Volatile Anesthetics Reduce Mortality in Cardiac Surgery

Myocardial Protection by Desflurane: From Basic Mechanisms to Clinical Applications

ABSTRACT

Coronary heart disease is an affliction that is common and has an adverse effect on patients' quality of life and survival while also raising the risk of intraoperative anesthesia. Mitochondria are the organelles most closely associated with the pathogenesis, development, and prognosis of coronary heart disease. Ion abnormalities, an acidic environment, the production of reactive oxygen species, and other changes during abnormal myocardial metabolism cause the opening of mitochondrial permeability transition pores, which disrupts electron transport, impairs mitochondrial function, and even causes cell death. Differences in reliability and cost-effectiveness between desflurane and other volatile anesthetics are minor, but desflurane has shown better myocardial protective benefits in the surgical management of patients with coronary artery disease. The results of myocardial protection by desflurane are briefly summarized in this review, and biological functions of the mitochondrial permeability transition pore, mitochondrial electron transport chain, reactive oxygen species, adenosine triphosphate-dependent potassium channels, G protein-coupled receptors, and protein kinase C are discussed in relation to the protective mechanism of desflurane. This article also discusses the effects of desflurane on patient hemodynamics, myocardial function, and postoperative parameters during coronary artery bypass grafting. Although there are limited and insufficient clinical investigations, they do highlight the possible advantages of desflurane and offer additional suggestions for patients.

Anesthetic Preferences for Cardiac Anesthesia: A Survey of the Society of Cardiovascular Anesthesiologists

BACKGROUND

Volatile anesthetics have been historically preferred for cardiac anesthesia, but the evidence for their superiority to intravenous agents is mixed. We conducted a survey to better understand the current state of practice and the rationale behind provider preferences for anesthesia for cardiac surgery with cardiopulmonary bypass. We hypothesized that anesthetic preference would vary considerably among surveyed providers without a clear majority, as would the rationale behind those preferences.

METHODS

Email invitations were sent to members of the Society of Cardiovascular Anesthesiologists, who were asked to identify the anesthetics or sedatives they typically prefer to administer during induction, prebypass, bypass, postbypass, and postoperative periods and why they prefer those agents. Members' beliefs regarding the importance of anesthetics on postoperative outcomes were also assessed.

RESULTS

Invitations were sent on 2 separate dates to 3328 and 3274 members, of whom 689 (21%) responded. The median (interquartile range [IQR]) respondent age was 45 (37-56) years, 79% were men, and 75% were fellowship trained. The most frequently chosen drug for induction was propofol (80%). Isoflurane was the most frequently selected primary agent for the prebypass (57%), bypass (62%), and postbypass periods (50%). Sevoflurane was the second most frequently selected (30%; 17%, and 24%, respectively). Propofol was the third most frequently selected agent for the bypass (14%) and postbypass periods (17%). Ease of use was the most frequently selected reason for administering isoflurane and sevoflurane for each period. During bypass, the second most frequently selected rationale for using isoflurane and sevoflurane was institutional practice. A total of 76% responded that the perfusionist typically delivers the bypass anesthetic. Ischemic preconditioning, organ protection, and postoperative cognitive function were infrequently selected as rationales for preferring the volatile anesthetics. Most respondents (73%) think that anesthetics have organ-protective properties, especially isoflurane (74%) and sevoflurane (59%), and 72% believed that anesthetic choice contributes to patient outcome. The median (IQR) agreement (0 = strongly disagree to 100 = strongly agree) was 72 (63-85) for the statement that "inhaled anesthetics are an optimal maintenance anesthetic for cardiac surgery."

CONCLUSIONS

In a survey of cardiac anesthesiologists, a majority of respondents indicated that they prefer volatile anesthetics for maintenance of anesthesia, that anesthetic selection impacts patient outcomes, and that volatile anesthetics have organ-protective properties. The members' rationales for preferring these agents possibly reflect that practical considerations, such as ease of use, effectiveness, and institutional practice, also influence anesthetic selection during cardiac surgery in addition to considerations such as organ protection.

Interleukin-6 Is an Early Plasma Marker of Severe Postoperative Complications in Thoracic Surgery: Exploratory Results From a Substudy of a Randomized Controlled Multicenter Trial

BACKGROUND

Postoperative complications in surgery are a significant burden, not only for the patients but also economically. While several predicting factors have already been identified, it is still not well known if increased levels of inflammatory markers in the immediate perioperative phase correlate with a higher incidence of postoperative complications. This study aimed to evaluate which patient characteristics and intraoperative parameters correlate with increased plasma values of monocyte chemoattractant protein 1 (MCP-1) and interleukin 6 (IL-6) of thoracic surgery patients. A second goal was to explore whether MCP-1 and IL-6 are associated with the incidence of postoperative complications. We hypothesized that there is a positive association between inflammatory markers and the occurrence of complications within 6 months after surgery.

METHODS

This is a substudy of a recent randomized controlled trial, which defined the effect of desflurane versus propofol anesthesia on morbidity and mortality in patients undergoing thoracic surgery. MCP-1 and IL-6 were determined in plasma obtained before and 30 minutes after 1-lung ventilation, 6 hours after surgery, and on postoperative days 1 and 2. Complications were recorded for 6 months. Mixed linear models were used to examine factors associated with MCP-1 and IL-6 levels. Logistic regression models and receiver operating characteristic curves were used to determine the association between MCP-1 and IL-6 and postoperative complications.

RESULTS

In the original study, 460 patients were included, MCP-1 and IL-6 levels were determined in 428 patients. MCP-1 was positively associated with the duration of surgery (P = .016), whereas IL-6 levels increased with both the length (P < .001) and invasiveness of lung surgery (thoracoscopic wedge resection or lobectomy versus open lobectomy, P = .005; thoracoscopic wedge resection or lobectomy versus pneumonectomy, P = .021). In an exploratory approach, elevated IL-6 plasma peaks were associated with the occurrence of severe complications defined as Clavien-Dindo score grade ≥IVa during the postoperative phase up to 6 months after thoracic surgery (P = .006).

CONCLUSIONS

In summary, this substudy reveals factors, which correlate with high MCP-1 and IL-6 values. Moreover, higher IL-6 seems to be associated with postoperative severe complications. Perioperative IL-6 monitoring might be helpful for risk estimation in the perioperative setting of patients after lung surgery.

Inhaled Anesthetics: Environmental Role, Occupational Risk, and Clinical Use

Inhaled anesthetics have been in clinical use for over 150 years and are still commonly used in daily practice. The initial view of inhaled anesthetics as indispensable for general anesthesia has evolved during the years and, currently, its general use has even been questioned. Beyond the traditional risks inherent to any drug in use, inhaled anesthetics are exceptionally strong greenhouse gases (GHG) and may pose considerable occupational risks. This emphasizes the importance of evaluating and considering its use in clinical practices. Despite the overwhelming scientific evidence of worsening climate changes, control measures are very slowly implemented. Therefore, it is the responsibility of all society sectors, including the health sector to maximally decrease GHG emissions where possible. Within the field of anesthesia, the potential to reduce GHG emissions can be briefly summarized as follows: Stop or avoid the use of nitrous oxide (N2O) and desflurane, consider the use of total intravenous or local-regional anesthesia, invest in the development of new technologies to minimize volatile anesthetics consumption, scavenging systems, and destruction of waste gas. The improved and sustained awareness of the medical community regarding the climate impact of inhaled anesthetics is mandatory to bring change in the current practice.

Volatile Anesthetics versus Propofol for Cardiac Surgery with Cardiopulmonary Bypass

Background

The aim of this systematic review and meta-analysis was to assess the effect of anesthesia maintenance with volatile agents compared with propofol on both short- and long-term mortality (primary outcomes) and major clinical events in adults undergoing cardiac surgery with cardiopulmonary bypass.

Methods

Randomized clinical trials on the effects of current volatile anesthetics versus propofol in adults undergoing cardiac surgery with cardiopulmonary bypass were searched (1965 to September 30, 2019) in PubMed, the Cochrane Library, and article reference lists. A random effect model on standardized mean difference for continuous outcomes and odds ratio for dichotomous outcomes were used to meta-analyze data.

Results

In total, 37 full-text articles (42 studies, 8,197 participants) were included. The class of volatile anesthetics compared with propofol was associated with lower 1-yr mortality (5.5 vs. 6.8%; odds ratio, 0.76 [95% CI, 0.60 to 0.96]; P = 0.023), myocardial infarction (odds ratio, 0.60 [95% CI, 0.39 to 0.92]; P = 0.023), cardiac troponin release (standardized mean difference, −0.39 [95% CI, −0.59 to −0.18], P = 0.0002), need for inotropic medications (odds ratio, 0.40 [95% CI, 0.24 to 0.67]; P = 0.0004), extubation time (standardized mean difference, −0.35 [95% CI, −0.68 to −0.02]; P = 0.038), and with higher cardiac index/output (standardized mean difference, 0.70 [95% CI, 0.37 to 1.04]; P &lt; 0.0001). The class of volatile anesthetics was not associated with changes in short-term mortality (1.63 vs. 1.65%; odds ratio, 1.04 [95% CI, 0.73 to 1.49]; P = 0.820) and acute kidney injury (odds ratio, 1.25 [95% CI, 0.77 to 2.03]; P = 0.358).

Conclusions

In adults undergoing cardiac surgery with cardiopulmonary bypass, the class of volatile anesthetics was superior to propofol with regard to long-term mortality, as well as to many secondary outcomes indicating myocardial protection.

Editor’s Perspective

What We Already Know about This Topic

What This Article Tells Us That Is New

The Impact of Anesthetic Regimen on Outcomes in Adult Cardiac Surgery: A Narrative Review

Despite improvements in surgical techniques and perioperative care, cardiac surgery still is burdened by relatively high mortality and frequent major postoperative complications, including myocardial dysfunction, pulmonary complications, neurologic injury, and acute kidney injury. Although the surgeon's skills and volume and patient- and procedure-related risk factors play a major role in the success of cardiac surgery, there is growing evidence that also optimizing perioperative care may improve outcomes significantly. The present review focuses on the aspects of perioperative care that are strictly related to the anesthesia regimen, with special reference to volatile anesthetics and neuraxial anesthesia, whose effect on outcome in adult cardiac surgery has been investigated extensively.

Pilose antler polypeptide protects against sevoflurane‑mediated neurocyte injury

Pilose antler polypeptide (PAP) is an active substance isolated from the traditional Chinese medicine pilose antler, which possesses multiple biological activities. In the present study, the role and mechanism of PAP in sevoflurane (SEV)-induced neurocyte injury was explored. Cell viability was determined by Cell Counting kit-8 assay. Cell proliferation and apoptosis were analyzed by flow cytometry. Western blotting and reverse transcription-quantitative polymerase chain reaction analysis were used to evaluate the protein and mRNA expression levels, respectively. The results revealed that PAP enhanced the cell viability of SEV-treated nerve cells. In addition, through modulation of apoptosis-associated protein expression, PAP suppressed SEV-induced nerve cell apoptosis. Furthermore, PAP activated the p38 mitogen-activated protein kinase (p38)/c-Jun N-terminal kinase (JNK) pathway in the neurocyte injury model, whereas inhibition of the p38/JNK pathway reversed the beneficial effects produced by PAP. In conclusion, PAP protected against SEV-mediated neurocyte injury via upregulation of the p38/JNK pathway. The present findings suggested that PAP may be an effective agent for neurocyte injury.

An innovative technique to improve safety of volatile anesthetics suction from the cardiopulmonary bypass circuit

Context:

Myocardial injury during cardiac surgery on cardiopulmonary bypass (CPB) is a major determinant of morbidity and mortality. Preclinical and clinical evidence of dose- and time-related cardioprotective effects of volatile anesthetic drugs exist and their use during the whole surgery duration could improve perioperative cardiac protection. Even if administering volatile agents during CPB are relatively easy, technical problems, such as waste gas scavenging, may prevent safe and manageable administration of halogenated vapors during CPB.

Aims:

The aim of this study is to improve the safe administration of volatile anesthesia during CPB.

Settings and Design:

Tertiary teaching hospital.

Subjects and Methods:

We describe an original device that collects and disposes of any volatile anesthetic vapors present in the exit stream of the oxygenator, hence preventing its dispersal into the operating theatre environment and adaptively regulates pressure of oxygenator chamber in the CPB circuit.

Results:

We have so far applied a prototype of this device in more than 1300 adult cardiac surgery patients who received volatile anesthetics during the CPB phase.

Conclusions:

Widespread implementation of scavenging system like the one we designed may facilitate the perfusionist and the anesthesiologist in delivering these cardioprotective drugs with beneficial impact on patients’ outcome without compromising on safety.

Economic Evaluation of Pharmacologic Pre- and Postconditioning With Sevoflurane Compared With Total Intravenous Anesthesia in Liver Surgery: A Cost Analysis

BACKGROUND

Pharmacologic pre- and postconditioning with sevoflurane compared with total IV anesthesia in patients undergoing liver surgery reduced complication rates as shown in 2 recent randomized controlled trials. However, the potential health economic consequences of these different anesthesia regimens have not yet been assessed.

METHODS

An expostcost analysis of these 2 trials in 129 patients treated between 2006 and 2010 was performed. We analyzed direct medical costs for in-hospital stay and compared pharmacologic pre- and postconditioning with sevoflurane (intervention) with total IV anesthesia (control) from the perspective of a Swiss university hospital. Year 2015 costs, converted to US dollars, were derived from hospital cost accounting data and compared with a multivariable regression analysis adjusting for relevant covariables. Costs with negative prefix indicate savings and costs with positive prefix represent higher spending in our analysis.

RESULTS

Treatment-related costs per patient showed a nonsignificant change by -12,697 US dollars (95% confidence interval [CI], 10,956 to -36,352; P = .29) with preconditioning and by -6139 US dollars (95% CI, 6723 to -19,000; P = .35) with postconditioning compared with the control group. Results were robust in our sensitivity analysis. For both procedures (control and intervention) together, major complications led to a significant increase in costs by 86,018 US dollars (95% CI, 13,839-158,198; P = .02) per patient compared with patients with no major complications.

CONCLUSIONS

In this cost analysis, reduced in-hospital costs by pharmacologic conditioning with sevoflurane in patients undergoing liver surgery are suggested. This possible difference in costs compared with total IV anesthesia is the result of reduced complication rates with pharmacologic conditioning, because major complications have significant cost implications.

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.

Volatile anaesthetics added to cardiopulmonary bypass are associated with reduced cardiac troponin

Background:

Every year, over 1 million cardiac surgical procedures are performed all over the world. Reducing myocardial necrosis could have strong implications in postoperative clinical outcomes. Volatile anaesthetics have cardiac protective properties in the perioperative period of cardiac surgery. However, little data exists on the administration of volatile agents during cardiopulmonary bypass. The aim of this study was to assess if volatile anaesthetics administration during cardiopulmonary bypass reduces cardiac troponin release after cardiac surgery.

Materials and methods:

We retrospectively analysed data from 942 patients who underwent cardiac surgery in a teaching hospital. The only difference between the groups was the management of anaesthesia during CPB. The volatile group received sevoflurane or desflurane while the control group received a combination of propofol infusion and fentanyl boluses. Patients who received volatile anaesthetics during cardiopulmonary bypass (n=314) were propensity-matched 1:2 with patients who did not receive volatile anaesthetics during CPB (n=628).

Results:

We found a reduction in peak postoperative troponin I, from 7.8 ng/ml (4.8-13.1) in the non-volatile group to 6.8 ng/ml (3.7-11.8) in the volatile group (p=0.013), with no differences in mortality [2 (0.6%) in the volatile group and 2 (0.3%) in the non-volatile group (p=0.6)].

Conclusions:

Adding volatile anaesthetics during cardiopulmonary bypass was associated with reduced peak postoperative troponin levels. Larger studies are required to confirm our data and to assess the effect of volatile agents on survival.

Tricks, tips, and literature review on the adapted vaporize system to deliver volatile agents during cardiopulmonary bypass

Background:

Recently, evidence of cardio-protection and reduction in mortality due to the use of volatile agents during cardiac surgery led to an increase in their use during cardiopulmonary bypass (CPB). These findings seem to be enhanced when the volatile agents are used during all the surgical procedure, including the CPB period.

Aims:

Since the administration of volatile agents through CPB can be beneficial to the patients, we decided to review the use of volatile agents vaporized in the CPB circuit and to summarize some tricks and tips of this technique using our 10-year experience of Brazilian and Italian centers with a large volume of cardiac surgeries.

Study Setting:

Hospital.

Methods:

A literature review.

Results:

During the use of the volatile agents in CPB, it is very important to analyze all gases that come in and go out of the membrane oxygenators. The proper monitoring of inhaled and exhaled fraction of the gas allows not only monitoring of anesthesia level, but also the detection of possible leakage in the circuit. Any volatile agent in the membrane oxygenator is supposed to pollute the operating theater. This is the major reason why proper scavenging systems are always necessary when this technique is used.

Conclusion:

While waiting for industry upgrades, we recommend that volatile agents should be used during CPB only by skilled perfusionists and physicians with the aim to reduce postoperative morbidity and mortality.

Feasibility of Anesthesia Maintenance With Sevoflurane During Cardiopulmonary Bypass: A Pilot Pharmacokinetics Study

OBJECTIVE

Adequate maintenance of hypnosis during anesthesia throughout surgery using sevoflurane alone was investigated. In addition, sevoflurane pharmacokinetics during cardiopulmonary bypass were analyzed.

DESIGN

This was a pilot pharmacokinetic study.

SETTING

Tertiary care university hospital.

PARTICIPANTS

The study comprised 10 patients aged between 18 and 75 years who underwent elective mitral valve surgery.

INTERVENTIONS

The end-tidal and sevoflurane plasma concentrations were measured throughout cardiac surgery procedures involving cardiopulmonary bypass. The sevoflurane plasma concentration was measured using gas chromatography. In addition, the ratio between sevoflurane alveolar concentration and inspired concentration over time (F_A/F_I) was analyzed to describe wash-in and wash-out curves.

MEASUREMENTS AND MAIN RESULTS

Hypnosis was maintained adequately throughout surgery using sevoflurane alone. The bispectral index was maintained between 40 and 60 during cardiopulmonary bypass. The end-tidal sevoflurane was significantly different before and during cardiopulmonary bypass (1.86%±0.54% v 1.30%±0.58%, respectively; p<0.001). However, the sevoflurane plasma concentration was not significantly different before and after cardiopulmonary bypass start-up (40.55 µg/mL [76.62-125.33] before cardiopulmonary bypass and 36.24 µg/mL [56.49-81-42] during cardiopulmonary bypass). This mismatch possibly can be explained by changes that occured after cardiopulmonary bypass start-up, such as reductions of body temperature (36.33°C±0.46°C v 32.98°C±2.38°C, respectively; p<0.001) and hematocrit (35.62%±3.98% v 25.5%±3.08%, respectively; p<0.001). The sevoflurane alveolar concentration varied according to sevoflurane plasma concentration and bispectral index values. No adverse events regarding sevoflurane administration during cardiopulmonary bypass were observed.

CONCLUSIONS

Sevoflurane end-tidal values were reliable indicators of adequate anesthesia during all cardiac surgery procedures involving cardiopulmonary bypass.

Comparison of isoflurane and sevoflurane in cardiac surgery: a randomized non-inferiority comparative effectiveness trial

Purpose

Volatile anesthetics possess cardioprotective properties, but it is unknown if the cardioprotective effects extend equally to all members of the class. Although sevoflurane is a relatively newer anesthetic than isoflurane, its introduction into practice was not preceded by a head-to-head comparison with isoflurane in a trial focusing on clinically important outcomes. Our objective was to determine whether sevoflurane was non-inferior to isoflurane on a clinically important primary outcome in a heterogeneous group of adults undergoing cardiac surgery.

Methods

This was a pragmatic randomized non-inferiority comparative effectiveness clinical trial in 464 adults having coronary artery bypass graft and/or single valve surgery during November 2011 to March 2014. The intervention was maintenance of anesthesia with sevoflurane (n = 231) or isoflurane (n = 233) administered at a dose of 0.5-2.0 MAC throughout the entire operation. All caregivers were blinded except for the anesthesiologist and perfusionist. The primary outcome was a composite of intensive care unit (ICU) length of stay ≥ 48 hr and all-cause 30-day mortality. We hypothesized that sevoflurane would be non-inferior to isoflurane (non-inferiority margin < 10% based on an expected event rate of 25%). Secondary outcomes included prolonged ICU stay, 30- and 365-day all-cause mortality, inotrope or vasopressor usage, new-onset hemodialysis or atrial fibrillation, stroke, and readmission to the ICU.

Results

No losses to follow-up occurred. The primary outcome occurred in 25% of sevoflurane patients and 30% of isoflurane patients (absolute difference, −5.4%; one-sided 95% confidence interval, 1.4), thus non-inferiority was declared. Sevoflurane was not superior to isoflurane for the primary outcome (P = 0.21) or for any secondary outcomes.

Conclusion

Sevoflurane is non-inferior to isoflurane on a composite outcome of prolonged ICU stay and all-cause 30-day mortality. Sevoflurane is not superior to isoflurane on any other of the clinically important outcomes. This trial was registered at clinicaltrials.gov; NCT01477151.

[Special aspects of analgosedation in cardiogenic shock patients]

Patients with cardiogenic shock pose a challenge to physicians due to cardiorespiratory instability in addition to the underlying medical condition. If analgosedation and ventilation are indicated, commonly administered drugs themselves often influence hemodynamics and oxygenation. The present article provides an overview of the available substances with consideration of the patients' condition, then monitoring and optimization of analgosedation.

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.

Effects of Sevoflurane Inhalation During Cardiopulmonary Bypass on Pediatric Patients: A Randomized Controlled Clinical Trial

The effects of sevoflurane inhalation during cardiopulmonary bypass (CPB) on postoperative courses and serum cardiac troponin I (cTnI) concentrations in pediatric patients undergoing cardiac surgery have not been extensively investigated. In this single-center, prospective, randomized trial, an anesthetic regimen containing 2% sevoflurane used throughout the CPB process was compared with a total intravenous anesthesia (TIVA) regimen. One hundred and three patients undergoing congenital heart defect repair with CPB were included in this prospective randomized controlled study. They were randomized into two groups: the sevoflurane group, who received 2% sevoflurane during CPB via an oxygenator, and the control group, who received only an oxygen-air mixture. The pre- and intra-operative parameters were comparable between the two groups. There was a slight but significant increase of arterial diastolic pressure in the sevoflurane group immediately after CPB compared with control patients (46.9 ± 9.3 mm Hg vs. 43.6 ± 8.9 mm Hg; p = 0.033). There was no death in either group. The postoperative ventilation time (in mean [95% confidence interval]) was shorter in the sevoflurane group than that in the control group (26.1 [19.2, 33.0] h vs. 37.7 [24.4, 50.9] h; p = 0.014). The postoperative ICU time, hospital days, and serial serum cTnI concentrations were not significantly different between the two groups. Inhalation of 2% sevoflurane during CPB is beneficial to the recovery of pediatric patients undergoing cardiac surgery but has no significant effect on postoperative cTnI release.

Peri-operative anaesthetic myocardial preconditioning and protection - cellular mechanisms and clinical relevance in cardiac anaesthesia

Preconditioning has been shown to reduce myocardial damage caused by ischaemia–reperfusion injury peri-operatively. Volatile anaesthetic agents have the potential to provide myocardial protection by anaesthetic preconditioning and, in addition, they also mediate renal and cerebral protection. A number of proof-of-concept trials have confirmed that the experimental evidence can be translated into clinical practice with regard to postoperative markers of myocardial injury; however, this effect has not been ubiquitous. The clinical trials published to date have also been too small to investigate clinical outcome and mortality. Data from recent meta-analyses in cardiac anaesthesia are also not conclusive regarding intra-operative volatile anaesthesia. These inconclusive clinical results have led to great variability currently in the type of anaesthetic agent used during cardiac surgery. This review summarises experimentally proposed mechanisms of anaesthetic preconditioning, and assesses randomised controlled clinical trials in cardiac anaesthesia that have been aimed at translating experimental results into the clinical setting.

Effect of apoptosis in neural stem cells treated with sevoflurane

BACKGROUND

At present, sevoflurane inhalation anesthesia used on infants is well-known. But long-time exposure to inhalation anesthetic could cause neurologic disorder, especially nerve degeneration in infant and developing brain. The central nervous system degeneration of infants could affect the memory and cognitive function. γ-Aminobutyric acid (GABA) is a known inhibitory neurotransmitter in central nervous system. Inhalation anesthetic sevoflurane may activate GABAA receptor to inhibit central nervous system, leading to apoptosis of neural degeneration, cognitive dysfunction in the critical period of brain development.

METHODS

Neural stem cells were derived from Wistar embryos, cultured in vitro. Third generation of neural stem cells were randomly divided into four groups according to cultured suspension: Sevoflurane group (Group S), GABAA receptor antagonists, Bicuculline group (Group B), Sevoflurane + GABAA receptor antagonists, Bicuculline group (Group S + B), dimethyl sulphoxide (DMSO) group (Group D). Group B and Group D did not receive sevoflurane preconditioning. Group S and Group S + B were pretreated with 1 minimum alveolar concentration (MAC) sevoflurane for 0 h, 3 h, 6 h, and 12 h. Group S + B and Group B were pretreated with bicuculline (10 uM). Group D was treated with DMSO (10 uL/mL). After treatments above, all groups were cultured for 48 h. Then we measured the cells viability by Cell Counting Kit (CCK-8) assay, cytotoxicity by Lactate Dehydrogenase (LDH) assay, apoptosis ratio with Annexin V/propidium iodide (PI) staining by flow cytometry, and the expression of GABAAR, anti-apoptotic protein Bcl-2, pro-apoptotic protein Bax and Caspase-3 by western blotting.

RESULTS

After exposing to sevoflurane for 0 h, 3 h, 6 h, and 12 h with 1MAC, we found that cell viability obviously decreased and cytotoxicity increased in time-dependent way. And Annexin V/PI staining indicated increased apoptosis ratio by flow cytometry. The protein level of GABAA receptor, pro-apoptotic protein Bax and apoptosis protein Caspase-3 increased; while anti-apoptotic protein Bcl-2 decreased. And bicuculline could reverse all detrimental results caused by sevoflurane.

CONCLUSION

Sevoflurane can inhibit the central nervous system by activating GABAA, resulting in apoptosis of neural stem cells, thus leading to the NSCs degeneration.

Cardiac surgery in 260 octogenarians: a case series

Background

The elderly undergo cardiac surgery more and more frequently, often present multiple comorbidities, assume chronic therapies, and present a unique physiology. Aim of our study was to analyze the experience of a referral cardiac surgery center with all types of cardiac surgery interventions performed in patients ≥80 years old over a six years’ period.

Methods

A retrospective observational study performed in a university hospital. 260 patients were included in the study (3.5% of the patients undergoing cardiac surgery in the study period).

Results

Mean age was 82 ± 1.8 years. Eighty-five percent of patients underwent elective surgery, 15% unplanned surgery and 4.2% redo surgery. Intervention for aortic valve pathology and coronary artery bypass grafting were performed in 51% and 46% of the patients, respectively. Interventions involving the mitral valve were the 26% of the total, those on the tricuspid valve were 13% and those on the ascending aortic arch the 9.6%. Postoperative low output syndrome was identified in 44 patients (17%). Mortality was 3.9% and most of the patients (91%) were discharged from hospital in good clinical conditions. Hospital mortality was lower in planned vs unplanned surgery: 3.8% vs 14% respectively. Chronic obstructive pulmonary disease (OR 9.106, CI 2.275 – 36.450) was the unique independent predictor of mortality.

Conclusions

Clinicians should be aware that cardiac surgery can be safely performed at all ages, that risk stratification is mandatory and that hemodynamic treatment to avoid complications is expected.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2253-15-15) contains supplementary material, which is available to authorized users.

Propofol and survival: a meta-analysis of randomized clinical trials

BACKGROUND

One of the most commonly used hypnotics is propofol. Several studies performed in cardiac surgery suggested an increased mortality in patients receiving a propofol-based total intravenous anaesthesia. Furthermore, the possibility of infections and the 'propofol syndrome' have suggested that propofol might be dangerous. Nonetheless, propofol is widely used in different settings because of its characteristics: fast induction, rapid elimination, short duration of action, smooth recovery from anaesthesia, few adverse effects, no teratogenic effects, characteristics that have undoubtedly contributed to its popularity. The effect of propofol on survival is unknown. We decided to carry out a meta-analysis of all randomized controlled studies ever performed on propofol vs. any comparator in any clinical setting.

METHODS

Pertinent studies were independently searched in BioMedCentral, PubMed, Embase, Clinicaltrial.gov, and Cochrane Central Register of Clinical Trials by expert investigators. The following inclusion criteria were used: random allocation to treatment, comparison between propofol and any comparator in any clinical setting.

RESULTS

One hundred thirty-three studies randomizing 14,516 patients were included. No differences in mortality between patients receiving propofol [349/6957 (5.0%)] vs. any comparator [340/7559 (4.5%)] were observed in the overall population [risk ratio = 1.05, 95% confidence interval (0.93 to 1.18), P = 0.5] and in several sub-analyses.

CONCLUSION

Inspite of theoretical concerns, propofol has no detrimental effect on survival according to the largest meta-analysis of randomized trials ever performed on hypnotic drug.

Sevoflurane induces endoplasmic reticulum stress mediated apoptosis in hippocampal neurons of aging rats

Elderly patients are more likely to suffer from postoperative memory impairment for volatile anesthetics could induce aging neurons degeneration and apoptosis while the mechanism was still elusive. Therefore we hypothesized that ER stress mediated hippocampal neurons apoptosis might play an important role in the mechanism of sevoflurane-induced cognitive impairment in aged rats. Thirty 18-month-old male Sprague-Dawley rats were divided into two groups: the sham anesthesia group (exposure to simply humidified 30-50% O2 balanced by N2 in an acrylic anesthetizing chamber for 5 hours) and the sevoflurane anesthesia group (received 2% sevoflurane in the same humidified mixed air in an identical chamber for the same time). Spatial memory of rats was assayed by the Morris water maze test. The ultrastructure of the hippocampus was observed by transmission electron microscopy (TEM). The expressions of C/EBP homologous protein (CHOP) and caspase-12 in the hippocampus were observed by immunohistochemistry and real-time PCR analysis. The apoptosis neurons were also assessed by TUNEL assay. The Morris water maze test showed that sevoflurane anesthesia induced spatial memory impairment in aging rats (P<0.05). The apoptotic neurons were condensed and had clumped chromatin with fragmentation of the nuclear membrane, verifying apoptotic degeneration in the sevoflurane group rats by TEM observation. The expressions of CHOP and caspase-12 increased, and the number of TUNEL positive cells of the hippocampus also increased in the sevoflurane group rats (P<0.05). The present results suggested that the long time exposure of sevoflurane could induce neuronal degeneration and cognitive impairment in aging rats. The ER stress mediated neurons apoptosis may play a role in the sevoflurane-induced memory impairment in aging rats.

Does pharmacological conditioning with the volatile anaesthetic sevoflurane offer protection in liver surgery?

BACKGROUND

A recently published randomized control trial (RCT) showed a protection of the remnant liver from ischemia-reperfusion (I/R) injury by pharmacological pre-conditioning with a volatile anaesthetic in patients undergoing hepatic resection. Whether the continuous application of volatile anaesthetics (pharmacological conditioning) also protects against I/R injury is unknown.

METHODS

Consecutive patients undergoing liver resection with inflow occlusion from 2005-2007 were included in the trial. Two groups of anaesthesia regimens with either continuous application of the volatile anaesthetic sevoflurane (pharmacological conditioning) or continuous infusion of the intravenous (i.v.) anaesthetic propofol (control group) were compared. Endpoints were serum-peak-aspartate aminotransferase (AST)/ alanine aminotranferease (ALT) levels, length of stay (LOS) and intensive care unit (ICU) stays, and the occurrence of post-operative complications.

RESULTS

Two hundred and twenty-seven patients were included. Pharmacological conditioning did not protect the remnant liver from IR injury (adjusted difference for peak-AST:61.9 U/l, 95% confidence interval (CI): -151.7-275.4 U/l, P = 0.568; peak-ALT:136.1 U/l, 95% CI: -113.7-385.9 U/l, P = 0.284) nor reduce LOS (adjusted difference 0.9 days, 95% CI: -2.6-4.3 days, P = 0.622) or ICU stay (1.6 days, 95% CI: -0.2-3.3 days, P = 0.079), and was not associated with reduced complication rates (adjusted OR 1.12, 95% CI:0.6-2.3, P = 0.761) compared with the control group.

CONCLUSION

In this retrospective study, continuous volatile anaesthesia in liver resection does not provide protection of the remnant liver from IR injury compared with continuous i.v. anaesthesia.

The role of Volatile Anesthetics in Cardioprotection: a systematic review

This review evaluates the mechanism of volatile anesthetics as cardioprotective agents in both clinical and laboratory research and furthermore assesses possible cardiac side effects upon usage. Cardiac as well as non-cardiac surgery may evoke perioperative adverse events including: ischemia, diverse arrhythmias and reperfusion injury. As volatile anesthetics have cardiovascular effects that can lead to hypotension, clinicians may choose to administer alternative anesthetics to patients with coronary artery disease, particularly if the patient has severe preoperative ischemia or cardiovascular instability. Increasing preclinical evidence demonstrated that administration of inhaled anesthetics - before and during surgery - reduces the degree of ischemia and reperfusion injury to the heart. Recently, this preclinical data has been implemented clinically, and beneficial effects have been found in some studies of patients undergoing coronary artery bypass graft surgery. Administration of volatile anesthetic gases was protective for patients undergoing cardiac surgery through manipulation of the potassium ATP (K_ATP) channel, mitochondrial permeability transition pore (mPTP), reactive oxygen species (ROS) production, as well as through cytoprotective Akt and extracellular-signal kinases (ERK) pathways. However, as not all studies have demonstrated improved outcomes, the risks for undesirable hemodynamic effects must be weighed against the possible benefits of using volatile anesthetics as a means to provide cardiac protection in patients with coronary artery disease who are undergoing surgery.

Aromatase inhibition attenuates desflurane-induced preconditioning against acute myocardial infarction in male mouse heart in vivo

The volatile anesthetic desflurane (DES) effectively reduces cardiac infarct size following experimental ischemia/reperfusion injury in the mouse heart. We hypothesized that endogenous estrogens play a role as mediators of desflurane-induced preconditioning against myocardial infarction. In this study, we tested the hypothesis that desflurane effects local estrogen synthesis by modulating enzyme aromatase expression and activity in the mouse heart. Aromatase metabolizes testosterone to 17β- estradiol (E2) and thereby significantly contributes to local estrogen synthesis. We tested aromatase effects in acute myocardial infarction model in male mice. The animals were randomized and subjected to four groups which were pre-treated with the selective aromatase inhibitor anastrozole (A group) and DES alone (DES group) or in combination (A+DES group) for 15 minutes prior to surgical intervention whereas the control group received 0.9% NaCl (CON group). All animals were subjected to 45 minutes ischemia following 180 minutes reperfusion. Anastrozole blocked DES induced preconditioning and increased infarct size compared to DES alone (37.94±15.5% vs. 17.1±3.62%) without affecting area at risk and systemic hemodynamic parameters following ischemia/reperfusion. Protein localization studies revealed that aromatase was abundant in the murine cardiovascular system with the highest expression levels in endothelial and smooth muscle cells. Desflurane application at pharmacological concentrations efficiently upregulated aromatase expression in vivo and in vitro. We conclude that desflurane efficiently regulates aromatase expression and activity which might lead to increased local estrogen synthesis and thus preserve cellular integrity and reduce cardiac damage in an acute myocardial infarction model.

The effect of isoflurane on survival and myocardial infarction: a meta-analysis of randomized controlled studies

OBJECTIVE

The aim of this meta-analysis was to investigate the cardioprotective properties of isoflurane versus any comparator in terms of the rate of myocardial infarction and all-cause mortality.

DESIGN

Pertinent studies were searched independently in Biomed, Central, PubMed, Embase, and the Cochrane Central Register of clinical trials. The primary endpoint was mortality at the longest follow-up available.

SETTING

A hospital.

PARTICIPANTS

Randomized controlled trials.

INTERVENTION

A meta-analysis of 37 trials.

MEASUREMENTS AND MAIN RESULTS

The 37 included trials randomized 3,539 patients in cardiac (16 studies) and in noncardiac surgery (21 studies) with noninhalation comparators in 55% of trials. The overall analysis showed no difference in mortality between the isoflurane and control groups (16/1,602 [1.0%] v 23/1,937 [1.2%], odds ratios (OR) = 0.76 [0.39-1.47], p = 0.4 with 37 studies included) and no difference in the rate of myocardial infarction (3/1,312 [0.2%] v 1/1,532 [0.07%], OR = 2.03 [0.27-15.49], p = 0.5 with 30 studies included). Mortality was reduced in the isoflurane group when only studies with a low risk of bias were included in the analyses (0/540 [0%] v 5/703 [0.7%] in the control arm, OR = 0.13 [0.02-0.76], p = 0.02) with 4 cardiac and 6 noncardiac trials included and 5 noninhalation and 5 inhalation agents as the comparator. A trend was noted when a subanalysis was performed with propofol as a comparator (1/544 [0.2%] v 6/546 [1.1%], p = 0.05, with 16 studies included).

CONCLUSIONS

Isoflurane reduced mortality in high-quality studies and showed a trend toward a reduction in mortality when it was compared with propofol. No differences in the rates of overall mortality and myocardial infarction were noted.

Sevoflurane vs. propofol in patients with coronary disease undergoing mitral surgery: a randomised study

BACKGROUND

Myocardial ischemic damage is reduced by volatile anaesthetics in patients undergoing low-risk coronary artery bypass graft surgery; few and discordant results exist in other settings. We therefore performed a randomised controlled trial (sevoflurane vs. propofol) to compare cardiac troponin release in patients with coronary disease undergoing mitral surgery.

METHODS

Patients with coronary artery disease undergoing mitral surgery were randomly allocated to receive either sevoflurane (50 patients) or propofol (50 patients) as main hypnotic. The primary endpoint of the study was peak post-operative cardiac troponin release defined as the maximum value among the post-operative values measured at intensive care unit arrival, 4 h later, on the first and second post-operative day.

RESULTS

There was no significant difference in post-operative peak troponin release, the median (25th-75th percentiles) values being 14.9 (10.1-22.1) ng/ml and 14.5 (8.8-17.6) ng/ml in the sevoflurane and propofol groups, respectively (P = 0.4). Fentanyl administration was different between the two groups: 1347 ± 447 μg in patients receiving sevoflurane and 1670 ± 469 μg in those receiving propofol, P = 0.002. The 1-year follow-up identified two patients who died in the propofol group (one myocardial infarction and one low cardiac output syndrome) and one in the sevoflurane group (myocardial infarction).

CONCLUSION

In this study, patients with coronary artery disease undergoing mitral surgery did not benefit from the cardioprotective properties of halogenated anaesthetics. Sevoflurane anaesthesia was not associated to lower cardiac troponin release when compared with propofol anaesthesia.

Comparison of the Effects of Ketamine-Dexmedetomidine and Sevoflurane-Sufentanil Anesthesia on Cardiac Biomarkers After Cardiac Surgery: An Observational Study

Inhalational anesthetics have demonstrated cardioprotective effects against myocardial ischemia-reperfusion injury. Clinical studies in cardiac surgery have supported these findings, although not with the consistency demonstrated in experimental studies. Recent investigations have questioned the advantages of inhalational over intravenous anesthetics with respect to cardiac protection. Ketamine has been shown to be comparable with sufentanil, and has even demonstrated anti-inflammatory properties. Dexmedetomidine has been established as a sedative/anesthetic drug with analgesic properties, and has also demonstrated myocardial protective effects. In this retrospective observational study, the influence of ketamine-dexmedetomidine-based anesthesia (KET-DEX group; n=17) on the release of cardiac biomarkers was compared with that of sevoflurane-sufentanil-based anesthesia (SEVO group; n=21) in patients undergoing elective coronary artery bypass grafting. Compared with the SEVO group, the KET-DEX group exhibited significantly reduced cardiac troponin I (2.22±1.73 vs. 3.63±2.37 µg/l; P=0.02) and myocardial fraction of creatine kinase (CK-MB) levels (12.4±10.4 vs. 20.3±11.2 µg/l; P=0.01) on the morning of the first postoperative day. Furthermore, cardiac troponin I release, evaluated as the area under the curve, was significantly reduced in the KET-DEX group (32.1±20.1 vs. 50.6±23.2; P=0.01). These results demonstrate the cardioprotective effects of ketamine-dexmedetomidine anesthesia compared with those of sevoflurane-sufentanil anesthesia.