Dexmedetomidine did not reduce the effects of tourniquet-induced ischemia-reperfusion injury during general anesthesia

Assessing the Antioxidant Activity of Dexmedetomidine by Measuring the Plasma Antioxidant Enzyme Activity of Catalase, Glutathione Peroxidase, and Superoxide Dismutase During Lumbar Spine Laminectomy

Background: Current knowledge on antioxidant properties of anesthetics is inconclusive. Nevertheless, experiments on different anesthesia-related drugs and techniques are growing. Objectives: The aim of this prospective blinded randomized study was to assess the effect of dexmedetomidine (Dex) infusion during anesthesia on oxidative stress resulting from lumbar laminectomy. Methods: The antioxidant activity of Dex compared to placebo (normal saline) was evaluated by measuring the antioxidant enzyme activity of catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPX). A total of 56 patients who underwent laminectomy surgery were allocated into two groups of intervention and control. Dex group received 0.6 µg.kg-1 dexmedetomidine infusion before induction of anesthesia over 15 minutes, followed by 0.4 µg.kg-1.hr-1 maintenance. Control group received the same volume and sequence of normal saline. Anesthesia protocol was similar in both groups. The antioxidant activity of the previously mentioned enzymes was measured at the beginning of the anesthesia (T1) and after surgery (T2). Propofol consumption, hemodynamic indices, shivering, bleeding volume, and pain numeric rating scale (NRS) were recorded. Results: Although the serum levels of CAT and GPX increased during the procedure, these changes were not significant (P-values 0.579 and 0.762, respectively). Also, the mean SOD level did not change over time in any of the groups, and it was not meaningfully different between the groups at any of the predetermined times (P-value 0.665). Conclusions: As expected, Dex decreased propofol consumption, mean heart rate, mean arterial pressure, and pain intensity allover the perioperative period. It seems that adding Dex to anesthesia regimen during laminectomy had no dominant antioxidant effects.

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.

Effect of dexmedetomidine on hemodynamic responses to tracheal intubation: A meta-analysis with meta-regression and trial sequential analysis

STUDY OBJECTIVE

An uncontrolled adrenergic response during tracheal intubation may lead to life-threatening complications. Dexmedetomidine binds to α2-receptors and may attenuate this response. The primary aim of our meta-analysis is to investigate dexmedetomidine efficacy in attenuating sympathetic response to tracheal intubation, compared with placebo or no dexmedetomidine, in terms of heart rate and blood pressure at intubation.

DESIGN

Meta-analysis with meta-regression and trial sequential analysis.

SETTING

Systematic search from inception until December 1, 2020 in the following databases: Pubmed, Scopus, the Cochrane Central Register of Controlled Trials, EMBASE and Google Scholar.

INTERVENTIONS

All randomized controlled trials investigating intravenous dexmedetomidine as premedication in adult patients undergoing tracheal intubation were included in our study. Studies were included without any language or publication date restriction. A trial sequential analysis and a post-hoc meta-regression were performed on the main outcomes.

MEASUREMENTS

Hemodynamic parameters and heart rate at tracheal intubation, dose of anesthetic needed for induction of anesthesia, total anesthetic requirement throughout the operative procedure, postoperative pain and percentage of patients requiring analgesics at 24 postoperative hours, postoperative nausea and vomiting, intraoperative and postoperative bradycardia, hypotension, dizziness, shivering and/or respiratory depression.

MAIN RESULTS

Ninety-nine included studies randomized 6833 patients. During laryngoscopy, all hemodynamic parameters were significantly greater in the no dexmedetomidine group. In particular, in the dexmedetomidine group, systolic blood pressure differed by -21.8 mm Hg (95% CI -26.6 to -17.1, p-value < 0.001, I² 97%), mean arterial pressure by -12.8 mm Hg (95% CI -15.6 to -10.0, p-value < 0.001, I² 98%), and heart rate by -16.9 bpm (95% CI -19.8 to -13.9, p-value < 0.001, I² 98%).

CONCLUSIONS

Patients receiving premedication with dexmedetomidine for tracheal intubation, compared with no dexmedetomidine, have a lower blood pressure and heart rate, however, the risk of bradycardia and hypotension is relevant and its use during daily practice should be cautiously evaluated for each patient.

Femoral artery block (FAB) attenuates thigh tourniquet-induced hypertension: a prospective randomized, double-blind, placebo-controlled trial

INTRODUCTION

Prolonged tourniquet inflation during surgery frequently leads to tourniquet hypertension (TH), which is thought to arise from compression of A-δ fibers leading to sympathetically mediated C fiber activation. In the lower extremity, C fibers and other sympathetic nerve fibers are carried along the femoral artery. We hypothesized that blockade of these fibers at the femoral artery would decrease the incidence of TH.

METHODS

Thirty American Society of Anesthesia 1-3 patients aged 18-75 undergoing total ankle arthroplasty were randomized to receive 15 mL of injectate (mepivacaine 1.5% or saline placebo) at the anteromedial aspect of the common femoral artery at the level of the inguinal crease under ultrasound guidance. Both groups received preoperative popliteal sciatic and saphenous nerve blocks for analgesia and a standardized general anesthetic. Esmolol was administered if systolic blood pressure rose >30% above baseline. Incidence of TH was the primary outcome.

RESULTS

TH was present in 93.3% of sham patients versus 33.3% of block patients. Mean systolic pressure at 120 min and 150 min of tourniquet time was significantly higher in the sham group compared with the block group. Esmolol requirement (95.3+107.6 v 8.0+14.2, p=<0.001) was also significantly higher in the sham group. No differences were noted in pain scores or opioid consumption, and no patient experienced sensory or motor block of the femoral nerve.

DISCUSSION

Under these experimental conditions, injection of local anesthetic around the femoral artery reduced the incidence of TH and intraoperative esmolol requirement.

TRIAL REGISTRATION NUMBER

www.clinicaltrials.gov (NCT03390426; December 28, 2017).

Reducing the dose of neuromuscular blocking agents with adjuncts: a systematic review and meta-analysis

BACKGROUND

Acute global shortages of neuromuscular blocking agents (NMBA) threaten to impact adversely on perioperative and critical care. The use of pharmacological adjuncts may reduce NMBA dose. However, the magnitude of any putative effects remains unclear.

METHODS

We conducted a systematic review and meta-analysis of RCTs. We searched Medline, Embase, Web of Science, and Cochrane Database (1970-2020) for RCTs comparing use of pharmacological adjuncts for NMBAs. We excluded RCTs not reporting perioperative NMBA dose. The primary outcome was total NMBA dose used to achieve a clinically acceptable depth of neuromuscular block. We assessed the quality of evidence using the GRADE (Grades of Recommendation, Assessment, Development, and Evaluation) criteria. Data are presented as the standardised mean difference (SMD); I² indicates percentage of variance attributable to heterogeneity.

RESULTS

From 3082 records, the full texts of 159 trials were retrieved. Thirty-one perioperative RCTs met the inclusion criteria for meta-analysis (n=1962). No studies were conducted in critically ill patients. Reduction in NMBA dose was associated with use of magnesium (SMD: -1.10 [-1.44 to -0.76], P<0.001; I²=85%; GRADE=moderate), dexmedetomidine (SMD: -0.89 [-1.55 to -0.22]; P=0.009; I²=87%; GRADE=low), and clonidine (SMD: -0.67 [-1.13 to -0.22]; P=0.004; I²=0%; GRADE=low) but not lidocaine (SMD: -0.46 [-1.01 to -0.09]; P=0.10; I²=68%; GRADE=moderate). Meta-analyses for nicardipine, diltiazem, and dexamethasone were not possible owing to the low numbers of studies. We estimated that 30-50 mg kg^-1 magnesium preoperatively (8-15 mg kg h^-1 intraoperatively) reduces rocuronium dose by 25.5% (inter-quartile range, 14.7-31).

CONCLUSIONS

Magnesium, dexmedetomidine, and clonidine may confer a clinically relevant sparing effect on the required dose of neuromuscular block ing drugs in the perioperative setting.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO: CRD42020183969.

Impact of Dexmedetomidine on Tourniquet-Induced Systemic Effects in Total Knee Arthroplasty under Spinal Anesthesia: a Prospective Randomized, Double-Blinded Study

Background

Clinical studies on the impact of dexmedetomidine on tourniquet-induced systemic effects have been inconsistent. We investigated the impact of dexmedetomidine on tourniquet-induced systemic effects in total knee arthroplasty.

Methods

Eighty patients were randomly assigned to either control (CON) or dexmedetomidine (DEX) group. The DEX group received an intravenous loading dose of 0.5 μg/kg DEX over 10 minutes, followed by a continuous infusion of 0.5 μg/kg/h from 10 minutes before the start of surgery until completion. The CON group received the same calculated volume of normal saline. Pain outcomes and metabolic and coagulative changes after tourniquet application and after tourniquet release were investigated.

Results

The frequency of fentanyl administration postoperatively, patient-controlled analgesia (PCA) volume at 24 hours postoperatively, total PCA volume consumed in 48 hours postoperatively, and VAS score for pain at 24 and 48 hours postoperatively were significantly lower in the DEX group than in the CON group. Ten minutes after the tourniquet release, the DEX group showed significantly higher pH and lower lactate level than those in the CON group. Antithrombin III activity and body temperature 10 minutes after tourniquet release were significantly lower in the DEX group than in the CON group. Ca²⁺, K⁺, HCO₃ ^-, base excess, and PCO₂ levels 10 minutes after tourniquet release were not significantly different between the two groups.

Conclusion

We showed that DEX attenuated pain and hemodynamic, metabolic, and coagulative effects induced by the tourniquet. However, these metabolic and coagulative changes were within normal limits. Therefore, DEX could be used as an analgesic adjuvant, but should not be considered for routine use to prevent the systemic effects induced by tourniquet use.

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.

Curcumin and dexmedetomidine prevents oxidative stress and renal injury in hind limb ischemia/reperfusion injury in a rat model

Curcumin and dexmedetomidine have been shown to have protective effects in ischemia-reperfusion injury on various organs. However, their protective effects on kidney tissue against ischemia-reperfusion injury remain unclear. We aimed to determine whether curcumin or dexmedetomidine prevents renal tissue from injury that was induced by hind limb ischemia-reperfusion in rats. Fifty rats were divided into five groups: sham, control, curcumin (CUR) group (200 mg/kg curcumin, n = 10), dexmedetomidine (DEX) group (25 μg/kg dexmedetomidine, n = 10), and curcumin-dexmedetomidine (CUR-DEX) group (200 mg/kg curcumin and 25 μg/kg dexmedetomidine). Curcumin and dexmedetomidine were administered intraperitoneally immediately after the end of 4 h ischemia, just 5 min before reperfusion. The extremity re-perfused for 2 h and then blood samples were taken and total antioxidant capacity (TAC), total oxidative status (TOS) levels, and oxidative stress index (OSI) were measured, and renal tissue samples were histopathologically examined. The TAC activity levels in blood samples were significantly lower in the control than the other groups (p < 0.01 for all comparisons). The TOS activity levels in blood samples were significantly higher in Control group and than the other groups (p <  0.01 for all comparison). The OSI were found to be significantly increased in the control group compared to others groups (p < 0.001 for all comparisons). Histopathological examination revealed less severe lesions in the sham, CUR, DEX, and CUR-DEX groups, compared with the control group (p < 0.01). Rat hind limb ischemia-reperfusion causes histopathological changes in the kidneys. Curcumin and dexmedetomidine administered intraperitoneally was effective in reducing oxidative stress and renal histopathologic injury in an acute hind limb I/R rat model.

Evaluation of matrix metalloproteinase, myeloperoxidase, and oxidative damage in mesenteric ischemia-reperfusion injury

BACKGROUND

In this study, we investigated the alterations of matrix metalloproteinase (MMP) and tissue inhibitors of metalloproteinases (TIMPs), acute inflammation, and oxidative damage in the circulatory system and the intestine in response to mesenteric ischemia/reperfusion (I/R).

METHODS

Twenty-one rats were divided randomly into the following three groups (n = 7 in each group): a sham group (CG), an ischemic group (IG), and an I/R group (I/RG). MMP-9, TIMP-1, and myeloperoxidase (MPO) were measured using the enzyme-linked immunosorbent assay method, and lipid peroxidation (quantified as thiobarbituric acid reactive substances (TBARS) content), ischemia-modified albumin, the prooxidant-antioxidant balance (PAB), and ferric-reducing antioxidant power (FRAP) were measured spectrophotometrically. The degree of intestinal injury was evaluated according to the Chiu scoring system.

RESULTS

A significant difference between the mean serum TIMP-1 and MMP-9 levels and the alanine transaminase activity was found among the groups. Compared with the I/RG group a significant difference in the mean tissue MMP-9, MPO, and TBARS levels in addition to the PAB and FRAP was found between the CG and IG groups. The level of MMP-9 also demonstrated a strong, positive, and valid correlation with the TBA-RS levels. A significant morphological change was observed in both the IG and the I/RG groups. The degree of intestinal injury was more severe in the I/R group and was characterized by either villous denudation or villous loss.

CONCLUSIONS

These results suggest that MMP-9, TIMP-1, MPO, and oxidative stress may be important in the intestinal injury development that is induced by acute mesenteric I/R in a rat model. MMP-9 overexpression may increase the extent of intestinal villous loss, particularly when MMP-9 is upregulated by the TBARS present in the intestinal injury.

Influence of Dexmedetomidine on the Tourniquet Related Responses in Hypertension Patients Receiving Unilateral Knee Arthroplasty under General Anesthesia

This study aimed to investigate the influence of dexmedetomidine (DEX) on the tourniquet related responses in hypertension patients receiving unilateral knee arthroplasty (UKA) under general anesthesia. Results showed that the incidence of tourniquet induced hypertension (TIH), hemodynamics, MAC and EtSEV in DEX group were significantly lower than those in control group, regardless of hypertension. However, significant differences in TIH, hemodynamics, minimum alveolar concentration (MAC) and end-tidal sevoflurane (EtSEV) were not observed between hypertension patients and non-hypertension patients in both control group and DEX group. Moreover, oxygen index (OI) and respiratory index (RI) remained unchanged after deflation and DEX failed to affect OI and RI within 30 min after deflation, regardless of hypertension. Taken together, DEX may significantly improve the hemodynamics, which is independent of pre-existing hypertension.

Dexmedetomidine pretreatment alleviates propofol injection pain

OBJECTIVE

The incidence of propofol injection pain during induction of general anesthesia varies from 28% to 90%. This prospective, randomized, double-blind, placebo-controlled study evaluated the effect of dexmedetomidine (DEX) for reducing the incidence and severity of propofol injection pain.

METHODS

Patients undergoing elective surgical procedures were randomly allocated into seven groups of 30 patients each. Experimental treatments were intravenously administered over 10 min (total volume 10 mL) prior to intravenous propofol injection, as follows: group I, the control group, was given isotonic saline. Patients in groups II, III, and IV received DEX 0.25 µg/kg, 0.5 µg/kg, or 1.0 µg/kg, respectively, mixed with isotonic saline immediately before propofol injection. Patients in groups V, VI, and VII received DEX as above, but 5 minutes before propofol injection. Propofol consisted of 1% long-chain triglyceride propofol (2.5 mg/kg) injected at 1 mL/s.

RESULTS

Median propofol injection pain score was 0.00 (IQR 0.00-3.00) in patients who received 1.0 µg/kg DEX 5 min before the propofol injection (group VII), and only 1 patient (of 30) in this group received a pain score >2. The median pain score and number of patients with pain scores >2 in group VII were both significantly less than in the control (group I; p = 0.000, both). There were no differences in either mean arterial pressure or heart rate at any time point after DEX injection among the groups.

CONCLUSIONS

Pretreatment with intravenous DEX 1 µg/kg 5 min prior to injection of long-chain triglyceride propofol is effective and safe in reducing the incidence and severity of pain due to propofol injection.

[Effects of various anesthesia maintenance on serum levels of selenium, copper, zinc, iron and antioxidant capacity]

BACKGROUND AND OBJECTIVES

In this study, we aimed to investigate the effects of sevoflurane, desflurane and propofol maintenances on serum levels of selenium, copper, zinc, iron, malondialdehyde, and glutathion peroxidase measurements, and antioxidant capacity.

METHODS

60 patients scheduled for unilateral lower extremity surgery which would be performed with tourniquet under general anesthesia were divided into three groups. Blood samples were collected to determine the baseline serum levels of selenium, copper, zinc, iron, malondialdehyde and glutathion peroxidase. Anesthesia was induced using 2-2.5mgkg(-1) propofol, 1mgkg(-1) lidocaine and 0.6mgkg(-1) rocuronium. In the maintenance of anesthesia, under carrier gas of 50:50% O2:N2O 4Lmin(-1), 1 MAC sevoflorane was administered to Group S and 1 MAC desflurane to Group D; and under carrier gas of 50:50% O2:air 4Lmin(-1) 6mgkgh(-1) propofol and 1μgkgh(-1) fentanyl infusion were administered to Group P. At postoperative blood specimens were collected again.

RESULTS

It was observed that only in Group S and P, levels of MDA decreased at postoperative 48th hour; levels of glutathion peroxidase increased in comparison to the baseline values. Selenium levels decreased in Group S and Group P, zinc levels decreased in Group P, and iron levels decreased in all three groups, and copper levels did not change in any groups in the postoperative period.

CONCLUSION

According to the markers of malondialdehyde and glutathion peroxidase, it was concluded that maintenance of general anesthesia using propofol and sevoflurane activated the antioxidant system against oxidative stress and using desflurane had no effects on oxidative stress and antioxidant system.

Lower limb ischaemia and reperfusion injury in healthy volunteers measured by oxidative and inflammatory biomarkers

Objective:

Ischaemia-reperfusion (IR) injury is partly caused by the release of reactive oxygen species and cytokines and may result in remote organ injury. Surgical patients are exposed to surgical stress and anaesthesia, both of which can influence the IR response. An IR model without these interfering factors of surgery is, therefore, useful to test the potential of antioxidant and cytokine-modulatory treatments. The aim of this study was to characterize a human ischaemia-reperfusion model with respect to oxidative and inflammatory biomarkers.

Materials and methods:

Ten male volunteers were exposed to 20 minutes of lower limb ischaemia. Muscle biopsies and blood samples were taken at baseline and 5, 15, 30, 60 and 90 minutes after tourniquet release and analysed for malondialdehyde (MDA), ascorbic acid, dehydroascorbic acid, tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-1 receptor antagonist (IL-1Ra), IL-6, IL-10, TNF-receptor (TNF-R)I, TNF-RII and YKL-40.

Results:

We found no significant increase in MDA in the muscle biopsies after reperfusion. Plasma levels of oxidative and pro- and anti-inflammatory parameters showed no significant differences between baseline and after reperfusion at any sampling time.

Conclusion:

Twenty minutes of lower limb ischaemia does not result in an ischaemia-reperfusion injury in healthy volunteers, measurable by oxidative and pro- and anti-inflammatory biomarkers in muscle biopsies and in the systemic circulation.

The effect of intravenous anesthetics on ischemia-reperfusion injury

The effects of intravenous anesthetics on ischemia-reperfusion injury (IRI) have been investigated in both animals and clinical studies. The protective effects and the dosages of the intravenous anesthetics on IRI were discussed in this paper. The prevention of the tissue injury after the IRI was demonstrated with intravenous anesthetics in some studies. In the future, the studies should be focused on the dosage of the anesthetics related to diminishing the tissue injuries. Further studies might be required in order to investigate the effects of the anesthetics on molecular levels.