Low-dose preoperative aspirin therapy, postoperative blood loss, and transfusion requirements

A longitudinal study to evaluate the bleeding pattern of patients on low dose aspirin therapy following dental extraction

Background and Aims:

Antiplatelet dugs are often interrupted preceding invasive dental extraction because of concern of bleeding complications. The fear of uncontrolled bleeding often prompts medical and dental practitioners to stop aspirin intake for 7 to 10 days before any surgical procedure, which puts the patient at risk from adverse thrombotic events. The aim of the study conducted was to evaluate the bleeding pattern after routine dental extraction among patients on low dose long term aspirin therapy.

Methods:

A total of 104 subjects in the age group of 30-65 years, who continued to have aspirin intake during extraction were included in the study. Dental extraction was performed without stopping aspirin therapy under local anesthesia. The post-operative blood loss was quantified by weighing the gauze pre and post operatively and adding total volume of fluid in the suction jar.

Results:

Of these 104 patients treated, 87% of patients had mild bleeding (<20 ml) and 13% of patients had moderate bleeding (20-30 ml). The total study population showed a mean blood loss of 16.15 ± 3.5 ml.

Conclusion:

Within in the limitations, our study concluded that the routine dental extraction in patients under low dose aspirin therapy did not cause clinically significant post extraction hemorrhage. Aspirin intake can be continued during routine dental extraction as post extraction bleeding encountered will be negligible.

Anticoagulation, bleeding and blood transfusion practices in Australasian cardiac surgical practice

We surveyed contemporary Australasian cardiac surgical and anaesthetic practice, focusing on antiplatelet and antifibrinolytic therapies and blood transfusion practices. The cohort included 499 sequential adult cardiac surgical patients in 12 Australasian teaching hospitals. A total of 282 (57%) patients received red cell or component transfusion. The median (IQR) red cell transfusion threshold haemogloblin levels were 66 (61-73) g/l intraoperative^ and 79 (74-85) g/l postoperatively. Many (40%) patients had aspirin within five days of surgery but this was not associated with blood loss or transfusion; 15% had Clopidogrel within seven days of surgery. In all, 30 patients (6%) required surgical re-exploration for bleeding. Factors associated with transfusion and excessive bleeding include pre-existing renal impairment, preoperative Clopidogrel therapy, and complex or emergency surgery. Despite frequent (67%) use of antifibrinolytic therapy, there was a marked variability in red cell transfusion rates between centres (range 17 to 79%, P <0.001). This suggests opportunities for improvement in implementation of guidelines and effective blood-sparing interventions. Many patients presenting for surgery receive antiplatelet and/or antifibrinolytic therapy, yet the subsequent benefits and risks remain unclear.

Heparin Dosing and Postoperative Blood Loss in Patients Taking Aspirin

A large number of patients scheduled to undergo elective coronary artery bypass grafting continue to take aspirin along with other antianginal medication up to the day of surgery. Patients taking aspirin preoperatively are known to bleed more in the postoperative period than those not taking aspirin. This study was undertaken to determine whether the method of heparin administration (protocol-based bolus dose versus an individualized dose) affected postoperative blood loss or requirements of blood and blood products in patients taking aspirin preoperatively. In this prospective study, 300 consecutive patients taking aspirin prior to coronary artery bypass graft surgery were randomly assigned to receive heparin either as a protocol-based bolus of 400 IU·kg−1 (group A) or according to a dose-response curve to obtain an activated coagulation time of 500 seconds on cardiopulmonarybypass (group B). Group B required significantly less heparin (mean 275 IU·kg−1)and less protamine than group A. Postoperative blood loss, requirement of blood and blood products, and time spent on hemostasis in group B was significantly less at 24 hours than group A. We concluded that individualized dosing of heparin using a dose-response curve is preferable to a protocol-based bolus heparin dose in patients taking preoperative aspirin.

Cerebrovascular emergencies in pregnancy

Caring for pregnant and postpartum patients with neurological disease carries specific challenges. In performing a diagnosis, it is often difficult to differentiate between true pathology and neurological symptoms resulting from normal pregnancy physiology. Treating the pregnant patient can be problematic as well. Providers need to be aware of the possible untoward effects of maternal treatments on the developing fetus, but not withhold therapies that reduce disease-related morbidity and mortality. Given the complexities of conducting trials during pregnancy, few treatments are based on high-quality data; observational data and clinical expert opinion often guide treatments. With the exception of preeclampsia/eclampsia, neurological diseases typically do not warrant early delivery in the absence of fetal distress. Multidisciplinary care, utilizing the expertise of anesthesiology, critical care medicine, emergency medicine, maternal-fetal medicine, neurology, and radiology, is essential in ensuring prompt diagnosis and treatment.

Influence of aspirin on post-extraction bleeding - A clinical study

Aim:

The aim of the study was to evaluate the influence of aspirin on post-extraction bleeding in a clinical setup.

Materials and Methods:

Two hundred patients aged between 50 and 65 years who were indicated for dental extraction for endodontic reason were selected from the outpatient Department of Oral and Maxillofacial Surgery. The patients were randomly divided into aspirin continuing group (group A) and aspirin discontinuing group (group B). After checking all the vital signs, the extractions were carried out. Bleeding time and clotting time were recorded for evaluation by Chi-square test.

Results:

Chi-square test revealed that the bleeding time increased (3.8 ± 0.75) in group A patients continued with the aspirin therapy where as group B discontinued aspirin. Similarly, the clotting time increased in group B patients and decreased in group A patients. But in both the groups, bleeding and clotting time remained within normal limits.

Conclusion:

Reviewing most of the dental and medical literature, it can be concluded that there is absolutely no need to discontinue antiplatelet therapy for any ambulatory dental procedure, and even if the practitioner wishes to discontinue, it should not be for more than 3 daAQ2ys. This is also stated in the guidelines of the American Heart Association.

Dental extraction can be performed safely in patients on aspirin therapy: a timely reminder

Cardiac patients on aspirin therapy may require extractions for their diseased teeth. It is a common practice among physicians and treating surgeons to stop aspirin prior to tooth extraction because of fear of bleeding complications. This practice often predisposes the patient to adverse thromboembolic events. This practice is based on theoretical risk of bleeding and on isolated case reports of excessive bleeding with aspirin therapy. The current consensus and recommendations are in favor of continuing aspirin therapy during simple tooth extraction as the bleeding complication incidence is very less and if it occurs can be controlled efficiently with local hemostasis measures.

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.

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.

Effect of timing of chronic preoperative aspirin discontinuation on morbidity and mortality in patients having combined coronary artery bypass grafting and valve surgery

The objective of this study was to determine if late use of aspirin before coronary artery bypass grafting (CABG) with valve surgery affects bleeding events and major adverse cardiovascular events. Aspirin has been shown to decrease postoperative CABG mortality and ischemic events. There are no data on the time of aspirin discontinuation and its effect on CABG with valve surgery and bleeding complications. From January 1, 2002 to January 31, 2008, 1,963 patients undergoing nonurgent plus valve surgery at the Cleveland Clinic were on preoperative aspirin; 1,404 (72%) discontinued aspirin ≥ 6 days before surgery (early discontinuation) and 559 (28%) continued aspirin within 5 days of surgery (late use). Propensity-score analysis and matching were employed for fair comparison of outcomes. There was no difference between early-discontinuation and late-use groups in the composite outcome of in-hospital mortality, myocardial infarction, and stroke (5.3% in the 2 groups). More patients in the late-use group received postoperative transfusions (49% vs 42%, p = 0.02). There was a trend toward increased reoperation for bleeding (6.1% vs 3.7%, p = 0.08) in the late-use group. In conclusion, in patients undergoing CABG with valve surgery, there was an increased use of postoperative red blood cell transfusion and a trend toward increased reoperation for bleeding in the late-use group. There was no difference in major adverse cardiac events between groups. Late use of aspirin in CABG with valve surgery must be weighed against an increased risk of bleeding.

Platelet function recovery after cessation of aspirin: preliminary study of volunteers and surgical patients

BACKGROUND AND OBJECTIVE

Recent evidence indicates that platelet function may recover more rapidly after cessation of aspirin therapy than previously thought. The present study evaluated the effect of aspirin on platelet function using platelet aggregometry in healthy individuals and in aspirin-treated patients scheduled for surgery.

METHODS

Platelet aggregation in response to arachidonic acid, epinephrine, and adenosine diphosphate was determined in 14 male volunteers during and after 10 days' aspirin administration (100 mg) and in 58 aspirin-treated patients during intake, on days 3, 4 or 6 after drug cessation, and on day 10 after drug cessation, prior to elective surgery. Urine thromboxane (11-dehydro-thromboxane B2) concentrations were also measured.

RESULTS

Platelet aggregation in response to arachidonic acid and epinephrine was significantly decreased in both volunteers and patients during aspirin administration. The aggregation normalized within 3 days of aspirin cessation in the volunteers and within 4-6 days in the patients. Urine concentration of 11-dehydro-thromboxane B2 was about three times lower with aspirin treatment than without, although in two patients concentrations were higher with aspirin.

CONCLUSION

Platelet aggregometry with arachidonic acid is a sensitive test for the evaluation of the effects of aspirin on platelet function. In most aspirin-treated patients, platelet function recovers 4 days after drug cessation, although the process is sometimes prolonged. Therefore, the time of aspirin cessation before scheduled surgery should be determined individually.

Management of platelet-directed pharmacotherapy in patients with atherosclerotic coronary artery disease undergoing elective endoscopic gastrointestinal procedures

The periprocedural management of patients with atherosclerotic coronary heart disease, including those who have heart disease and those who are undergoing percutaneous coronary intervention and stent placement who might require temporary interruption of platelet-directed pharmacotherapy for the purpose of an elective endoscopic gastrointestinal procedure, is a common clinical scenario in daily practice. Herein, we summarize the available information that can be employed for making management decisions and provide general guidance for risk assessment.

Management of platelet-directed pharmacotherapy in patients with atherosclerotic coronary artery disease undergoing elective endoscopic gastrointestinal procedures

The periprocedural management of patients with atherosclerotic coronary heart disease, including those who have heart disease and those who are undergoing percutaneous coronary intervention and stent placement who might require temporary interruption of platelet-directed pharmacotherapy for the purpose of an elective endoscopic gastrointestinal procedure, is a common clinical scenario in daily practice. Herein, we summarize the available information that can be employed for making management decisions and provide general guidance for risk assessment.

Aspirin in pregnancy

Aspirin, acetylsalicylic acid, is the most frequently consumed drug in pregnancy, taken mostly without a prescription because of headache or a minor ailment. Numerous preparations containing acetylsalicylic acid are freely available over the counter under a variety of proprietary names, and in many cases pregnant women and their doctors may be unaware that aspirin is being taken.

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.

Patients with rheumatoid arthritis undergoing surgery: how should we deal with antirheumatic treatment?

OBJECTIVES

To review published data on the perioperative management of antirheumatic treatment and perioperative outcome in patients with rheumatoid arthritis (RA).

METHODS

The review is based on a MEDLINE (PubMed) search of the English-language literature from 1965 to 2005, using the index keywords "rheumatoid arthritis" and "surgery". As co-indexing terms the different disease-modifying antirheumatic drugs (DMARDs) as well as nonsteroidal anti-inflammatory drugs (NSAIDs) and "glucocorticoids" were used. In addition, citations from retrieved articles were scanned for additional references. Furthermore, because the number of published articles is so limited, relevant abstracts presented at congresses were included in the analysis.

RESULTS

Continuation of methotrexate (MTX) appears to be safe in the perioperative period. Only a limited number of studies address the use of leflunomide and the results are conflicting. Because of the very long drug half-life, its discontinuation would need to be of long duration and is probably not necessary. Data on hydroxychloroquine do not show increased risks of infection. Regarding sulfasalazine, there are no studies from which definite answers could be drawn on whether it should be withheld perioperatively. Preliminary data show that the risk of infections during treatment with TNF-blocking agents may be lower than initially expected. The only available recommendation (Club Rhumatismes et Inflammation, CRI) suggests discontinuing the drugs before surgery for several weeks, depending on the risk of infection and the drug used. They should not be restarted until wound healing is complete. To avoid the antiplatelet effect during surgery, NSAIDs other than aspirin should be withheld for a duration of 4 to 5 times the drug half-life. Patients with chronic glucocorticoid therapy and suppressed hypothalamic-pituitary-adrenal (HPA) axis need perioperative supplementation.

CONCLUSIONS

While continuation of MTX likely is safe, data on other DMARDs are sparse. In particular, more data on the perioperative use of the biologic agents are needed.

Discontinuation of perioperative antiplatelet and anticoagulant therapy in stroke patients

Growing evidence suggests that perioperative withdrawal of ASA for secondary stroke prevention increases thromboembolic risk without the associated benefit of decreased bleeding complications. ASA maintenance is acceptable in many procedures, including invasive ones. Many procedures, in particular ophthalmologic, dermatologic, and dental surgeries, also are safe while continuing oral AC. Warfarin has been continued successfully even in some surgeries that have high bleeding risk. When the risk is too high, temporary bridging therapy with LWMH is safe in many populations. Although the exact thromboembolic risks associated with temporary cessation of AP and AC are unknown and likely low, morbidity and mortality associated with thromboembolism are high. Further studies investigating the risks and benefits of maintaining AP and AC during procedures, particularly invasive ones, are needed. Meanwhile, it is critical that physicians understand the risks and benefits of perioperative AP and AC and the variety of procedures in which these agents can be safely continued.

Low-dose aspirin before intracranial surgery--results of a survey among neurosurgeons in Germany

BACKGROUND

Increasing numbers of patients presenting for intracranial surgery are receiving concurrent medication with low-dose aspirin, leading to dysfunctional circulating platelets, which might increase the peri-operative risk of bleeding.

OBJECTIVE

To survey the opinions and working practices of neurosurgical facilities in Germany regarding patients who present with low-dose aspirin medication before elective intracranial surgery. Methods. Questionnaires were sent to 210 neurosurgical facilities asking five main questions: (1) the adherence of any policy of stopping aspirin pre-operatively, (2) the personal risk assessment for patients with brain surgery under low-dose aspirin medication, (3) the preferred method of treatment for excessive bleeding in this context, (4) personal knowledge of haemorrhagic complications in this group of patients, and (5) the characteristics of the neurosurgical units concerned.

RESULTS

There were 138 (65.7%) valid responses. Of the respondents, 111 (80.4%) had a departmental policy for the discontinuation of pre-operative aspirin treatment. The mean time for discontinuation of aspirin pre-operatively was 7.3 days (range: 0-21 days). 107 respondents (77.5%) considered that patients taking low-dose aspirin were at increased risk for excessive peri-operative haemorrhage, and 80 (58%) reported having personal experience of such problems. Ninety-seven respondents (70.3%) would use special medical therapy, preferably desmopressin, if haemorrhagic complications developed intra-operatively. The mean amount of intracranial operations per year in each neurosurgical facility was 494 (range: 50-1700).

CONCLUSIONS

The majority of neurosurgical facilities in Germany have distinct departmental policies concerning the discontinuation of low-dose aspirin pre-operatively, with an average of 7.3 days. Three-quarter of the respondents felt that aspirin was a risk factor for haemorrhagic complications associated with intracranial procedures, and more than half of the interviewees reported having personal experience of such problems. Various medicamentous methods of counteracting aspirin-induced platelet dysfunction and excessive bleeding in this context are discussed and evaluated.

Low-dose aspirin before spinal surgery: results of a survey among neurosurgeons in Germany

The main problem faced by the increasing numbers of patients presenting for spinal surgery are receiving concurrent medication with low-dose aspirin, leading to dysfunctional circulating platelets. The contribution of low-dose aspirin to increased peri-operative risk of bleeding and blood loss is a contentious issue with conflicting published results from different surgical groups. Data from neurosurgical spine patients is sparse, but aspirin has been identified as an important risk factor in the development of post-operative hematoma following intracranial surgery. We surveyed the opinions and working practices of the neurosurgical facilities performing spinal operations in Germany regarding patients who present for elective spinal surgery. Identical questionnaires were sent to 210 neurosurgical facilities and proffered five main questions: (1) the adherence of any policy of stopping aspirin pre-operatively, (2) the personal risk assessment for patients with spinal surgery under low-dose aspirin medication, (3) the preferred method of treatment for excessive bleeding in this context, (4) personal knowledge of hemorrhagic complications in this group of patients, and (5) the characteristics of the neurosurgical units concerned. There were 145 (69.1%) responses of which 142 (67.6%) were valid. Of the respondents, 114 (80.3%) had a (written) departmental policy for the discontinuation of pre-operative aspirin treatment, 28 (19.7%) were unaware of such a policy. The mean time suggested for discontinuation of aspirin pre-operatively was 6.9 days (range: 0-21 days), with seven respondents who perform the operations despite the ongoing aspirin medication. Ninety-four respondents (66.2%) considered that patients taking low-dose aspirin were at increased risk for excessive peri-operative hemorrhage or were indetermined (8.6%), and 73 (51.4%) reported having personal experience of such problems. Ninety-two respondents (65.5%) would use special medical therapy, preferably Desmopressin alone or in combination with other blood products or prohemostatic agents (46.1%), if hemorrhagic complications developed intra- or post-operatively. The average number of spinal operations per year in each service was 607.9 (range: 40-1,500). Despite the existence of distinct departmental policies concerning the discontinuation of low-dose aspirin pre-operatively in the majority of neurosurgical facilities performing spinal operations, there is a wide range of the moment of this interruption with an average of 7 days. Two-thirds of the respondents felt that aspirin was a risk factor for hemorrhagic complications associated with spinal procedures, and more than half of the interviewees reported having personal experience of such problems. Finally, various medicamentous methods of counteracting aspirin-induced platelet dysfunction and excessive bleeding in this context are elicited, discussed and evaluated.

Balancing the benefit and risk of oral antiplatelet agents in coronary artery bypass surgery

Concern about possible hemorrhagic complications arising from use of oral antiplatelet agents in immediate proximity to coronary artery bypass graft (CABG) surgery leads many clinicians to avoid or discontinue these agents preoperatively. Recent evidence suggests that aspirin and clopidogrel can be used with relative safety in the preoperative period; dual antiplatelet therapy in the 5 days immediately preceding CABG surgery results in a moderate and variable increase in the risk of procedural bleeding. This modest hemorrhagic risk may be acceptable, given the clinical benefits of sustained antiplatelet therapy in preventing graft occlusion and ischemic complications pre- and post-CABG. Because the bleeding risk with aspirin is dose dependent, use of a low dose is preferred post-CABG.

Antithrombotic therapy in cardiac surgery

PURPOSE

To review the perioperative management of antithrombotic therapy in cardiac surgery, including the management of cardiopulmonary bypass (CPB) and off-pump surgery.

METHODS

A review of the relevant English literature over the period 1975-2005 was undertaken, in addition to a review of international practices in antithrombotic therapy in cardiac surgery.

PRINCIPAL FINDINGS

Cardiopulmonary bypass is required in most procedures and makes anticoagulation mandatory. Anticoagulation is, usually, achieved with unfractionnated heparin (UFH). Unfractionated heparin is monitored by point-of-care (POC) testing, such as the activated clotting time or the determination of heparin concentration. The target values of both tests remain empirical, with no clearly validated thresholds. The target value needs to be adjusted according to the POC test, given significant variations between devices and activators. After CABG, the need for antiplatelet therapy is well demonstrated, in order to limit the risk of postoperative death or ischemic events, and improve venous graft patency. Immediately after valvular surgery, antithrombotic therapy should take into account the specific risk carried by each patient and by each prosthetic device. The risk of venous thromboembolism, though poorly defined, is also present in the postoperative period and may require additional attention. Given the frequent exposure to UFH, occurrence of heparin-induced thrombocytopenia is not infrequent in these patients and requires careful individual management.

CONCLUSIONS

Antithrombotic therapy is an essential component of cardiac surgery. Yet, with the exception of antiplatelet agents in CABG patients, antithrombotic therapy is often based on the clinical experience of medical teams more than on an evidence-based assessment of the literature.

A comparison of Plateletworks and platelet aggregometry for the assessment of aspirin-related platelet dysfunction in cardiac surgical patients

OBJECTIVE

To compare the assessment of aspirin-related platelet dysfunction using Plateletworks (Helena Laboratories, Beaumont, TX), a new point-of-care platelet function analyzer, with turbidometric platelet aggregometry, in cardiac surgical patients.

DESIGN

Prospective observational study.

SETTING

University-affiliated teaching hospital.

PARTICIPANTS

Fifty consecutive adult patients undergoing elective cardiac surgery for coronary artery bypass grafting or cardiac valve replacement.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Platelet function was assessed by Plateletworks and turbidometric platelet aggregometry before the commencement of anesthesia. Collagen, 10 microg/mL, was used as the agonist for both techniques. The area under the receiver-operator curve for the identification of recent aspirin ingestion (<or=48 hours v >or=72 hours) using Plateletworks was 0.58 (95% confidence interval [CI] 0.42-0.75) versus 0.77 (95% CI 0.61-0.95) for turbidometric platelet aggregometry. The Spearman correlation coefficient (rho) between preoperative Plateletworks trade mark and postoperative mediastinal blood loss was 0.07 (p = 0.58), and between preoperative turbidometric platelet aggregometry and postoperative mediastinal blood loss was -0.31 (p = 0.03). On completion of surgery, the correlation coefficients were 0.14 (p = 0.34) and -0.29 (p = 0.08), respectively.

CONCLUSION

These findings suggest that Plateletworks is of limited use for the detection of aspirin-related platelet defects in cardiac surgical patients.

Prophylactic Treatment with Desmopressin Does Not Reduce Postoperative Bleeding After Coronary Surgery in Patients Treated with Aspirin Before Surgery

The synthetic vasopressin analog desmopressin has hemostatic properties and may reduce postoperative bleeding after coronary artery bypass grafting (CABG). A study on the effects of recent aspirin ingestion on platelet function in cardiac surgery showed a greater impairment of platelet function in patients treated with aspirin <2 days before the operation. We evaluated the effects of desmopressin on postoperative bleeding in CABG patients who were treated with aspirin 75 or 160 mg until the day before surgery. The study was a prospective, randomized, double-blinded, placebo-controlled, parallel group trial. One-hundred patients were included and divided into two groups. One group received desmopressin 0.3 micro g/kg and the other received placebo (0.9% NaCl) after the neutralization of heparin with protamine sulfate. Postoperative blood loss was recorded for 16 h. The mean (SD) bleeding was 606 (237) mL in the desmopressin group and 601 (301) mL in the placebo group (P = 0.93), representing no significant difference (95% confidence interval, -107 to 117 mL). We conclude that desmopressin does not reduce postoperative bleeding in CABG patients treated with aspirin until the day before surgery.

IMPLICATIONS

Continuation of aspirin until the day before coronary artery bypass grafting may increase postoperative bleeding. The administration of desmopressin to these patients after the neutralization of heparin with protamine sulfate does not reduce postoperative bleeding.

Aspirin therapy and bleeding during proximal femoral fracture surgery

To assess the effect of daily low-dose aspirin therapy on perioperative bleeding of patients operated on for proximal femoral fracture, we did a prospective case-control study. During 14 months, we followed up 104 patients, 39 of whom were taking aspirin before the injury. The bleeding was estimated by the number of blood units needed perioperatively, the change in hemoglobin values, and followup on complications and drain volume. The aspirin-treated group received an average of 0.5 units of blood more than the control group, postoperatively. This finding was statistically significant. The groups did not differ significantly in any other bleeding parameter. No major bleeding occurred in the patients. It is safe to do surgery for a proximal femoral fracture in patients who are taking aspirin.

Single-dose tranexamic acid reduces postoperative bleeding after coronary surgery in patients treated with aspirin until surgery

Tranexamic acid reduces postoperative bleeding after coronary artery bypass grafting. We evaluated the effects of a single dose of tranexamic acid given immediately before cardiopulmonary bypass (CPB) in patients treated with aspirin until the day before surgery. The study was a prospective, randomized, double-blinded, placebo-controlled, parallel-group trial. Eighty patients were included and divided into two groups: one group received tranexamic acid 30 mg/kg, and one group received placebo (0.9% NaCl) as a bolus injection before CPB. Postoperative blood loss was recorded for 16 h. Transfusions of blood products were recorded for the whole hospital stay. Transfusions of packed red cells were given when the hematocrit value was less than 20% during CPB and less than 25% after surgery. The patients in the tranexamic acid group had significantly less postoperative bleeding compared with the patients in the placebo group (mean [SD]) (475 [274] mL versus 713 [243] mL; P < 0.001). An effective inhibition of fibrinolysis was found in patients receiving tranexamic acid. Tranexamic acid reduces postoperative bleeding in coronary artery bypass grafting patients treated with aspirin until the day before surgery.

IMPLICATIONS

Continuation of aspirin medication until the day before coronary artery bypass grafting may increase postoperative bleeding. The administration of a single dose of tranexamic acid (30 mg/kg) immediately before cardiopulmonary bypass significantly reduced postoperative bleeding and inhibited fibrinolysis in these patients.

Factors affecting transfusion of fresh frozen plasma, platelets, and red blood cells during elective coronary artery bypass graft surgery

CONTEXT

The ability to predict the use of blood components during surgery will improve the blood bank's ability to provide efficient service.

OBJECTIVE

Develop prediction models using preoperative risk factors to assess blood component usage during elective coronary artery bypass graft surgery (CABG).

DESIGN

Eighty-three preoperative, multidimensional risk variables were evaluated for patients undergoing elective CABG-only surgery.

MAIN OUTCOMES MEASURES

The study endpoints included transfusion of fresh frozen plasma (FFP), platelets, and red blood cells (RBC). Multivariate logistic regression models were built to assess the predictors related to each of these endpoints.

SETTING

Department of Veterans Affairs (VA) health care system.

PATIENTS

Records for 3034 patients undergoing elective CABG-only procedures; 1033 patients received a blood component transfusion during CABG.

RESULTS

Previous heart surgery and decreased ejection fraction were significant predictors of transfusion for all blood components. Platelet count was predictive of platelet transfusion and FFP utilization. Baseline hemoglobin was a predictive factor for more than 2 units of RBC. Some significant hospital variation was noted beyond that predicted by patient risk factors alone.

CONCLUSIONS

Prediction models based on preoperative variables may facilitate blood component management for patients undergoing elective CABG. Algorithms are available to predict transfusion resources to assist blood banks in improving responsiveness to clinical needs. Predictors for use of each blood component may be identified prior to elective CABG for VA patients.

Monitoring aspirin 100 mg and clopidogrel 75 mg therapy with the PFA-100 device in patients with peripheral arterial disease

A tool to identify vascular patients who receive antiplatelet therapy nd to distinguish between responders and non-responders to antiplatelet therapy could be of clinical importance. The present observational study was designed to investigate whether the PFA-100 device (Dade Behring) is suitable to detect long-term therapy of aspirin (100 mg/d) and/or clopidogrel (75 mg/d) in a cohort of patients with peripheral arterial disease (PAD). A total of 150 consecutive patients with PAD were studied; 34 patients were excluded from the study due to irregular intake of antiplatelet therapy or due to method limitations. Of the remaining 116 patients, 42 had no antiplatelet therapy, 47 had daily aspirin (100 mg) intake, 19 were administered clopidogrel 75 mg daily, and 10 received a medication with 100 mg aspirin plus clopidogrel 75 mg daily, all for at least 10 days. Nonparametric Kruskal-Wallis test with post hoc comparisons showed that collagen plus epinephrine (CEPI) closure times of the patient group receiving aspirin and the group receiving aspirin plus clopidogrel were similar (p>0.05). In contrast, both patient groups exhibited prolonged CEPI values compared to patients without antiplatelet therapy and patients taking clopidogrel (p<0.001). Finally, both patients without antiplatelet therapy and patients with clopidogrel did not show marked differences with respect to their CEPI values (p>0.05). However, Kruskal-Wallis test results revealed that collagen plus adenosine-5'-diphosphate closure times were not significantly different in all four patient groups (p=0.257). In conclusion, the PFA-100 device may be a suitable tool for monitoring aspirin 100 mg therapy, but it is not appropriate for the detection of clopidogrel administration in its current setup. Although it appears plausible that patients with PAD could benefit from monitoring platelet inhibition, clear evidence for this concept is still lacking.

Perioperative medication management

One of the consultant's roles is to make recommendations regarding the use of medications in the perioperative period. Unfortunately, the data in this area are often insufficient to provide evidence-based recommendations. In this article, we have provided advice considering the pharmacokinetics of the drug, the effect on the primary disease of stopping medications, and the effect of the medication on perioperative risk, including potential drug interactions with anesthetic agents.

Aspirin and mortality from coronary bypass surgery

BACKGROUND

There is no therapy known to reduce the risk of complications or death after coronary bypass surgery. Because platelet activation constitutes a pivotal mechanism for injury in patients with atherosclerosis, we assessed whether early treatment with aspirin could improve survival after coronary bypass surgery.

METHODS

At 70 centers in 17 countries, we prospectively studied 5065 patients undergoing coronary bypass surgery, of whom 5022 survived the first 48 hours after surgery. We gathered data on 7500 variables per patient and adjudicated outcomes centrally. The primary focus was to discern the relation between early aspirin use and fatal and nonfatal outcomes.

RESULTS

During hospitalization, 164 patients died (3.2 percent), and 812 others (16.0 percent) had nonfatal cardiac, cerebral, renal, or gastrointestinal ischemic complications. Among patients who received aspirin (up to 650 mg) within 48 hours after revascularization, subsequent mortality was 1.3 percent (40 of 2999 patients), as compared with 4.0 percent among those who did not receive aspirin during this period (81 of 2023, P<0.001). Aspirin therapy was associated with a 48 percent reduction in the incidence of myocardial infarction (2.8 percent vs. 5.4 percent, P<0.001), a 50 percent reduction in the incidence of stroke (1.3 percent vs. 2.6 percent, P=0.01), a 74 percent reduction in the incidence of renal failure (0.9 percent vs. 3.4 percent, P<0.001), and a 62 percent reduction in the incidence of bowel infarction (0.3 percent vs. 0.8 percent, P=0.01). Multivariate analysis showed that no other factor or medication was independently associated with reduced rates of these outcomes and that the risk of hemorrhage, gastritis, infection, or impaired wound healing was not increased with aspirin use (odds ratio for these adverse events, 0.63; 95 percent confidence interval, 0.54 to 0.74).

CONCLUSIONS

Early use of aspirin after coronary bypass surgery is safe and is associated with a reduced risk of death and ischemic complications involving the heart, brain, kidneys, and gastrointestinal tract.

The effect of clopidogrel in combination with aspirin when given before coronary artery bypass grafting

OBJECTIVES

This study was designed to evaluate the effect of preoperative clopidogrel on coronary artery bypass graft surgery (CABG) outcomes.

BACKGROUND

Clopidogrel in combination with aspirin, given before percutaneous coronary intervention, has become the standard for stent thrombosis prevention. Some premedicated patients, however, are found to have surgical disease on angiography, and irreversible platelet inhibition becomes a concern for upcoming CABG.

METHODS

We prospectively studied 224 consecutive patients undergoing nonemergent first-time CABG, and compared those with preoperative clopidogrel exposure within seven days (n = 59) to those without exposure (n = 165).

RESULTS

The groups were comparable in age, gender, body surface area, preoperative hematocrit, preoperative prothrombin time and prior myocardial infarction. The clopidogrel group had higher 24-h mean chest tube output (1,224 ml vs. 840 ml, p = 0.001), and more transfusions of red blood cells (2.51 U vs. 1.74 U, p = 0.036), platelets (0.86 U vs. 0.24 U, p = 0.001) and fresh frozen plasma (0.68 U vs. 0.24 U, p = 0.015). Moreover, reoperation for bleeding was 10-fold higher in the clopidogrel group (6.8% vs. 0.6%, p = 0.018). The clopidogrel group also had less extubation within 8 h (54.2% vs. 75.8%, p = 0.002) and a trend towards less hospital discharge within five days (33.9% vs. 46.7%, p = 0.094).

CONCLUSIONS

Clopidogrel in combination with aspirin before CABG is associated with higher postoperative bleeding and morbidity. These findings raise concern regarding the routine administration of clopidogrel before anticipated coronary stent implantation.

Stopping and restarting medications in the perioperative period

Medical consultants in the care of patients undergoing surgery have many tasks. One of these is to recommend the safest and most effective use of medication in the perioperative period. The physician must balance the urge to simplify with the need to maintain stability in the patient and his or her chronic diseases. The physician must consider the patient, the particulars of the patient's life, the patient's illnesses, and the patient's desires. At times, the physician can rely on well-supported data for guidance. Much of the time, however, the physician must operate on limited information and hunches about the best advice. Above all, the physician must communicate clearly with the patient, the surgeon, the anesthesiologist, and other members of the medical team to ensure a safe transition through surgery and return to good health.

The effect of perioperative aspirin therapy in peripheral vascular surgery: a decision analysis

Patients who undergo infrainguinal revascularization surgery are at increased risk for perioperative thrombotic complications. Aspirin decreases thrombotic events in the nonoperative setting; however, aspirin is often discontinued to avoid perioperative hemorrhagic complications. We used a decision analysis to determine whether aspirin should be discontinued before infrainguinal revascularization surgery. Two strategies were compared: aspirin cessation 2 wk before surgery and aspirin continuation throughout the perioperative period. Clinical events examined included myocardial infarction, thrombotic cerebrovascular accident, hemorrhagic cerebrovascular accident, gastrointestinal hemorrhage, and incisional hemorrhagic complications. Event rates and effect of aspirin were obtained by using MEDLINE. The outcomes were perioperative mortality, life expectancy, and quality-adjusted life expectancy. According to the model, continued aspirin use decreased perioperative mortality rates from 2.78% to 2.05%. Continued aspirin use increased life expectancy from 14.83 to 14.89 yr and increased quality-adjusted life expectancy from 14.72 to 14.79 yr. Aspirin increased the number of hemorrhagic complications by 2.46%, primarily because of an increased incidence of non-life-threatening complications.

The effects of recent aspirin ingestion on platelet function in cardiac surgical patients

OBJECTIVE

To examine the effects of the preoperative aspirin-free interval on platelet function in cardiac surgical patients.

DESIGN

Prospective clinical investigation.

SETTING

University-affiliated teaching hospital.

PARTICIPANTS

Patients undergoing elective coronary artery bypass graft surgery (n = 100).

INTERVENTIONS

The patients were divided into 3 groups based on the number of days since they last ingested aspirin: < or =2 days, 3 to 7 days, and >7 days. Preoperative platelet function was assessed in all patients using platelet aggregation responses to arachidonic acid, 5 microg/mL, and Platelet Function Analyser (PFA100) collagen/epinephrine closure times.

MEASUREMENTS AND MAIN RESULTS

Patients who ceased aspirin < or =2 days preoperatively had weaker platelet aggregation responses (18.5% +/- 7% maximum aggregation, mean +/- SD, n = 36) than patients who ceased aspirin 3 to 7 days preoperatively (68.8% +/- 29%, n = 48, p < 0.001) or >7 days preoperatively (68.3% +/- 28%, n = 16, p < 0.001). Similarly, patients who ceased aspirin < or =2 days preoperatively had longer PFA100 closure times (168 +/- 52 sec) than patients who ceased aspirin 3 to 7 days preoperatively (122 +/- 43 sec, p < 0.001) or >7 days preoperatively (128 +/- 42 sec, p < 0.01). The percentage of abnormal responses was also greatest in the aspirin < or =2 days group.

CONCLUSION

Cardiac surgical patients who ingest aspirin < or =2 days preoperatively have greater impairment of platelet function than patients who have a longer preoperative aspirin-free interval.

Effect of preoperative aspirin use on mortality in coronary artery bypass grafting patients

BACKGROUND

Discontinuing aspirin use in patients before coronary artery bypass grafting (CABG) has focused on bleeding risks. The effect of aspirin use on overall mortality with this procedure has not been studied.

METHODS

We performed a case patient-control patient study of the 8,641 consecutive isolated CABG procedures performed between July 1987 and May 1991 in Maine, New Hampshire, and Vermont. Patients included all 368 deaths. Each case patient was paired with approximately two matched survivors (control patients). Aspirin use was defined by identification of ingestion within 7 days before the operation.

RESULTS

CABG patients using preoperative aspirin were less likely to experience in-hospital mortality in univariate (odds ratio [OR] = 0.73, 95% confidence interval [0.54, 0.97]) and multivariate [OR = 0.55, (0.31, 0.98)] analysis compared to nonusers. No significant difference was seen in the amount of chest tube drainage, transfusion of blood products, or need for reexploration for hemorrhage between patients who did and did not receive aspirin.

CONCLUSIONS

Preoperative aspirin use appears to be associated with a decreased risk of mortality in CABG patients without significant increase in hemorrhage, blood product requirements, or related morbidities.

Amelioration of the bleeding tendency of preoperative aspirin after aortocoronary bypass grafting

BACKGROUND

Aspirin therapy is widely used in the treatment of cardiac disease. It has been recognized as a causative factor for increased bleeding and blood loss after open heart operations.

METHODS

To determine whether high-dose aprotinin maintained its efficacy in reducing blood loss in the presence of aspirin pretreatment in patients undergoing aortocoronary bypass, we performed a double blind study on 60 adult patients. Half received high-dose aprotinin (Trasylol) and half placebo.

RESULTS

Total hemoglobin loss, the primary efficacy variable was reduced from 36.1 +/- 31.4 g (mean +/- SD) to 14.1 +/- 16.0 g (p = 0.002). Blood loss was reduced intraoperatively and total loss was reduced from 837.3 mL +/- 404.9 mL to 368.7 mL +/- 164.3 mL (p < 0.001). The number of patients who did not receive any donor blood products was significantly higher in the aprotinin-treated patients (56.7% versus 23.3%, p = 0.008). Activation of the clotting cascade was significantly less in the treated patients toward the end of cardiopulmonary bypass both by measurement of thrombin-antithrombin III complex (p < 0.0001) and prothrombin fragment 1 + 2 (p < 0.0001). D-Dimer generation was significantly less from the onset of bypass and after reversal of heparin in the aprotinin-treated patients (p < 0.0001).

CONCLUSIONS

High-dose aprotinin was highly effective in reducing bleeding in this high-risk group of patients. Biochemical analyses suggest the mechanism by which aspirin increases blood loss after cardiopulmonary bypass is different from the blood-preserving effects of aprotinin, which is acting as an antifibrinolytic agent.