Targeting the opioid remifentanil: Protective effects and molecular mechanisms against organ ischemia-reperfusion injury

Opioids are widely used in clinical practice by activating opioid receptors (OPRs), but their clinical application is limited by a series of side effects. Researchers have been making tremendous efforts to promote the development and application of opioids. Fortunately, recent studies have identified the additional effects of opioids in addition to anesthesia and analgesia, particularly in terms of organ protection against ischemia-reperfusion (I/R) injury, with unique advantages. I/R injury in vital organs not only leads to cell dysfunction and structural damage but also induces acute and chronic organ failure, even death. Early prevention and appropriate therapeutic targets for I/R injury are crucial for organ protection. Opioids have shown cardioprotective effects for over 20 years, especially remifentanil, a derivative of fentanyl, which is a new ultra-short-acting opioid analgesic widely used in clinical anesthesia induction and maintenance. In this review, we provide current knowledge about the physiological effects related to OPR-mediated organ protection, focusing on the protective effect and mechanism of remifentanil on I/R injury in the heart and other vital organs. Herein, we also explored the potential application of remifentanil in clinical I/R injury. These findings provide a theoretical basis for the use of remifentanil to inhibit or alleviate organ I/R injury during the perioperative period and provide insights for opioid-induced human organ protection and drug development.

Measurement of tissue oxygen saturation during arthroscopic surgery of knee with a tourniquet

BACKGROUND

Tourniquets provide better tissue visibility during arthroscopic surgery. However, multiple postoperative adverse events associated with ischemia may be caused by excessive inflation pressure and duration. We aimed to evaluate the degree of tourniquet-induced ischemia using a noninvasive continuous real-time monitoring method and the relationship between changes in tissue oxygen saturation (StO2) and blood biochemical markers of ischemic injuries in patients undergoing arthroscopic knee surgery.

METHODS

This was a prospective observational study using near-infrared spectroscopy (NIRS). Data were collected from 29 consecutive patients who underwent arthroscopic procedures. Twenty-five patients underwent anterior cruciate ligament reconstruction, and four underwent meniscal repair. We investigated tourniquet-induced changes in StO2, monitored using NIRS, and blood biochemical markers of ischemic injuries.

RESULTS

A significant decrease in the mean StO2 from the baseline was observed during tourniquet inflation in the operative legs. The average decrease in the mean StO2 was 58%. A comparison of mean StO2 between the nonoperative and operative legs before tourniquet deflation showed that mean values of StO2 in the operative legs were significantly lower than those in the nonoperative legs. No significant clinical relationships were observed between changes in StO2 and blood biochemical markers of ischemic injuries (creatine kinase) (p = 0.04, r = 0.38) or tourniquet duration (p = 0.05, r = 0.366).

CONCLUSIONS

Our results demonstrated that StO2 could be used to evaluate tissue perfusion in real time but did not support the hypothesis that StO2 is a useful method for predicting the degree of tourniquet-induced injury during arthroscopic knee surgery.

A randomized controlled trial: Comparison of one-per-mil tumescent technique and tourniquet in surgery for burn hand contracture in creating clear operative field and assessment of functional outcome

BACKGROUND

This study aims to compare the use of one-per-mil tumescent solution (a mixture of epinephrine and 0.2% lidocaine in a ratio of 1:1,000,000 in normal saline solution) and tourniquet to create clear operative fields and to evaluate the functional outcomes after post burn hand contracture surgery.

METHODS

The subjects of this randomized controlled trial were divided into one-permil tumescent technique and tourniquet group for a similar surgical procedure. Three independent assessors evaluated the clarity of the operative fields through recorded videos for the first 15 min and the first 10-minute of each hour of the surgery. Functional outcome was evaluated at least three months postoperatively using total active and passive motion (TAM and TPM) of each digit. Malondialdehyde (MDA) and tumor necrosis factor alpha (TNF-α) were tested during baseline (5 min before the procedures), ischemia phase, and reperfusion phase (a phase when the blood flow returned to the tissue).

RESULTS

35 subjects were included in this study: 17 in the tumescent group and 18 in the tourniquet group. We found a significant difference in the clarity of operative field between tumescent and tourniquet groups, 5 vs 35 bloodless operative fields, respectively (p < 0.05). TAM and TPM of each digit before surgery and 3 months postoperatively showed no significant difference between both groups (p > 0.05). Furthermore, we found no difference in MDA and TNF-α levels between both groups at their respective phases.

CONCLUSIONS

The use of one-per-mil tumescent technique does not replace tourniquet use to create bloodless operative fields in burned hand contracture surgery. However, the postoperative functional results were similar in both groups showing that tumescent technique can be used as an alternative to tourniquet without compromising outcomes. The MDA and TNF-α examinations do not provide conclusive outcomes regarding ischemia and reperfusion injury.

MicroRNA as a Potential Biomarker and Treatment Strategy for Ischemia-Reperfusion Injury

Ischemia-reperfusion (I/R) injury is a progressive injury that aggravates the pathological state when the organ tissue restores blood supply after a certain period of ischemia, including the myocardial, brain, liver, kidney, and intestinal. With growing evidence that microRNAs (miRNAs) play an important role as posttranscription gene silencing mediators in many I/R injury, in this review, we highlight the microRNAs that are related to I/R injury and their regulatory molecular pathways. In addition, we discussed the potential role of miRNA as a biomarker and its role as a target in I/R injury treatment. Developing miRNAs are not without its challenges, but prudent design combined with existing clinical treatments will result in more effective therapies for I/R injury. This review is aimed at providing new research results obtained in this research field. It is hoped that new research on this topic will not only generate new insights into the pathophysiology of miRNA in I/R injury but also can provide a basis for the clinical application of miRNA in I/R.

Effects of remifentanil and propofol on distant organ lung injury in an ischemia-reperfusion model

Our aim was to evaluate lung injury due to oxidative stress and antioxidant activity levels in an infrarenal ischemia-reperfusion model and to compare prevention effects of single and combined use of propofol and remifentanil. In this study, a total of 40 adult Wistar Albino rats were randomly divided into five groups of eight rats as SHAM, physiological saline, intraperitoneal propofol, remifentanil, and propofol and remifentanil groups. Blood and tissue samples were obtained after 80 min of reperfusion. The malondialdehyde (MDA) level, a measure of lipid peroxidation, was measured in lung tissue samples and red blood cells; additionally, total oxidant status and total antioxidant capacity of lung tissues were measured and histopathological examination was performed. Distant organ (lung) injury developed due to lower extremity ischemia-reperfusion was created by infrarenal aortic clamping. The lipid peroxidation product MDA and total oxidant levels were increased, but there was insufficient antioxidant protection both in the lung tissues and red blood cells. While propofol prevented this injury consistent with its proposed antioxidant properties; no protective effect of remifentanil was observed. On the contrary, it showed oxidative stress increasing effect. This study concluded that the antioxidant effect of propofol was suppressed by remifentanil in the case of combined use.

The Comparison of Inflammatory Cytokines between Spinal and General Anesthesia following Changes in Ischemic Reperfusion due to Tourniquet during Lower Limb Surgery

Methods

In this randomized controlled clinical trial, 34 patients with lower limb surgery admitted at the orthopedic ward of Imam Reza Hospital, Birjand, Iran, were selected by the available sampling method. They were randomly divided into two groups as follows: general anesthesia (n = 17) and spinal anesthesia (n = 17). Venous blood samples were taken from the patients of both groups at baseline (before the use of tourniquet) and 12 and 24 hours after reperfusion. Interleukin-6 (IL-6), tumor necrotizing factor-α (TNF-α), high-sensitivity C-reactive protein (hs-CRP), and ferritin were measured and recorded. The data were analyzed using independent t-test, chi-square, and repeated measure at the significant level of 0.05.

Results

The results showed that hs-CRP and IL-6 significantly increased during the study (p < 0.001); however, the mean changes of TNF-α and ferritin were not significant during the study. Moreover, none of the inflammatory cytokines indicated significant differences between these two study groups (p < 0.05).

Conclusion

According to the results, the use of tourniquet can lead to inflammation, and the inflammation is similar in both groups.

Increased inspired oxygen concentration does not adversely affect oxidative stress and the resolution of inflammation during reperfusion in patients undergoing knee replacement surgery

The level of inspired oxygen during surgery may modify free radical release, and reperfusion injury. This controlled trial examined the effect of inspired oxygen on F₂-isoprostanes (F₂-IsoPs), isofurans (IsoFs), and specialized mediators of inflammation resolution (SPM) during knee replacement surgery. Patients received either 30% O₂ (control n = 21), 50% O₂ (n = 20), or 80% O₂ (n = 19) O₂, in a parallel design. Hemoglobin (Hb) was measured throughout the surgery and F₂-IsoPs, IsoFs and SPM were analyzed by mass spectrometry. The effect of O₂ on F₂-IsoPs and IsoFs was examined during tourniquet inflation and after tourniquet release. SPM were measured at baseline and the end of surgery. There was a significant interaction between O₂ and Hb concentrations with plasma IsoFs during tourniquet inflation. An increase in plasma IsoFs over time was attenuated in the 80% O₂ group (p=.012) compared with the 30% O₂ group after adjusting for Hb concentration. After tourniquet release, plasma F₂-IsoPs were significantly lower in the 50% and 80% O₂ groups (p=.009 and p=.001, respectively) compared with the 30% O₂ group after adjustment for Hb concentration. The SPM RvD2 and RvE2 were increased with 50% and 80% O₂ (RvD2, p=.014 and p=.002, respectively; RvE2, p=.032 with 50% O₂) compared with the 30% O₂ group, in analyses that corrected for Hb concentration. We have shown for the first time that higher O₂ levels may be beneficial in reducing oxidative stress and increasing resolution of inflammation during surgery that involves reperfusion after application of a tourniquet.

Dexamethasone Improves Wound Healing by Decreased Inflammation and Increased Vasculogenesis in Mouse Skin Frostbite Model

INTRODUCTION

Frostbite is thought to result from initial vasoconstriction, ischemia, intracellular ice crystal formation, and inflammation caused by reperfusion injury. Corticosteroids have demonstrated beneficial anti-inflammatory effects in the treatment of other ischemia/reperfusion clinical conditions. The objective of this study was to determine the effect of dexamethasone (dex) on wound healing, inflammatory response, and vasculogenesis in a mouse skin frostbite model.

METHODS

Treatment and control groups of C57/BL6 mice were subjected to frostbite using a previously described model. Treatment with intraperitoneal dex (1 mg·kg^-1·d^-1) began on the day of frostbite induction and lasted for 7 d. Over 4 wk, we compared wound diameter; morphology by visual inspection, hematoxylin-eosin staining, and Masson's trichrome staining; density of inflammatory cytokines IL-1β and TNFα using Western blot analysis; and formation of microvasculature using immunofluorescence staining. Data were analyzed using 1-way or 1-way repeated-measures analysis of variance.

RESULTS

After frostbite injury, morphological images demonstrated epidermal necrosis and loss in the frostbitten skin as well as infiltration of inflammation-related leukocytes. Increased production of inflammatory cytokines and disappearance of the microvasculature also occurred in the frostbitten skin. In comparison to the control group, treatment with dex promoted wound healing as demonstrated by decreased wound diameter; decreased levels of inflammatory cytokines, and accelerated formation of mature microvasculature.

CONCLUSIONS

In this animal model, dex improved wound healing in frostbitten skin and demonstrated both anti-inflammatory effects and stimulation of vasculogenesis. This study suggests that the use of potent anti-inflammatory agents may be an effective strategy for mitigating frostbite injury.

Acute remote ischemic preconditioning alleviates free radical injury and inflammatory response in cerebral ischemia/reperfusion rats

Remote ischemic preconditioning (IPreC) is an effective strategy to defend against cerebral ischemia/reperfusion (IR) injury; however, its mechanisms remain to be elucidated. The aim of the present study was to investigate the effect of IPreC on brain tissue following cerebral ischemia, as well as the underlying mechanisms. Adult male Sprague-Dawley rats were treated with IPreC for 72 h prior to the induction of transient cerebral ischemia and reperfusion. The results demonstrated that IPreC reduced the area of cerebral infarction in the IR rats by 2,3,5-triphenyl-tetrazolium chloride staining. In addition, cell apoptosis was markedly suppressed by IPreC with an increased expression of B-cell lymphoma 2 (Bcl-2)/Bcl-2-associatd X protein using Terminal deoxynucleotidyl-transferase-mediated dUTP nick end labeling assay and western blot analysis. IR induced a decrease in the level of superoxide dismutase, and IPreC significantly suppressed increased levels of malondialdehyde, lactate dehydrogenase and nitric oxide. The expression of CD11b and CD18 was markedly inhibited by IpreC unsing flow cytometry. Furthermore, IPreC markedly decreased the release of pro-inflammatory factors interleukin (IL)-6 and IL-1β, and enhanced the level of anti-inflammatory factors (IL-10 and IL-1 receptor antagonist) by ELISA assay. Finally, IPreC reduced the levels of transforming growth factor-β-activated kinase 1, phosphorylated-P65/P65, and tumor necrosis factor-α, indicating that the nuclear factor-κB pathway was involved in IPreC-mediated protection against cerebral ischemia. Taken together, the results suggested that IPreC decreased ischemic brain injury through alleviating free radical injury and the inflammatory response in cerebral IR rats.

Ascorbic Acid Attenuates Multifidus Muscles Injury and Atrophy After Posterior Lumbar Spine Surgery by Suppressing Inflammation and Oxidative Stress in a Rat Model

STUDY DESIGN

A rat model of multifidus muscles injury and atrophy after posterior lumbar spine surgery.

OBJECTIVE

We determined the effect of ascorbic acid (AA) on the postoperative multifidus muscles in rat model.

SUMMARY OF BACKGROUND DATA

Previous studies show oxidative stress and inflammation are two main molecular mechanisms in multifidus muscle injury and atrophy after posterior lumbar surgery. AA may have a protective effect in postoperative multifidus muscles.

METHODS

Rats were divided into sham surgery, control surgery, and surgery plus AA groups. Multifidus muscles of the control and AA groups were excised from the osseous structures. The muscles were retracted continuously for 2 hours. In the sham and AA groups, AA was administered via oral gavage daily in the first week. In each group, the oxidative stress was evaluated by measuring malondialdehyde (MDA) and Total superoxide dismutase (T-SOD). The inflammation, fat degeneration, or fibrosis of multifidus muscle were evaluated by quantitative real-time polymerase chain reaction (q-PCR), histology, or immunohistochemical analysis.

RESULTS

T-SOD activity was significantly lower in the control group than that in the AA group in the first week. MDA levels were significantly higher in the AA group. Interleukin-6 and tumor necrosis factor-α in multifidus muscles also showed significant differences when treated with AA. The inflammation score on histology was significantly lower in the AA group postoperatively in the first week. In the long run, marker genes for fibrosis and fat degeneration, and fibrosis and fat degeneration scores, were significantly lower in the AA than the control group on days 14 and 28 postoperatively.

CONCLUSION

In conclusion, AA attenuated the oxidative stress and inflammation response in the postoperative multifidus muscles, and remarkable differences were observed from the histological assessment and related marker genes expression. Our results provided important insight into the anti-inflammatory and anti-oxidative effects of AA in the postoperative multifidus muscles.

LEVEL OF EVIDENCE

N/A.