Aspirin and postoperative bleeding after coronary artery bypass grafting

Intraoperative use of fibrin glue in blepharoplasty: a possible solution to reduce postoperative complication

The purpose of this study was to investigate the effects of intraoperative fibrin glue use on surgery for blepharoptosis. This retrospective study included patients with acquired blepharoptosis who underwent surgical correction and were followed for at least one month. Patients were classified into two groups depending on whether treated with antithrombotic agents or otherwise. All patients taking antithrombotic agents discontinued with the treatment one week prior to surgery in accordance with our clinical guidelines. Preoperative and postoperative marginal reflex distance 1(MRD1) and ecchymosis grade were evaluated and compared. The subjects were 56 patients (111 eyes) who discontinued antithrombotic agents before surgery and 59 patients (117 eyes) who had never taken antithrombotic agents. Fibrin glue was used in 13 patients (26 eyes, 23.4%) in the antithrombotic group, and 11 patients (21 eyes, 17.9%) in the non-antithrombotic group. The rate of severe ecchymosis was significantly lower in patients who used fibrin glue in the antithrombotic group at 1 week (11.5 vs 40.0%, p = 0.008). However, in non-antithrombotic group, there was no difference in the rate of severe ecchymosis according to the use of fibrin glue at 1 week (14.3 vs 30.2%, p = 0.181). In patients with a history of taking antithrombotic agents, the intraoperative use of fibrin glue is thought to be helpful as it could significantly reduce significant ecchymosis.

Blood loss after coronary artery bypass by aspirin responsiveness assessed with preoperative VerifyNow aspirin testing

BACKGROUND

Aspirin is important for preventing thrombotic events but also increases bleeding complications. Minimizing bleeding while preventing thrombotic events remains challenging in patients undergoing coronary artery bypass grafting (CABG). Establishing the patient's preoperative aspirin response could distinguish patients at risk for perioperative blood loss.

OBJECTIVE

Aim was to compare 12-h blood loss after CABG between aspirin-sensitive and aspirin-resistant patients.

PATIENTS/METHODS

The primary analysis of this substudy of the POPular CABG trial (NCT02352402) included patients that used aspirin monotherapy preoperatively. A preoperative platelet function test by the VerifyNow aspirin assay was performed before CABG and patients were classified as aspirin-sensitive or aspirin-resistant based on an aspirin reaction units cutoff value of 550. The primary end point was 12-hour blood loss after CABG. The secondary end point was, among others, clinical bleeding events after CABG.

RESULTS

A total of 128 patients were included in the primary analysis. Of these, 116 patients were aspirin sensitive and 12 were aspirin resistant. Mean blood loss 12 hours after CABG was 555 ± 278 mL in aspirin-sensitive patients and 406±110 mL in aspirin-resistant patients (P = .04). All bleeding events (n = 15; 11.7%) occurred in aspirin-sensitive patients.

CONCLUSIONS

In patients who are on aspirin preoperatively, aspirin sensitivity was associated with 12-hour blood loss after CABG, suggesting that preoperative VerifyNow aspirin testing could identify patients undergoing CABG at high risk for perioperative bleeding.

Effect of Preoperative Continuation of Aspirin on Postoperative Bleeding After Off-Pump Coronary Artery Bypass Graft: A Prospective Cohort Study

Background

Despite ample evidence of continuing preoperative aspirin to improve coronary artery bypass surgery outcomes, practice for the routine continuation of preoperative aspirin is inconsistent due to concern for increased postoperative bleeding. The purpose of this study was to investigate preoperative aspirin use and its effect on postoperative bleeding after off-pump coronary artery bypass grafting (OPCABG).

Methodology

This cohort study involved patients (n = 74) who underwent OPCABG at a single center between August 2017 and January 2018. After considering the inclusion and exclusion criteria, the patients were divided into two groups: one (n = 37) received tablet aspirin 75 mg till the day of the surgery, and for the other group (n = 37) aspirin was stopped five days before the surgery. Postoperative bleeding was recorded in both groups. After considering preoperative, intraoperative, and postoperative variables, statistical analysis was performed.

Results

There was no significant difference between the two groups concerning peroperative and postoperative variables. In addition, no significant difference was observed between the two groups in chest tube drainage at one, two, three, twenty-four, forty-eight, and seventy-two hours (p = 0.845, 0.126, 0.568, 0.478, 0.342, and 0.717, respectively). No significant difference was seen in the transfusion requirement of blood and fresh frozen plasma (FFP).

Conclusions

Continuation of preoperative aspirin till the day of the surgery is neither associated with an increase in chest tube drainage, reoperation for bleeding complications nor transfusion of blood and FFP.

Is continuation of anti-platelet treatment safe for elective total hip arthroplasty patients?

INTRODUCTION

Acetylsalicylic acid (aspirin) is a commonly prescribed medication, especially in the age group of individuals who undergo elective total hip arthroplasty (THA). Preoperative discontinuation of aspirin is believed to reduce intraoperative bleeding and other complications, but it may increase the risk of perioperative cardiovascular events. In this study we have sought to evaluate the safety of continuous aspirin treatment in patients undergoing elective THA.

MATERIALS AND METHODS

This is a retrospective analysis of a consecutive cohort who underwent elective THA in a tertiary medical center between 2011 and 2018. The cohort was divided into two groups-one that received continuous preoperative aspirin treatment and one that did not. Blood loss, peri- and postoperative complications, readmissions, and short- and long-term mortality were compared between groups.

RESULTS

Out of 757 consecutive patients (293 males, 464 females) who underwent elective primary THA, 552 were in the "non-aspirin" group and 205 were in the "aspirin" group and were not treated preoperative with other medication affecting hemostasis. Perioperative continuation of aspirin treatment did not significantly increase perioperative bleeding, as indicated by changes in hemoglobin levels (P = 0.72). There were no significant differences in short- and long-term mortality (P = 0.47 and P = 0.4, respectively) or other perioperative complications, such as readmission (P = 0.78), deep or superficial infection (P = 1 and P = 0.47, respectively), and cardiovascular events (none in both groups).

CONCLUSION

Peri-operative continuation of aspirin treatment in patients undergoing elective primary THA did not increase perioperative complications or mortality compared to the non-aspirin-treated patients. The protective effects of aspirin from postoperative thrombotic and cardiovascular events are well documented. The current findings dispute the need to preoperatively withhold aspirin treatment in patients undergoing elective primary THA.

Impact of Thrombocytopenia on Postoperative Bleeding Incidence in Patients Receiving Aspirin Following Coronary Artery Bypass Grafting

BACKGROUND

Early postoperative aspirin following coronary artery bypass graft (CABG) surgery has been shown to maintain bypass graft patency, reduce mortality, and prevent adverse cardiovascular events. Despite this known benefit, aspirin may be delayed due to thrombocytopenia and perceived higher bleeding risk. The purpose of this study was to assess the impact of postoperative platelet count on bleeding in patients receiving aspirin after CABG.

METHODS

A retrospective analysis included all patients who underwent CABG surgery at our institution from April 2014 to June 2018 and received aspirin within 24 hours. The primary outcome was International Society on Thrombosis and Hemostasis (ISTH) major bleeding within 7 days (or up to discharge) following CABG surgery compared between patients with and without postoperative thrombocytopenia.

RESULTS

This study included 280 patients. Major bleeding occurred in 24.6% of the population, with no difference when stratified by the presence or absence of postoperative thrombocytopenia (27.3% versus 23.8%, p = 0.571). There was no significant difference in hemoglobin fall (13.6% versus 14%, p = 0.948), transfusion requirement (6.1% versus 4.2%, p = 0.531), or critical site bleeding (12.1% versus 7.9%, p = 0.298).

CONCLUSION

In this single-center analysis of patients who received aspirin within 24 hours of CABG, postoperative thrombocytopenia was not associated with an increase in bleeding.

Early Outcomes of Low Postoperative Bleeding after Off-Pump Coronary Artery Bypass Grafting

Objective

To investigate whether low bleeding influences the early outcomes after off-pump coronary artery bypass grafting (CABG).

Methods

Retrospective analysis of ischemic heart disease patients who underwent off-pump CABG from January 2013 to December 2017. Patients were divided into low-bleeding group (n=659) and bleeding group (n=270), according to total drainage from chest tube during the first postoperative 12 hours. Clinical material and early outcomes were compared between the groups.

Results

Baseline was similar in the two groups. Operation time was 270±51 min in the low-bleeding group and 235±46 min in the bleeding group (P<0.0001). The low-bleeding group presented smaller drainage during the first 12 h (237±47 ml) and shorter mechanical ventilation time (6.86±3.78 h) than the bleeding group (557±169 ml and 10.66±5.19 h, respectively) (P<0.0001). Hemodynamic status was more stable in the low-bleeding group (P<0.0001) and usage rate of more than two vasoactive agents in this group was lower than in the bleeding group (P<0.0001). Number of distal anastomosis, reoperation for bleeding, suddenly increase in chest tube output, intensive care unit (ICU) stay, hospital stay, and other early outcomes had no statistical significance between the groups (P>0.05).

Conclusion

Postoperative bleeding < 300 ml/12 h in off-pump CABG patients did not require blood product transfusion and reoperation and that would contribute to reduction in mechanical ventilation time and maintaining hemodynamic stability. Bleeding < 800 ml during the first postoperative 12 h did not increase infection rates and ICU length of stay.

Comparison of preoperative continuation and discontinuation of aspirin in patients undergoing total hip or knee arthroplasty

INTRODUCTION

Preoperative discontinuation of aspirin (acetylsalicylic acid) can reduce bleeding risk but may increase the risk of perioperative cardiovascular events.

MATERIALS AND METHODS

We retrospectively assessed the impact of preoperative continuation versus discontinuation of aspirin compared with a control group in a cohort of 739 consecutive patients undergoing total hip (THA) (n = 396) or knee arthroplasty (TKA) (n = 343) at a tertiary hospital. Bleeding risk, local complications, orthopaedic outcome, and cardiac and cerebral complications were assessed.

RESULTS

Four hundred and sixty-five patients did not receive antithrombotic or full-dose anticoagulant medication, 175 patients were taking low-dose aspirin, 99 vitamin K antagonists, clopidogrel, or a combination of these drugs. Of the patients taking aspirin, 139 discontinued and 36 continued aspirin. Blood loss and local bleeding complications were comparable in these two groups. TKA patients who continued aspirin more frequently showed marked knee swelling after 1 week than those discontinuing aspirin (35.1 vs. 81.3 %; p = 0.001). However, orthopaedic outcome did not differ significantly between the two groups. There was a trend towards an increased risk of cardiac complications in patients who discontinued aspirin (6.5 vs. 0.0 %; p = 0.107).

CONCLUSIONS

Continuation or discontinuation of aspirin did not show a statistically significant difference in the risk of relevant perioperative bleeding complications in our study. Continuation of aspirin was associated with a transitory increase in knee swelling, but had no effect on orthopaedic outcome. Continuation of aspirin may be associated with a favourable perioperative cardiac outcome. Our data support perioperative continuation of aspirin intake in patients undergoing THA or TKA.

State of the Art: Medical treatment of aspirin exacerbated respiratory disease (AERD)

Aspirin exacerbated respiratory disease (AERD) is characterized as adult onset asthma, nasal polyps, chronic rhinosinusitis, and hypersensitivity to a cyclooxygenase-1 (COX-1) inhibitor, viz aspirin or nonsteroidal antiinflammatory drugs (NSAIDs). The method for diagnosing AERD is with aspirin challenge, and treatment includes aspirin desensitization followed by continued daily aspirin. Although oral challenge has been the mainstay in the United States, lysyl-aspirin has been validated as a diagnostic tool for aspirin-sensitive asthma and will be discussed further in this article. The challenges with aspirin therapy surrounding endoscopy and perioperative aspirin therapy will be discussed. Additionally, daily aspirin therapy is not for everyone. Aspirin is relatively contraindicated in those with a history of gastrointestinal bleed and an absolute contraindication in pregnancy. Aspirin desensitization and subsequent treatment has been shown to be highly effective for AERD.

Safety and Efficacy Outcomes of Preoperative Aspirin in Patients Undergoing Coronary Artery Bypass Grafting

Background:

The administration of aspirin is traditionally discontinued prior to coronary artery bypass grafting (CABG), given a potential risk of excessive postoperative bleeding. Few studies have previously suggested the benefits of continuing aspirin until the time of surgery. The primary aim of this review is to evaluate the effects of preoperative aspirin therapy on several clinically important outcomes in patients undergoing CABG.

Methods:

A meta-analysis of eligible studies of patients undergoing CABG, reporting preoperative aspirin in comparison with no aspirin/placebo and our outcomes, was carried out. The safety outcomes included postoperative bleeding, packed red blood cell (PRBC) transfusion requirements, and reoperation for bleeding. The efficacy outcomes included perioperative myocardial infarction (MI), cerebrovascular accidents (CVAs), and mortality.

Results:

In 8 randomized controlled trials (RCTs; n = 1538), preoperative aspirin increased postoperative bleeding (difference in means = 132.30 mL; 95 % confidence interval [CI] 47.10-217.51; P = .002), PRBC transfusion requirements (difference in means = 0.67 units; 95% CI 0.10-1.24; P = .02), and reoperation for bleeding (odds ratio [OR] = 1.76; 95% CI 1.05-2.93; P = .03). In 19 observational studies (n = 19551), preoperative aspirin increased postoperative bleeding (difference in means = 132.74 mL; 95% CI 45.77-219.72; P = .003) and PRBC transfusion requirements (difference in means = 0.19 units; 95% CI 0.02-0.35; P = .02) but not reoperation for bleeding (OR = 1.13; 95% CI 0.91-1.42; P = .27). Subgroup analyses for RCTs demonstrated that aspirin given at doses ≤ 100 mg/d might not increase the postoperative bleeding, and the dose of 325 mg/d might not be a cutoff value that has clinical and statistical significance. No statistically significant differences in the rate of perioperative MI, CVAs, or mortality were seen between the 2 groups.

Conclusions:

Preoperative aspirin therapy is associated with increased postoperative bleeding, PRBC transfusion requirements, and reoperation for bleeding in patients undergoing CABG. Doses lower than 100 mg/d may minimize the risk of bleeding. Additional RCTs are needed to assess the effects of preoperative aspirin on the safety and efficacy outcomes in patients undergoing CABG.

Antithrombotic effects of aspirin on 1- or 2-level lumbar spinal fusion surgery: a comparison between 2 groups discontinuing aspirin use before and after 7 days prior to surgery

STUDY DESIGN

Retrospective clinical analysis.

OBJECTIVE

To study proper discontinuation date of aspirin in spinal fusion surgery.

SUMMARY OF BACKGROUND DATA

It is thought that excess bleeding can be normalized if aspirin intake is discontinued approximately 7 days before surgery; however, the average life span of a platelet is generally regarded to be 7 to 10 days.

METHODS

From January 2004 to December 2009, a single surgeon performed 182 cases of 1- or 2-level lumbar fusion surgical procedures. Patients who were aspirin users (n = 86) were divided into 2 groups according to the number of days prior to surgery that they discontinued their aspirin use: the aspirin 1 group discontinued their aspirin use 3 to 7 days before surgery and the aspirin 2 group discontinued their aspirin use 7 to 10 days before surgery. Ninety-six patients who did not use aspirin before surgery were selected for the control group. We retrospectively compared the several hematological parameters among the 2 aspirin groups and the control group.

RESULTS

Both the total amount of drained blood and the duration of indwelling of the drainage catheter were significantly less in the control group than in the aspirin 1 group in patients who underwent either type of 1-level fusion surgery. However, those were not significantly different between aspirin 2 group and control group in patients who underwent either type of 1-level fusion surgery. Only drainage catheter was significantly less in the control group than in the aspirin 1 group in patients who underwent 2-level fusion surgery.

CONCLUSION

Only the aspirin 1 group, wherein patients discontinued aspirin use 3 to 7 days before surgery, showed a greater drained blood and drainage catheter than the control group. If aspirin was discontinued 7 days or longer before surgery, there was no difference in the study parameters, compared with the control group.

LEVEL OF EVIDENCE

3.

Safety, Tolerability, Pharmacodynamics, and Pharmacokinetics of Rivaroxaban-an Oral, Direct Factor Xa Inhibitor-Are Not Affected by Aspirin

Rivaroxaban (BAY 59-7939) is an oral, direct Factor Xa inhibitor in advanced clinical development for the prevention and treatment of thromboembolic disorders. This was a randomized, 2-way crossover study in healthy male subjects, with an aspirin run-in period, to examine whether aspirin influences the safety, tolerability, pharmacodynamics, and pharmacokinetics of rivaroxaban. All treatments were well tolerated; drug-related adverse events were mild and transient. Aspirin did not alter the effects of rivaroxaban on Factor Xa activity or clotting tests. Platelet aggregation and bleeding time were not affected by rivaroxaban, and rivaroxaban did not influence the effects of aspirin on these parameters to a clinically relevant extent. Aspirin did not affect the pharmacokinetics of rivaroxaban, including the fraction unbound. This study suggests that there is no clinically relevant interaction between rivaroxaban and aspirin and that the 2 drugs could be administered concomitantly at the doses used in this study.

Antiplatelet drugs: mechanisms and risks of bleeding following cardiac operations

Preoperative antiplatelet drug use is common in patients undergoing coronary artery bypass grafting (CABG). The impact of these drugs on bleeding and blood transfusion varies. We hypothesize that review of available evidence regarding drug-related bleeding risk, underlying mechanisms of platelet dysfunction, and variations in patient response to antiplatelet drugs will aid surgeons as they assess preoperative risk and attempt to limit perioperative bleeding. The purpose of this review is to (1) examine the role that antiplatelet drugs play in excessive postoperative blood transfusion, (2) identify possible mechanisms to explain patient response to antiplatelet drugs, and (3) formulate a strategy to limit excessive blood product usage in these patients. We reviewed available published evidence regarding bleeding risk in patients taking preoperative antiplatelet drugs. In addition, we summarized our previous research into mechanisms of antiplatelet drug-related platelet dysfunction. Aspirin users have a slight but significant increase in blood product usage after CABG (0.5 U of nonautologous blood per treated patient). Platelet adenosine diphosphate (ADP) receptor inhibitors are more potent antiplatelet drugs than aspirin but have a half-life similar to aspirin, around 5 to 10 days. The American Heart Association/American College of Cardiology and the Society of Thoracic Surgeons guidelines recommend discontinuation, if possible, of ADP inhibitors 5 to 7 days before operation because of excessive bleeding risk, whereas aspirin should be continued during the entire perioperative period in most patients. Individual variability in response to aspirin and other antiplatelet drugs is common with both hyper- and hyporesponsiveness seen in 5 to 25% of patients. Use of preoperative antiplatelet drugs is a risk factor for increased perioperative bleeding and blood transfusion. Point-of-care tests can identify patients at high risk for perioperative bleeding and blood transfusion, although these tests have limitations. Available evidence suggests that multiple blood conservation techniques benefit high-risk patients taking antiplatelet drugs before operation. Guidelines for patients who take aspirin and/or thienopyridines before cardiac procedures include some or all of the following: (1) preoperative identification of high-risk patients using point-of-care testing; (2) withdrawal of aspirin or other antiplatelet drugs for a few days and delay of operation in patients at high risk for bleeding if clinical circumstances permit; (3) selective perioperative use of evidence-based blood conservation interventions (e.g., short-course erythropoietin, off-pump procedures, and use of intraoperative blood conservation techniques), especially in high-risk patients; and (4) platelet transfusions if clinical bleeding occurs.

A review of antiplatelet drugs, coronary artery diseases and cardiopulmonary bypass

Platelets play a major role in the thromboembolic diseases and upon vascular injury, especially arterial vascular injury. These platelets rapidly adhere to the exposed subendothelial area, where they become activated by contacting with stimulants. Antiplatelet therapy remains extremely important in treatment and prophylaxis of arterial thromboembolic disorders such as coronary arterial diseases and stroke. The antiplatelet drugs (APDs) are among the most widely used in the world. Based on the molecular targets, APDs are classified as Thromboxane A2 pathway blockers, ADP receptor antagonists, GPIIa/IIIb antagonists, adenosine reuptake inhibitors, phosphodiesterase inhibitors, thrombin receptor inhibitors, and others. Coronary artery bypass graft (CABG) surgery is an important therapeutic approach to treat coronary artery disease. Long-term success after CABG depends on the patency of the bypass vessels. Since platelets play a crucial role in the pathogenesis of thrombosis in the blood vessels, APDs are broadly used to reduce serious cardiovascular events. Platelets also are an integral part of inflammation and APDs have demonstrated to reduce the inflammation mediators in the healthy volunteers and coronary artery disease patients; it will be an interesting topic to determine if platelet inhibition will attenuate CPB-induced systemic inflammatory response syndrome. Due to concerns of post-op bleeding with use of APDs, it is a common practice to withhold APDs prior to surgery; however, recent studies have demonstrated that continuation of APDs prior to surgery (even until the day of surgery) does not increase the risk of post-op bleeding. With extensive use of APDs in cardiovascular thromboembolic events, APD resistance becomes problematic in clinical antiplatelet therapy. Since there is no standardized or universal definition available to quantify APDs resistance, a clinically meaningful definition of APD resistance needs to be developed based on data linking laboratory tests to clinical outcomes in patients.

KEYWORDS

antiplatelet drug, coronary artery diseases, cardiopulmonary bypass, clinical trials, drug resistance, platelet mapping.

Decision making after aspirin, clopidogrel and GPIIb/IIIa inhibitor use

The expanding use of antiplatelet agents in patients who undergo coronary bypass grafting raises the problem of balancing the benefit of this treatment and the risk of increased bleeding after surgery. Aspirin and clopidogrel have different mechanisms of actions, but have in common the irreversibility of the inhibition mechanism. Even if platelets half-life is around 10 days, it is not necessary to wait for this period of time. It can be reasonable to discontinue aspirin two to three days and clopidogrel five days before surgery, even if it was recently suggested to reduce the discontinuation interval to two to three days for the clopidogrel as well. GPIIb/IIIa inhibitors have a short acting action. Reasonably, abciximab has to be stopped, when possible, at least 12 hours before surgery, preferably before 24 hours. On the contrary, tirofiban can also be stopped at the moment of skin incision without harmful effects. Very little is known of eptifibatide, but it seems that it is safe to stop it two to four hours before surgery. Patients with acute coronary syndrome do not need to discontinue any antiplatelet treatment.

The cost-effectiveness of Maze procedures using ablation techniques at the time of mitral valve surgery

BACKGROUND

The classic cut and sew surgical Maze procedure has been shown to reduce atrial fibrillation (AF), and recently newer surgical ablation techniques with reduced technical complexity have been introduced. This study sought to systematically review the efficacy and safety of these newer techniques and to evaluate their long-term cost-effectiveness at the time of scheduled mitral valve (MV) surgery.

METHODS

A systematic literature search and meta-analysis was performed to generate the most reliable efficacy and safety parameter estimates for a Markov decision analysis model comparing MV surgery alone to MV surgery plus an ablation Maze procedure. Both basic and probabilistic sensitivity analyses were conducted.

RESULTS

Based on the six randomized controlled trials (RCTs) identified, the pooled 1-year estimate of AF after surgery alone was 71 percent (95 percent confidence interval [CI], 64 percent to 78 percent). The pooled risk ratio of AF after surgical ablation treatment at the time of mitral valve surgery relative to valve surgery alone was 0.33 (95 percent CI, 0.19 to 0.55). The pooled analyses showed that no statistical significant increases in operative mortality, permanent pacemaker implantation, and postoperative bleeding with the ablative Maze procedures. An ablation-based Maze procedure at the time of mitral valve surgery had an incremental cost-effectiveness ratio (ICER) of $4,446CAD ($3,850US) per quality-adjusted life-year (QALY) compared with valve surgery alone. Specifically costs were an extra $900CAD but with improved clinical outcomes (0.20 QALYs), including a prolonged life expectancy of 0.10 life-years. In one-way sensitivity analyses, survival time after MV surgery had the largest impact on ICER. Other variables influencing the ICER included the risk ratio of AF, utility, and cost estimates. Probabilistic sensitivity analysis suggests that 58.1 percent, 73.9 percent, and 89.3 percent of the simulations of the Maze strategy are cost-effective at willingness to pay thresholds of $20,000, $50,000, and $100,000CAD per QALY gained, respectively.

CONCLUSIONS

Our meta-analysis suggests that a Maze surgical ablation procedure at the time of MV surgery is associated with a reduced postoperative AF risk. Our economic model further suggests that the surgical ablation strategy at the time of mitral valve surgery is likely a cost-effective intervention, provided patients have a good long-term postsurgical prognosis.

Variability in platelet response to the antiplatelet agents aspirin and clopidogrel: mechanisms, measurement, and clinical relevance

Platelet reactivity (eg, platelet adhesion, activation, aggregation) is the underlying pathology for atherothrombotic processes and subsequent ischemic complications. Antiplatelet drugs, including aspirin, dipyridamole, thienopyridines (clopidogrel and ticlopidine), and glycoprotein IIb/IIIa antagonists, have proven efficacy in atherothrombotic event prevention. However, variability of platelet response measured in the laboratory has been reported and is a subject of keen interest.It is unclear to what extent variability of platelet response to antiplatelet agents is associated with clinical outcomes. A better understanding of this issue requires a general consensus for a standard, preferably point-of-care, ex vivo or in vitro assay to determine the effects of antiplatelet agents on key platelet functions. Currently, results using various methods have not yielded an obvious answer. Small-scale studies have examined the correlation between ex vivo inhibition of platelet aggregation or residual platelet activity and clinical endpoints, and although evidence shows that such correlations may exist, results have not been consistent or definitive. Data from large-scale prospective trials are needed to expand our current understanding of the benefits and limitations of utilizing platelet function tests to effectively manage the balance between protection and risks associated with the antiplatelet therapies, aspirin, and clopidogrel.

Aspirin and Tranexamic Acid for Coronary Artery Surgery (ATACAS) Trial: rationale and design

BACKGROUND

Despite some concern that recent aspirin ingestion increases blood loss after coronary artery surgery, there is some evidence that this may reduce thrombotic complications. In contrast, antifibrinolytic drugs can reduce blood loss in this setting, but there is concern that they may increase thrombotic complications. Published guidelines are limited by a lack of large randomized trials addressing the risks and benefits of each of these commonly used therapies in cardiac surgery. The ATACAS Trial is a study comparing aspirin, tranexamic acid, or both, with placebo in patients undergoing on-pump or off-pump coronary artery surgery.

METHODS

We discuss the rationale for conducting ATACAS, a 4600-patient, multicenter randomized trial in at-risk coronary artery surgery, and the features of the ATACAS study design (objectives, end points, target population, allocation, treatments, patient follow-up, and analysis).

CONCLUSIONS

The ATACAS Trial will be the largest study yet conducted to ascertain the benefits and risks of aspirin and antifibrinolytic therapy in coronary artery surgery. Results of the trial will guide the routine clinical care of patients in this setting.

Perioperative blood transfusion and blood conservation in cardiac surgery: the Society of Thoracic Surgeons and The Society of Cardiovascular Anesthesiologists clinical practice guideline

BACKGROUND

A minority of patients having cardiac procedures (15% to 20%) consume more than 80% of the blood products transfused at operation. Blood must be viewed as a scarce resource that carries risks and benefits. A careful review of available evidence can provide guidelines to allocate this valuable resource and improve patient outcomes.

METHODS

We reviewed all available published evidence related to blood conservation during cardiac operations, including randomized controlled trials, published observational information, and case reports. Conventional methods identified the level of evidence available for each of the blood conservation interventions. After considering the level of evidence, recommendations were made regarding each intervention using the American Heart Association/American College of Cardiology classification scheme.

RESULTS

Review of published reports identified a high-risk profile associated with increased postoperative blood transfusion. Six variables stand out as important indicators of risk: (1) advanced age, (2) low preoperative red blood cell volume (preoperative anemia or small body size), (3) preoperative antiplatelet or antithrombotic drugs, (4) reoperative or complex procedures, (5) emergency operations, and (6) noncardiac patient comorbidities. Careful review revealed preoperative and perioperative interventions that are likely to reduce bleeding and postoperative blood transfusion. Preoperative interventions that are likely to reduce blood transfusion include identification of high-risk patients who should receive all available preoperative and perioperative blood conservation interventions and limitation of antithrombotic drugs. Perioperative blood conservation interventions include use of antifibrinolytic drugs, selective use of off-pump coronary artery bypass graft surgery, routine use of a cell-saving device, and implementation of appropriate transfusion indications. An important intervention is application of a multimodality blood conservation program that is institution based, accepted by all health care providers, and that involves well thought out transfusion algorithms to guide transfusion decisions.

CONCLUSIONS

Based on available evidence, institution-specific protocols should screen for high-risk patients, as blood conservation interventions are likely to be most productive for this high-risk subset. Available evidence-based blood conservation techniques include (1) drugs that increase preoperative blood volume (eg, erythropoietin) or decrease postoperative bleeding (eg, antifibrinolytics), (2) devices that conserve blood (eg, intraoperative blood salvage and blood sparing interventions), (3) interventions that protect the patient's own blood from the stress of operation (eg, autologous predonation and normovolemic hemodilution), (4) consensus, institution-specific blood transfusion algorithms supplemented with point-of-care testing, and most importantly, (5) a multimodality approach to blood conservation combining all of the above.

Does the Use of Preoperative Aspirin Increase the Risk of Bleeding in Patients Undergoing Coronary Artery Bypass Grafting Surgery? Systematic Review and Meta-Analysis

BACKGROUND

The traditional recommendation has been to stop Aspirin seven to 10 days prior to coronary artery bypass surgery to reduce the potential risk of bleeding. A few reports have shown that Aspirin did not increase the risk of bleeding and may be beneficial to be continued until the time of surgery. The objective of this review was to evaluate the effect of preoperative Aspirin on bleeding in patients undergoing elective bypass surgery.

METHODS

A meta-analysis of 10 randomized and nonrandomized studies reporting comparisons between Aspirin and control was undertaken. The primary outcome was the total amount of postoperative chest tube drainage. Secondary outcomes were the number of units of packed red blood cell transfusion, platelet transfusion, fresh frozen plasma transfusion, and number of patients reexplored for bleeding.

RESULTS

Ten studies, involving 1748 patients, met the inclusion criteria for this review of whom 913 were in the Aspirin group and 835 were in the control group. Pooling the results of all studies showed a significant increase in blood loss and transfusion of red blood cells and fresh frozen plasma in the Aspirin group (p < 0.05). There was no significant difference between the two groups in the rate of platelet transfusion, or the incidence of reexploration (p > 0.05). Included studies were heterogeneous and of low methodological quality.

CONCLUSION

Aspirin is associated with increased chest tube drainage and may be associated with a greater requirement for blood products. High-quality prospective studies are warranted to reassess the effect of Aspirin on important postoperative outcomes.

Antiplatelet therapy preceding coronary artery surgery

BACKGROUND AND OBJECTIVE

Bleeding after cardiac surgery correlates with morbidity and mortality. The aim of this study was to determine the influence of antiplatelet therapy on bleeding and transfusion rates in coronary artery bypass grafting.

METHODS

Forty patients receiving aspirin and/or clopidogrel/ticlopidine within 7 days prior to surgery were retrospectively compared to 40 control patients lacking antiplatelet therapy for at least 8 preoperative days. Blood loss was assessed as chest-tube drainage during the first 12 h after surgery. Units transfused were recorded intraoperatively and during stay in the intensive care unit.

RESULTS

Both groups were comparable for pre- and intraoperative data. Irrespective of single or combined antiplatelet therapy, treated patients demonstrated lower fractions of the creatine-kinase isoenzyme MB (5.8 +/- 3.1 vs. 8.2 +/- 4.1%; P = 0.004) and infarction rates (0 vs. 3; P = 0.240) than control patients, but had significantly more haemorrhages (940 +/- 861 mL vs. 412 +/- 590 mL; P = 0.002) and transfusion requirements (red cells: 4.5 +/- 4.9 vs. 1.5 +/- 2.3, plasma: 4.9 +/- 6.4 vs. 1.3 +/- 2.5, platelets: 1.5 +/- 1.3 vs. 0.1 +/- 0.2; all P < or = 0.001). The differences to control patients were more pronounced for only short antiplatelet therapy free intervals or ongoing antiplatelet therapy (P < or = 2 days < or = 0.019). For antiplatelet therapy free intervals longer than 2 days, bleeding and transfusion rates (except for platelets) were nonsignificantly higher as compared to control patients (P > or = 0.058).

CONCLUSIONS

To overcome increased blood loss and transfusion rates, antiplatelet therapy should be discontinued for at least 2 days before elective coronary surgery. Whether patients at high risk for myocardial infarction might benefit from ongoing antiplatelet therapy remains to be investigated.

Update on the role of non-opioids for postoperative pain treatment

Non-opioids play an ever increasing role in the treatment of postoperative pain; either on their own for mild to moderate pain or in combination with other analgesic approaches, in particular opioids, as a component of multimodal analgesia. The analgesics paracetamol (acetaminophen) and dipyrone (metamizole) as well as compounds with an additional anti-inflammatory effect (non-selective non-steroidal anti-inflammatory drugs and selective cyclo-oxygenase-2 inhibitors) are used widely in the perioperative period. Paracetamol is gaining renewed interest in this setting due to its minimal adverse effects and recent availability in a parenteral preparation, but its benefits are insufficiently studied. Dipyrone continues to be used in many countries despite the ongoing debate on the incidence and relevance of its ability to cause agranulocytosis. Among the anti-inflammatory drugs, selective cyclo-oxygenase-2 inhibitors have the most supportive data for their beneficial effects as a component of multimodal analgesia and offer benefits with regard to their adverse effect profile.

The influence of new antithrombotic drugs on regional anesthesia

PURPOSE OF REVIEW

Antithrombotic drugs are known to increase the risk of spinal epidural hematoma after neuraxial blockade. During the last few years, several new anticoagulants have been introduced, some of them more potent than the drugs currently available. More potency, however, may also indicate a higher risk of bleeding.

RECENT FINDINGS

Case series from the last few years indicate that spinal epidural hematoma is more common then previously estimated, with a prevalence from 1: 100,000 in obstetric patients to as high as 1: 3,600 in female orthopedic patients. In order to diminish this risk, most national societies have issued guidelines in which time intervals were established between administration of antithrombotic drugs and performance of neuraxial blockade.

SUMMARY

Guidelines are perceived to be capable of reducing the incidence of spinal epidural hematoma with the inherent risk of permanent paraplegia. These guidelines, however, will only be a valuable aid for clinicians if they are constantly updated and newer antithrombotic drugs are included. Although the resurge of peripheral nerve blocks may diminish patient hazards, deep nerve blocks such as lumbar sympathetic blockade are not devoid of serious complications and should probably be handled in the same way as neuraxial blockade.

Impact of platelet testing on presurgical screening and implications for cardiac and noncardiac surgical procedures

Bleeding is a common complication of cardiac surgery, accounting for a significant portion of the total transfusions performed in the United States. This may be due in part to surgical factors and to the fibrinolysis and platelet activation induced by cardiopulmonary bypass. The increasing frequency with which antiplatelet medications are used to prevent thrombosis in cardiac surgical patients with cardiovascular disease also elevates the risk for postoperative bleeding. The resulting coagulopathy and need for transfusions may increase morbidity and mortality risk in cardiac surgical patients, depending on the specific antiplatelet agent used, as well as on patient factors. Empiric platelet transfusion, the frequency of which varies greatly among institutions, does not reliably prevent these complications and may even increase the risk for adverse outcomes. Platelet function testing, particularly with newer testing systems, may be a valuable tool for making decisions about stopping antiplatelet drug administration, surgical timing with respect to bleeding risk, and platelet transfusion in cardiac surgical patients.