The effects of different anesthetic regimens on fibrinolysis and the development of postoperative arterial thrombosis. Perioperative Ischemia Randomized Anesthesia Trial Study Group

Anesthetic management for lower extremity vascular bypass procedures: The impact of general or regional anesthesia on clinical outcomes

PURPOSE

Postoperative complications after major surgery, especially vascular procedures, are associated with a significant increase in costs and mortality. Previous studies evaluating general anesthesia versus regional or neuraxial anesthesia for infrainguinal bypass have produced conflicting results. The main aim of the present study is to review current evidence on the application of regional or general anesthesia in patients undergoing infrainguinal bypass surgery and its potential favorable effects on postoperative outcomes.

CONTENTS

Patients undergoing vascular surgery often have multiple comorbidities, and it is important to outline both benefits and risks of regional anesthesia techniques. Neuraxial anesthesia in vascular surgery allows overall avoidance of general anesthesia and does provide short-term benefits beyond analgesia. Previous observational studies suggest that neuraxial anesthesia for lower limb revascularization may reduce morbidity and length of stay. However, evidence of long-term benefits is lacking in most procedures and further work is still warranted.

CONCLUSIONS

Neuraxial anesthesia is usually an effective anesthesia technique for infrainguinal bypass surgery. Elderly patients and those with underlying respiratory problems may display some benefit from neuraxial anesthesia. Further evaluation within institutions should be performed to identify which patients would most benefit from regional techniques. Notably, systemic antithrombotic and anticoagulation therapy is common among this population and may affect anesthetic choices.

Is General Anesthesia for Peripheral Vascular Surgery Correlated with Impaired Outcome in Patients with Cardiac Comorbidity? A Closer Look into the Nationwide Danish Cohort

OBJECTIVE

General anesthesia (GA) may impair outcome after vascular surgery. The use of anticoagulant medication is often used in patients with cardiac comorbidity. Regional anesthesia (RA) requires planning of discontinuation before neuraxial blockade(s) in this subgroup. This study aimed to describe the effect of anesthesia choice on outcome after vascular surgery in patients with known cardiac comorbidity.

DESIGN

Retrospective cohort study.

SETTING

Danish hospitals.

PARTICIPANTS

6302 patients with known cardiac comorbidity, defined as ischemic heart disease, valve disease, pulmonary vascular disease, heart failure, and cardiac arrhythmias, undergoing lower extremity vascular surgery between 2005 and 2017.

INTERVENTIONS

GA versus RA.

MEASUREMENTS AND MAIN RESULTS

Data were extracted from national registries. GA was defined as anesthesia with mechanical ventilation. Multivariable regression models were used to describe the incidence of postoperative complications as well as 30-day mortality, hypothesizing that better outcomes would be seen after RA. The rate of RA decreased from 48% in 2005 to 20% in 2017. The number of patients with 1 or more complications was 9.7% vs 6.2% (p < 0.001), and 30-day mortality was 6.0% vs 3.4% (p < 0.001) after GA. After adjusting for baseline differences, the odds ratio (OR) was significantly lower for medical complications (cardiac, pulmonary, renal, new dialysis, intensive care unit and other medical complications; OR, 0.97; 95% confidence interval [CI], 0.95-0.98) and 30-day mortality (OR 0.98; 95% CI, 0.97-0.99) after RA.

CONCLUSIONS

RA may be associated with a better outcome than GA after lower extremity vascular surgery in patients with a cardiac comorbidity. Prioritizing RA, despite the inconvenience of discontinuing anticoagulants, may be recommended.

Strategies to prevent blood loss and reduce transfusion in emergency general surgery, WSES-AAST consensus paper

Emergency general surgeons often provide care to severely ill patients requiring surgical interventions and intensive support. One of the primary drivers of morbidity and mortality is perioperative bleeding. In general, when addressing life threatening haemorrhage, blood transfusion can become an essential part of overall resuscitation. However, under all circumstances, indications for blood transfusion must be accurately evaluated. When patients decline blood transfusions, regardless of the reason, surgeons should aim to provide optimal care and respect and accommodate each patient's values and target the best outcome possible given the patient's desires and his/her clinical condition. The aim of this position paper was to perform a review of the existing literature and to provide comprehensive recommendations on organizational, surgical, anaesthetic, and haemostatic strategies that can be used to provide optimal peri-operative blood management, reduce, or avoid blood transfusions and ultimately improve patient outcomes.

Risk of Postoperative Ischemic Stroke and Myocardial Infarction in Patients Operated for Cancer

BACKGROUND

Risk assessment for ischemic stroke (IS) and myocardial infarction (MI) is done routinely before surgery, but the increase in risks associated with surgery is not known. The aim of this study is to assess the risk of arterial ischemic events during the first year after oncological surgery.

METHODS

We used Swedish healthcare databases to identify 443,300 patients who underwent cancer surgery between 1987 and 2016 and 4,127,761 matched comparison subjects. We estimated odds ratios (ORs) for myocardial infarction and ischemic stroke during the hospitalization with logistic regression and calculated 1-year cumulative incidences and hazard ratios (HRs) with 95% confidence intervals (CIs) for the outcomes after discharge.

RESULTS

The cumulative incidences of myocardial infarction and ischemic stroke during the first postoperative year were 1.33% and 1.25%, respectively. In the comparison cohort, the corresponding 1-year cumulative incidences were 1.04% and 1.00%. During the hospitalization, the OR for myocardial infarction was 8.81 (95% CI 8.24-9.42) and the OR for ischemic stroke was 6.71 (95% CI 6.22-7.23). After discharge, the average HR during follow-up for 365 days was 0.90 (95% CI 0.87-0.93) for myocardial infarction and 1.02 (95% CI 0.99-1.05) for ischemic stroke.

CONCLUSIONS

We found an overall increased risk of IS and MI during the first year after cancer surgery that was attributable to events occurring during the hospitalization period. After discharge from the hospital, the overall risk of myocardial infarction was lower among the cancer surgery patients than among matched comparison subjects.

Outcomes After Neuraxial or Regional Anaesthesia Instead of General Anaesthesia for Lower Limb Revascularisation Surgery: A Systematic Review and Meta-Analysis of Randomised and Non-Randomised Studies

OBJECTIVE

To determine whether receipt of neuraxial or regional anaesthesia instead of general anaesthesia for lower limb revascularisation surgery affects patient outcomes.

DATA SOURCES

MEDLINE, EMBASE, Evidence Based Medicine Reviews, and Google Scholar.

REVIEW METHODS

After protocol registration, the data sources were searched for randomised and non-randomised studies comparing neuraxial or regional anaesthesia with general anaesthesia for lower limb revascularisation surgery in adults. Two investigators independently selected articles, extracted data, and assessed risks of bias. Data were pooled using random effects models. GRADE was used to assess certainty in cumulative evidence.

RESULTS

From 10 755 citations identified, five randomised (n = 970) and 13 non-randomised (n = 96 800) studies were included. Use of neuraxial instead of general anaesthesia for lower limb revascularisation surgery was associated with no statistically significant reduction in short term (in hospital or 30 day) mortality in randomised studies (pooled odds ratio [OR] 0.77; 95% confidence interval [CI] 0.33 - 1.81; low certainty) and a statistically significant reduction in adjusted short term mortality in non-randomised studies (pooled OR 0.67; 95% CI 0.56 - 0.81; low certainty). Adults allocated to neuraxial anaesthesia in randomised studies had fewer pulmonary complications (pooled OR 0.35; 95% CI 0.16 - 0.76; low certainty). In non-randomised studies, neuraxial instead of general anaesthesia was associated with a lower adjusted odds of any morbidity (pooled OR 0.66; 95% CI 0.52 - 0.84), cardiac complications (pooled OR 0.68; 95% CI 0.58 - 0.79), pneumonia (pooled OR 0.81; 95% CI 0.64 - 1.02), prolonged mechanical ventilation (OR 0.09; 95% CI 0.002 - 0.55), and bypass graft thrombosis (OR 0.70; 95% CI 0.59 - 0.85), as well as a shorter operative duration (low certainty for all). Use of a nerve block instead of general anaesthesia was associated with a lower adjusted odds of delirium (OR 0.16; 95% CI 0.06 - 0.42) and a shorter operative duration (low certainty for both).

CONCLUSION

Randomised and non-randomised data suggest that neuraxial anaesthesia for lower limb revascularisation surgery reduces morbidity and possibly mortality. Until randomised trials with a low risk of bias become available, this study supports use of neuraxial anaesthesia for these procedures where appropriate.

Hospital-, Anesthesiologist-, Surgeon-, and Patient-Level Variations in Neuraxial Anesthesia Use for Lower Limb Revascularization Surgery: A Population-Based Cross-Sectional Study

BACKGROUND

Although neuraxial anesthesia may promote improved outcomes for patients undergoing lower limb revascularization surgery, its use is decreasing over time. Our objective was to estimate variation in neuraxial (versus general) anesthesia use for lower limb revascularization at the hospital, anesthesiologist, surgeon, and patient levels, which could inform strategies to increase uptake.

METHODS

Following protocol registration, we conducted a historical cross-sectional analysis of population-based linked health administrative data in Ontario, Canada. All adults undergoing lower limb revascularization surgery between 2009 and 2018 were identified. Generalized linear models with binomial response distributions, logit links and random intercepts for hospitals, anesthesiologists, and surgeons were used to estimate the variation in neuraxial anesthesia use at the hospital, anesthesiologist, surgeon, and patient levels using variance partition coefficients and median odds ratios. Patient- and hospital-level predictors of neuraxial anesthesia use were identified.

RESULTS

We identified 11,849 patients; 3489 (29.4%) received neuraxial anesthesia. The largest proportion of variation was attributable to the hospital level (50.3%), followed by the patient level (35.7%); anesthesiologists and surgeons had small attributable variation (11.3% and 2.8%, respectively). Mean odds ratio estimates suggested that 2 similar patients would experience a 5.7-fold difference in their odds of receiving a neuraxial anesthetic were they randomly sent to 2 different hospitals. Results were consistent in sensitivity analyses, including limiting analysis to patients with diagnosed peripheral artery disease and separately to those aged >66 years with complete prescription anticoagulant and antiplatelet usage data.

CONCLUSIONS

Neuraxial anesthesia use primarily varies at the hospital level. Efforts to promote use of neuraxial anesthesia for lower limb revascularization should likely focus on the hospital context.

Red Blood Cell Transfusions and Risk of Postoperative Venous Thromboembolism

INTRODUCTION

Postoperative venous thromboembolism (VTE) is a major risk for orthopaedic surgery and associated with notable morbidity and mortality. Knowing a patient's risk for VTE may help guide the choice of perioperative VTE prophylaxis. Recently, red blood cells (RBCs) have been implicated for their role in pathologic thrombosis. Therefore, we examine the association between perioperative RBC transfusion and postoperative VTE after orthopaedic surgery.

METHODS

A retrospective cohort study was done by conducting a secondary analysis of data obtained from the 2016 American College of Surgeons National Surgical Quality Improvement Program database. Our population consisted of 234,608 adults who underwent orthopaedic surgery. The exposure was whether patients received a perioperative RBC transfusion. The primary outcome was postoperative VTE within 30 days of surgery that warranted therapeutic intervention, which was subsequently split into symptomatic deep vein thrombosis (DVT) and pulmonary embolism (PE). Odds ratios (ORs) were estimated using a multivariate logistic regression model.

RESULTS

At baseline, 1,952 patients (0.83%) had postoperative VTE (DVT in 1,299 [0.55%], PE in 801 [0.34%], and both DVT and PE in 148 [0.06%]). Seven hundred ninety-five patients (0.3%) received preoperative RBC transfusions only, 11,587 patients (4.9%) received postoperative RBC transfusions only, and 848 patients (0.4%) received both preoperative and postoperative RBC transfusions. Postoperative RBC transfusion was associated with higher odds of VTE (adjusted OR [aOR], 1.47; 95% confidence interval [CI], 1.19-1.81), DVT (aOR, 1.40; 95% CI, 1.09-1.79), PE (aOR, 1.59; 95% CI, 1.14-2.22), and 30-day mortality (aOR, 1.21; 95% CI, 1.01-1.45) independent of various presumed risk factors. When creating subgroups within orthopaedics by Current Procedural Terminology codes, postoperative transfusions in spine (aOR, 2.03; 95% CI, 1.13-3.67) and trauma (aOR, 1.40; 95% CI, 1.06-1.86) were associated with higher odds of postoperative VTE.

CONCLUSION

Our results suggest that postoperative RBC transfusion may be associated with an increased risk of postoperative VTE, both symptomatic DVT and life-threatening PE, independent of confounders. Additional prospective validation in cohort studies is necessary to confirm these findings. In addition, careful perioperative planning for patients deemed to be at high risk of requiring blood transfusion may reduce these postoperative complications in orthopaedic patients.

LEVEL OF EVIDENCE

III.

Outcomes After Receipt of Neuraxial or Regional Anesthesia Instead of General Anesthesia for Lower Limb Revascularization Surgery: Protocol for a Systematic Review and Meta-analysis

BACKGROUND

Patients undergoing lower limb revascularization surgery for peripheral artery disease (PAD) have a high risk of perioperative morbidity and mortality and often have long hospital stays. Use of neuraxial or regional anesthesia instead of general anesthesia may represent one approach to improving outcomes and reducing resource use among these patients.

OBJECTIVE

The aim is to conduct a systematic review and meta-analysis to determine whether receipt of neuraxial or regional anesthesia instead of general anesthesia in adults undergoing lower limb revascularization surgery for PAD results in improved health outcomes and costs and a shorter length of hospitalization.

METHODS

We will search electronic bibliographic databases (MEDLINE, EMBASE, the seven databases in Evidence-Based Medicine Reviews, medRxiv, bioRxiv, and Google Scholar), review papers identified during the search, and included article bibliographies. We will include randomized and nonrandomized studies comparing the use of neuraxial or regional anesthesia instead of general anesthesia in adults undergoing lower limb revascularization surgery for PAD. Two investigators will independently evaluate the risk of bias. The primary outcome will be short-term (in-hospital or 30-day) mortality. Secondary outcomes will include longer-term mortality; major adverse cardiovascular, pulmonary, renal, and limb events; delirium; deep vein thrombosis or pulmonary embolism; neuraxial or regional anesthesia-related complications; graft-related outcomes; length of operation and hospital stay; costs; and patient-reported or functional outcomes. We will calculate summary odds ratios (ORs) and standardized mean differences (SMDs) using random-effects models. Heterogeneity will be explored using stratified meta-analyses and meta-regression. We will assess for publication bias using the Begg and Egger tests and use the trim-and-fill method to estimate the potential influence of this bias on summary estimates. Finally, we will use Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) methodology to make an overall rating of the quality of evidence in our effect estimates.

RESULTS

The protocol was registered in the International Prospective Register of Systematic Reviews (PROSPERO). We executed the peer-reviewed search strategy on March 2, 2021. We completed the review of titles and abstracts on July 30, 2021, and plan to complete the review of full-text papers by September 30, 2021. We will complete full-text study data extraction and the risk-of-bias assessment by November 15, 2021, and conduct qualitative and then quantitative data synthesis and GRADE assessment of results by January 1, 2022, before drafting the manuscript. We anticipate that we will be able to submit the manuscript for peer review by the end of February 2022.

CONCLUSIONS

This study will synthesize existing evidence regarding whether receipt of neuraxial or regional anesthesia instead of general anesthesia in adults undergoing lower limb revascularization surgery for PAD results in improved health outcomes, graft patency, and costs and a shorter length of hospital stay. Study results will be used to inform practice and future research, including creation of a pilot and then multicenter randomized controlled trial.

TRIAL REGISTRATION

Prospero CRD42021237060; https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=237060.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

PRR1-10.2196/32170.

Association between neuraxial anaesthesia or general anaesthesia for lower limb revascularisation surgery in adults and clinical outcomes: population based comparative effectiveness study

OBJECTIVE

To examine the associations between neuraxial anaesthesia or general anaesthesia and clinical outcomes, length of hospital stay, and readmission in adults undergoing lower limb revascularisation surgery.

DESIGN

Comparative effectiveness study using linked, validated, population based databases.

SETTING

Ontario, Canada, 1 April 2002 to 31 March 2015.

PARTICIPANTS

20 988 patients Ontario residents aged 18 years or older who underwent their first lower limb revascularisation surgery in hospitals performing 50 or more of these surgeries annually.

MAIN OUTCOME MEASURES

Primary outcome was 30 day all cause mortality. Secondary outcomes were in-hospital cardiopulmonary and renal complications, length of hospital stay, and 30 day readmissions. Multivariable, mixed effects regression models, adjusting for patient, procedural, and hospital characteristics, were used to estimate associations between anaesthetic technique and outcomes. Robustness of analyses were evaluated by conducting instrumental variable, propensity score matched, and survival sensitivity analyses.

RESULTS

Of 20 988 patients who underwent lower limb revascularisation surgery, 6453 (30.7%) received neuraxial anaesthesia and 14 535 (69.3%) received general anaesthesia. The percentage of neuraxial anaesthesia use ranged from 0.6% to 90.6% across included hospitals. Furthermore, use of neuraxial anaesthesia declined by 17% over the study period. Death within 30 days occurred in 204 (3.2%) patients who received neuraxial anaesthesia and 646 (4.4%) patients who received general anaesthesia. After multivariable, multilevel adjustment, use of neuraxial anaesthesia compared with use of general anaesthesia was associated with decreased 30 day mortality (absolute risk reduction 0.72%, 95% confidence interval 0.65% to 0.79%; odds ratio 0.68, 95% confidence interval 0.57 to 0.83; number needed to treat to prevent one death=139). A similar direction and magnitude of association was found in instrumental variable, propensity score matched, and survival analyses. Use of neuraxial anaesthesia compared with use of general anaesthesia was also associated with decreased in-hospital cardiopulmonary and renal complications (odds ratio 0.73, 0.63 to 0.85) and a reduced length of hospital stay (-0.5 days, -0.3 to-0.6 days).

CONCLUSIONS

Use of neuraxial anaesthesia compared with general anaesthesia for lower limb revascularisation surgery was associated with decreased 30 day mortality and hospital length of stay. These findings might have been related to reduced cardiopulmonary and renal complications after neuraxial anaesthesia and support the increased use of neuraxial anaesthesia in patients undergoing these surgeries until the results of a large, confirmatory randomised trial become available.

Anesthetic Agents and Cardiovascular Outcomes of Noncardiac Surgery after Coronary Stent Insertion

Patients undergoing noncardiac surgery after coronary stent implantation are at an increased risk of thrombotic complications. Volatile anesthetics are reported to have organ-protective effects against ischemic injury. Propofol has an anti-inflammatory action that can mitigate ischemia-reperfusion injury. However, the association between anesthetic agents and the risk of major adverse cardiovascular and cerebral event (MACCE) has never been studied before. In the present study, a total of 1630 cases were reviewed. Four different propensity score matchings were performed to minimize selection bias (propofol-based total intravenous anesthesia (TIVA) vs. volatile anesthetics; TIVA vs. sevoflurane; TIVA vs. desflurane; and sevoflurane vs. desflurane). The incidence of MACCE in these four propensity score-matched cohorts was compared. As a sensitivity analysis, a multivariable logistic regression analysis was performed to identify independent predictors for MACCE during the postoperative 30 days both in total and matched cohorts (TIVA vs. volatile agent). MACCE occurred in 6.0% of the patients. Before matching, there was a significant difference in the incidence of MACCE between TIVA and sevoflurane groups (TIVA 5.1% vs. sevoflurane 8.2%, p = 0.006). After matching, there was no significant difference in the incidence of MACCE between the groups of any pairs (TIVA 6.5% vs. sevoflurane 7.7%; p = 0.507). The multivariable logistic regression analysis revealed no significant association of the volatile agent with MACCE (odds ratio 1.48, 95% confidence interval 0.92–2.37, p = 0.104). In conclusion, the choice of anesthetic agent for noncardiac surgery did not significantly affect the development of MACCE in patients with previous coronary stent implantation. However, further randomized trials are needed to confirm our results.

Strategies to minimize intraoperative blood loss during major surgery

Background

Reducing operative blood loss improves patient outcomes and reduces healthcare costs. The aim of this article was to review current surgical, anaesthetic and haemostatic intraoperative blood conservation strategies.

Methods

This narrative review was based on a literature search of relevant databases up to 31 July 2019 for publications relevant to reducing blood loss in the surgical patient.

Results

Interventions can begin early in the preoperative phase through identification of patients at high risk of bleeding. Directly acting anticoagulants can be stopped 48 h before most surgery in the presence of normal renal function. Aspirin can be continued for most procedures. Intraoperative cell salvage is recommended when anticipated blood loss is greater than 500 ml and this can be continued after surgery in certain situations. Tranexamic acid is safe, cheap and effective, and routine administration is recommended when anticipated blood loss is high. However, the optimal dose, timing and route of administration remain unclear. The use of topical agents, tourniquet and drains remains at the discretion of the surgeon. Anaesthetic techniques include correct patient positioning, avoidance of hypothermia and regional anaesthesia. Permissive hypotension may be beneficial in selected patients. Promising haemostatic strategies include use of pharmacological agents such as desmopressin, prothrombin complex concentrate and fibrinogen concentrate, and use of viscoelastic haemostatic assays.

Conclusion

Reducing perioperative blood loss requires a multimodal and multidisciplinary approach. Although high-quality evidence exists in certain areas, the overall evidence base for reducing intraoperative blood loss remains limited.

Association of Perioperative Red Blood Cell Transfusions With Venous Thromboembolism in a North American Registry

Importance

Increasing evidence supports the role of red blood cells (RBCs) in physiological hemostasis and pathologic thrombosis. Red blood cells are commonly transfused in the perioperative period; however, their association with postoperative thrombotic events remains unclear.

Objective

To examine the association between perioperative RBC transfusions and postoperative venous thromboembolism (VTE) within 30 days of surgery.

Design, Setting, and Participants

This analysis used prospectively collected registry data from the American College of Surgery National Surgical Quality Improvement Program (ACS-NSQIP) database, a validated registry of 525 teaching and nonteaching hospitals in North America. Participants included patients in the ACS-NSQIP registry who underwent a surgical procedure from January 1 through December 31, 2014. Data were analyzed from July 1, 2016, through March 15, 2018.

Main Outcomes and Measures

Risk-adjusted odds ratios (aORs) were estimated using multivariable logistic regression. The primary outcome was the development of postoperative VTE (deep venous thrombosis [DVT] and pulmonary embolism [PE]) within 30 days of surgery that warranted therapeutic intervention; DVT and PE were also examined separately as secondary outcomes. Subgroup analyses were performed by surgical subtypes. Propensity score matching was performed for sensitivity analyses.

Results

Of 750 937 patients (56.8% women; median age, 58 years; interquartile range, 44-69 years), 47 410 (6.3%) received at least 1 perioperative RBC transfusion. Postoperative VTE occurred in 6309 patients (0.8%) (DVT in 4336 [0.6%]; PE in 2514 [0.3%]; both DVT and PE in 541 [0.1%]). Perioperative RBC transfusion was associated with higher odds of VTE (aOR, 2.1; 95% CI, 2.0-2.3), DVT (aOR, 2.2; 95% CI, 2.1-2.4), and PE (aOR, 1.9; 95% CI, 1.7-2.1), independent of various putative risk factors. A significant dose-response effect was observed with increased odds of VTE as the number of intraoperative and/or postoperative RBC transfusion events increased (aOR, 2.1 [95% CI, 2.0-2.3] for 1 event; 3.1 [95% CI, 1.7-5.7] for 2 events; and 4.5 [95% CI, 1.0-19.4] for ≥3 events vs no intraoperative or postoperative RBC transfusion; P < .001 for trend). In subgroup analyses, the association between any perioperative RBC transfusion and postoperative VTE remained statistically significant across all surgical subspecialties analyzed. The association between any perioperative RBC transfusion and the development of postoperative VTE also remained robust after 1:1 propensity score matching (47 142 matched pairs; matched OR, 1.9; 95% CI, 1.8-2.1).

Conclusions and Relevance

The results of this study suggest that perioperative RBC transfusions may be significantly associated with the development of new or progressive postoperative VTE, independent of several putative confounders. These findings, if validated, should reinforce the importance of rigorous perioperative management of blood transfusion practices.

[Perioperative myocardial ischemia : Current aspects and concepts]

In the future an increasing number of older patients with significant comorbidities will have to undergo major surgical procedures. Perioperative cardiovascular events account for many major complications and even fatalities. While perioperative myocardial infarction (PMI) is a generally well-known and recognized complication, the less severe myocardial injury after non-cardiac surgery (MINS) has not gained widespread scientific attention until recently; however, two large observational trials (VISION 1 and VISION 2) have shown a significantly increased mortality after MINS with even subtle increases in troponin T being associated with an increased risk of death. This review summarizes the current knowledge pertaining to PMI and MINS and proposes a diagnostic and therapeutic framework for optimally guiding patients at risk through the perioperative period.

Intravenous Tranexamic Acid Bolus plus Infusion Is Not More Effective than a Single Bolus in Primary Hip Arthroplasty

Background

Preoperative administration of the antifibrinolytic agent tranexamic acid reduces bleeding in patients undergoing hip arthroplasty. Increased fibrinolytic activity is maintained throughout the first day postoperation. The objective of the study was to determine whether additional perioperative administration of tranexamic acid would further reduce blood loss.

Methods

This prospective, double-blind, parallel-arm, randomized, superiority study was conducted in 168 patients undergoing unilateral primary hip arthroplasty. Patients received a preoperative intravenous bolus of 1 g of tranexamic acid followed by a continuous infusion of either tranexamic acid 1 g (bolus-plus-infusion group) or placebo (bolus group) for 8 h. The primary outcome was calculated perioperative blood loss up to day 5. Erythrocyte transfusion was implemented according to a restrictive transfusion trigger strategy.

Results

The mean perioperative blood loss was 919 ± 338 ml in the bolus-plus-infusion group (84 patients analyzed) and 888 ± 366 ml in the bolus group (83 patients analyzed); mean difference, 30 ml (95% CI, −77 to 137; P = 0.58). Within 6 weeks postsurgery, three patients in each group (3.6%) underwent erythrocyte transfusion and two patients in the bolus group experienced distal deep-vein thrombosis. A meta-analysis combining data from this study with those of five other trials showed no incremental efficacy of additional perioperative administration of tranexamic acid.

Conclusions

A preoperative bolus of tranexamic acid, associated with a restrictive transfusion trigger strategy, resulted in low erythrocyte transfusion rates in patients undergoing hip arthroplasty. Supplementary perioperative administration of tranexamic acid did not achieve any further reduction in blood loss.

[Neuraxial anaesthesia and NOACs]

BACKGROUND

Cardiovascular comorbidities in surgical patients are frequent and have a substantial impact on the postoperative outcome. Neuraxial blockades are able to reduce perioperative morbidity and mortality. The increasing use of new oral anticoagulants (NOAC) requires a high level of attention, especially in patients undergoing neuraxial blockades or requiring postoperative analgesia.

OBJECTIVE

The goal of this article is to present the benefit of neuraxial anaesthesia and analgesia in patients with cardiovascular risks and perioperative management of NOAC in this setting.

MATERIALS AND METHODS

Review of the respective literature in PubMed during the last 25 years as well as presentation of the S1 guideline "Neuraxial anaesthesia and thrombo-embolic prophylaxis/antithrombotic medication" of the German Society of Anaesthesiology and Intensive Care Medicine (DGAI).

RESULTS

Thoracic epidural anaesthesia and analgesia contribute to an improved outcome in surgical patients with high cardiovascular risk. In order to avoid severe complications in patients on NOACs undergoing neuraxial blockades the S1 guideline of the DGAI must be respected and close interdisciplinary consultations between anaesthetist, cardiologist and surgeon are mandatory.

CONCLUSION

In consideration of the respective guideline neuraxial blockades can be performed in cardiovascular risk patients on NOACs, since these techniques contribute to an improved postoperative outcome.

Pain Management After Vascular Surgery

Patients presenting for vascular surgery usually have concomitant disease processes that may increase the likelihood of adverse outcomes after major surgery. Because of the advanced nature of the underlying medical condition, it is important to optimize postopera tive pain control to adequately control postoperative discomfort, stress response, hypercoagulability, myocar dial ischemia, and graft failure. This article discusses methods of pain control after vascular surgery and their effects on physiology and outcome.

Hypercoagulable States

The hypercoagulable states consist of a group of prothrombotic clinical disorders associated with an increased risk for thromboembolic events. The abnormalities lead to inappropriate thrombus formation. After a review of the coagulation process, inherited disorders (including antithrombin-III deficiency, protein CS system deficiencies, disorders of plasmin generation, dysfibrinogenemias, and homocysteinuria) and acquired disorders (including responses to surgery, cancer, drugs, and the antiphospholipid syndrome) are described. Screening and management methods are discussed. Copyright © 1997 by W. B. Saunders Company.

Anesthesia for hip arthroscopy: a narrative review

PURPOSE

Hip arthroscopy is a minimally invasive surgical procedure indicated for the treatment of specific hip disorders. In this narrative review, we aim to examine the key components in providing anesthesia for this procedure.

SOURCE

MEDLINE(®), PubMed, and EMBASE™ databases were searched for peer-reviewed articles discussing the anesthetic management of patients undergoing hip arthroscopy.

PRINCIPAL FINDINGS

The primary anesthetic regimen used for hip arthroscopy should balance patient factors, preferences of the surgeon, and the demands of the procedure itself. Both general and neuraxial anesthetic techniques are well suited for this mostly ambulatory surgical procedure. There is a lack of current literature specifically comparing the benefits and risks of the two techniques in this setting. Postoperative pain management consists mainly of intravenous and oral opioids; however, a variety of regional anesthesia techniques, such as lumbar plexus block and fascia iliaca block, can be performed pre- or postoperatively. Overall, hip arthroscopy is safe, although positioning-related difficulties, extravasation of irrigation fluid, hypothermia, infections, and thromboembolic events are potential perioperative complications that warrant specific monitoring and prompt treatment.

CONCLUSIONS

Until now, the anesthetic technique for hip arthroscopy has not been well studied. Thus, increasing emphasis should be directed towards examining relevant clinical outcomes that can better inform evidence-based decision-making in the anesthetic management of hip arthroscopy patients. In the meantime, awareness of potential complications and vigilant monitoring are paramount in providing safe anesthetic care for patients undergoing hip arthroscopy.

Coagulation, Fibrinolysis, and Platelet Activation Following Open Surgical or Percutaneous Angioplasty Revascularization for Symptomatic Lower Limb Chronic Ischemia

Introduction:

Critical limb ischemia (CLI) is associated with a prothrombotic diathesis that involves a complex balance between the coagulation and fibrinolytic systems. Knowledge of this is essential when considering revascularization procedures but is often overlooked. The aim of this review is to summarize the available literature and provide an overview of the effects of lower limb angioplasty and open surgical revascularization on coagulation, fibrinolysis, and platelet activation.

Methods:

A MEDLINE and EMBASE search was conducted between 1973 and 2014 for articles relating to the effects of revascularization for patients with CLI on the fibrinolytic and coagulation pathways. Studies with a small cohort of patients (<5) were rejected.

Results:

Many of the studies included in this analysis had small cohorts. Multiple markers were assessed across the published literature including von Willebrand factor, tissue factor, prothrombin fragments 1 and 2, platelets, soluble platelet selectin, plasminogen activator inhibitor 1, tissue plasminogen activator, and thrombin–antithrombin complex. Percutaneous intervention causes an exaggerated prothrombotic and a disturbed fibrinolytic effect. Surgery seems to cause a similar prothrombotic derangement with reduced fibrinolysis and platelet hyperactivity, but this appears to be maintained for a considerable amount of time postoperatively.

Conclusion:

There is a sparse amount published on the effects of the coagulation and fibrinolytic systems in patients undergoing intervention for CLI. Much of these studies are small, historical, and completely heterogeneous, making it difficult to draw meaningful conclusions. The literature does identify a prothrombotic state in patients with CLI, which appears to be exacerbated by any form of intervention and prolonged in those having surgery. Understanding this may allow us to tailor the intervention offered to patients and prevent limb loss.

Oxidative stress and rheologic properties of stored red blood cells before and after transfusion to surgical patients

BACKGROUND

The loss of structural and functional integrity of red blood cells (RBCs) during storage, collectively referred to as "storage lesion," has been implicated in reduced oxygen delivery after transfusion. RBCs are highly susceptible to oxidative damage from generation of reactive oxygen species by autoxidation of hemoglobin. Therefore, we examined whether increased oxidative stress (OS) in stored RBCs is associated with impaired cell membrane deformability before or after transfusion.

STUDY DESIGN AND METHODS

Thirty-four patients undergoing multilevel spine fusion surgery were enrolled. OS in RBCs was assessed by the presence of fluorescent heme degradation products and methemoglobin, which were measured with fluorimetric and spectrophotometric methods, respectively. Deformability and aggregation were determined by ektacytometry in stored RBCs, autologous salvaged RBCs, and posttransfusion blood samples.

RESULTS

OS in stored RBCs was significantly increased with longer storage (R = 0.54, p = 0.032) and significantly higher than that in fresh RBCs (9.1 ± 1.3 fluorescent arbitrary units vs. 7.7 ± 0.9 fluorescent arbitrary units, p < 0.001). Deformability decreased (R = -0.60, p = 0.009) with increasing storage duration. OS was elevated (p < 0.05) and deformability was decreased (p < 0.05) in postoperative blood from patients who had undergone moderate (≥4 RBC units) but not minimal or no transfusion. Neither the decrease in deformability of RBCs nor the aggregation changes were correlated with OS.

CONCLUSIONS

Although stored RBCs show signs of increased OS and loss of cell membrane deformability, these changes were not directly correlated and were only evident after moderate but not lower dose transfusion in postoperative surgical patients. These findings suggest that factors other than OS may contribute to impaired rheology with stored RBCs in the clinical setting.

Perioperative management of lower extremity revascularization

Patients presenting for lower extremity revascularization often have multiple systemic comorbidities, making them high-risk surgical candidates. Neuraxial anesthesia and general anesthesia are equivocal in their effect on perioperative cardiac morbidity and improved graft patency. Postoperative epidural analgesia may improve perioperative cardiac morbidity. Systemic antithrombotic and anticoagulation therapy is common among this patient population and may affect anesthetic techniques.

Carotid endarterectomy under local and/or regional anesthesia has less risk of myocardial infarction compared to general anesthesia: An analysis of national surgical quality improvement program database

Multiple studies have evaluated the effect of anesthesia type on carotid endarterectomy with inconsistent results. Our study compared 30-day postoperative myocardial infarction, stroke, and mortality between carotid endarterectomy under local or regional anesthesia and carotid endarterectomy under general anesthesia utilizing National Surgical Quality Improvement Program database. All patients listed in National Surgical Quality Improvement Program database that underwent carotid endarterectomy under general anesthesia and local or regional anesthesia from 2005 to 2011 were included with the exception of patients undergoing simultaneous carotid endarterectomy and coronary artery bypass grafting. The data revealed substantial differences between the two groups compared, and these were adjusted using multiple logistic regression. Postoperative myocardial infarction, stroke, and death at 30 days were compared between the two groups. A total of 42,265 carotid endarterectomy cases were included. A total of 37,502 (88.7%) were performed under general anesthesia and 4763 (11.3%) under local or regional anesthesia. Carotid endarterectomy under local or regional anesthesia had a significantly decreased risk of 30-day postoperative myocardial infarction when compared to carotid endarterectomy under general anesthesia (0.4% vs 0.86%, p = 0.012). No statistically significant differences were found in postoperative stroke or mortality. Carotid endarterectomy under local or regional anesthesia carries a decreased risk of postoperative myocardial infarction when compared to carotid endarterectomy under general anesthesia. Therefore, patients at risk of postoperative myocardial infarction undergoing carotid endarterectomy, consideration of local or regional anesthesia may reduce that risk.

Fibrinogen α-chain-derived peptide is upregulated in hippocampus of rats exposed to acute morphine injection and spontaneous alternation testing

Fibrinogen is a secreted glycoprotein that is synthesized in the liver, although recent in situ hybridization data support its expression in the brain. It is involved in blood clotting and is released in the brain upon injury. Here, we report changes in the extracellular levels of fibrinogen α-chain-derived peptides in the brain after injections of saline and morphine. More specifically, in order to assess hippocampus-related working memory, an approach pairing in vivo microdialysis with mass spectrometry was used to characterize extracellular peptide release from the hippocampus of rats in response to saline or morphine injection coupled with a spontaneous alternation task. Two fibrinopeptide A-related peptides derived from the fibrinogen α-chain – fibrinopeptide A (ADTGTTSEFIEAGGDIR) and a fibrinopeptide A-derived peptide (DTGTTSEFIEAGGDIR) – were shown to be consistently elevated in the hippocampal microdialysate. Fibrinopeptide A was significantly upregulated in rats exposed to morphine and spontaneous alternation testing compared with rats exposed to saline and spontaneous alternation testing (P < 0.001), morphine alone (P < 0.01), or saline alone (P < 0.01), respectively. The increase in fibrinopeptide A in rats subjected to morphine and a memory task suggests that a complex interaction between fibrinogen and morphine takes place in the hippocampus.

Pain Management Strategies for Thoracotomy and Thoracic Pain Syndromes

Pain after thoracic surgery can be severe and, in the acute phase, contribute to perioperative morbidity and mortality. Unfortunately, patients also incur a significant risk of chronic pain. Although there are guidelines for postoperative pain management in these patients, there is no widespread surgical or anesthetic “best practice.” Here, we review the recent literature on techniques specific to perioperative pain control for thoracic patients, including medical management, neuraxial blockade, and other regional techniques, and suggest an algorithm for developing a multimodal pain management strategy.

Regional anesthesia for vascular surgery

Vascular surgical patients are a diverse group of patients who tend to be elderly, with multiple comorbidities, while vascular procedures may involve significant blood loss and ischemia of tissues beyond the arterial obstruction. Regional anesthesia techniques may offer benefits to patients undergoing vascular surgery because of their cardiorespiratory comorbidities. However, this group of patients is commonly receiving multiple medications, including anticoagulants, so regional techniques are not without risks. This review will discuss this topic based around 3 fundamental revascularization procedures, carotid, abdominal aortic aneurysm repair, and infrainguinal surgery, discussing the clinical applications of regional techniques relevant to each key area.

Levobupivacaine differentially suppresses platelet aggregation by modulating calcium release in a dose-dependent manner

OBJECTIVE

Levobupivacaine, an amide local anesthetic widely used in regional anesthesia, is reported in recent studies that it is a potent inhibitor of platelet functions. However, the concentrations of levobupivacaine were limitedly estimated in these reports. Additionally, the mechanisms by which it affects platelet function and blood coagulation is still not entirely known. The purpose of this study was to further investigate its effects on platelet function and the possible signaling mechanisms under various concentrations of levobupivacaine.

METHODS

Blood samples collected from healthy volunteers were separated into whole blood, platelet-rich-plasma and washed platelets. The effect of levobupivacaine on platelet aggregation was studied using platelet function analyzer (PFA-100) and platelet aggregometer. Agonist-induced platelet adenosine triphosphate (ATP) release, cytosolic calcium mobilization, thromboxane B2 (TxB2) secretion and platelet P-selectin translocation under various concentrations of levobupivacaine were investigated.

RESULTS

Our results indicated that levobupivacaine possessed negative effect on platelet aggregation. The closure times of (PFA-100) were lengthened and the agonist-induced platelet aggregation was significantly attenuated by levobupivacaine even at a low dose (50 μgml(-1)). Pretreatment with levobupivacaine produced significant changes in agonist-induced platelet P-selectin translocation, ATP release, thromboxane A2 (TxA2) production, and calcium mobilization in a dose-dependent manner. The p38 mitogen-activated protein kinases (MAPK), protein kinase C (PKC) δ subtype, cytosolic phospholipase A2 (cPLA2), and protein kinase B (PKB or Akt) were involved in collagen-induced platelet signaling, which would be responsible for antiplatelet effects of levobupivacaine.

CONCLUSION

We explored possible targets of levobupivacaine on platelets aggregation signaling mechanisms. Our data revealed that p38 MAPK, PKC δ subtype, cPLA2, and Akt were pathways involved in collagen-induced platelet signaling, which might be responsible for antiplatelet effects of levobupivacaine. Our study did provide direct evidence bolstering the critical mechanisms of levobupivacaine within different contexts. Additionally, levobupivacaine imposed a negative effect on platelet aggregation through multiple signaling pathways.

Outcomes of carotid endarterectomy under general and regional anesthesia from the American College of Surgeons' National Surgical Quality Improvement Program

OBJECTIVE

Despite multiple studies over more than 3 decades, there still is no consensus about the influence of anesthesia type on postoperative outcomes following carotid endarterectomy (CEA). The objective of this study was to investigate whether anesthesia type, either general anesthesia (GA) or regional anesthesia (RA), independently contributes to the risk of postoperative cardiovascular complications or death using the American College of Surgeons' National Surgical Quality Improvement Program (ACS NSQIP) database.

METHODS

Retrospective analysis of elective cases of CEA from 2005 through 2009 was performed. A propensity score model using 45 covariates, including demographic factors, comorbidities, stroke history, measures of general health, and laboratory values, was used to adjust for bias and to determine the independent influence of anesthesia type on postoperative stroke, myocardial infarction (MI), and death.

RESULTS

Of 26,070 cases listed in the ACS NSQIP database, GA and RA were used in 22,054 (84.6%) and 4016 (15.4%) cases, respectively. Postoperative stroke, MI, and death occurred in 360 (1.63%), 133 (0.6%), and 154 (0.70%) patients of the GA group, respectively, and in 58 (1.44%), 11 (0.27%), and 27 (0.67%) patients of the RA group, respectively. Stratification by propensity score quintile and adjustment for covariates demonstrated GA to be a significant risk factor for postoperative MI with an adjusted odds ratio (OR) and confidence interval (CI) of 2.18 (95% CI, 1.17-4.04), P = .01 in the entire study population. The OR for MI was 5.41 (95% CI, 1.32-22.16; P = .019) in the subgroup of patients with preoperative neurologic symptoms, and 1.44 (95% CI, 0.71-2.90; P = .31) in the subgroup of patients without preoperative neurologic symptoms.

CONCLUSIONS

This analysis of a large, prospectively collected and validated multicenter database indicates that GA for CEA is an independent risk factor for postoperative MI, particularly in patients with preoperative neurologic symptoms.

Coronary artery bypass graft surgery up-regulates genes involved in platelet aggregation

BACKGROUND

During and shortly after coronary artery bypass graft (CABG) surgery, there is an increase in thromboembolic events. CABG, a strong inflammatory stimulus, is associated with a hypercoaguable state. Platelets might contribute to this hypercoaguable state because they have a pivotal role in thrombosis. In the days following surgery there is augmented platelet regeneration in response to the inflammatory stimulus.

OBJECTIVES

The aim of this study was to investigate any changes in platelet mRNA profiles to test the hypothesis that post-CABG surgery platelets are associated with a prothrombotic state.

METHODS

Blood was sampled and platelets purified from 11 patients before and 3-6 days after CABG. Gene expression profiling was performed using low density array (LDA) plates for seven of the patients.

RESULTS

Forty-five genes were examined and those significantly up-regulated were glycoprotein (GP)IIb, GPIIIa and cyclooxygenase-1 (COX-1). These findings were confirmed in four more patients, including flow cytometry analysis of the GPIIb/IIIa receptor.

CONCLUSIONS

CABG surgery up-regulates mRNA and protein levels of proteins that are key players in platelet aggregation. Marked elevation of GPIIb/IIIa mRNA levels results in significantly increased GPIIb/IIIa expression in platelets post-CABG surgery, which may be a reason for increased thrombus formation and myocardial infarction after CABG.

The avantgarde carbostent in patients scheduled for undelayable noncardiac surgery

Background. Treatment of patients who need coronary revascularization before undelayable non-cardiac surgery is challenging. Methods. We assessed the safety and efficacy of percutaneous coronary interventions (PCI) using the Avantgarde( TM) Carbostent (CID, Italy) in patients undergoing PCI before undelayable non-cardiac surgery. The Multiplate analyzer point-of-care was used to assess residual platelet reactivity. One major cardiac events (MACE, defined as death, myocardial infarction, and stent thrombosis and major bleeding) were assessed. Results. 42 consecutive patients were analyzed. Total stent length ≥25 mm was observed in 16 (37%) patients. Multivessel stenting was performed in 11 (31.5%) patients. Clopidogrel was interrupted 5 days before surgery in 35 patients, whereas it was stopped the day of the surgery in 7 patients. Surgery was performed after 27 ± 9 (7-42) days from PCI. MACE occurred in one patient (2.4%; 95% confidence interval: 0.01-13%), who had fatal acute myocardial infarction 3 days after abdominal aortic aneurysm surgery and 12 days after stent implantation. No case of major bleeding in the postoperative phase was observed. Conclusions. The present pilot study suggests that, although at least 10-14 days of dual antiplatelet therapy remain mandatory, the Avantgarde( TM) stent seems to have a role in patients requiring undelayable surgery.

Pathogenesis of postoperative adhesion formation

Background

Current views on the pathogenesis of adhesion formation are based on the ‘classical concept of adhesion formation’, namely that a reduction in peritoneal fibrinolytic activity following peritoneal trauma is of key importance in adhesion development.

Methods

A non-systematic literature search (1960–2010) was performed in PubMed to identify all original articles on the pathogenesis of adhesion formation. Information was sought on the role of the fibrinolytic, coagulatory and inflammatory systems in the disease process.

Results

One unifying concept emerged when assessing 50 years of studies in animals and humans on the pathogenesis of adhesion formation. Peritoneal damage inflicted by surgical trauma or other insults evokes an inflammatory response, thereby promoting procoagulatory and antifibrinolytic reactions, and a subsequent significant increase in fibrin formation. Importantly, peritoneal inflammatory status seems a crucial factor in determining the duration and extent of the imbalance between fibrin formation and fibrin dissolution, and therefore in the persistence of fibrin deposits, determining whether or not adhesions develop.

Conclusion

Suppression of inflammation, manipulation of coagulation as well as direct augmentation of fibrinolytic activity may be promising antiadhesion treatment strategies.

Deep vein thrombosis and pulmonary embolism - Prevention, management, and anaesthetic considerations

There is high incidence of venous thromboembolism, comprising of deep vein thrombosis and pulmonary embolism, in hospitalized patients. The need for systemic thromboprophylaxis is essential, especially in patients with inherited or acquired patient-specific risk factors or in patients undergoing surgeries associated with high incidence of postoperative deep vein thrombosis and pulmonary embolism. These patients, on prophylactic or therapeutic doses of anticoagulants, may present for surgery. General or regional anaesthesia may be considered depending on the type and urgency of surgery and degree of anticoagulation as judged by investigations. The dilemma regarding the type of anaesthesia can be solved if the anaesthesiologist is aware of the pharmacokinetics of drugs affecting haemostasis. The anaesthesiologist must keep abreast with the latest developments of methods and drugs used in the prevention and management of venous thromboembolism and their implications in the conduct of anaesthesia.

Activation of Coagulation and Fibrinolysis after Off-Pump Coronary Artery Bypass Grafting with or without Endotracheal General Anesthesia

Objective

In this study, we measured the activity of coagulation and fibrinolysis and clarified the presence of certain differences between off-pump coronary artery bypass grafting (OPCAB) cases and awake off-pump coronary artery bypass grafting (AOCAB) cases to evaluate whether AOCAB is actually safe from the viewpoint of coagulability.

Methods

8 underwent OPCAB and 6 underwent AOCAB. The following factors inducing coagulation and fibrinolysis were measured for upto 5 days after the operation: platelet counts, prothrombin time, activated partial thromboplastin time, fibrinogen, fibrin degeneration products, D-dimer, thrombin-antithrombin III complex (TAT), α2-plasmin inhibitor-plasmin complex, prothrombin fragment 1, 2 (F1+2), thrombomodulin, β-thromboglobulin (β-TG), and platelet factor-4.

Results

At 5 days after the operation, fibrin degeneration products, D-dimer, α2–plasmin inhibitor-plasmin complex, and F1 + 2 levels of the OPCAB group were significantly higher compared with their baseline values and those of the AOCAB group. At 5 days after the operation, thrombin-antithrombin III complex levels of the OPCAB group were significantly higher than those of the AOCAB group. Fibrinogen levels of the OPCAB group were significantly higher than their baseline values at 3 days after the operation (POD3) and 5 days after the operation (POD5).

Conclusions

In this study, the hypercoagulable state at POD5 was suggested in the patients in the OPCAB group, but not in those in the AOCAB group. Further study is necessary to confirm these results, and future studies would evaluate the potential benefit of AOCAB procedure from the viewpoint of perioperative coagulability.

β-blockers and risk of all-cause mortality in non-cardiac surgery

Myocardial ischemia is a frequent complication in patients undergoing non-cardiac surgery and β-blockers may exert a protective effect. The main benefit of β-blockers in perioperative cardiovascular morbidity and mortality is believed to be linked to specific effects on myocardial oxygen supply and demand. β-blockers may exert anti-inflammatory and anti-arrhythmic effects. Randomized clinical trials which evaluated the effects of β-blockers on all-cause mortality in patients undergoing non-cardiac surgery have yielded conflicting results. In 9 trials, 10,544 patients with non-cardiac surgery were randomized to β-blockers (n = 5274) or placebo (n = 5270) and there were a total of 304 deaths. Patients randomized to β-blockers group showed a 19% increased risk of all-cause mortality (odds ratio [OR] 1.19, 95% confidence interval (CI) 0.95-1.50; p = 0.135). However, trials included in the meta-analysis differed in several aspects, and a significant degree of heterogeneity (I 2 = 46.5%) was noted. A recent analysis showed that the surgical risk category had a substantial influence on the overall estimate of the effect of β-blockers. Compared with patients in the intermediate-high-surgical-risk category, those in the high-risk category showed a 73% reduction in the risk of total mortality with β-blockers compared with placebo (OR 0.27, 95% CI 0.10-0.71, p = 0.016). These data suggest that perioperative β-blockers confer a benefit which is mostly limited to patients undergoing high-risk surgery.