal injection 1 h after each chelerythrine injection, and lipopolysaccharide was injected 1 h after the last dose of dexmedetomidine. The lung wet/dry weight ratio, oxidative stress, inflammatory response, and expression levels of PKC-α, Nrf2, HO-1, Mfn1, Mfn2, OPA1, Drp1, and Fis1 were determined.

RESULTS

Dexmedetomidine administration attenuated lung oxidative stress, decreased inflammatory cytokines secretion, and downregulated the expression levels of Drp1 and Fis1. Moreover, dexmedetomidine increased levels of Mfn1, Mfn2, and OPA1, and alleviated endotoxin-induced lung injury. Administration of chelerythrine partially reversed the pneumoprotective effects of dexmedetomidine.

CONCLUSIONS

Dexmedetomidine may activate the PKC-ɑ/HO-1 pathway to increase the expression of Mfn1, Mfn2, and OPA1, while decreasing Drp1 and Fis1 expression, thereby reduce endotoxin-induced acute lung injury.

Effects of Perioperative Dexmedetomidine on Immunomodulation in Uterine Cancer Surgery: A Randomized, Controlled Trial

Objective

Dexmedetomidine has sympatholytic, anti-inflammatory, and analgesic effects and may exert anti-tumor effect by acting on α2A adrenoreceptor. We investigated whether perioperative dexmedetomidine preserves immune function in patients undergoing uterine cancer surgery.

Methods

One hundred patients were randomly assigned to the control or dexmedetomidine groups (50 patients each). Dexmedetomidine was infused at rates of 0.4 μg/kg/h intraoperatively and 0.15 μg/kg/h during the first 24 h postoperatively. The primary outcome was natural killer (NK) cell activity, which was measured preoperatively and 1, 3, and 5 days postoperatively. The inflammatory response was measured by interleukin-6, interferon-γ, and neutrophil/lymphocyte ratio, and pain scores and opioid consumption were assessed. Cancer recurrence or metastasis and death were evaluated 2 years postoperatively.

Results

NK cell activity decreased postoperatively in both groups and changes over time were not different between groups (P=0.496). Interferon-γ increased postoperatively in the dexmedetomidine group, whereas it maintained at the baseline value in the control group. Change in interferon-γ differed significantly between groups (P=0.003). Changes in interleukin-6 and neutrophil-lymphocyte ratio were comparable between groups. Both pain score with activity during the first 1 h and opioid consumption during the first 1–24 h postoperatively were lower in the dexmedetomidine group. Rates of cancer recurrence/metastasis (16.3% vs. 8.7%, P=0.227) and death within 2 years postoperatively (6.7% vs. 2.2%, P=0.318) were not different between groups.

Conclusions

Perioperative dexmedetomidine had no favorable impacts on NK cell activity, inflammatory responses, or prognosis, whereas it increased interferon-γ and reduced early postoperative pain severity and opioid consumption in uterine cancer surgery patients.

Dexmedetomidine Suppressed the Biological Behavior of HK-2 Cells Treated with LPS by Down-Regulating ALKBH5

Dexmedetomidine inhibits the release of inflammatory cytokines and exerts a systemic anti-inflammatory effect and has potential protective effects on vital organs such as lung, heart, and kidneys. The aim of this study was to investigate the effect of dexmedetomidine on LPS-treated HK-2 cells in vitro and explore the potential mechanisms. The HK-2 cells were pretreated with dexmedetomidine before LPS induction. CCK-8, flow cytometry, ELISA, or qRT-PCR was performed to detect cell proliferation, apoptosis, and proinflammatory cytokine expression. The levels of MALAT1 in HK-2 cells under different stimulation were measured by qRT-PCR. Then, m6A RNA immunoprecipitation was performed to detect methylated MALAT1 in HK-2 cells. The results showed dexmedetomidine suppressed cell viability, induced cell apoptosis, and reduced inflammation cytokine production of LPS-treated HK-2 cells. Besides, dexmedetomidine reduced the expression of MALAT1 in HK-2 cells under LPS stimulation. In addition, ALKBH5 could up-regulate MALAT1 expression by demethylation. Furthermore, dexmedetomidine inhibited the expression of ALKBH5 in LPS-treated HK-2 cells. ALKBH5 knockdown inhibited cell viability, induced cell apoptosis, and decreased inflammation cytokine production of LPS-treated HK-2 cells. In short, dexmedetomidine suppressed the biological behavior of HK-2 cells treated with LPS by inhibiting the expression of ALKBH5 in vitro, which may provide potential targets for the prevention and treatment of sepsis-induced kidney injury.

Effect of dexmedetomidine on hemodynamics in patients undergoing hysterectomy: a meta-analysis and systematic review

Objective

We conducted a meta-analysis and systematic review to evaluate the effects of dexmedetomidine on the hemodynamics of patients undergoing hysterectomy.

Methods

We searched the Medline, Embase, and Cochrane Central Register of Controlled Trials databases for clinical randomized controlled trials (RCTs) that allowed direct or indirect comparisons of hemodynamic indicators. We also searched nine English-language databases up to April 2021 to identify relevant research. The Cochrane risk-of-bias tool for RCTs was applied to assess the methodological quality of the eligible studies. The meta-analysis was conducted using RevMan 5.4 software.

Results

Nine trials were included in this systematic review. The effect of dexmedetomidine on heart rate during surgery was significantly smaller than that of other sedatives. Intraoperative systolic and diastolic blood pressure and mean arterial pressure were more stable in the dexmedetomidine group compared with the control group. The postoperative modified Observer’s Assessment of Alertness Score was also better in the dexmedetomidine compared with the control group.

Conclusions

Dexmedetomidine increases hemodynamic stability in patients undergoing hysterectomy, reduces the cardiovascular stress response during surgery, and effectively prevents postoperative adverse reactions, with good safety.

[Effects of dexmedetomidine doses on postoperative cognitive dysfunction and serum β- amyloid and cytokine levels in elderly patients after spine surgery: a randomized controlled trial]

OBJECTIVE

To explore the immunomodulatory mechanism and optimal dose of dexmedetomidine (DEX) for preventing postoperative cognitive dysfunction (POCD) in elderly patients undergoing spinal surgery.

OBJECTIVE

A total of 120 elderly patients undergoing elective spinal surgery with general anesthesia were randomized into 4 groups to receive a loading dose of 0.3 μg/kg DEX for 10 min before anesthesia induction followed by maintenance doses of 0.2, 0.5, and 0.8 μg · kg^-1·h^-1 (low-, medium-, and high-dose DEX groups, respectively) or an equal volume of normal saline (control group). DEX and saline was discontinued 40 min before the end of the surgery. Before induction (D₀) and on day 1 (D₁), day 3 (D₂) and day 7 (D₃) after the operation, the cognitive function of the patients was assessed using the MMSE scale and their serum levels of β-amyloid (Aβ), TNF-α, IL-1β and IL-6 were measured. The occurrence of adverse effects including bradycardia and hypotension and the recovery time of the patients were recorded.

OBJECTIVE

Compared with those on D₀, serum levels of Aβ, IL-1β, IL-6, and TNF-α on D₁ were markedly increased in all the groups (P < 0.05); the levels of Aβ decreased to the baseline level on D₃ in medium- and high-dose DEX groups (P > 0.05) but remained high in the other two groups. On D₂, TNF-α, L-1β and IL-6 recovered their baseline levels in medium- and high-dose DEX groups (P > 0.05) but remained elevated in the other two groups. The incidences of POCD in medium- and high-dose DEX groups were comparable but significantly lower than that in the control group (P < 0.05). The incidences of hypotension and bradycardia were the highest in high-dose DEX group (P < 0.01), which also had longer recovery time than the other 3 groups (P < 0.05).

OBJECTIVE

With a loading dose of 0.3 μg/kg followed by a maintenance doses of 0.5 μg · kg^-1·h^-1, DEX can effectively reduce the incidence of POCD in elderly patients undergoing spinal surgery by inhibiting the production of Aβ and pro-inflammatory cytokines.

Emerging benefits and drawbacks of α2 -adrenoceptor agonists in the management of sepsis and critical illness

Agonists of α₂ -adrenoceptors are increasingly being used for the provision of comfort, sedation and the management of delirium in critically ill patients, with and without sepsis. In this context, increased sympathetic and inflammatory activity are common pathophysiological features linked to multi-organ dysfunction, particularly in patients with sepsis or those undergoing cardiac surgery requiring cardiopulmonary bypass. Experimental and clinical studies support the notion that the α₂ -adrenoceptor agonists, dexmedetomidine and clonidine, mitigate sympathetic and inflammatory overactivity in sepsis and cardiac surgery requiring cardiopulmonary bypass. These effects can protect vital organs, including the cardiovascular system, kidneys, heart and brain. We review the pharmacodynamic mechanisms by which α₂ -adrenoceptor agonists might mitigate multi-organ dysfunction arising from pathophysiological conditions associated with excessive inflammatory and adrenergic stress in experimental studies. We also outline recent clinical trials that have examined the use of dexmedetomidine in critically ill patients with and without sepsis and in patients undergoing cardiac surgery.

Evaluation of the Effect of Dexmedetomidine on Postoperative Cognitive Dysfunction through Aβ and Cytokines Analysis

Postoperative cognitive dysfunction is a common postoperative neurological complication in elderly patients, and has some relationship with neuroinflammation. some studies have shown ability of dexmedetomidine to improve cognitive performance in elderly individuals who underwent thoracic surgery. Therefore, our study hypothesized that dexmedetomidine treatment may reduce the incidence of POCD in elderly patients.In addition,this study detected the antineuroinflammatory effects of dexmedetomidine by β-amyloid aggregation inhibitors and release of cytokines in elderly patients . The results show that dexmedetomidine used during operation can inhibit the postoperative release of Aβ and cytokines in elderly patients, and dexmedetomidine used during operation can reduce the incidence of postoperative cognitive dysfunction, with dose-dependence. These results provide a clinical application direction for clinical anesthesiologists and ICU physicians.

Dexmedetomidine inhibits LPS-induced inflammatory responses through peroxisome proliferator-activated receptor gamma (PPARγ) activation following binding to α2 adrenoceptors

Over the past decade, dexmedetomidine (DEX) has been found to possess an anti-inflammatory effect. However, the local anti-inflammatory mechanism of DEX has not been fully clarified. Some intracellular inflammatory pathways lead to negative feedback during the inflammatory process. The cyclooxygenase (COX) cascade synthesizes prostaglandins (PGs) and plays a key role in inflammation, but is known to also have anti-inflammatory properties through an alternative route of a PGD₂ metabolite, 15-deoxy-delta-12,14-prostaglandin J₂ (15d-PGJ₂), and its receptor, peroxisome proliferator-activated receptor gamma (PPARγ). Therefore, we hypothesized that DEX inhibits LPS-induced inflammatory responses through 15d-PGJ₂ and/or PPARγ activation, and evaluated the effects of DEX on these responses. The RAW264.7 mouse macrophage-like cells were pre-incubated with DEX, followed by the addition of LPS to induce inflammatory responses. Concentrations of TNFα, IL-6, PGE₂, and 15d-PGJ₂ in the supernatants of the cells were measured, and gene expressions of PPARγ and COX-2 were evaluated in the cells. Furthermore, we evaluated whether a selective α₂ adrenoceptor antagonist, yohimbine or a selective PPARγ antagonist, T0070907, reversed the effects of DEX on the LPS-induced inflammatory responses. DEX inhibited LPS-induced TNFα, IL-6, and PGE₂ productions and COX-2 mRNA expression, and the effects of DEX were reversed by yohimbine. On the other hand, DEX significantly increased 15d-PGJ₂ production and PPARγ mRNA expression, and yohimbine reversed these DEX's effects. Furthermore, T0070907 reversed the anti-inflammatory effects of DEX on TNFα and IL-6 productions in the cells. These results suggest that DEX inhibits LPS-induced inflammatory responses through PPARγ activation following binding to α₂ adrenoceptors.

Dexmedetomidine reduces ventilator-induced lung injury via ERK1/2 pathway activation

Mechanical ventilation (MV) can contribute to ventilator-induced lung injury (VILI); dexmedetomidine (Dex) treatment attenuates MV-related pulmonary inflammation, but the mechanisms remain unclear. Therefore, the present study aimed to explore the protective effect and the possible molecular mechanisms of Dex in a VILI rodent model. Adult male Sprague-Dawley rats were randomly assigned to one of seven groups (n=24 rats/group). Rats were euthanized after 4 h of continuous MV, and pathological changes, lung wet/dry (W/D) weight ratio, the levels of inflammatory cytokines (IL-1β, TNF-α and IL-6) in the bronchoalveolar lavage fluid (BALF), and the expression levels of Bcl-2 homologous antagonist/killer (Bak), Bcl-2, pro-caspase-3, cleaved caspase-3 and the phosphorylation of ERK1/2 in the lung tissues were measured. Propidium iodide uptake and TUNEL staining were used to detect epithelial cell death. The Dex pretreatment group exhibited fewer pathological changes, lower W/D ratios and lower expression levels of inflammatory cytokines in BALF compared with the VILI group. Dex significantly attenuated the ratio of Bak/Bcl-2, cleaved caspase-3 expression levels and epithelial cell death, and increased the expression of phosphorylated ERK1/2. The protective effects of Dex could be partially reversed by PD98059, which is a mitogen-activated protein kinase (upstream of ERK1/2) inhibitor. Overall, dexmedetomidine was found to reduce the inflammatory response and epithelial cell death caused by VILI, via the activation of the ERK1/2 signaling pathway.

Effect of dexmedetomidine on inflammation in patients with sepsis requiring mechanical ventilation: a sub-analysis of a multicenter randomized clinical trial

BACKGROUND

Administration of dexmedetomidine has been reported to improve inflammatory response in animals. We explored the effects of administering dexmedetomidine on the levels of C-reactive protein (CRP) and procalcitonin, and thus on inflammation, in patients with sepsis enrolled in a randomized clinical trial.

METHODS

The DESIRE trial was a multicenter randomized clinical trial in which adult patients with sepsis were sedated with (DEX group) or without (non-DEX group) dexmedetomidine while on mechanical ventilators. As a prespecified sub-analysis, we compared CRP and procalcitonin levels during the first 14 days of treatment between the two groups. The 14-day mortality rate, albumin level, and the number of patients with disseminated intravascular coagulation (DIC) were also assessed. We used generalized linear models to estimate the differences in these outcomes between groups. We also used the Kaplan-Meier method to estimate the 14-day mortality rate and the log-rank test to assess between-group differences.

RESULTS

Our study comprised 201 patients: 100 in the DEX group and 101 in the non-DEX group. CRP and procalcitonin levels were lower in the DEX vs. non-DEX group during the 14-day treatment period [CRP-range, 5.6-20.3 vs. 8.3-21.1 mg/dL (P = 0.03); procalcitonin-range, 1.2-37.4 vs. 1.7-52.9 ng/mL (P = 0.04)]. Albumin levels were higher in the DEX group (range, 2.3-2.6 g/dL) than in the non-DEX group (range, 2.1-2.7 g/dL; P = 0.01). The percentage of patients with DIC did not significantly differ between the groups (range, 21-59% and 17-56% for the DEX and non-DEX groups, respectively; P = 0.49). The 14-day mortality rates in the DEX and non-DEX groups were 13 and 21%, respectively (P = 0.16).

CONCLUSION

Sedation using dexmedetomidine reduced inflammation in patients with sepsis requiring mechanical ventilation.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT01760967 . Registered on 4 January 2013.

The effect of dexmedetomidine on vasopressor requirements in patients with septic shock: a subgroup analysis of the Sedation Practice in Intensive Care Evaluation [SPICE III] Trial

BACKGROUND

Septic shock is associated with decreased vasopressor responsiveness. Experimental data suggest that central alpha2-agonists like dexmedetomidine (DEX) increase vasopressor responsiveness and reduce catecholamine requirements in septic shock. However, DEX may also cause hypotension and bradycardia. Thus, it remains unclear whether DEX is hemodynamically safe or helpful in this setting.

METHODS

In this post hoc subgroup analysis of the Sedation Practice in Intensive Care Evaluation (SPICE III) trial, an international randomized trial comparing early sedation with dexmedetomidine to usual care in critically patients receiving mechanical ventilation, we studied patients with septic shock admitted to two tertiary ICUs in Australia and Switzerland. The primary outcome was vasopressor requirements in the first 48 h after randomization, expressed as noradrenaline equivalent dose (NEq [μg/kg/min] = noradrenaline + adrenaline + vasopressin/0.4).

RESULTS

Between November 2013 and February 2018, 417 patients were recruited into the SPICE III trial at both sites. Eighty-three patients with septic shock were included in this subgroup analysis. Of these, 44 (53%) received DEX and 39 (47%) usual care. Vasopressor requirements in the first 48 h were similar between the two groups. Median NEq dose was 0.03 [0.01, 0.07] μg/kg/min in the DEX group and 0.04 [0.01, 0.16] μg/kg/min in the usual care group (p = 0.17). However, patients in the DEX group had a lower NEq/MAP ratio, indicating lower vasopressor requirements to maintain the target MAP. Moreover, on adjusted multivariable analysis, higher dexmedetomidine dose was associated with a lower NEq/MAP ratio.

CONCLUSIONS

In critically ill patients with septic shock, patients in the DEX group received similar vasopressor doses in the first 48 h compared to the usual care group. On multivariable adjusted analysis, dexmedetomidine appeared to be associated with lower vasopressor requirements to maintain the target MAP.

TRIAL REGISTRATION

The SPICE III trial was registered at ClinicalTrials.gov ( NCT01728558 ).

Structure and Function of HECT E3 Ubiquitin Ligases and their Role in Oxidative Stress

Ubiquitination is a modification after protein transcription that plays a vital role in maintaining the homeostasis of the cellular environment. The Homologous to E6AP C-terminus (HECT) family E3 ubiquitin ligases are a kind of E3 ubiquitin ligases with a C-terminal HECT domain that mediates the binding of ubiquitin to substrate proteins and a variable-length N-terminal extension. HECT-ubiquitinated ligases can be divided into three categories: NEDD4 superfamily, HERC superfamily, and other HECT superfamilies. HECT ubiquitin ligase plays an essential role in the development of many human diseases. In this review, we focus on the physiological and pathological processes involved in oxidative stress and the role of E3 ubiquitin ligase of the HECT family.

Perioperative Dexmedetomidine Improves Outcomes of Kidney Transplant

Graft function is crucial for successful kidney transplantation. Many factors may affect graft function or cause delayed graft function (DGF), which decreases the prognosis for graft survival. This study was designed to evaluate whether the perioperative use of dexmedetomidine (Dex) could improve the incidence of function of graft kidney and complications after kidney transplantation. A total of 780 patients underwent kidney transplantations, 315 received intravenous Dex infusion during surgery, and 465 did not. Data were adjusted with propensity scores and multivariate logistic regression was used. The primary outcomes are major adverse complications, including DGF and acute rejection in the early post‐transplantation phase. The secondary outcomes included length of hospital stay (LOS), infection, overall complication, graft functional status, post‐transplantation serum creatinine values, and estimated glomerular filtration rate (eGFR). Dex use significantly decreased DGF (19.37% vs. 23.66%; adjusted odds ratio, 0.744; 95% confidence interval, 0.564–0.981; P = 0.036), risk of infection, risk of acute rejection in the early post‐transplantation phase, the risk of overall complications, and LOS. However, there were no statistical differences in 90‐day graft functional status or 7‐day, 30‐day, and 90‐day eGFR. Perioperative Dex use reduced incidence of DGF, risk of infection, risk of acute rejection, overall complications, and LOS in patients who underwent kidney transplantation.

Organ-Protective Effects and the Underlying Mechanism of Dexmedetomidine

Dexmedetomidine (DEX) is a highly selective α2 adrenergic receptor (α2AR) agonist currently used in clinical settings. Because DEX has dose-dependent advantages of sedation, analgesia, antianxiety, inhibition of sympathetic nervous system activity, cardiovascular stabilization, and significant reduction of postoperative delirium and agitation, but does not produce respiratory depression and agitation, it is widely used in clinical anesthesia and ICU departments. In recent years, much clinical study and basic research has confirmed that DEX has a protective effect on a variety of organs, including the nervous system, heart, lungs, kidneys, liver, and small intestine. It acts by reducing the inflammatory response in these organs, activating antiapoptotic signaling pathways which protect cells from damage. Therefore, based on wide clinical application and safety, DEX may become a promising clinical multiorgan protection drug in the future. In this article, we review the physiological effects related to organ protection in α2AR agonists along with the organ-protective effects and mechanisms of DEX to understand their combined application value.

Clonidine for pain in non-ventilated infants

BACKGROUND

Critically ill newborn infants undergo a variety of painful procedures or experience a variety of painful conditions during their early life in the neonatal unit. In the critically ill paediatric and neonatal population, clonidine is prescribed as an adjunct to opioids or benzodiazepines aiming to reduce the doses of these drugs that are required for analgesia or sedation, or to facilitate weaning from mechanical ventilation. It has been shown that clonidine premedication might have a positive effect on postoperative pain in children.

OBJECTIVES

To assess the benefit and harms of clonidine for the prevention or treatment of procedural pain; postoperative pain; or pain associated with clinical conditions in non-ventilated neonates.

SEARCH METHODS

We used the standard search strategy of Cochrane Neonatal to search the CENTRAL, MEDLINE via PubMed, Embase, and CINAHL to December 2018. We also searched clinical trials databases, conference proceedings, and the reference lists of retrieved articles for randomised controlled trials and quasi-randomised trials. We ran an updated search from 1 January 2018 to 11 March 2020 in CENTRAL via CRS Web, MEDLINE via Ovid, and CINAHL via EBSCOhost.

SELECTION CRITERIA

Randomised controlled trials, quasi-randomised controlled trials, and cluster trials comparing clonidine to placebo or no treatment, opioids, paracetamol, dexmedetomidine, or non-pharmacological pain-reducing interventions for the management of procedural pain, postoperative pain, and pain associated with clinical conditions in preterm and term newborns.

DATA COLLECTION AND ANALYSIS

Two review authors independently planned to extract data (e.g. number of participants, birth weight, gestational age, modality of administration, and dose of clonidine) and assess the risk of bias (e.g. adequacy of randomisation, blinding, completeness of follow-up). The primary outcome considered was pain: for procedural pain, the mean values of each analgesia scale assessed during the procedure and at one to two hours after the procedure; for postoperative pain and for pain associated with clinical conditions, the mean values of each analgesia scale assessed at 30 minutes, three hours, and 12 hours after the administration of the intervention. We planned to use the GRADE approach to assess the quality of evidence.

MAIN RESULTS

Our search strategy yielded 3383 references. Two review authors independently assessed all references for inclusion. We did not find any completed studies for inclusion. We excluded three trials where clonidine was administered for spinal anaesthesia.

AUTHORS' CONCLUSIONS

We did not find any studies that met our inclusion criteria and hence there is no evidence to recommend or refute the use of clonidine for the prevention or treatment of procedural or postoperative pain, or pain associated with clinical conditions in neonates.

Dexmedetomidine improved renal function in patients with severe sepsis: an exploratory analysis of a randomized controlled trial

Background

Dexmedetomidine has been reported to improve organ dysfunction in critically ill patients. In a recent randomized controlled trial (Dexmedetomidine for Sepsis in Intensive Care Unit (ICU) Randomized Evolution [DESIRE]), we demonstrated that dexmedetomidine was associated with reduced mortality risk among patients with severe sepsis. We performed this exploratory sub-analysis to examine the mechanism underlying improved survival in patients sedated with dexmedetomidine.

Methods

The DESIRE trial compared a sedation strategy with and without dexmedetomidine among 201 mechanically ventilated adult patients with sepsis across eight ICUs in Japan. In the present study, we included 104 patients with Acute Physiology and Chronic Health Evaluation II (APACHE II) scores of ≥ 23 (54 in the dexmedetomidine [DEX] group and 50 in the non-dexmedetomidine [non-DEX] group). Initially, we compared the changes in the sequential organ failure assessment (SOFA) scores from the baseline within 6 days after randomization between groups. Subsequently, we evaluated the variables comprising the organ component of the SOFA score that showed relevant improvement in the initial comparison.

Results

The mean patient age was 71.0 ± 14.1 years. There was no difference in the median APACHE II score between the two groups (29 [interquartile range (IQR), 25–31] vs. 30 [IQR, 25–33]; p = 0.35). The median SOFA score at the baseline was lower in the DEX group (9 [IQR, 7–11] vs. 11 [IQR, 9–13]; p = 0.01). While the renal SOFA subscore at the baseline was similar for both groups, it significantly decreased in the DEX group on day 4 (p = 0.02). During the first 6 days, the urinary output was not significantly different (p = 0.09), but serum creatinine levels were significantly lower (p = 0.04) in the DEX group. The 28-day and in-hospital mortality rates were significantly lower in the DEX group (22% vs. 42%; p = 0.03, 28% vs. 52%; p = 0.01, respectively).

Conclusion

A sedation strategy with dexmedetomidine is associated with improved renal function and decrease mortality rates among patients with severe sepsis.

Trial registration

This trial was registered on ClinicalTrials.gov (NCT01760967) on January 1, 2013.

The effect of dexmedetomidine and clonidine on the inflammatory response in critical illness: a systematic review of animal and human studies

Background

The α2 agonists, dexmedetomidine and clonidine, are used as sedative drugs during critical illness. These drugs may have anti-inflammatory effects, which might be relevant to critical illness, but a systematic review of published literature has not been published. We reviewed animal and human studies relevant to critical illness to summarise the evidence for an anti-inflammatory effect from α2 agonists.

Methods

We searched PubMed, the Cochrane library, and Medline. Animal and human studies published in English were included. Broad search terms were used: dexmedetomidine or clonidine, sepsis, and inflammation. Reference lists were screened for additional publications. Titles and abstracts were screened independently by two reviewers and full-text articles obtained for potentially eligible studies. Data extraction used a bespoke template given study diversity, and quality assessment was qualitative.

Results

Study diversity meant meta-analysis was not feasible so descriptive synthesis was undertaken. We identified 30 animal studies (caecal ligation/puncture (9), lipopolysaccharide (14), acute lung injury (5), and ischaemia-reperfusion syndrome (5)), and 9 human studies. Most animal (26 dexmedetomidine, 4 clonidine) and all human studies used dexmedetomidine. In animal studies, α2 agonists reduced serum and/or tissue TNFα (20 studies), IL-6 (17 studies), IL-1β (7 studies), NFκB (6 studies), TLR4 (6 studies), and a range of other mediators. Timing and doses varied widely, but in many cases were not directly relevant to human sedation use. In human studies, dexmedetomidine reduced CRP (4 studies), TNFα (5 studies), IL-6 (6 studies), IL-1β (3 studies), and altered several other mediators. Most studies were small and low quality. No studies related effects to clinical outcomes.

Conclusion

Evidence supports potential anti-inflammatory effects from α2 agonists, but the relevance to clinically important outcomes is uncertain. Further work should explore whether dose relationships with inflammation and clinical outcomes are present which might be separate from sedation-mediated effects.

Dexmedetomidine inhibits the NF-κB pathway and NLRP3 inflammasome to attenuate papain-induced osteoarthritis in rats

Context: Dexmedetomidine (Dex) has been reported to have an anti-inflammatory effect. However, its role on osteoarthritis (OA) has not been explored. Objective: This study investigates the effect of Dex on OA rat model induced by papain. Materials and methods: The OA Wistar rat model was induced by intraluminal injection of 20 mL of papain mixed solution (4% papain 0.2 mL mixed with 0.03 mol L^-1 l-cysteine 0.1 mL) into the right knee joint. Two weeks after papain injection, OA rats were treated by intra-articular injection of Dex (5, 10, or 20 μg kg^-1) into the right knee (once a day, continuously for 4 weeks). Articular cartilage tissue was obtained after Dex treatment was completed. Results: The gait behavior scores (2.83 ± 0.49), PWMT (15.2 ± 1.78) and PTWL (14.81 ± 0.92) in H-DEX group were higher than that of OA group, while Mankin score (5.5 ± 0.81) was decreased (p < 0.05). Compared with the OA group, the IL-1β (153.11 ± 16.05 pg mg^-1), IL-18 (3.71 ± 0.7 pg mg^-1), IL-6 (14.15 ± 1.94 pg/mg) and TNF-α (40.45 ± 10.28 pg mg^-1) levels in H-DEX group were decreased (p < 0.05). MMP-13, NLRP3, and caspase-1 p10 expression in Dex groups were significantly lower than that of OA group (p < 0.05), while collagen II was increased (p < 0.05). p65 in the nucleus of Dex groups was significantly down-regulated than that of OA group (p < 0.05). Discussion and Conclusions: Dex can improve pain symptoms and cartilage tissue damage of OA rats, which may be related to its inhibition of the activation of NF-κB and NLRP3 inflammasome.

Dexmedetomidine prevents septic myocardial dysfunction in rats via activation of α7nAChR and PI3K/Akt- mediated autophagy

BACKGROUND AND PURPOSE

Dexmedetomidine (Dex) has been shown to elicit cardio-protective effects in sepsis. The aim of this study was to investigate the role of autophagy in the protective effects of Dex and its possible mechanism in vivo and vitro.

EXPERIMENTAL APPROACH

6-8-week-old male Wistar rats were performed cecal ligation puncture (CLP) and administered 0.9% saline (CLP group), 50 μg/kg Dex (Dex group), Dex plus chloroquine (20 mg/kg; Dex + CQ group), or 40 μg/kg methyllycaconitin (Dex + MLA group), or 25 μM LY294002 (Dex + LY294002 group). After study, cardiac histology, cardiac function, level of autophagy, cardiomyocytes apoptosis and inflammatory mediators including protein IL-1β, IL-6, and TNF-α were measured. The LPS induced-H9C2 cardiomyocytes were treated with Dex, Dex + CQ and detected for cell apoptosis, autophagy level and cell cycle.

KEY RESULTS

CLP-induced sepsis resulted in cardiac dysfunction, apoptosis, and inflammatory response. Dex exhibited protective effects on the myocardium by the induction of myocardial autophagy and ameliorated the LPS-induced blockade of autophagic flux in H9C2 cells. CQ was found to significantly inhibit Dex-mediated protection of myocardial apoptosis and inflammation. CLP rats treated with Dex in combination with MLA, an antagonist of α7 nicotinic acetylcholine receptor (α7nAChR), exhibited decreased autophagy and increased inflammation and cell death, identifying α7nAchR was involved in the Dex-mediated pathway. In addition, we found that the PI3K/Akt pathway is involved in Dex-mediated autophagy and convergent with α7nAChR-mediated stimulation of autophagy response.

CONCLUSIONS AND IMPLICATIONS

For the first time, these data indicate that autophagy is central in Dex-mediated cardio-protection in sepsis. These observations provide the foundation for further study, and may serve as the basis for innovative therapeutic strategies against septic myocardial dysfunction.

Preventive Effects of Dexmedetomidine on Renal Dysfunction and Hemodynamic Stability in Malignant Obstructive Jaundice Patients During Peri-Operative Period

Background

This study aimed to investigate effects of intra-operative administration with dexmedetomidine (Dex) on hemodynamics and renal function in patients with malignant obstructive jaundice.

Material/Methods

Our randomized, double-blinded, placebo-controlled study was conducted among 40 patients with malignant obstructive jaundice between August 2009 and March 2011 in The Affiliated Hospital of Inner Mongolia Medical University. The 40 patients were randomly divided into 2 groups: the Dex group (receiving Dex 0.5 μg/kg 10-minutes before induction and then a 0.5 μg/kg/hour maintenance infusion until end of operation 30 minutes) and the Control group (receiving normal saline of same amount and at same rate). The adverse events, including incidence of cardiovascular complications and nausea and vomiting, and length of hospital stay were determined. The level of cystatin C (CysC), retinol-binding protein (RBP), creatinine (Scr), and blood urea nitrogen (BUN) were also evaluated.

Results

Dexmedetomidine administration significantly decreased heart rate (HR) and stroke volume variation (SVV) and significantly increased capital venous pressure (CVP) and mean arterial pressure (MAP) values compared to that in the Control group (P<0.05). Dexmedetomidine administration significantly upregulated urine volume and significantly downregulated atropine levels compared to the Control group (P<0.05). Dexmedetomidine administration significantly improved renal functions, by modulating CysC, RBP, Scr and BUN levels compared to the Control group (P<0.05). Dexmedetomidine administration demonstrated no additional side-effects. Dexmedetomidine administration significantly shortened length of hospitalization in the Dex group compared to the Control group (P<0.05).

Conclusions

Dexmedetomidine plays preventive effects on renal dysfunction and hemodynamic stability in malignant obstructive jaundice patients during peri-operative period.

Dexmedetomidine protects against lung injury induced by limb ischemia-reperfusion via the TLR4/MyD88/NF-κB pathway

Dexmedetomidine (DEX) can protect the lung from ischemia-reperfusion (I/R) injury, but the underlying mechanisms are not fully understood. The aims of this study were to determine whether DEX attenuates lung injury following lower extremity I/R and to investigate the related toll-like receptor 4 (TLR4) signaling pathway. Twenty-eight SD rats were divided into four groups (n = 7): Sham, I/R, I/R + DEX (25 μg/kg prior to ischemia), and I/R + DEX + Atip (250 μg/kg atipamezole before DEX treatment). Lower extremity I/R was induced by left femoral artery clamping for 3 hours and followed by 2 hours reperfusion. Quantitative alveolar damage and the wet/dry (W/D) ratio were calculated. Interleukin (IL)-1, IL-6, and tumor necrosis factor (TNF)-α in the bronchoalveolar lavage fluid (BALF) and serum and myeloperoxidase (MPO) in the lung were measured. The TLR4 and MyD88 mRNA expression levels were measured by RT-PCR, nuclear factor (NF)-κB, and phosphorylated NF-κB by western blot, respectively. Quantitative alveolar damage, W/D ratio, MPO, BALF and serum IL-1, IL-6, and TNF-α, and TLR4, MyD88, NF-κB, and p-NF-κB expression significantly increased in the I/R group relative to the Sham group. DEX preconditioning significantly reduced lung edema, and histological injury relative to the I/R group. Serum and BALF IL-1, IL-6, and TNF-α levels, MPO activity and TLR4, MyD88, NF-κB, and p-NF-κB expression were also significantly reduced in the I/R + DEX group compared with the I/R group. Atipamezole partially reversed all the aforementioned effects. DEX preconditioning protects the lungs against lower extremity I/R injury via α2-adrenoceptor-dependent and α2-adrenoceptor-independent mechanisms. It also suppresses the TLR4 pathway and reduces inflammation.

Dexmedetomidine effects in different experimental sepsis in vivo models

Sepsis is a major cause of death and the most common cause of death among critically ill, non-ICU patients. Dexmedetomidine (DEX), an <alpha>₂ adrenergic receptor agonist, presents sympatholytic action in certain parts of the brain with anxiolytic, sedative, and pain killing effects. Additionally, through the activation of <alpha>₇ nicotinic acetylcholine receptor receptors, DEX reduces cytokine transcription and inhibits inflammation, rendering it beneficial during septic conditions. Moreover, there is a lot of interest in designing experimental sepsis models, where the administration of DEX is evaluated for its impact on multiple systems. This review focuses on experimental studies published between 1999 to March 2019 that were using DEX administration in sepsis in vivo models. From these, 36 articles were selected and summarized. Overall results show evidence that DEX may decrease mortality and inhibit inflammation, as it enhances the activity of the immune system while reducing its systemic reaction and lowering cytokine concentrations. Moreover DEX succeeds to alleviate heart injury during sepsis, acting beneficially for microcirculation and shows a neuroprotective role by inhibiting apoptotic pathways. In addition, DEX appears to have a protective role for liver and spleen as well as a beneficial role for the function of lungs and kidneys as it reduces sepsis-induced injuries and apoptosis in intra-abdominal experimental sepsis models.

Efficacy of dexmedetomidine for treatment of patients with sepsis: A meta-analysis of randomized controlled trials

BACKGROUND

This meta-analysis aimed to evaluate the effect of dexmedetomidine on prognosis in patients with sepsis.

METHODS

Computer-related electronic databases were searched, including PubMed, Embase, Web of Science, the Cochrane Library, and the China National Knowledge Infrastructure, from the date of database construction to January 2019. Stata 12.0 was used to perform a meta-analysis of short-term mortality [intensive care unit (ICU) mortality or 28-day mortality], ICU length of stay, and mechanical ventilation. Mortality was expressed using risk ratio (RR) and 95% confidence interval (CI). ICU length of stay and mechanical ventilation were expressed as weighted mean difference (WMD) and 95% CIs.

RESULTS

We finally included 8 randomized controlled trials in this meta-analysis. Compared with the control group, the dexmedetomidine group had a lower occurrence of 28-day mortality (RR, 0.49; 95% CI, 0.35 to 0.69; P = .000) and ICU mortality (RR, 0.44; 95% CI, 0.23 to 0.84; P = .013). However, there was no statistically significant difference for the length of hospital stay (WMD, -0.05; 95% CI, -0.59 to 0.48; P = .840) and mechanical ventilation time (WMD, 1.05; 95% CI, -0.27 to 2.37; P = .392) between dexmedetomidine group and control group.

CONCLUSIONS

In patients with sepsis, dexmedetomidine can reduce the short-term mortality of patients, but could not shorten the ICU length of stay and mechanical ventilation time. More clinical randomized controlled trials are needed to verify the efficacy and safety of dexmedetomidine on the length of hospital stay and mechanical ventilation time.

Effects of Intraneural Injection of Dexmedetomidine in Combination With Ropivacaine in Rat Sciatic Nerve Block

BACKGROUND AND OBJECTIVES

Dexmedetomidine is known to have neural protection effect via attenuation of inflammatory responses induced by local anesthetics. We investigated whether intraneural dexmedetomidine is effective for attenuating or preventing neural injury resulting from inadvertent intraneural injection of local anesthetic.

METHODS

Rats were randomly divided, and left sciatic nerve was surgically exposed. The rats received no injection (control group) or intraneural injections of 0.2 mL of normal saline (saline group), 0.2 mL of 0.5% ropivacaine (ropivacaine group), or 0.2 mL of 0.5% ropivacaine and 0.5 μg/kg of dexmedetomidine (ropivacaine plus dexmedetomidine group). Interleukin (IL)-6 and IL-1β messenger RNA (mRNA) levels were detected at 60 minutes after intraneural injection in experiment 1 (5 per group). Sensory and motor functions were assessed until the return of normal sensory and motor functions, and histopathological and ultrastructure analysis were performed at 4 weeks after intraneural injection in experiment 2 (8 per group).

RESULTS

Dexmedetomidine with ropivacaine better enhanced sensory and motor blockade than ropivacaine alone. IL-6 (3.2 ± 1.0 vs 5.9 ± 2.1), IL-1β (1.1 ± 0.1 vs 2.2 ± 0.7) levels, scores of axon and myelinated fiber degeneration (1 [0-2] vs 2 [1-3]), and demyelinated fiber percentages (20.1 ± 10.4 vs 48.3 ± 12.7) were lower in the ropivacaine plus dexmedetomidine group than in the ropivacaine group. No animals showed any signs of permanent neurological deficit.

CONCLUSIONS

Intraneural dexmedetomidine has sensory and motor blockade-enhancing effects, anti-inflammatory properties, and protective effects against neural injury. These findings suggest that dexmedetomidine as an adjuvant has beneficial effects in rat when intraneural injection of local anesthetic occurs.

Dexmedetomidine Reduces Diabetic Neuropathy Pain in Rats through the Wnt 10a/β-Catenin Signaling Pathway

Diabetic neuropathy pain (DNP), a spontaneous pain with hyperalgesia and allodynia, greatly compromises patients' quality of life. Our previous study suggested that dexmedetomidine (DEX) can relieve hyperalgesia in rats by inhibiting inflammation and apoptosis at the level of the spinal cord. In the present study, we aimed to evaluate the role of Wnt 10a/β-catenin signaling in DEX-induced alleviation of DNP in rats. Forty-eight rats were randomly allocated to four groups (n=12/group): control, DNP, DEX, and yohimbine groups. The DNP model was established by streptozotocin (STZ) injection. The effects of DEX with or without the α₂ adrenergic antagonist yohimbine were assessed by behavior tests (mechanical withdrawal threshold and thermal withdrawal latency). Spinal cord tissue was evaluated by immunofluorescence staining of astrocytes as well as for Wnt 10a and β-catenin expression, western blot analysis of Wnt 10a and β-catenin expression, and enzyme-linked immunosorbent assay measurement of proinflammatory cytokines (tumor necrosis factor-α and interleukin-1β). Rats with STZ-induced DNP had a decreased pain threshold, activated astrocytes, increased expression of Wnt 10a and β-catenin, and increased levels of proinflammatory cytokines compared to the control group, and these effects were ameliorated by treatment with DEX. Yohimbine administration partly abolished the protective effects of DEX in the DNP model rats. In conclusion, DEX alleviated DNP in rats by inhibiting inflammation and astrocyte activation, which may be attributed to downregulation of the Wnt 10a/β-catenin signaling pathway.

Dexmedetomidine preserves the endothelial glycocalyx and improves survival in a rat heatstroke model

PURPOSE

Heatstroke causes systemic inflammation, followed by vascular endothelial damage. The normal vascular endothelium is coated by endothelial glycocalyx (EGCX). Dexmedetomidine (DEX) has an anti-inflammatory effect, but there has been little investigation on the influence of heatstroke on EGCX and the effect of DEX on this condition. Therefore, we examined whether EGCX was disrupted in heatstroke and if DEX improved survival and preserves EGCX.

METHODS

Anesthetized Wistar rats were randomly assigned to three groups: a DEX group treated with DEX (5 µg/kg/h) and 0.9% saline infused continuously at 10 ml/kg/h during heat exposure; a NSS group given 0.9% saline during heat exposure; and a SHAM group given 0.9% saline alone without heat exposure. Heatstroke was induced by exposure to an ambient temperature of 40 °C with relative humidity of 60%. The survival rate was assessed up to 2 h after the start of heat exposure. Plasma levels of syndecan-1 and the thickness of EGCX using electron microscopy were measured when the systolic blood pressure fell to less than 80 mmHg.

RESULTS

The survival rate after 2 h of heat exposure was significantly higher in the DEX group compared to the NSS group (89% vs. 22%, P = 0.004). Plasma levels of syndecan-1 were 0.6 ± 1.3, 9.7 ± 5.9, and 2.1 ± 3.4 ng/ml in the SHAM, NSS and DEX groups, respectively (P = 0.013). The thickness of EGCX was significantly higher in the DEX group compared with the NSS group (P = 0.001).

CONCLUSIONS

EGCX was disrupted in heatstroke, and DEX improved survival and preserved EGCX.

Sepsis-induced acute kidney injury: A disease of the microcirculation

AKI is a common complication of sepsis and is significantly associated with mortality. Sepsis accounts for more than 50% of the cases of AKI, with a mortality rate of up to 40%. The pathogenesis of septic AKI is complex, but there is emerging evidence that, at least in the first 48 hours, the defects may be functional rather than structural in nature. For example, septic AKI is associated with an absence of histopathological changes, but with microvascular abnormalities and tubular stress. In this context, renal medullary hypoxia due to redistribution of intra-renal perfusion is emerging as a critical mediator of septic AKI. Clinically, vasopressor drugs remain the cornerstone of therapy for maintenance of blood pressure and organ perfusion. However, in septic AKI, there is insensitivity to vasopressors such as norepinephrine, leading to persistent hypotension and organ failure. Vasopressin, angiotensin II, and, paradoxically, α₂ -adrenergic receptor agonists (clonidine and dexmedetomidine) may be feasible adjunct therapies for catecholamine-resistant vasodilatory shock. In this review, we outline the recent progress made in understanding how these drugs may influence the renal microcirculation, which represents a crucial step toward developing better approaches for the circulatory management of patients with septic AKI.

Effects of Dexmedetomidine Infusion on Inflammatory Responses and Injury of Lung Tidal Volume Changes during One-Lung Ventilation in Thoracoscopic Surgery: A Randomized Controlled Trial

One-lung ventilation in thoracic surgery provokes profound systemic inflammatory responses and injury related to lung tidal volume changes. We hypothesized that the highly selective a2-adrenergic agonist dexmedetomidine attenuates these injurious responses. Sixty patients were randomly assigned to receive dexmedetomidine or saline during thoracoscopic surgery. There is a trend of less postoperative medical complication including that no patients in the dexmedetomidine group developed postoperative medical complications, whereas four patients in the saline group did (0% versus 13.3%, p = 0.1124). Plasma inflammatory and injurious biomarkers between the baseline and after resumption of two-lung ventilation were particularly notable. The plasma high-mobility group box 1 level decreased significantly from 51.7 (58.1) to 33.9 (45.0) ng.ml⁻¹ (p < 0.05) in the dexmedetomidine group, which was not observed in the saline group. Plasma monocyte chemoattractant protein 1 [151.8 (115.1) to 235.2 (186.9) pg.ml⁻¹, p < 0.05] and neutrophil elastase [350.8 (154.5) to 421.9 (106.1) ng.ml⁻¹, p < 0.05] increased significantly only in the saline group. In addition, plasma interleukin-6 was higher in the saline group than in the dexmedetomidine group at postoperative day 1 [118.8 (68.8) versus 78.5 (58.8) pg.ml⁻¹, p = 0.0271]. We conclude that dexmedetomidine attenuates one-lung ventilation-associated inflammatory and injurious responses by inhibiting alveolar neutrophil recruitment in thoracoscopic surgery.

Intraoperative dexmedetomidine attenuates postoperative systemic inflammatory response syndrome in patients who underwent percutaneous nephrolithotomy: a retrospective cohort study

Purpose

Dexmedetomidine (DEX) has been reported to attenuate inflammation in rats. The present retrospective cohort study aimed to investigate whether intraoperative administration with DEX could reduce the incidence of postoperative systemic inflammatory response syndrome (SIRS) in patients following percutaneous nephrolithotomy (PCNL).

Patients and methods

A total of 251 patients were included in the analysis. Among these patients, 175 received intravenous DEX infusion during the intraoperative period and 76 did not. The primary outcome measures were the incidences of postoperative SIRS and fever. Secondary outcomes included patient-controlled analgesia (tramadol) requirements, length of postoperative hospitalization stay, serum creatinine (Scr) and serum blood urea nitrogen (BUN) concentration, and adverse events (bradycardia, hypotension, renal artery thrombosis).

Results

Administration of DEX not only significantly attenuated the incidence of SIRS and fever (P=0.029, P=0.042, respectively), but also reduced analgesia requirements (P=0.028). The length of postoperative hospitalization stay, Scr and BUN concentration, and adverse events did not differ significantly between the two groups. Further univariate and multivariate logistic regression analysis indicated that intraoperative DEX administration was a protective factor against SIRS after PCNL (OR 0.476 [95% CI: 0.257-0.835]; P=0.019).

Conclusion

Intraoperative administration of DEX might be associated with reductions in the incidences of SIRS and fever after PCNL.

Dose-related effects of dexmedetomidine on immunomodulation and mortality to septic shock in rats

BACKGROUND

Dexmedetomidine has already been used in septic patients as a new sedative agent, few studies have examined its effects on immunomodulation. Therefore, the authors have designed a controlled experimental study to characterize the immunomodulation effects of dexmedetomidine in the cecal ligation and puncture (CLP) model in rats.

METHODS

After CLP, 48 Wistar rats were randomly allocated into four groups: (1) CLP group; (2) small-dose treatment group (2.5 μg·kg^-1·h^-1); (3) medium-dose treatment group (5.0 μg·kg^-1· h^-1); and (4) large-dose treatment group (10.0 μg·kg^-1·h^-1). HLA-DR and plasma cytokine (IL-4, IL-6, IL-10 and TNF-α) levels were measured, and the mean arterial blood pressure (MAP), heart rate (HR), arterial blood gases, lactate concentrations and mortality were also documented.

RESULTS

The HLA-DR level, inflammatory mediator levels, MAP and HR had no obvious changes among Dexmedetomidine treatment groups (DEX groups). Compared with the CLP group, the DEX groups exhibited decreased HLA-DR levels (P_group=0.0202) and increased IL-6 production, which was increased at 3 h (P= 0.0113) and was then attenuated at 5 h; additionally, the DEX groups exhibited decreased HR (P<0.001) while maintaining MAP (P_group=0.1238), and remarkably improving lactate (P<0.0001). All of these factors led to a significant decrease in the mortality, with observed rates of 91.7%, 66.7%, 25% and 18% for the CLP, DEX2.5, DEX5.0, DEX10.0 groups, respectively.

CONCLUSION

Dexmedetomidine treatment in the setting of a CLP sepsis rat model has partially induced immunomodulation that was initiated within 5 h, causing a decreased HR while maintaining MAP, remarkably improving metabolic acidosis and improving mortality dose-dependently.

Use of Dexmedetomidine in Cardiothoracic and Vascular Anesthesia

Dexmedetomidine is a highly selective α₂-adrenergic agonist with analgesic and sedative properties. In the United States, the Food and Drug Administration approved the use of the drug for short-lasting sedation (24 h) in intensive care units (ICUs) in patients undergoing mechanical ventilation and endotracheal intubation. In October 2008, the Food and Drug Administration extended use of the drug for the sedation of nonintubated patients before and during surgical and nonsurgical procedures. In the European Union, the European Medicine Agency approved the use of dexmedetomidine in September 2011 with a single recognized indication: ICU adult patients requiring mild sedation and awakening in response to verbal stimulus. At present, the use of dexmedetomidine for sedation outside the ICU remains an off-label indication. The benefits of dexmedetomidine in critically ill patients and in cardiac, electrophysiology-related, vascular, and thoracic procedures are discussed.

Sedation After Cardiac Surgery: Is One Drug Better Than Another?

The classic high-dose narcotic-based cardiac anesthetic has been modified to facilitate a fast-track, rapid recovery in the intensive care unit (ICU). Postoperative sedation is consequently now an essential component in recovery of the patient undergoing cardiac surgery. It must facilitate the patient's unawareness of the environment as well as reduce the discomfort and anxiety caused by surgery, intubation, mechanical ventilation, suction, and physiotherapy. Benzodiazepines seem well suited for this role, but propofol, opioids, and dexmedetomidine are among other agents commonly used for sedation in the ICU. However, what is an ideal sedative for this application? When compared with benzodiazepine-based sedation regimens, nonbenzodiazepines have been associated with shorter duration of mechanical ventilation and ICU length of stay. Current sedation guidelines recommend avoiding benzodiazepine use in the ICU. However, there are no recommendations on which alternatives should be used. In postcardiac surgery patients, inotropes and vasoactive medications are often required because of the poor cardiac function. This makes sedation after cardiac surgery unique in comparison with the requirements for most other ICU patient populations. We reviewed the current literature to try to determine if 1 sedative regimen might be better than others; in particular, we compare outcomes of propofol and dexmedetomidine in postoperative sedation in the cardiac surgical ICU.