Effects of enflurane, isoflurane, sevoflurane and desflurane on reperfusion injury after regional myocardial ischaemia in the rabbit heart in vivo

Postconditioning with Lactate-Enriched Blood for Reducing Lethal Reperfusion Injury in Humans

Ischemic myocardium cannot survive without reperfusion. However, reperfusion of the ischemic myocardium paradoxically induces myocyte death; this phenomenon is termed lethal reperfusion injury. To date, no effective approach has been demonstrated for ST-segment elevation myocardial infarction (STEMI) in clinical settings. Recently, we demonstrated a novel approach for cardioprotection, termed postconditioning with lactate-enriched blood (PCLeB). PCLeB comprises intermittent reperfusion and timely coronary injections of lactated Ringer's solution, which is implemented at the beginning of reperfusion. This approach is aimed at reducing lethal reperfusion injury via prolonging intracellular acidosis during the early period of reperfusion, compared with the original postconditioning protocol. Patients with STEMI treated using PCLeB have reported positive outcomes. This article represents an effort, with a perspective different from current insights, toward preventing lethal reperfusion injury, in light of the historical background of reperfusion injury research. PCLeB is considered the new approach for cardioprotection.

Experimental and Clinical Aspects of Sevoflurane Preconditioning and Postconditioning to Alleviate Hepatic Ischemia-Reperfusion Injury: A Scoping Review

Ischemia-reperfusion injury (IRI) is an inflammatory process inherent in organ transplantation procedures. It is associated with tissue damage and, depending on its intensity, can impact early graft function. In liver transplantation (LT), strategies to alleviate IRI are essential in order to increase the use of extended criteria donor (ECD) grafts, which are more susceptible to IRI, as well as to improve postoperative graft and patient outcomes. Sevoflurane, a commonly used volatile anesthetic, has been shown to reduce IRI. This scoping review aims to give a comprehensive overview of the existing experimental and clinical data regarding the potential benefits of sevoflurane for hepatic IRI (HIRI) and to identify any gaps in knowledge to guide further research. We searched Medline and Embase for relevant articles. A total of 380 articles were identified, 45 of which were included in this review. In most experimental studies, the use of sevoflurane was associated with a significant decrease in biomarkers of acute liver damage and oxidative stress. Administration of sevoflurane before hepatic ischemia (preconditioning) or after reperfusion (postconditioning) appears to be protective. However, in the clinical setting, results are conflicting. While some studies showed a reduction of postoperative markers of liver injury, the benefit of sevoflurane on clinical outcomes and graft survival remains unclear. Further prospective clinical trials remain necessary to assess the clinical relevance of the use of sevoflurane as a protective factor against HIRI.

The Protective Effect of Sevoflurane Conditionings Against Myocardial Ischemia/Reperfusion Injury: A Systematic Review and Meta-Analysis of Preclinical Trials in in-vivo Models

Objective

Myocardial ischemia/reperfusion injury (IRI) is a common and serious complication in clinical practice. Sevoflurane conditionings have been identified to provide a protection against myocardial IRI in animal experiments, but their true clinical benefits remain controversial. Here, we aimed to analyze the preclinical evidences obtained in animal models of myocardial IRI and explore the possible reasons for controversial clinical benefits.

Methods

Our primary outcome was the difference in mean infarct size between the sevoflurane and control groups in animal models of myocardial IRI. After searching the databases of PubMed, Embase, Web of Science, and the Cochrane Library, a systematic review retrieved 37 eligible studies, from which 28 studies controlled comparisons of sevoflurane preconditioning (SPreC) and 40 studies controlled comparisons of sevoflurane postconditioning (SPostC) that were made in a pooled random-effects meta-analysis. In total, this analysis included data from 313 control animals and 536 animals subject to sevoflurane conditionings.

Results

Pooled estimates for primary outcome demonstrated that sevoflurane could significantly reduce the infarct size after myocardial IRI whether preconditioning [weighted mean difference (WMD): −18.56, 95% CI: −23.27 to −13.85, P < 0.01; I² = 94.1%, P < 0.01] or postconditioning (WMD: −18.35, 95% CI: −20.88 to −15.83, P < 0.01; I² = 90.5%, P < 0.01) was performed. Interestingly, there was significant heterogeneity in effect size that could not be explained by any of the prespecified variables by meta-regression and stratified analysis. However, sensitivity analysis still identified the cardioprotective benefits of sevoflurane conditionings with robust results.

Conclusion

Sevoflurane conditionings can significantly reduce infarct size in in-vivo models of myocardial IRI. Given the fact that there is a lack of consistency in the quality and design of included studies, more well-performed in-vivo studies with the detailed characterization of sevoflurane protocols, especially studies in larger animals regarding cardioprotection effects of sevoflurane, are still required.

Sevoflurane Post-treatment Upregulated miR-203 Expression to Attenuate Cerebral Ischemia-Reperfusion-Induced Neuroinflammation by Targeting MyD88

To investigate the expression of miR-203 by sevoflurane treatment and its effect on neuroinflammation induced by cerebral ischemia-reperfusion. Rats were randomly divided into sham operation group (C), cerebral ischemia-reperfusion group (I/R), and sevoflurane treatment group (S). The neurological function score was evaluated. The area of cerebral infarction was evaluated by TTC staining. The expression of inflammatory factor in brain tissue was detected by ELISA. The apoptosis of neurons was detected by TUNEL. A miR-203 agonist and inhibitor treated the cerebral ischemia-reperfusion model. The luciferase assay verified whether miR-203 targeted MyD88. To further verify the relationship between miR-203 and MyD88, the I/R group was treated with MyD88 activator and inhibitor, and the mRNA expressions of miR-203 and MyD88 in brain tissue were detected by RT-PCR. Western blot was used to detect the expression of MyD88 protein in brain tissue, and the above experiment was repeated. Compared with the I/R group, miR-203 mRNA was significantly increased in brain tissue and the neurological function score, the area of cerebral infarction, the expression of inflammatory factor, and MyD88 mRNA were decreased in the S group (P < 0.05). After treatment of miR-203 agonist and inhibitor in the I/R group, overexpression of miR-203 could alleviate cerebral ischemia-reperfusion injury, and miR-203 inhibitor could aggravate cerebral ischemia-reperfusion injury. The miR-203 agonist could enhance the action of sevoflurane, and the miR-203 inhibitor could reverse the action of sevoflurane. miR-203 agonist treatment could inhibit the expression of MyD88 gene and protein and reduce the neuroinflammation induced by cerebral ischemia-reperfusion. The treatment of sevoflurane upregulated miR-203 expression, which targeted MyD88 and attenuate neuroinflammation induced by cerebral ischemia-reperfusion.

Desflurane Preconditioning Protects Against Renal Ischemia-Reperfusion Injury and Inhibits Inflammation and Oxidative Stress in Rats Through Regulating the Nrf2-Keap1-ARE Signaling Pathway

OBJECTIVE

Kidney is sensitive to ischemia-reperfusion (I/R) injury because of its special structure and function. In this study, we aimed to explore the mechanism of desflurane (DFE) preconditioning effecting on renal I/R injury in rats.

METHODS

Renal I/R injury rats model was constructed, and the expressions of serum renal function parameters (blood urea nitrogen (BUN) and serum creatinine (SCr)) and lipid peroxidation-related factors were detected using corresponding commercial kits to assess the degrees of renal functional damage and oxidative stress. Hematoxylin--eosin (HE) staining and Masson trichrome staining were applied to measure the renal histologic damage. The expressions of inflammation-related factors were determined by ELISA assay. The cell apoptosis was analyzed using TUNEL, Western blot and immunohistochemistry (IHC). IHC was also used to detect the number of myeloperoxidase (MPO)-positive cells. The expressions of proteins associated with the Nrf2-Keap1-ARE pathway were assessed by Western blot and IHC.

RESULTS

DFE preconditioning inhibited I/R injury-induced BUN and SCr increase and renal histologic injury in rats. Also, DFE suppressed the inflammation, apoptosis and oxidative stress caused by renal I/R injury in vivo. In addition, DFE preconditioning repressed peroxide-related factors (MDA, MPO and NO) expressions and promoted antioxidant-related factors (GSH, SOD, GPx and CAT) expressions. In addition, DFE promoted Nrf2-Keap1-ARE-related proteins including Nrf2, NQO1, HO-1, γ-GCS, GSR and GCLc expressions.

CONCLUSION

DFE preconditioning protected the kidney as well as inhibited the inflammation, cell apoptosis and oxidative stress in renal I/R injury rats by activating the Nrf2-Keap1-ARE signaling pathway.

Comparison of Inflammatory Markers Between the Sevoflurane and Isoflurane Anesthesia in a Rat Model of Liver Ischemia/Reperfusion Injury

BACKGROUND

Sevoflurane and isoflurane had been reported to improve ischemia/reperfusion injury (I/R) through amelioration of the inflammatory response. We aimed to explore and compare the molecular mechanisms involved in sevoflurane and isoflurane anesthesia in liver ischemia-reperfusion of rat model.

METHODS

Forty male Wistar rats were randomly divided into 4 groups: sham group, I/R group, sevoflurane group, and isoflurane group. The liver I/R injury model was established to investigate the effect of sevoflurane and isoflurane anesthesia on liver ischemia/reperfusion. The inflammatory markers and complement C3, C5a, and C6 were detected by enzyme-linked immunosorbent assay. Oxidative stress was detected by measuring the levels of malondialdehyde (MDA), superoxide dismutase (SOD), and nitric oxide (NO).

RESULTS

Our results showed that sevoflurane anesthesia significantly decreased alanine transaminase, aspartate transaminase, and lactate dehydrogenase levels compared with isoflurane and controls. Sevoflurane inhibited I/R injury induced production of tumor necrosis factor α, interleukin 1, interleukin 6, and intercellular cell adhesion molecule-1 and promoted interleukin 10 production more significantly compared with isoflurane. Reduced MDA and NO and elevated SOD release suggested that oxidative stress was attenuated by sevoflurane and isoflurane anesthesia. Both sevoflurane and isoflurane anesthesia significantly decreased plasma C3 levels compared with the I/R injury group without differences.

CONCLUSION

Sevoflurane anesthesia produced a more significant inhibitive effect on inflammatory cytokines and oxidative stress in liver I/R injury model than isoflurane, suggesting that sevoflurane is more suitable in surgery.

Evaluation of the Effect of Regional Anaesthesia on Microvascular Free Flaps

Objective

Multiple factors influence the success of microvascular free flap surgeries. Anaesthesia is an important factor to maximise the success rate of microvascular free flaps both by controlling haemodynamics and improving the perfusion of free vascularised tissue. The debate on the usefulness of regional and general anaesthesia for free tissue transfer is ongoing. This retrospective study was conducted to evaluate the effects of regional anaesthesia and other perioperative factors on outcomes of microvascular free flaps.

Methods

This retrospective observational study was conducted on 165 patients undergoing microvascular free flap surgeries between January 2014 and December 2015 after obtaining approval from the Institutional Ethics Committee (Nizams Institute Ethics Committee, Nizams Institute of Medical Sciences, India). Perioperative variables analysed included the type of surgery, indication, ASA physical status, type of anaesthesia, perioperative haemodynamics, fluids used, duration of surgery, re-explorations, blood transfusion and duration of hospital stay. The primary outcome measure was to assess the effect of regional anaesthesia on the success of free flap.

Results

Multivariate analysis identified the type of anaesthesia and preoperative haemodynamics as independent risk factors for predicting the failure of flap with an odds ratio of 0.208 and 7.469, respectively. A subgroup analysis of 55 acute trauma patients revealed preoperative haemodynamic instability as an individual independent risk factor for graft failure with an odds ratio of 11.90.

Conclusion

The results of this study emphasise the importance of the choice of anaesthesia and preoperative optimisation in improving the success of free flap surgeries.

Ischemic Preconditioning Produces Comparable Protection Against Hepatic Ischemia/Reperfusion Injury Under Isoflurane and Sevoflurane Anesthesia in Rats

BACKGROUND

Various volatile anesthetics and ischemic preconditioning (IP) have been demonstrated to exert protective effect against ischemia/reperfusion (I/R) injury in liver. We aimed to determine whether application of IP under isoflurane and sevoflurane anesthesia would confer protection against hepatic I/R injury in rats.

METHODS

Thirty-eight rats weighing 270 to 300 grams were randomly divided into 2 groups: isoflurane (1.5%) and sevoflurane (2.5%) anesthesia groups. Each group was subdivided into sham (n = 3), non-IP (n = 8; 45 minutes of hepatic ischemia), and IP (n = 8, IP consisting of 10-minute ischemia plus 15-minute reperfusion before prolonged ischemia) groups. The degree of hepatic injury and expressions of B-cell lymphoma 2 (Bcl-2) and caspase 3 were compared at 2 hours after reperfusion.

RESULTS

Hepatic ischemia induced significant degree of I/R injuries in both isoflurane and sevoflurane non-IP groups. In both anesthetic groups, introduction of IP dramatically attenuated I/R injuries as marked by significantly lower aspartate aminotransferase and aminotransferase levels and better histologic grades compared with corresponding non-IP groups. There were 2.3- and 1.7-fold increases in Bcl-2 mRNA levels in isoflurane and sevoflurane IP groups, respectively, compared with corresponding non-IP groups (both P < .05). Caspase 3 level was significantly high in the isoflurane non-IP group compared with the sham group; however, there were no differences among the sevoflurane groups.

CONCLUSIONS

The degree of hepatic I/R injury was significantly high in both isoflurane and sevoflurane groups in rats. However, application of IP significantly protected against I/R injury in both volatile anesthetic groups to similar degrees, and upregulation of Bcl-2 might be an important mechanism.

The in vitro zebrafish heart as a model to investigate the chronotropic effects of vapor anesthetics

In addition to their intended clinical actions, all general anesthetic agents in common use have detrimental intrasurgical and postsurgical side effects on organs and systems, including the heart. The major cardiac side effect of anesthesia is bradycardia, which increases the probability of insufficient systemic perfusion during surgery. These side effects also occur in all vertebrate species so far examined, but the underlying mechanisms are not clear. The zebrafish heart is a powerful model for studying cardiac electrophysiology, employing the same pacemaker system and neural control as do mammalian hearts. In this study, isolated zebrafish hearts were significantly bradycardic during exposure to the vapor anesthetics sevoflurane (SEVO), desflurane (DES), and isoflurane (ISO). Bradycardia induced by DES and ISO continued during pharmacological blockade of the intracardiac portion of the autonomic nervous system, but the chronotropic effect of SEVO was eliminated during blockade. Bradycardia evoked by vagosympathetic nerve stimulation was augmented during DES and ISO exposure; nerve stimulation during SEVO exposure had no effect. Together, these results support the hypothesis that the cardiac chronotropic effect of SEVO occurs via a neurally mediated mechanism, while DES and ISO act directly upon cardiac pacemaker cells via an as yet unknown mechanism.

A clinical review of inhalation anesthesia with sevoflurane: from early research to emerging topics

A large number of studies during the past two decades have demonstrated the efficacy and safety of sevoflurane across patient populations. Clinical researchers have also investigated the effects of sevoflurane, its hemodynamic characteristics, its potential protective effects on several organ systems, and the incidence of delirium and cognitive deficiency. This review examines the clinical profiles of sevoflurane and other anesthetic agents, and focuses upon emerging topics such as organ protection, postoperative cognitive deficiency and delirium, and novel ways to improve postanesthesia outcomes.

[Cardioprotection in cardiac surgical patients : Everything good comes from the heart]

BACKGROUND

Despite substantial success in the anesthetic and surgical management of cardiac surgery, patients frequently show postoperative complications and organ dysfunctions. This is highly relevant for mid- to long-term outcomes.

OBJECTIVES

To evaluate cardioprotective strategies that may offer effective protection in vulnerable cardiac surgery patients.

METHODS

To demonstrate recent cardioprotective approaches for cardiac surgery patients, aiming to modulate the body's own protective mechanisms in cardiac surgery patients.

RESULTS

Both cardioplegia and hypothermia belong to the well-established protective strategies during myocardial ischemia. Volatile anesthetics have been repeatedly shown to improve the left ventricular function and reduce the extent of myocardial injury compared to a control group with intravenous anesthesia. Furthermore, patients receiving volatile anesthetics showed a significantly shortened stay in the ICU and in hospital after cardiac surgery. In contrast, numerous other protective strategies failed translation into the clinical practice. Despite the published reduction of troponin release after remote ischemic preconditioning, two recent large-scale randomized multicenter trials were unable to demonstrate a clinical benefit.

CONCLUSIONS

Beside the use of cardioplegia and hypothermia, the use of volatile anesthetics is well-established during cardiac surgery because of its conditioning and protective properties. Regardless of the promising results derived from experimental studies and small clinical trials, the majority of other approaches failed to translate their findings into the clinic. Therefore, systematic experimental studies are needed to identify potential confounding factors that may affect the protective effects.

The mechanisms of cardio-protective effects of desflurane and sevoflurane at the time of reperfusion: anaesthetic post-conditioning potentially translatable to humans?

Myocardial conditioning is actually an essential strategy in the management of ischaemia-reperfusion injury. The concept of anaesthetic post-conditioning is intriguing, its action occurring at a pivotal moment (that of reperfusion when ischaemia reperfusion lesions are initiated) where the activation of these cardio-protective mechanisms could overpower the mechanisms leading to ischaemia reperfusion injuries. Desflurane and sevoflurane are volatile anaesthetics frequently used during cardiac surgery. This review focuses on the efficacy of desflurane and sevoflurane administered during early reperfusion as a potential cardio-protective strategy. In the context of experimental studies in animal models and in human atrial tissues in vitro, the mechanisms underlying the cardio-protective effect of these agents and their capacity to induce post-conditioning have been reviewed in detail, underlining the role of reactive oxygen species generation, the activation of the cellular signalling pathways, and the actions on mitochondria along with the translatable actions in humans; this might well be sufficient to set the basis for launching randomized clinical studies, actually needed to confirm this strategy as one of real impact.

Post-conditioning with Cyclosporine A after a 24-hour cold ischemia in ex vivo reperfused pig lungs

OBJECTIVE

To evaluate the effects of 1 and 5 μM of Cyclosporine A (CsA), administered 24 hours after a cold ischemic period, in an ex vivo reperfused pig lung model.

METHODS

The experiments were performed in 15 pigs. Each pair of lungs was surgically separated. Extracorporeal perfusion and mechanical ventilation were started after a cold ischemia of 2 hours for one lung and 24 hours for the contralateral. We constituted three groups (n = 5 each): two groups for which the lung underwent a 24-hour ischemia received either 1 or 5 μM of CsA at the time of reperfusion, and a control group without CsA. For each group, lungs undergoing a 2-hour ischemia did not receive CsA.

RESULTS

Reperfusion with either CsA increased the PO2 levels in a dose dependent manner, and reduced concentrations of the receptor for advanced glycation endproducts, compared to the control. The pulmonary arterial pressure, the capillary pressure, and the pulmonary vascular resistances were not increased, even with 5 μM of CsA. No significant change was shown on cytokines levels.

DISCUSSION

Postconditioning with CsA improves lung function, after a 24-hour cold ischemic period. Either 1 or 5 μM seemed to be safe regarding the pulmonary vascular pressures and resistances.

Effects of cyclosporine a in ex vivo reperfused pig lungs

OBJECTIVE

Several works highlight the role of CsA in the prevention of IRI, but none focus on isolated lungs. Our objective was to evaluate the effects of CsA on IRI on ex vivo reperfused pig lungs.

METHODS

Thirty-two pairs of pig lungs were collected and stored for 30 minutes at 4 °C. The study was performed in four groups. First, a control group and then three groups receiving different concentrations of CsA (1, 10, and 30 μM) at two different times: once at the moment of lung procurement and another during the reperfusion procedure. The ex vivo lung preparation was set up using an extracorporeal perfusion circuit. Gas exchange parameters, pulmonary hemodynamics, and biological markers of lung injury were collected for the evaluation.

RESULTS

CsA improved the PaO2 /FiO2 ratio, but it also increased PAP, Pcap, and pulmonary vascular resistances with dose-dependent effects. Lungs treated with high doses of CsA displayed higher capillary-alveolar permeability to proteins, lower AFC capacities, and elevated concentrations of pro-inflammatory cytokines.

CONCLUSIONS

These data suggest a possible deleterious imbalance between the beneficial cell properties of CsA in IRI and its hemodynamic effects on microvascularization.

Cellular mechanisms against ischemia reperfusion injury induced by the use of anesthetic pharmacological agents

Ischemia-reperfusion (IR) cycle in the myocardium is associated with activation of an injurious cascade, thus leading to new myocardial challenges, which account for up to 50% of infarct size. Some evidence implicates reactive oxygen species (ROS) as a probable cause of myocardial injury in prooxidant clinical settings. Damage occurs during both ischemia and post-ischemic reperfusion in animal and human models. The mechanisms that contribute to this damage include the increase in cellular calcium (Ca(2+)) concentration and induction of ROS sources during reperfusion. Pharmacological preconditioning, which includes pharmacological strategies that counteract the ROS burst and Ca(2+) overload followed to IR cycle in the myocardium, could be effective in limiting injury. Currently widespread evidence supports the use of anesthetics agents as an important cardioprotective strategy that act at various levels such as metabotropic receptors, ion channels or mitochondrial level. Their administration before a prolonged ischemic episode is known as anesthetic preconditioning, whereas when given at the very onset of reperfusion, is termed anesthetic postconditioning. Both types of anesthetic conditioning reduce, albeit not to the same degree, the extent of myocardial injury. This review focuses on cellular and pathophysiological concepts on the myocardial damage induced by IR and how anesthetic pharmacological agents commonly used could attenuate the functional and structural effects induced by oxidative stress in cardiac tissue.

The Role of Cyclooxygenase-1 and -2 in Sevoflurane-Induced Postconditioning Against Myocardial Infarction

Cyclooxygenase (COX)-2 mediates ischemic pre- and postconditioning as well as anesthetic-induced preconditioning. However, the role of COX-1 and -2 in anesthetic-induced postconditioning has not been investigated. We evaluated the role of COX-1 and -2 in sevoflurane-induced postconditioning in vivo. Pentobarbital-anaesthetized male C57BL/6 mice were subjected to 45 minutes of coronary artery occlusion and 3 hours of reperfusion. Animals received either no intervention, the vehicle dimethyl sulfoxide (DMSO, 10 µL/g intraperitoneally), acetylsalicylic acid (ASA, 5 µg/g intraperitoneally), the selective COX-1 inhibitor SC-560 (10 µg/g intraperitoneally), or the selective COX-2 inhibitor NS-398 (5 µg/g intraperitoneally). 1.0 MAC (minimum alveolar concentration) sevoflurane was administered for 18 minutes during early reperfusion either alone or in combination with ASA, SC-560, and NS-398. Infarct size was determined with triphenyltetrazolium chloride. Statistical analysis was performed using 1-way and 2-way analyses of variance with post hoc Duncan testing. The infarct size in the control group was 44% ± 9%. DMSO (42% ± 7%), ASA (36% ± 6%), and NS-398 (44% ± 18%) had no effect on infarct size. Sevoflurane (17% ± 4%; P < .05) and SC-560 (26% ± 10%; P < .05) significantly reduced the infarct size compared with control condition. Sevoflurane-induced postconditioning was not abolished by ASA (16% ± 5%) and SC-560 (22% ± 4%). NS-398 abolished sevoflurane-induced postconditioning (33% ± 14%). It was concluded that sevoflurane induces postconditioning in mice. Inhibition of COX-1 elicits a myocardial infarct size reduction and does not abolish sevoflurane-induced postconditioning. Blockade of COX-2 abolishes sevoflurane-induced postconditioning. These results indicate that sevoflurane-induced postconditioning is mediated by COX-2.

The anesthesia in abdominal aortic surgery (ABSENT) study: a prospective, randomized, controlled trial comparing troponin T release with fentanyl-sevoflurane and propofol-remifentanil anesthesia in major vascular surgery

BACKGROUND

On the basis of data indicating that volatile anesthetics induce cardioprotection in cardiac surgery, current guidelines recommend volatile anesthetics for maintenance of general anesthesia during noncardiac surgery in hemodynamic stable patients at risk for perioperative myocardial ischemia. The aim of the current study was to compare increased troponin T (TnT) values in patients receiving sevoflurane-based anesthesia or total intravenous anesthesia in elective abdominal aortic surgery.

METHODS

A prospective, randomized, open, parallel-group trial comparing sevoflurane-based anesthesia (group S) and total intravenous anesthesia (group T) with regard to cardioprotection in 193 patients scheduled for elective abdominal aortic surgery. Increased TnT level on the first postoperative day was the primary endpoint. Secondary endpoints were postoperative complications, nonfatal coronary events and mortality.

RESULTS

On the first postoperative day increased TnT values (>13 ng/l) were found in 43 (44%) patients in group S versus 41 (43%) in group T (P = 0.999), with no significant differences in TnT levels between the groups at any time point. Although underpowered, the authors found no differences in postoperative complications, nonfatal coronary events or mortality between the groups.

CONCLUSIONS

In elective abdominal aortic surgery sevoflurane-based anesthesia did not reduce myocardial injury, evaluated by TnT release, compared with total intravenous anesthesia. These data indicate that potential cardioprotective effects of volatile anesthetics found in cardiac surgery are less obvious in major vascular surgery.

Effects of anesthetics, sedatives, and opioids on ventilatory control

This article provides a comprehensive, up to date summary of the effects of volatile, gaseous, and intravenous anesthetics and opioid agonists on ventilatory control. Emphasis is placed on data from human studies. Further mechanistic insights are provided by in vivo and in vitro data from other mammalian species. The focus is on the effects of clinically relevant agonist concentrations and studies using pharmacological, that is, supraclinical agonist concentrations are de-emphasized or excluded.

Pharmacologic therapy that simulates conditioning for cardiac ischemic/reperfusion injury

Cardiovascular disease remains a leading cause of deaths due to noncommunicable diseases, of which ischemic heart disease forms a large percentage. The main therapeutic strategy to treat ischemic heart disease is reperfusion that could either be medical or surgical. However, reperfusion following ischemia is known to increase the infarct size further. Newer strategies such as ischemic preconditioning (IPC), ischemic postconditioning, and remote IPC have been shown to condition the myocardium to ischemia-reperfusion injury and thus reduce the final infarct size. Research over the past 3 decades has deepened our understanding of cellular and subcellular pathways that mediate ischemia-reperfusion injury. This in turn has resulted in the development of several pharmacological agents that act as conditioning agents, which reduce the final myocardial infarct size following ischemia-reperfusion. This review discusses many of these agents, their mechanisms of action, and the animal and clinical evidence behind them.

Sevoflurane Protects Ventricular Myocytes against Oxidative Stress-induced Cellular Ca2+ Overload and Hypercontracture

Background:

Oxidative stress is implicated in pathogenesis of cardiac reperfusion injury, characterized by cellular Ca2+ overload and hypercontracture. Volatile anesthetics protect the heart against reperfusion injury primarily by attenuating Ca2+ overload. This study investigated electrophysiological mechanisms underlying cardioprotective effects of sevoflurane against oxidative stress-induced cellular injury.

Methods:

The cytosolic Ca2+ levels and cell morphology were assessed in mouse ventricular myocytes, using confocal fluo-3 fluorescence imaging, whereas membrane potentials and L-type Ca2+ current (ICa,L) were recorded using whole-cell patch-clamp techniques. Phosphorylation of Ca2+/calmodulin-dependent protein kinase II was examined by Western blotting.

Results:

Exposure to H2O2 (100 μm) for 15 min evoked cytosolic Ca2+ elevation and hypercontracture in 56.8% of ventricular myocytes in 11 experiments, which was partly but significantly reduced by nifedipine, tetracaine, or SEA0400. Sevoflurane prevented H2O2-induced cellular Ca2+ overload in a concentration-dependent way (IC50 = 1.35%). Isoflurane (2%) and desflurane (10%) also protected ventricular myocytes by a degree similar to sevoflurane (3%). Sevoflurane suppressed H2O2-induced electrophysiological disturbances, including early afterdepolarizations, voltage fluctuations in resting potential, and abnormal automaticities. H2O2 significantly enhanced ICa,L by activating Ca2+/calmodulin-dependent protein kinase II, and subsequent addition of sevoflurane, isoflurane, or desflurane similarly reduced ICa,L to below baseline levels. Phosphorylated Ca2+/calmodulin-dependent protein kinase II increased after 10-min incubation with H2O2, which was significantly prevented by concomitant administration of sevoflurane.

Conclusions:

Sevoflurane protected ventricular myocytes against H2O2-induced Ca2+ overload and hypercontracture, presumably by affecting multiple Ca2+ transport pathways, including ICa,L, Na+/Ca2+ exchanger and ryanodine receptor. These actions appear to mediate cardioprotection against reperfusion injury associated with oxidative stress.

Use of volatile anesthetics in extracorporeal circulation

BACKGROUND AND OBJECTIVES

The use of volatile anesthetics in cardiac surgery is not recent. Since the introduction of halothane in clinical practice, several cardiac surgery centers started to use these anesthetics constantly.

CONTENT

In the last years a great number of studies have shown that the volatile anesthetics have a protecting effect against myocardial ischemic dysfunction. Experimental evidences have shown that the halogenated anesthetics have cardioprotective effects that cannot be only explained by coronary flow alterations or by the balance between myocardium available and consumed oxygen. In addition to that, the use of volatile anesthetics during extracorporeal circulation (ECC) in cardiac surgery plays an important role. Recent studies have proven that these agents have cardioprotective properties and produce better results when the volatile anesthetic is used during the whole surgery procedure, including ECC. The use of halogenated anesthetics through calibrated vaporizers adapted to the ECC circuit via oxygenator membranes has become popular. Therefore, the professionals involved such as anesthesiologists and perfusionists should learn specifics in order to solve possible doubts.

Isoflurane post-conditioning protects against intestinal ischemia-reperfusion injury and multiorgan dysfunction via transforming growth factor-β1 generation

OBJECTIVE

This study examined volatile anesthetic-mediated protection against intestinal ischemia-reperfusion injury (IRI).

BACKGROUND

Intestinal IRI is a devastating complication in the perioperative period leading to systemic inflammation and multiorgan dysfunction. Volatile anesthetics, including isoflurane, have anti-inflammatory effects. We aimed to determine whether isoflurane, given after intestinal ischemia, protects against intestinal IRI and the mechanisms involved in this protection.

METHODS

: After IACUC approval, mice were anesthetized with pentobarbital and subjected to 30 minutes of superior mesenteric artery ischemia, followed by 4 hours of equianesthetic doses of pentobarbital or isoflurane. Five hours after reperfusion, small intestine tissues were analyzed for morphological injury, apoptosis, neutrophil infiltration, proinflammatory mRNAs, and TGF-(Transforming Growth Factor-)β1 levels. We also assessed hepatic and renal injury after intestinal IRI.

RESULTS

Intestinal IRI with pentobarbital led to significant small intestinal dysfunction with increased mucosal injury, TUNEL (transferase biotin-dUTP nick end-labeling)-positive cells, neutrophil infiltration, and proinflammatory mRNAs as well as elevated plasma alanine aminotransferase and creatinine levels. Isoflurane exposure after IRI led to significant attenuation of intestinal, hepatic, and renal injuries. Furthermore, the protective effects of isoflurane were abolished by treatment with a TGF-β1 neutralizing antibody before induction of IRI. Finally, isoflurane exposure led to increased TGF-β1 levels in intestinal epithelial cells and in plasma.

CONCLUSIONS

Our findings demonstrate that isoflurane post-conditioning protects against small intestinal injury and hepatic and renal dysfunction after severe intestinal IRI via induction of intestinal epithelial TGF-β1. Our findings support therapeutic applications of volatile anesthetics during the intraoperative and postoperative periods and imply an important role of TGF-β1 signaling in modulating multiorgan injury.

Clinical application of the cardioprotective effects of volatile anaesthetics: PRO--get an extra benefit from a proven anaesthetic free of charge

Volatile anaesthetic agents have been used in millions of patients around the world and have proved to be both well tolerated and efficient. In recent years, cardioprotective properties of these drugs have been demonstrated unequivocally in numerous experimental investigations, but the beneficial effects of volatile anaesthetics in daily clinical practice are still under debate. In order to elucidate their cardioprotective properties in an unbiased way, the STAIR (Stroke Therapy Academic Industry Roundtable Preclinical Recommendation) criteria proposed as a framework for researchers in the field of neuroprotection can be applied to research conducted in the field of cardioprotection by volatile anaesthetics. All STAIR criteria have already been clearly fulfilled when all experimental and clinical studies are considered. Specifically, a dose-response pattern has been found with a minimal alveolar concentration value and a ceiling effect; volatile anaesthetics show two distinct therapeutic windows after application; important outcome measures such as hospital length of stay have been addressed; and multiple species have been studied by different independent groups of researchers who were largely able to reproduce their findings. Given the numerous confounding factors capable of attenuating or even abolishing the cardioprotective properties of volatile anaesthetics in laboratory investigations, the positive effects found in the majority of clinical trials point to the fact that the cardioprotective effects exerted by volatile anaesthetics are robust and triggered by interactions with several distinct cellular and subcellular targets, thereby providing multiplication and reiteration. The available evidence indicates that volatile anaesthetic agents should be used routinely in clinical practice in order to claim an extra benefit for our patients 'free of charge'.

Effect of remote ischemic conditioning on atrial fibrillation and outcome after coronary artery bypass grafting (RICO-trial)

Background

Pre- and postconditioning describe mechanisms whereby short ischemic periods protect an organ against a longer period of ischemia. Interestingly, short ischemic periods of a limb, in itself harmless, may increase the ischemia tolerance of remote organs, e.g. the heart (remote conditioning, RC). Although several studies have shown reduced biomarker release by RC, a reduction of complications and improvement of patient outcome still has to be demonstrated. Atrial fibrillation (AF) is one of the most common complications after coronary artery bypass graft surgery (CABG), affecting 27-46% of patients. It is associated with increased mortality, adverse cardiovascular events, and prolonged in-hospital stay. We hypothesize that remote ischemic pre- and/or post-conditioning reduce the incidence of AF following CABG, and improve patient outcome.

Methods/design

This study is a randomized, controlled, patient and investigator blinded multicenter trial. Elective CABG patients are randomized to one of the following four groups: 1) control, 2) remote ischemic preconditioning, 3) remote ischemic postconditioning, or 4) remote ischemic pre- and postconditioning. Remote conditioning is applied at the arm by 3 cycles of 5 minutes of ischemia and reperfusion. Primary endpoint is the incidence AF in the first 72 hours after surgery, detected using a Holter-monitor. Secondary endpoints include length-of-stay on the intensive care unit and in-hospital, and the occurrence of major adverse cardiovascular events at 30 days, 3 months and 1 year.

Based on an expected incidence in the control group of 27%, 195 patients per group are needed to detect with 80% power a reduction by 45% following either pre- or postconditioning, while allowing for a 10% dropout and at an alpha of 0.05. With the combined intervention expected to be stronger, we need 75 patients in this group to detect a reduction in incidence of AF of 60%.

Discussion

The RICO-trial (the effect of Remote Ischemic Conditioning on atrial fibrillation and Outcome) is a randomized controlled multicenter trial, designed to investigate whether remote ischemic pre- and/or post-conditioning of the arm reduce the incidence of AF following CABG surgery.

Trial registration

ClinicalTrials.gov under NCT01107184.

Myocardial Injury in Remifentanil-Based Anaesthesia for off-Pump Coronary Artery Bypass Surgery: An Equipotent Dose of Sevoflurane versus Propofol

This randomised controlled trial compared the effect of equipotent anaesthetic doses of sevoflurane (S group) versus propofol (P group), during remifentanil-based anaesthesia for off-pump coronary artery bypass surgery, on myocardial injury. Either sevoflurane or propofol was titrated to maintain bispectral index values between 40 and 50. In both groups, a targeted concentration of remifentanil 20 ng.ml-1 was maintained during anaesthesia. The concentrations of creatine kinase MB and troponin I were measured before the start of surgery, on admission to the intensive care unit, and at 12 and 24 hours after intensive care unit admission. The postoperative values of creatine kinase MB (S group: 15.08±18.97, 20.78±20.92, 12.76±12.82 vs 2.09±1.54 ng.ml-1; P group: 10.99±13.15, 27.16±56.55, 11.88±18.80 vs 1.84±1.67 ng.ml-1) and troponin I (S group: 3.56±5.19, 5.66±7.89, 3.35±4.55 vs 0.52±1.90 ng.ml-1; P group: 2.42±3.33, 4.11±6.01, 3.04±5.31 vs 0.43±1.28 ng.ml-1) were significantly higher than preoperative values in both groups but there were no significant differences between the two groups. There were no significant differences in time to extubation (S group, 476±284 minutes; P group, 450±268 minutes) and intensive care unit length of stay (S group, 2775±1449 minutes; P group, 2797±1534 minutes) between the two groups. In conclusion, sevoflurane and propofol at equipotent doses guided by bispectral index with remifentanil 20 ng.ml-1 had similar creatine kinase MB and troponin I values.

Postconditioning by xenon and hypothermia in the rat heart in vivo

BACKGROUND AND OBJECTIVE

Hypothermia protects against myocardial reperfusion injury. However, inducing hypothermia takes time, which makes it unsuitable as an emergency treatment. Combining mild hypothermia with low-dose xenon, applied either simultaneously or one after the other, protects the neonatal rat brain against reperfusion injury. We investigated whether xenon, administered prior to hypothermia or simultaneously with hypothermia, also protects the rat heart from reperfusion injury.

METHODS

Anaesthetized rats (chloralose, ketamine, diazepam) were randomly allocated to five groups and subjected to 25 min coronary artery occlusion, followed by 120 min reperfusion. At the onset of reperfusion, controls received no intervention and inhaled oxygen in air with an inspired oxygen fraction of 0.8 (Con80). Further groups received either 1 h of mild hypothermia of 34 degrees C (Hypo34) or 30 min of xenon 20% (Xe20). Additional groups received xenon 20% and hypothermia 34 degrees C simultaneously (Xe20 + Hypo34) or in succession (Xe20-->Hypo34). Infarct sizes were assessed by triphenyltetrazolium chloride staining.

RESULTS

The combination of xenon 20% and hypothermia 34 degrees C significantly reduced infarct size [Xe20 + Hypo34: 55(22)%, mean (SD)] compared with control [Con80: 76(12)%, P = 0.03]. Xenon and hypothermia in succession produced no infarct size reduction.

CONCLUSION

The combination of xenon 20% and hypothermia of 34 degrees C, applied during early reperfusion, reduces infarct size in the rat heart in vivo.

Sevoflurane postconditioning reduces myocardial reperfusion injury in rat isolated hearts via activation of PI3K/Akt signaling and modulation of Bcl-2 family proteins

Sevoflurane postconditioning reduces myocardial infarct size. The objective of this study was to examine the role of the phosphatidylinositol-3-kinase (PI3K)/Akt pathway in anesthetic postconditioning and to determine whether PI3K/Akt signaling modulates the expression of pro- and antiapoptotic proteins in sevoflurane postconditioning. Isolated and perfused rat hearts were prepared first, and then randomly assigned to the following groups: Sham-operation (Sham), ischemia/reperfusion (Con), sevoflurane postconditioning (SPC), Sham plus 100 nmol/L wortmannin (Sham+Wort), Con+Wort, SPC+Wort, and Con+dimethylsulphoxide (DMSO). Sevoflurane postconditioning was induced by administration of sevoflurane (2.5%, v/v) for 10 min from the onset of reperfusion. Left ventricular developed pressure (LVDP), left ventricular end-diastolic pressure (LVEDP), maximum increase in rate of LVDP (+dP/dt), maximum decrease in rate of LVDP (-dP/dt), heart rate (HR), and coronary flow (CF) were measured at baseline, R30 min (30 min of reperfusion), R60 min, R90 min, and R120 min. Creatine kinase (CK) and lactate dehydrogenase (LDH) were measured after 5 min and 10 min reperfusion. Infarct size was determined by triphenyltetrazolium chloride staining at the end of reperfusion. Total Akt and phosphorylated Akt (phospho-Akt), Bax, Bcl-2, Bad, and phospho-Bad were determined by Western blot analysis. Analysis of variance (ANOVA) and Student-Newman-Keuls' test were used to investigate the significance of differences between groups. The LVDP, + or - dP/dt, and CF were higher and LVEDP was lower in the SPC group than in the Con group at all points of reperfusion (P<0.05). The SPC group had significantly reduced CK and LDH release and decreased infarct size compared with the Con group [(22.9 + or - 8)% vs. (42.4 + or - 9.4)%, respectively; P<0.05]. The SPC group also had increased the expression of phospho-Akt, Bcl-2, and phospho-Bad, and decreased the expression of Bax. Wortmannin abolished the cardioprotection of sevoflurane postconditioning. Sevoflurane postconditioning may protect the isolated rat heart. Activation of PI3K and modulation of the expression of pro- and antiapoptotic proteins may play an important role in sevoflurane-induced myocardial protection.

Cyclosporine A administered during reperfusion fails to restore cardioprotection in prediabetic Zucker obese rats in vivo

BACKGROUND AND AIMS

Hyperglycaemia blocks sevoflurane-induced postconditioning, and cardioprotection in hyperglycaemic myocardium can be restored by inhibition of the mitochondrial permeability transition pore (mPTP). We investigated whether sevoflurane-induced postconditioning is also blocked in the prediabetic heart and if so, whether cardioprotection could be restored by inhibiting mPTP.

METHODS AND RESULTS

Zucker lean (ZL) and Zucker obese (ZO) rats were assigned to one of seven groups. Animals underwent 25 min of ischaemia and 120 min of reperfusion. Control (ZL-/ZO Con) animals were not further treated. postconditioning groups (ZL-/ZO Sevo-post) received sevoflurane for 5 min starting 1min prior to the onset of reperfusion. The mPTP inhibitor cyclosporine A (CsA) was administered intravenously in a concentration of 5 (ZO CsA and ZO CsA+Sevo-post) or 10 mg/kg (ZO CsA10+Sevo-post) 5 min before the onset of reperfusion. At the end of reperfusion, infarct sizes were measured by TTC staining. Blood samples were collected to measure plasma levels of insulin, cholesterol and triglycerides. Sevoflurane postconditioning reduced infarct size in ZL rats to 35±12% (p<0.05 vs. ZL Con: 60±6%). In ZO rats sevoflurane postconditioning was abolished (ZO Sevo-post: 59±12%, n.s. vs. ZO Con: 58±6%). 5 mg and 10 mg CsA could not restore cardioprotection (ZO CsA+Sevo-post: 59±7%, ZO CsA10+Sevo-post: 57±14%; n.s. vs. ZO Con). In ZO rats insulin, cholesterol and triglyceride levels were significant higher than in ZL rats (all p<0.05).

CONCLUSION

Inhibition of mPTP with CsA failed to restore cardioprotection in the prediabetic but normoglycaemic heart of Zucker obese rats in vivo.

Cyclosporine does not reduce myocardial infarct size in a porcine ischemia-reperfusion model

Cyclosporine A (CsA) has been shown to protect against myocardial ischemia and reperfusion (I/R) injury in small animal models. The aim of the current study was to evaluate the effects of CsA on myocardial I/R injury in a porcine model. Pigs were randomized between CsA (10mg/kg; n = 12) or placebo (n = 15) and anesthetized with either isoflurane (phase I) or pentobarbital (phase II). By catheterization, the left descending coronary artery was occluded for 45 minutes, followed by reperfusion for 2 hours. Hearts were stained to quantify area at risk (AAR) and infarct size (IS). Myocardial biopsies were obtained for terminal dUTP nick end labeling and immunoblot analysis of proapoptotic proteins (apoptosis-inducing factor [AIF], BCL2/adenovirus E1B 19-kd interacting protein 3 [BNIP-3], and active caspase-3). Cyclosporine A did not reduce IS/AAR compared with placebo (49% vs 41%, respectively; P = .21). Pigs anesthetized with isoflurane had lower IS/AAR than pigs anesthetized with pentobarbital (39% vs 51%, respectively; P = .03). This reduction in IS/AAR seemed to be attenuated by CsA. Apoptosis-inducing factor protein expression was higher after CsA administration than after placebo (P = .02). Thus, CsA did not protect against I/R injury in this porcine model. The data suggest a possible deleterious interaction of CsA and isoflurane.

Sevoflurane-induced post-conditioning has no beneficial effects on neuroprotection after incomplete cerebral ischemia in rats

BACKGROUND

The aim of this study was to investigate whether sevoflurane-induced post-conditioning has a neuroprotective effect against incomplete cerebral ischemia in rats.

METHODS

After cerebral ischemia by right common carotid artery occlusion in combination with hemorrhagic hypotension (35 mmHg) for 30 min, 1.0 minimum alveolar concentration of sevoflurane was administered for 15 min (Post-C 15, n=8), 30 min (Post-C 30, n=8), or 60 min (Post-C 60, n=8) in rats. Sevoflurane was not administered in control (n=8) and sham control rats (n=8). Neurologic evaluations were performed at 24, 48, and 72 h after ischemia. Degrees of neuronal damage in ischemic hippocampal CA1 and the cortex were assessed by counting eosinophilic neurons, and detection of DNA fragmentation was performed by terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) staining.

RESULTS

Neurologic deficit scores in the Post-C 60 group were higher than in the control group at 48 and 72 h post-ischemia (P<0.05). No differences were observed in the percentages of eosinophilic neurons among the control (CA1: 37.3 +/- 25.4, cortex: 26.0 +/- 8.9), Post-C 15 (CA1: 54.0 +/- 21.4, cortex: 30.8 +/- 19.9), or Post-C 30 (CA1: 68.4 +/- 17.5, cortex: 38.0 +/- 11.0) groups in ischemic CA1 and cortices. However, in the Post-C 60 group, the percentages of eosinophilic neurons were higher than in the control group in CA1 and cortices (P<0.05). The percentages of TUNEL-positive cell were similar in the control group and the post-conditioned groups.

CONCLUSION

These findings show that sevoflurane administration after ischemia does not provide neuroprotection in rats subjected to incomplete cerebral ischemia.

Drugs mediating myocardial protection

The occurrence of myocardial ischaemia will result in either reversible or irreversible myocardial dysfunction. Even when revascularization is successful, some reperfusion injury may occur that transiently impairs myocardial function. Therefore, treatment should not only be directed towards prompt restoration of myocardial blood flow but measures should also be taken to prevent or alleviate the consequences of myocardial reperfusion injury. Over the years, various strategies have been developed. The present contribution reviews a number of these strategies focusing on pharmacological treatments that have been developed to address myocardial reperfusion injury.

Sevoflurane postconditioning converts persistent ventricular fibrillation into regular rhythm

BACKGROUND AND OBJECTIVE

Recent studies showed that ischaemic postconditioning converted persistent ventricular fibrillation to sinus rhythm. The influence of anaesthetic postconditioning on ventricular fibrillation has not yet been determined. In the present study, we studied the possible effect of sevoflurane postconditioning on persistent reperfusion-induced ventricular fibrillation in the isolated rat heart model.

METHODS

Isolated Langendorff-perfused rat hearts (n=80) were subjected to 40 min of global ischaemia and reperfusion. The hearts with persistent ventricular fibrillation (n=16) present after 15 min of reperfusion were then randomly assigned into one of the two groups: controls (n=8), reperfusion was continued for 25 min without any intervention, and sevoflurane postconditioning (n=8), rat hearts in the sevoflurane postconditioning group were exposed to sevoflurane at a concentration of 8.0% for 2 min followed by 23 min of reperfusion. As for the third group, the rest of the hearts were included in the nonpersistently fibrillating hearts group (n=64). Left ventricular pressures, heart rate, coronary flow, electrogram and infarct size were measured as variables of ventricular function and cellular injury, respectively.

RESULTS

Conversion of ventricular fibrillation into regular rhythm was observed in all hearts subjected to sevofluane postconditioning. Regular beating was maintained by all anaesthetic postconditioned hearts during the subsequent reperfusion. None of the hearts in the control group had normal rhythm at the end of the experiment. At the end of reperfusion, the coronary flow was increased in sevoflurane postconditioned hearts compared with the hearts that did not develop persistent ventricular fibrillation.

CONCLUSION

Sevoflurane postconditioning possesses strong antiarrhythmic effect against persistent reperfusion-induced ventricular fibrillation. Anaesthetic postconditioning may have the potential to be an antiarrhythmic therapy for reperfusion-related arrhythmias.

The use of a volatile anesthetic regimen protects against acute normovolemic hemodilution induced myocardial depression in patients with coronary artery disease

BACKGROUND

Previous studies indicated that acute normovolemic hemodilution (ANH) was associated with a depression of myocardial function in coronary surgery patients with baseline heart rate faster than 90 bpm. It was suggested that this phenomenon could be explained by the occurrence of myocardial ischemia. In the present study, we hypothesized that the cardioprotective properties of a volatile anesthetic regimen might protect against the ANH related myocardial functional impairment.

MATERIALS AND METHODS

Forty elective coronary surgery patients with baseline heart rate faster than 90 bpm were randomly allocated to receive different anesthetic regimens. Group A (n = 20) received midazolam-based anesthesia. Group B (n = 20) received a sevoflurane-based anesthesia. Five-lead electrocardiogram, pulse oximetry, capnography, radial arterial pressure, and Swan Ganz continuous thermodilution cardiac output via right internal jugular vein were monitored. Measurements were obtained before and after ANH. Data were compared using paired t test. All data were expressed as mean +/- SD. Data were considered significant if P < 0.05.

RESULTS

After ANH, systemic vascular resistance was slightly decreased in group A while there was a significant decrease in group B. In group A, cardiac output was slightly decreased from 5.07+/-1.17 l/min to 5.02+/-1.28 l/min after ANH, whereas in group B, cardiac output was significantly increased from 4.84+/-1.21 l/min to 6.02+/-1.28 l/min after ANH.

CONCLUSION

In coronary surgery patients, with baseline heart rate faster than 90 bpm, anesthesia with sevoflurane during ANH was associated with an improvement in myocardial function after ANH, which was not present in patients anesthetized with midazolam.

Organ protection by volatile anesthetics in non-coronary artery bypass grafting surgery

The cardioprotective properties of volatile anesthetics have been widely demonstrated by numerous randomized studies and meta-analyses in the setting of cardiac surgery, above of all during coronary artery bypass grafting procedures. Recently, conflicting results have been presented in cardiac non-coronary artery bypass grafting surgery. Unfortunately, despite the existence of a great number of studies comparing a total intravenous anesthetic regimen with an inhalational regimen, at present there are no randomized studies presenting data regarding mortality and important outcomes, such as myocardial infarction, in non-cardiac surgery. In this review we analyze and present the results of the most recent and important studies regarding anesthetic preconditioning in cardiac and in noncardiac surgery. Furthermore, we focus on the emerging data from animal experiments, discussing in particular the molecular mechanisms underlying anesthetic preconditioning.

Mechanism of cardiac preconditioning with volatile anaesthetics

In recent years, there has been increased interest in the mechanisms involved in anaesthetic-induced cardioprotection. It is not thoroughly understood how volatile anaesthetics protect the myocardium from ischaemia or reperfusion injury, but the overall mechanism is likely to be multifactorial. This review examines the recent experimental and clinical research underlying the cellular and molecular mechanisms involved in anaesthetic-induced preconditioning. A variety of intracellular signalling pathways have been implicated in the protective phenomenon. Ischaemic preconditioning and anaesthetic-induced preconditioning share similar molecular mechanisms, including activation of guanine nucleotide-binding proteins, triggering of second messenger pathways, activation of multiple kinases, mediation of nitric oxide formation and reactive oxygen species release, maintenance of intracellular and/or mitochondrial Ca2+ homeostasis and moderation of the opening of adenosine-triphosphate-sensitive potassium channels. A more thorough understanding of the multiple signalling steps and the ultimate cytoprotective mechanisms underlying anaesthetic-induced preconditioning may lead to improvements in the management of ischaemia and/or reperfusion injury.

Sevoflurane- and desflurane-induced human myocardial post-conditioning through Phosphatidylinositol-3-kinase/Akt signalling

BACKGROUND

The role of phosphatidylinositol-3-kinase (PI3K) in sevoflurane- and desflurane-induced myocardial post-conditioning remains unknown.

METHODS

We recorded isometric contraction of isolated human right atrial trabeculae (oxygenated Tyrode's at 34 degrees C, stimulation frequency 1 Hz). In all groups, a 30-min hypoxic period was followed by a 60-min reoxygenation period. At the onset of reoxygenation, muscles were exposed to 5 min of sevoflurane 1%, 2%, and 3%, and desflurane 3%, 6%, and 9%. In separate groups, sevoflurane 2% and desflurane 6% were administered in the presence of 100 nM wortmannin, a PI3K inhibitor. Recovery of force after the 60-min reoxygenation period was compared between groups (mean +/- SD).

RESULT

As compared with the Control group (49 +/- 7% of baseline) PostC by sevoflurane 1%, 2%, and 3% (78 +/- 4%, 79 +/- 5%, and 85 +/- 4% of baseline, respectively) and desflurane 3%, 6%, and 9% (74 +/- 5%, 84 +/- 4%, and 86 +/- 11% of baseline, respectively) enhanced the recovery of force. This effect was abolished in the presence of wortmannin (56 +/- 5% of baseline for sevoflurane 2%+wortmannin; 56 +/- 3% of baseline for desflurane 6%+wortmannin). Wortmannin alone had no effect on the recovery of force (57 +/- 7% of baseline).

CONCLUSION

In vitro, sevoflurane and desflurane post-conditioned human myocardium against hypoxia through activation of phosphatidylinositol-3-kinase.

Intraoperative awareness during sevoflurane-remifentanil anesthesia for minimal invasive mitral valvuloplasty: A case report

We report a case of unintentional intraoperative awareness during sevoflurane-remifentanil anesthesia in a 26 years old woman undergoing elective minimal invasive mitral valvuloplasty. Cardioprotective effects of sevoflurane were clinically most apparent when administered throughout the surgical procedure. Also use of sevoflurane during cardiopulmonary bypass decreases incidence of awareness. Although awareness during cardiac anesthesia has been previously described with sevoflurane, the implication of this case is that unexpected awareness can occur in patients with sevoflurane during cardiopulmonary bypass on cardiac surgery. Therefore, more attention is needed to use sevoflurane during cardiopulmonary bypass.

Anaesthesia and myocardial ischaemia/reperfusion injury

Anaesthetists are confronted on a daily basis with patients with coronary artery disease, myocardial ischaemia, or both during the perioperative period. Therefore, prevention and ultimately adequate therapy of perioperative myocardial ischaemia and its consequences are the major challenges in current anaesthetic practice. This review will focus on the translation of the laboratory evidence of anaesthetic-induced cardioprotection into daily clinical practice.

Sevoflurane and nitrous oxide exert cardioprotective effects against hypoxia-reoxygenation injury in the isolated rat heart

It is unclear whether nitrous oxide (N(2)O) has a protective effect on cardiac function in vitro. In addition, little is known about the cardioprotective effect of anesthesia administered during hypoxia or ischemia. We therefore studied the cardioprotective effects of N(2)O and sevoflurane administered before or during hypoxia in isolated rat hearts. Rat hearts were excised and perfused using the Langendorff technique. For hypoxia-reoxygenation, hearts were made hypoxic (95% N(2), 5% CO(2)) for 45 min and then reoxygenated (95% O(2), 5% CO(2)) for 40 min (control: CT group). Preconditioning was achieved through three cycles of application of 4% sevoflurane (sevo-pre group) or 50% N(2)O (N(2)O-pre group) for 5 min with 5-min washouts in between. Hypoxic conditions were achieved by administering the 4% sevoflurane (sevo-hypo group) or 50% N(2)O (N(2)O-hypo group) during the 45-min hypoxic period. L-type calcium channel currents (I(Ca,L)) were recorded on rabbit myocytes. (1) Both 4% sevoflurane and 50% N(2)O significantly reduced left ventricular developed pressure (LVDP). Sevoflurane also increased left ventricular end-diastolic pressure, though N(2)O did not. (2) The recoveries of LVDP and pressure-rate product (PRP) after hypoxia-reoxygenation were better in the sevo-pre group than in the CT or N(2)O-pre group. (3) Application of either sevoflurane or N(2)O during hypoxia improved recovery of LVDP and PRP, and GOT release was significantly lower than in the CT group. (4) Sevoflurane and N(2)O reduced I(Ca,L) to similar extents. Although sevoflurane administered before or during hypoxia exerts a cardioprotective effect, while N(2)O shows a cardioprotective effect only when administered during hypoxia.

Effects of emulsified isoflurane on haemodynamics and cardiomyocyte apoptosis in rats with myocardial ischaemia

1. It has been shown that inhaled isoflurane limits the size of myocardial infarcts. The aim of the present study was to examine the effects of emulsified isoflurane on cardiac function and myocardial apoptosis in an ischaemia model of myocardial injury. 2. In the first study, 48 rats were randomly allocated to six groups (n = 8 in each): control (saline); emulsified isoflurane (EIso) at 1, 2 or 4 mL/kg; 30% intralipid (vehicle for EIso); and sham operated. Rats received isovolumetric intravenous infusions for 30 min and then, 30 min after cessation of the infusion, 90 min coronary occlusion. Haemodynamics and myocardial infarct size were measured. In the second study, another 48 rats were randomized into six groups (n = 8 in each). After 90 min ischaemia, rats were killed for histopathological study, immunohistochemical evaluation and apoptosis measurement. 3. Pretreatment with 2 and 4 mL/kg EIso significantly attenuated decreases in left ventricular systolic pressure and dP/dt(max), and increases in left ventricular end-diastolic pressure and -dP/dp(max), and alleviated myocardial injury compared with the control, intralipid and 1 mL/kg EIso groups (P < 0.05). Infusion of 1 mL/kg EIso and intralipid had no effect on haemodynamics, infarct size or histological variables. 4. Expression of Bcl-2 was increased, whereas expression of Bax and caspase 3 was decreased, after preconditioning with 2 and 4 mL/kg EIso (P < 0.05). The apoptotic index in the 2 and 4 mL/kg Eiso-treated groups was reduced compared with that in the control and intralipid groups (P < 0.01). 5. In conclusion, EIso ameliorates cardiac dysfunction, attenuates myocardial damage and inhibits apoptosis after ischaemia, which may be attributed, in part, to diminished expression of apoptosis-related protein.