Use of dexmedetomidine to prevent pulmonary injury after pneumoperitoneum in ventilated rats

Comparison of effects of dexmedetomidine and amifostine against X-ray radiation-induced parotid damage

Radiotherapy can be employed as a therapeutic modality alone in the early stages of cancer and is used together with other treatments such as surgery and chemotherapy in more advanced stages. However, exposure to ionizing radiation in association with radiotherapy affects several organs in the head and neck and can give rise to early and late side effects. Exposure to ionizing radiation used in radiotherapy is known to cause cell damage by leading to oxygen stress through the production of free oxygen radicals (such as superoxide radicals, hydroxyl radical, hydrogen peroxide, and singlet oxygen), depending on the total radiation dosage, the fractionation rate, radiosensitivity, and linear energy transfer. The purpose of the present study was to determine the potential protective role of a powerful and highly selective α2-adrenoreceptor agonist with a broad pharmacological spectrum against salivary gland damage induced by ionizing radiation exposure. Forty Sprague-Dawley rats were divided into five groups-control, ionizing radiation, ionizing radiation + dexmedetomidine (100 µg/kg), ionizing radiation + dexmedetomidine (200 µg/kg), and ionizing radiation + amifostine (200 mg/kg). Following exposure to ionizing radiation, we observed necrosis, fibrosis, and vascular congestions in parotid gland epithelial cells. We also observed increases in malondialdehyde (MDA) and cleaved Caspase-3 levels and a decrease in glutathione (GSH). In groups receiving dexmedetomidine, we observed necrotic epithelial cells, fibrosis and vascular congestion in parotid gland tissue, a decrease in MDA levels, and an increase in GSH. Dexmedetomidine may be a promising antioxidant agent for the prevention of oxidative damage following radiation exposure.

Protective effect of dexmedetomidine on intestinal mucosal barrier function in rats after cardiopulmonary bypass

Cardiopulmonary bypass can result in damage to the intestines, leading to the occurrence of systemic inflammatory response syndrome. Dexmedetomidine is reported to confer anti-inflammatory properties. Here, the purpose of this study is to investigate the effect of dexmedetomidine on the intestinal mucosa barrier damage in a rat model of cardiopulmonary bypass. It was observed that cardiopulmonary bypass greatly decreased the levels of hemodynamic parameters than SHAM group, whereas dexmedetomidine pretreatment in a cardiopulmonary bypass model rat prevented this reduction. Also, it showed that compared with control animals, cardiopulmonary bypass caused obvious mucosal damage, which was attenuated in dexmedetomidine + cardiopulmonary bypass group. The above findings were in line with that of dexmedetomidine pretreatment, which increased the expression of tight junction proteins, but it decreased the levels of DAO, D-LA, FABP2, and endotoxin. Moreover, the results demonstrated that due to pre-administration of dexmedetomidine, the level of pro-inflammatory factors was decreased, while the level of anti-inflammatory cytokine was increased. Also, it showed that dexmedetomidine suppressed TLR4/JAK2/STAT3 pathway that was activated by cardiopulmonary bypass. Together, these results revealed that dexmedetomidine pretreatment relieves intestinal microcirculation, attenuates intestinal damage, and inhibits the inflammatory response of cardiopulmonary bypass model rats, demonstrating that in CPB-induced damage of intestinal mucosal barrier function, dexmedetomidine pretreatment plays a protective role by inactivating TLR4/JAK2/STAT3-mediated inflammatory pathway.

Effect and Mechanism of Lidocaine Pretreatment Combined with Dexmedetomidine on Oxidative Stress in Patients with Intracranial Aneurysm Clipping

This study aimed to explore the effect and mechanism of lidocaine pretreatment combined with dexmedetomidine on oxidative stress in patients with intracranial aneurysm clipping. Many studies have used various drugs such as lidocaine to explore the effect and mechanism of lidocaine pretreatment. A total of 80 patients with intracranial aneurysm clipping surgery were randomly divided into 4 groups: the single lidocaine group, single dexmedetomidine group, lidocaine combined with dexmedetomidine group, and control group. The thread embolism method was used to establish a stable intracranial aneurysm model of Hashimoto rats. Fifty adult rats were randomly divided into a sham operation group, ligation of the left common carotid artery and bilateral posterior branch of renal artery, lidocaine group, dexmedetomidine group, and lidocaine combined with dexmedetomidine group. The colorimetric method was used to determine the oxidative stress indicators in brain tissue: MDA content, SOD activity, and T-AOC content. The western blot method characterized the protein levels related to oxidative stress: nNOS, iNOS, and NADPH oxidase subunits p22phox, gp91phox, and p47phox. The differences in each index between the groups were statistically significant (P < 0.05). Animal experiment results revealed that the content of MDA in the brain tissue of rats in the LD group was significantly lower than that in the single-drug group and sham group. The T-AOC and SOD concentrations in the LD group were significantly higher than those in the single-drug group and sham group, and the differences between the groups were statistically significant (P < 0.05). The protein expression of the LD group was significantly lower than that of the drug-alone group and model group, and the difference between groups was statistically significant (P < 0.05). To sum up, lidocaine pretreatment combined with dexmedetomidine can effectively maintain the hemodynamic stability of patients with intracranial aneurysm clipping and reduce postoperative oxidative stress response. Its mechanism of action may be related to the inhibition of oxidative stress damage mediated by nNOS, iNOS, and p22phox, gp91phox, and p47phox in the hippocampus. Our study has significant and applicable medical aspects in lidocaine pretreatment combined with dexmedetomidine on oxidative stress in patients.

Exploration of Potential Molecular Targets of Dexmedetomidine in the Intestinal Repair of Burnt Rats

Background

More and more burn survivors were suffering from varying degrees of damage to the intestinal barrier. Dexmedetomidine (Dex) was frequently used as sedative in more cases, but it was found to have repair effect on intestinal barrier dysfunction recently. This study aimed to explore the potential specific targets of Dex in intestinal barrier repair in burn rats model.

Methods

Male adult SD rats were used to establish 40% TBSA III degree scald model in our study. The samples were divided into four groups: burn rats (Burn), burn rats with Dex medication (Burn-Dex), sham rats (Sham) and sham rats with Dex medication (Sham-Dex). And plasma FITC-dextran and diamine oxidase (DAO) were detected to determine the intestinal permeability. Differentially expressed proteins were further adopted to protein-protein interaction network analysis, Gene Ontology analysis (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis.

Results

It showed that 40% TBSA III degree scald model was successfully constructed. And plasma FITC-dextran and DAO decreased significantly after Dex administration. Additionally, differentially expressed genes Psmb10, Psmb7 among the experimental groups were screened, which were significantly enriched in proteasome and other several pathways.

Conclusion

The results above suggested that Q4KM35 and Q9JHW0, which are encoded by Psmb10 and Psmb7, respectively, are two possible protein targets of Dex in intestinal barrier repair.

Immunomodulators in anesthesia

PURPOSE OF REVIEW

Anesthetics are known to have immunomodulatory effects. These can be detrimental, inducing immunosuppression and facilitating the development of opportunistic infections, especially when used at high doses, for prolonged periods, or in patients with preexisting immune deficiency; or beneficial, modulating the inflammatory response, particularly in critical illness and systemic hyperinflammatory states.

RECENT FINDINGS

Anesthetics can have microbicidal properties, and both anti- and pro-inflammatory effects. They can act directly on immune cells as well as modulate immunity through indirect pathways, acting on the neuroimmune stress response, and have recently been described to interact with the gut microbiota.

SUMMARY

Anesthesiologists should take into consideration the immunomodulatory properties of anesthetic agents in addition to their hemodynamic, neuroprotective, and other impacts. In future, patient stratification according to the perioperative assessment of serum biomarkers associated with postoperative complications may be used to guide anesthetic agent selection based on their immunomodulatory properties.

Effect of Dexmedetomidine on Postoperative Lung Injury during One-Lung Ventilation in Thoracoscopic Surgery

Objective

To investigate the effect of dexmedetomidine on postoperative lung injury in patients undergoing thoracoscopic surgery.

Methods

From March 2019 to October 2019, 40 patients were randomly divided into two groups: dexmedetomidine group (group D) and control group (group C). Except recording the general condition of the patients in both groups preoperatively and intraoperatively, the oxygenation index (OI) and alveolar-arterial oxygen partial pressure difference (A-aDO₂) were monitored at admission (T0), immediately after one-lung ventilation (T1), 0.5 h after one-lung ventilation (T2), and 15 minutes after inhaling air before leaving the room (T3). The content of IL-8 in arterial blood was measured by enzyme-linked immunosorbent assay (ELISA) at T0 and T2, and the expression of AQP1 protein in isolated lung tissue was measured by immunohistochemistry and Western blot. The incidence of postoperative pulmonary complications (atelectasis, pneumonia, and acute respiratory distress syndrome) was used as the index of lung injury.

Results

There was no significant difference in the general condition before and during operation between the two groups. There was no significant difference in arterial blood IL-8 content between the two groups at the T0 time point, but the arterial blood IL-8 content at the T2 time point was significantly higher than that at the T0 time point, especially in group C. The results of immunohistochemistry and Western blot showed that the expression level of AQP1 protein in the isolated lung tissue of group D was significantly higher than that of group C (P < 0 05). At T3, the OI of group D was significantly higher than that of group C, and the A-aDO₂ of group D was significantly lower than that of group C (P < 0.05). There was no significant difference in the incidence of postoperative PPCs between the two groups.

Conclusion

Dexmedetomidine can reduce the level of plasma IL-8 and upregulate the expression of AQP1 in the lung tissue of patients undergoing thoracoscopic surgery under one-lung ventilation, but it has no significant effect on the incidence of postoperative PPCs. Dexmedetomidine can be safely used in thoracoscopic surgery and has a certain protective effect on lung injury.

The Effects of Dexmedetomidine and Ketamine on Oxidative Injuries and Histological Changes Following Blunt Chest Trauma

BACKGROUND

The objective of this research was to evaluate the oxidative and histopathological effects of dexmedetomidine and ketamine on the pulmonary contusion model resulting from blunt chest trauma.

METHODS

Rats were randomly assigned to 5 equal groups (n=6): control group (Group C), pulmonary contusion group (Group PC), PC-dexmedetomidine group (Group PC-D), PC-ketamine group (Group PC-K), and PC-dexmedetomidine + ketamine (Group PC-D+K). The PC was performed by dropping a weight of 500 g (2.45 Joules) from a height of 50 cm. In Group PC-D, after chest trauma, dexmedetomidine (100 µg/kg) was administered intraperitoneally. In Group PC-K, after chest trauma, ketamine (100 mg/kg) was administered intraperitoneally. In Group PC-D+K, dexmedetomidine and ketamine were administered together. At the end of the 6th hour, rats were sacrificed. Malondialdehyde (MDA) level, superoxide dismutase (SOD) enzyme activities, neutrophil infiltration/aggregation, and thickness of the alveolar wall were evaluated.

RESULTS

MDA levels were significantly higher in Group PC than Groups C, PC-D, and PC-D+K. SOD enzyme activity was significantly higher in Group PC than Groups C, PC-D, and PC-D+K. In addition, neutrophil infiltration/aggregation and total pulmonary injury scores were significantly higher in Group PC than in other groups, and the thickness of the alveolar wall was significantly higher in Group PC compared to Groups C, PC-D, and PC-D+K. MDA level, SOD enzyme activities, neutrophil infiltration/aggregation, and thickness of alveolar wall were similar in PC-D and PC-D+K groups.

CONCLUSION

Dexmedetomidine and dexmedetomidine+ketamine have protective effects on blunt chest trauma but no protective effect was observed when ketamine was administered alone. We concluded that the administration of dexmedetomidine and ketamine after contusion is beneficial against pulmonary injury in rats.

The MAP2K4/JNK/c-Jun Signaling Pathway Plays A Key Role In Dexmedetomidine Protection Against Acetaminophen-Induced Liver Toxicity

Purpose

Dexmedetomidine [DEX; (S)-4-[1-(2,3-dimethylphenyl)ethyl]-3H-imidazole] is a selective α₂-adrenergic receptor (α₂-AR) agonist that attenuates the liver damage associated with local or systemic inflammation. However, it remains unclear whether DEX has protective effects against acetaminophen (Paracetamol, PARA)-induced liver toxicity (PILT).

Methods

PILT mice were established by intraperitoneal administration of a hepatotoxic dose of acetaminophen (300 mg/kg). Thirty minutes later, the mice were treated with DEX at a concentration of 0, 5, 25, or 50 μg/kg. Blood and liver samples were obtained for further analysis.

Results

DEX treatment significantly attenuated PILT in mice, with the strongest beneficial effects at a dose of 25 μg/kg. The levels of hepatic cytokines, tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6), in addition to myeloperoxidase (MPO) activity, were significantly decreased following DEX treatment. Moreover, DEX treatment reduced macrophage recruitment around the area of hepatotoxicity and the expression levels of hepatic phosphorylated mitogen-activated protein kinase kinase 4 (MAP2K4), c-jun N-terminal kinase (JNK), and c-Jun expression induced by acetaminophen overdose.

Conclusion

The data suggest that DEX likely downregulates the JNK signaling pathway and its downstream effectors to promote its hepatoprotective effect, providing a clinical application of DEX for the attenuation of PILT.

Protective Role of Dexmedetomidine on Ileum and Kidney Damage Caused by Mesenchymal Ischaemia in Rats

Objective

The aim of this study was to demonstrate ischaemia reperfusion (IR) injury on the ileum and kidney tissue in rats and to evaluate the effect of dexmedetomidine administered at different doses and dosing schedules on recovery.

Methods

A total of 30 rats were randomly divided into five groups. Group I: sham; Group II: control; Group III: dexmedetomidine before ischaemia; Group IV: dexmedetomidine after ischaemia; and Group V: dexmedetomidine before and after ischaemia. The malondialdehyde (MDA) and signal peptide-CUB-EGF (epidermal growth factor) domain-containing protein 1 (SCUBE-1) levels of all subjects were studied from the serum, ileum, and kidney tissues. Moreover, the histopathology of ileum and kidney tissues was examined.

Results

The SCUBE-1 levels were found to be highly similar to the MDA levels in ischaemic groups. The serum SCUBE-1 levels obtained were significantly lower in Group V compared to Groups II, III and IV (p<0.001, p=0.003, p=0.013, respectively). The apoptosis indexes were found to be lower in groups receiving dexmedetomidine compared to Group II. The groups receiving dexmedetomidine were detected to have normal morphological appearance when compared to Group II.

Conclusion

In this study, the use of dexmedetomidine in the preoperative and peroperative periods may be beneficial in reducing the negative effects of IR injury.

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.

Perioperative "remote" acute lung injury: recent update

Perioperative acute lung injury (ALI) is a syndrome characterised by hypoxia and chest radiograph changes. It is a serious post-operative complication, associated with considerable mortality and morbidity. In addition to mechanical ventilation, remote organ insult could also trigger systemic responses which induce ALI. Currently, there are limited treatment options available beyond conservative respiratory support. However, increasing understanding of the pathophysiology of ALI and the biochemical pathways involved will aid the development of novel treatments and help to improve patient outcome as well as to reduce cost to the health service. In this review we will discuss the epidemiology of peri-operative ALI; the cellular and molecular mechanisms involved on the pathological process; the clinical considerations in preventing and managing perioperative ALI and the potential future treatment options.

Dexmedetomidine protects from post-myocardial ischaemia reperfusion lung damage in diabetic rats

OBJECTIVE

Diabetic complications and lipid peroxidation are known to have a close association. Lipid peroxidation commonly occurs at sites exposed to ischaemia, but distant organs and tissues also get damaged during ischaemia/reperfusion (I/R). Some of these targets are vital organs, such as the lung, liver, and kidney; the lung is the most frequently affected. The aim of our study was to investigate the effects of dexmedetomidine on I/R damage in lung tissue and on the oxidant/anti-oxidant system in diabetic rats.

MATERIAL AND METHODS

Diabetes was induced with streptozotocin (55 mg/kg) in 18 Wistar Albino rats, which were then randomly divided into three groups (diabetes control (DC), diabetes plus ischaemia-reperfusion (DIR), and diabetes plus dexmedetomidine-ischaemia/reperfusion (DIRD)) after the effects of diabetes were clearly evident. The rats underwent a left thoracotomy and then ischaemia was produced in the myocardium muscle by a left anterior descending artery ligation for 30 min in the DIR and DIRD groups. I/R was performed for 120 min. The DIRD group received a single intraperitoneal dose of dexmedetomidine (100 µg/kg); the DIR group received no dexmedetomidine. Group DC was evaluated as the diabetic control group and also included six rats (C group) in which diabetes was not induced. These mice underwent only left thoracotomy and were closed without undergoing myocardial ischaemia. Histopathological changes, activities of catalase (CAT) and glutathione-S-transferase anti-oxidant enzymes, and malondialdehyde (MDA) levels were evaluated in the lung tissues of all rats.

RESULTS

Neutrophil infiltration/aggregation was higher in the DIR group than in the C, DC, and DIRD groups (p=0.001, p=0.013, and p=0.042, respectively). The lung injury score was significantly higher in the DIR group than in the C and DC groups (p<0.0001 and p=0.024, respectively). The levels of MDA were significantly higher in the DIR group than in the C and DIRD groups. CAT activity was significantly higher in the DIR group than in the DIRD and C groups.

CONCLUSION

Our results confirm that dexmedetomidine has protective effects against the lung damage resulting from I/R in diabetic rats. Future studies conducted to evaluate the effects of the use of dexmedetomidine on damage to various organs following different I/R durations may help understanding possible protective effects of dexmedetomidine and underlying mechanisms in tissue damage related to I/R injury.

Bradycardia in perspective-not all reductions in heart rate need immediate intervention

According to Wikipedia, the word 'bradycardia' stems from the Greek βραδύς, bradys, 'slow', and καρδία, kardia, 'heart'. Thus, the meaning of bradycardia is slow heart rate but not necessarily too slow heart rate. If looking at top endurance athletes they may have a resting heart rate in the very low thirties without needing emergent intervention with anticholinergics, isoprenaline, epinephrine, chest compressions or the insertion of an emergency pacemaker (Figure 1). In fact, they withstand these episodes without incident, accommodating with a compensatory increase in stroke volume to preserve and maintain cardiac output. With this in mind, it is difficult for the authors to fully understand and agree with the general sentiment amongst many pediatric anesthesiologists that all isolated bradycardia portends impending doom and must be immediately treated with resuscitative measures.

Molecular targets and mechanism of action of dexmedetomidine in treatment of ischemia/reperfusion injury

Dexmedetomidine (DEX), a highly specific α2-adrenergic agonist, which exhibits anaesthetic-sparing, analgesia and sympatholytic properties. DEX modulates gene expression, channel activation, transmitter release, inflammatory processes and apoptotic and necrotic cell death. It has also been demonstrated to have protective effects in a variety of animal models of ischemia/reperfusion (I/R) injury, including the intestine, myocardial, renal, lung, cerebral and liver. The broad spectrum of biological activities associated with DEX continues to expand, and its diverse effects suggest that it may offer a novel therapeutic approach for the treatment of human diseases with I/R involvement.