Preoperative aspirin ingestion increases operative blood loss after coronary artery bypass grafting

Artificial cerebrospinal fluid restores aspirin-inhibited physiological hemostasis through recovery of platelet aggregation function

BACKGROUND

Optimal hemostasis provides safety and reliability during neurosurgery which improves surgical outcomes. Previously, artificial cerebrospinal fluid (aCSF) and its component sodium bicarbonate were found to facilitate physiological hemostasis by amplifying platelet aggregation. This study aimed to verify whether aCSF amplifies platelet-dependent hemostasis in the presence of antiplatelet agents.

METHODS

We prepared platelet-rich plasma (PRP) or washed platelets using aspirin (acetylsalicylic acid, (ASA)) or normal saline (NS). We evaluated samples treated with a commercially available aCSF solution or NS for amplification of aggregation, activation of integrin αIIbβ3, phosphatidylserine (PS) exposure, P-selectin (CD62P) expression, and formation of microparticles (MPs). We assessed the effect of aCSF on in vivo hemostasis in the presence of ASA by measuring the tail bleeding time in ASA-or NS-injected C57BL/6 N mice.

RESULTS

Compared with NS, aCSF amplified ASA-inhibited platelet aggregation by recovering platelet activation including PS exposure, MP release, CD62P expression, and integrin αIIbβ3 activation. When using washed platelets, aCSF almost completely counteracted the inhibition of platelet aggregation by ASA. Prolonged bleeding time from the amputated tail of ASA-injected mice was significantly shortened by the treatment with aCSF compared to NS. Sodium bicarbonate also directly amplified ASA-inhibited platelet aggregation.

CONCLUSIONS

aCSF and sodium bicarbonate facilitate physiological hemostasis through the recovery of inhibited platelet aggregation even in the presence of ASA. The utilization of aCSF in the operative field may be advantageous for facilitating hemostasis in patients with impaired platelet function and contribute to improving outcomes of neurosurgery.

Effect of anti-platelet therapy on peri-operative blood loss in patients undergoing off-pump coronary artery bypass grafting

Purpose:

The purpose of this study was to review the effect of the pre-operative use of clopidogrel and aspirin on peri-operative bleeding, blood product transfusion, and resource utilization after coronary artery bypass grafting (CABG).

Materials and Methods:

A total of 1200 patients who underwent off-pump CABG (OPCABG) between 2010 and 2012 were retrospectively studied. Patients were divided into three groups: group 1: discontinued aspirin and clopidogrel 6 days prior to surgery (n = 468), group 2: discontinued both drugs 3 to 5 days prior to surgery (n = 621), and group 3: discontinued both drugs 2 days prior to surgery (n = 111). The bleeding pattern and blood product transfusion were studied and compared between the groups. Patients having history of other drugs affecting the coagulation profile, other organ dysfunction, on-pump CABG, and the combined procedure were excluded from the study.

Results:

Group 2 patients had a higher rate of bleeding and a reduced mean value of hemoglobin (Hb) as compared to other groups. The same results were seen in blood and blood product transfusion. Patients of group 2 and group 3 were associated with higher blood loss in terms of drainage at 12 and 24 hours. Post-operatively, this was statistically significant. Re-exploration was statisitically significant in group 3 patients (9.01%) than in group 2 (2.58%) and group 1 (1.07%) patients.

Conclusion:

The pre-operative use of clopidogrel and aspirin in patients undergoing OPCABG showed limited clinical benefits; however, its use significantly increased the risk of bleeding and blood transfusion, thus increasing morbidity and resource utilization. Hence, clopidogrel and aspirin should be stopped at least 6 days prior to surgery.

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.

Pleiotropic Effects of Acetylsalicylic Acid after Coronary Artery Bypass Grafting-Beyond Platelet Inhibition

Acetylsalicylic acid (ASA) is one of the most frequently used medications worldwide. Yet, the main indications for ASA are the atherosclerosis-based cardiovascular diseases, including coronary artery disease (CAD). Despite the increasing number of percutaneous procedures to treat CAD, coronary artery bypass grafting (CABG) remains the treatment of choice in patients with multivessel CAD and intermediate or high anatomical lesion complexity. Taking into account that CABG is a potent activator of inflammation, ASA is an important part in the postoperative therapy, not only due to ASA antiplatelet action, but also as an anti-inflammatory agent. Additional benefits of ASA after CABG include anticancerogenic, hypotensive, antiproliferative, anti-osteoporotic, and neuroprotective effects, which are especially important in patients after CABG, prone to hypertension, graft occlusion, atherosclerosis progression, and cognitive impairment. Here, we discuss the pleiotropic effects of ASA after CABG and provide insights into the mechanisms underlying the benefits of treatment with ASA, beyond platelet inhibition. Since some of ASA pleiotropic effects seem to increase the risk of bleeding, it could be considered a starting point to investigate whether the increase of the intensity of the treatment with ASA after CABG is beneficial for the CABG group of patients.

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.

The Effects of Preoperative Aspirin on Coronary Artery Bypass Surgery: a Systematic Meta-Analysis

Background and Objectives

Aspirin plays an important role in the maintenance of graft patency and the prevention of thrombotic event after coronary artery bypass graft surgery (CABG). However, the use of preoperative aspirin is still under debate due to the risk of bleeding.

Methods

From PubMed, EMBASE, and Cochrane Central Register of Controlled Trials, data were extracted by 2 independent reviewers. Meta-analysis using random effect model was performed.

Results

We performed a systemic meta-analysis of 17 studies (12 randomized controlled studies and 5 non-randomized registries) which compared clinical outcomes of 9,101 patients who underwent CABG with or without preoperative aspirin administration. Preoperative aspirin increased chest tube drainage (weighted mean difference 177.4 mL, 95% confidence interval [CI], 41.3–313.4; p=0.011). However, the risk of re-operation for bleeding was not different between the preoperative aspirin group and the control group (3.2% vs. 2.4%; odds ratio [OR], 1.23; 95% CI, 0.94–1.60; p=0.102). There was no difference in the rates of all-cause mortality (1.6% vs. 1.5%; OR, 0.98; 95% CI, 0.64–1.49; p=0.920) and myocardial infarction (MI) (8.7% vs. 10.4%; OR, 0.83; 95% CI, 0.66–1.04; p=0.102) between patients with and without preoperative aspirin administration.

Conclusions

Although aspirin increased the amount of chest tube drainage, it was not associated with increased risk of re-operation for bleeding. In addition, the risks of early postoperative all-cause mortality and MI were not reduced by using preoperative aspirin.

Pre-operative use of aspirin in patients undergoing coronary artery bypass grafting: a systematic review and updated meta-analysis

Background

Aspirin therapy improves saphenous vein graft (SVG) patency in patients undergoing coronary artery bypass graft (CABG), however, its use in the pre-operative period remains controversial. Therefore, we conducted a systematic review and meta-analysis of randomized-controlled trials (RCTs) to update the evidence about risk and benefits of pre-operative aspirin therapy in patients undergoing CABG.

Methods

Electronic databases (Medline, Embase, PubMed, Cochrane Library, and Scopus) were searched to identify RCTs evaluating the effect of aspirin versus placebo/control before CABG. Two investigators independently and in duplicate screened citations and extracted data and rated the risk of bias. The strength of evidence was appraised using the Grading of Recommendation Assessment, Development, and Evaluation (GRADE) approach. Meta-analysis was performed using a random-effects model. The main outcomes of interest were 30-day mortality, peri-operative myocardial infarction (MI), chest tube drainage and SVG occlusion.

Results

A total of 13 RCTs involving 4,377 participants (2,266/2,111 pre-operative aspirin/control) met the inclusion criteria. Pre-operative aspirin reduced the risk of SVG occlusion [risk ratio (RR): 0.69, 95% confidence interval (CI): 0.49-0.97, P=0.03, I²=16%], but no differences in mortality (RR: 1.41, 95% Cl: 0.73-2.74, I²=0%) and MI (RR: 0.84, 95% CI: 0.69-1.03, I²=0%) were found. However, pre-operative aspirin increased chest tube drainage (MD: 100.40 mL, 95% CI: 24.32-176.47 mL, P=0.01, I²=84%) and surgical re-exploration (RR: 1.52, 95% CI: 1.02-2.27, P=0.04, I²=8%), with no significant difference in RBC transfusion (RR: 1.06, 95% CI: 0.90-1.25, I²=35%).

Conclusions

Based on trials where the rated body of evidence was of low to very-low quality, pre-operative aspirin improves SVG patency but increases chest tube drainage and need for surgical re-exploration.

Preoperative aspirin use and acute kidney injury after cardiac surgery: A propensity-score matched observational study

BACKGROUND

The association between preoperative aspirin use and postoperative acute kidney injury (AKI) in cardiovascular surgery is unclear. We sought to evaluate the effect of preoperative aspirin use on postoperative AKI in cardiac surgery.

METHODS

A total of 770 patients who underwent cardiovascular surgery under cardiopulmonary bypass were reviewed. Perioperative clinical parameters including preoperative aspirin administration were retrieved. We matched 108 patients who took preoperative aspirin continuously with patients who stopped aspirin more than 7 days or did not take aspirin for the month before surgery. The parameters used in the matching included variables related to surgery type, patient's demographics, underlying medical conditions and preoperative medications.

RESULTS

In the first seven postoperative days, 399 patients (51.8%) developed AKI, as defined by the Kidney Disease Improving Global Outcomes (KDIGO) criteria and 128 patients (16.6%) required hemodialysis. Most patients took aspirin 100 mg once daily (n = 195, 96.5%) and the remaining 75 mg once daily. Multivariable analysis showed that preoperative maintenance of aspirin was independently associated with decreased incidence of postoperative AKI (odds ratio [OR] 0.46, 95% confidence interval [CI] 0.21-0.98, P = 0.048; after propensity score matching: OR 0.39, 95% CI 0.22-0.67, P = 0.001). Preoperative maintenance of aspirin was associated with less incidence of AKI defined by KDIGO both in the entire and matched cohort (n = 44 [40.7%] vs. 69 [63.9%] in aspirin and non-aspirin group, respectively in matched sample, relative risk [RR] 0.64, 95% CI 0.49, 0.83, P = 0.001). Preoperative aspirin was associated with decreased postoperative hospital stay after matching (12 [9-18] days vs. 16 [10-25] in aspirin and non-aspirin group, respectively, P = 0.038). Intraoperative estimated or calculated blood loss using hematocrit difference and estimated total blood volume showed no difference according to aspirin administration in both entire and matched cohort.

CONCLUSIONS

Preoperative low dose aspirin administration without discontinuation was protective against postoperative AKI defined by KDIGO criteria independently in both entire and matched cohort. Preoperative aspirin was also associated with decreased hemodialysis requirements and decreased postoperative hospital stay without increasing bleeding. However, differences in AKI and hospital stay were not associated with in-hospital mortality.

Use of aprotinin in repeat myocardial revascularization: Cleveland Clinic experience

Preliminary findings of a prospective, randomized, double-blind study of aprotinin in patients undergoing repeat myocardial revascularization procedures are presented. Use of high- or low-dose aprotinin led to signfiicant (p < 0.001) reductions in postoperative chest tube drainage compared with placebo (720 ± 753 ml, 866 ± 1636 ml, and 1121 ± 683 ml, respectively). Aprotinin also yielded significant reductions in transfusion requirements (2.1 ± 4.2 units, 4.8 ± 11.8 units, and 4.1 ± 6.2 units). These reductions were similar in a subgroup of patients who received aspirin preoperatively. In both aprotinin groups, there was a non-significant trend toward increased risk of Q-wave myocardial infarction. In six of 12 vein grafts studied at post-mortem examination from aprotinin-treated patients, acute vein graft thrombosis was found. This was not seen in any of five grafts from placebo-treated patients. In conclusion, aprotinin significantly reduces bleeding and transfusion requirements in patients undergoing repeat myocardial revascularization. The non-significantly increased risk of graft thrombosis requires further study.

An Assessment of the Incidence of Prolonged Postoperative Bleeding After Dental Extraction Among Patients on Uninterrupted Low Dose Aspirin Therapy and to Evaluate the Need to Stop Such Medication Prior to Dental Extractions

PURPOSE

To propose that low dose aspirin therapy need not be withdrawn for routine dental extraction procedure.

AIM

This study was designed to evaluate the post operative bleeding in patients on low dose aspirin therapy by dividing them into two groups: one with withdrawing and the other without withdrawing the regime before dental extraction.

MATERIALS AND METHODS

This study included 80 patients on low dose aspirin therapy. They were divided into two groups of 40 patients each; Group I (control group) included patients on who were asked to stop the medication 5 days prior to dental extraction; Group II (test group) included patients who were asked not to stop the medication prior to dental extraction. Strict atraumatic extractions were performed by a single surgeon. Data were analyzed using the independent "t" test @ 80 % power.

RESULTS

The mean pre-operative bleeding time in the control group was 87.75 s and the test group was 95.75 s which was statistically significant (p < 0.05). The mean pre-operative clotting time in the control group was 228.63 s and the test group was 246.25 s which was also statistically significant (p < 0.05). No patients in either group had any episode of prolonged postoperative bleeding following extraction from the surgical site and no local haemostatic measures had to be used except for one patient in Group II.

CONCLUSION

Authors conclude from this study that dental extraction procedures in patients on low-dose therapy can be safely carried out without stopping the antiplatelet therapy.

The Effect of Aspirin on Bleeding and Transfusion in Contemporary Cardiac Surgery

OBJECTIVE

Despite evidence that preoperative aspirin improves outcomes in cardiac surgery, recommendations for aspirin use are inconsistent due to aspirin's anti-platelet effect and concern for bleeding. The purpose of this study was to investigate preoperative aspirin use and its effect on bleeding and transfusion in cardiac surgery.

METHODS

This retrospective study involved consecutive patients (n=1571) who underwent CABG, valve, or combined CABG and valve surgery at a single center between March 2007 and July 2012. Of all patients, 728 met the inclusion criteria and were divided into two groups: those using (n=603) or not using (n=125) aspirin within 5 days of surgery. Data were collected on chest tube drainage, re-operation for bleeding, and transfusion of red blood cells (RBCs), fresh frozen plasma (FFP), and platelets.

RESULTS

No significant difference was observed between the two groups in chest tube drainage or re-operation for bleeding. An increase in patients transfused with RBCs was observed in the aspirin group (61.9 vs 51.2%, adjusted OR 1.77, p=0.027); however, among those transfused RBCs, no significant difference in mean units transfused or massive transfusion was observed. No significant difference was seen in transfusion requirement of FFP or platelets.

CONCLUSIONS

In patients undergoing CABG, valve, or combined CABG/valve surgery, preoperative aspirin, within 5 days of surgery, was associated with an increased probability of receiving an RBC transfusion. Preoperative aspirin was not associated with an increase in chest tube drainage, re-operation for bleeding complications, or transfusion of FFP or platelets.

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.

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.

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.

To continue or discontinue aspirin in the perioperative period: a randomized, controlled clinical trial

BACKGROUND

Major adverse cardiac events (MACEs) are a common cause of death after non-cardiac surgery. Despite evidence for the benefit of aspirin for secondary prevention, it is often discontinued in the perioperative period due to the risk of bleeding.

METHODS

We conducted a randomized, double-blind, placebo-controlled trial in order to compare the effect of low-dose aspirin with that of placebo on myocardial damage, cardiovascular, and bleeding complications in high-risk patients undergoing non-cardiac surgery. Aspirin (75 mg) or placebo was given 7 days before surgery and continued until the third postoperative day. Patients were followed up for 30 days after surgery.

RESULTS

A total of 220 patients were enrolled, 109 patients received aspirin and 111 received placebo. Four patients (3.7%) in the aspirin group and 10 patients (9.0%) in the placebo group had elevated troponin T levels in the postoperative period (P=0.10). Twelve patients (5.4%) had an MACE during the first 30 postoperative days. Two of these patients (1.8%) were in the aspirin group and 10 patients (9.0%) were in the placebo group (P=0.02). Treatment with aspirin resulted in a 7.2% absolute risk reduction [95% confidence interval (CI), 1.3-13%] for postoperative MACE. The relative risk reduction was 80% (95% CI, 9.2-95%). Numbers needed to treat were 14 (95% CI, 7.6-78). No significant differences in bleeding complications were seen between the two groups.

CONCLUSIONS

In high-risk patients undergoing non-cardiac surgery, perioperative aspirin reduced the risk of MACE without increasing bleeding complications. However, the study was not powered to evaluate bleeding complications.

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.

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.

The use of desmopressin in open-heart surgery

Desmopressin (l-deamino-8-D-arginine vasopressin, DDAVP) is a synthetic analogue of the antidiuretic hormone vasopressin. Like the natural antidiuretic hormone, desmopressin increases the plasma levels of factor VIII and von Willebrand factor (vWF), with the advantage, compared to vasopressin, that it produces little or no vasoconstriction, no increase in blood pressure, and no contraction of the uterus or gastrointestinal tract, so that it is well tolerated when administered to humans. In 1977, desmopressin was used for the first time in patients with mild hemophilia A and von Willebrand disease (vWD) for the prevention and treatment of bleeding, first during dental extractions and then during major surgical procedures. The clinical indications for desmopressin rapidly expanded beyond hemophilia and vWD. The compound was shown to be efficacious even in bleeding disorders not involving a deficiency or dysfunction of factor VIII or vWF, including congenital and acquired defects of platelet function and such frequent abnormalities of hemostasis as those associated with chronic kidney and liver diseases. Desmopressin has also been used prophylactically in patients undergoing surgical operations characterized by large blood loss and transfusion requirements.

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.

Management of antiplatelet therapy for minimization of bleeding risk before cardiac surgery

Antiplatelet therapy is commonly administered for primary and secondary prevention of stroke, recurrent angina, myocardial infarction, and death in patients with cardiovascular disorders. It also is associated with an increased risk of bleeding. We describe the management of antiplatelet therapy in patients undergoing coronary artery bypass graft surgery. In addition, we provide basic information about the mechanisms of action by which the most common antiplatelet agents inhibit platelet function. This information is integrated with results from pharmacologic studies and clinical trials. Determining the net effect in patients undergoing coronary artery bypass graft surgery requires knowledge about the pharmacokinetics, pharmacodynamics, and clinical efficacy of each drug, and an estimation of the absolute thrombotic versus hemorrhagic risk for each patient.

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.

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 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.

Minor Oral Surgery Without Stopping Daily Low-Dose Aspirin Therapy: A Study of 51 Patients

PURPOSE

The risk of excessive bleeding prompts physicians to stop low-dose long-term aspirin regimens before surgery, which puts the patient at risk from adverse thrombotic events. We hypothesize that most minor oral surgical procedures can be carried out safely without stopping low-dose aspirin.

PATIENTS AND METHODS

All minor oral surgery patients at our hospital (Madan Dental Hospital, Ahmedabad, India) from May 2002 to May 2003, who were also on long-term low-dose aspirin therapy regimens (acetylsalicylic acid 75 mg to 100 mg/day), were included. Investigation of bleeding time and platelet count was performed. If within normal limits, aspirin was not stopped before surgery. Patients were operated under local anesthesia on an outpatient basis. All wounds were sutured and followed up at 24, 48, and 72 hours, 1 week, and 2 weeks after the procedure.

RESULTS

The study included 51 patients (32 males, 19 females), ranging in age from 45 to 70 years. Preoperative values were within normal limits for all patients. Aspirin was not stopped for a single patient. There was no excessive intraoperative bleeding in all cases except 1; there was no postoperative bleeding in all cases.

CONCLUSION

We conclude that most minor oral surgery procedures can be carried out safely without stopping long-term low-dose aspirin regimen.