Is there a bleeding problem with platelet-active drugs?

Postoperative bleeding risk for oral surgery under continued clopidogrel antiplatelet therapy

Object. To determine the incidence of postoperative bleeding for oral osteotomy carried out under continued monoantiplatelet therapy with clopidogrel and dual therapy with clopidogrel/aspirin. Design. Retrospective single center observatory study of two study groups and a control group. Methods. A total of 64 and 60 oral osteotomy procedures carried out under continued monoclopidogrel therapy and dual clopidogrel/aspirin therapy, respectively, were followed for two weeks for postoperative bleeding. Another 281 similar procedures were also followed as a control group. All oral osteotomy procedures were carried out on an outpatient basis. Results. We observed postoperative bleeding in 2/281 (0.7%) cases in the control group, in 1/64 (1.6%) cases in the clopidogrel group, and in 2/60 (3.3%) cases in the dual clopidogrel/aspirin group. The corresponding 95% confidence intervals are 0–1.7%, 0–4.7%, and 0–7.8%, respectively, and the incidences did not differ significantly among the three groups (P > 0.09). Postoperative hemorrhage was treated successfully in all cases with local measures. No changes of antiplatelet medication, transfusion, nor hospitalisation were necessary. No major cardiovascular events were recorded. Conclusions. Our results indicate that minor oral surgery can be performed safely under continued monoantiplatelet medication with clopidogrel or dual antiplatelet medication with clopidogrel/aspirin.

Withholding clopidogrel for 3 to 6 versus 7 days or more before surgery in hip fracture patients

PURPOSE. To compare morbidity and mortality after hip fracture surgery in patients withholding clopidogrel for 3 to 6 days versus ≥7 days or more. METHODS. Records of 16 men and 31 women aged 49 to 92 (mean, 80.2) years who underwent hip fracture surgery after withholding clopidogrel for 3 to 6 days (n=24) versus ≥7 days or more (n=23) were compared. The patients were taking clopidogrel owing to ischaemic heart disease (n=37), cerebrovascular disease (n=7), and intolerance to aspirin (n=3). Patient demographics, American Society of Anesthesiologists status, preoperative delay, length of hospital stay, perioperative haemoglobin reduction, receipt of blood and platelet transfusions, morbidity, and mortality were recorded. RESULTS. Respectively in the early-surgery and delayed-surgery groups, the mean surgical delay was 4.2 and 8.0 days, the mean length of hospital stay was 21.1 and 28.7 days, the mean peri-operative haemoglobin reduction was 1.5 and 1.1 g/dl, the mean units of blood transfusion per patient was 0.8 and 0.7. No severe intra-operative bleeding or wound haematoma was encountered in either group. Two patients in each group died within one month, and 2 more in the delayed-surgery group died within 3 months. The main cause of death was cardiovascular. CONCLUSION. Withholding clopidogrel for <7 days before surgery conferred no increased risk in hip fracture patients.

Point-of-care assessment of antiplatelet agents in the perioperative period: a review

The aim of this paper was to review the strengths and limitations of current 'point-of-care' techniques for the detection of antiplatelet drug effects. The review was based on a Medline search for articles with key words related to "platelet function tests", "point-of-care", and "anaesthesia", published in English between January 1996 and September 2008. It was found that global assessments of 'haemostasis', such as the standard thrombelastograph, Sonoclot, Clot Signature Analyser and Hemodyne, are not specific for platelet function and are essentially insensitive to cyclooxygenase inhibitors (aspirin, non-steroidal anti-inflammatory drugs) and P2Y12 antagonists (ticlopidine, clopidogrel). Global assessments of 'platelet function', such as the PFA-100 and PlateletWorks, are more specific for platelet function, but also have limited sensitivity for cyclooxygenase inhibitors and P2Y12 antagonists. The newer devices developed specifically for the assessment of antiplatelet drugs, such as Platelet Mapping, the Impact Cone and Platelet Analyser and the VerifyNow, are more promising, but are not as sensitive as laboratory platelet aggregometry. All three categories of devices detect G(p)II(b)/III(a) antagonists (abciximab, tirofiban, eptifibatide) activity, but not all provide quantitative assessments for monitoring therapy. The limitations appeared to be related to the complexity of platelet function, the multiple pathways of platelet activation, the wide interpatient variability in platelet responses and the interdependence between platelets and other aspects of coagulation. The strengths and limitations of point-of-care devices should be appreciated before they are used to assist clinical decision-making in the perioperative period.

[Drug-eluting stents: implications for surgery patients]

Percutaneous coronary intervention (PCI) has a special role in the treatment of coronary heart disease. The insertion of drug-eluting stents (DES) requires dual anti-platelet therapy for at least 1 year which makes planned and emergency surgery difficult. There is a dilemma between high risk of stent thrombosis and perioperative bleeding. There is no evidence-based, bridging therapy option available perioperatively. This complex of problems should be considered whenever PCI is performed. An interdisciplinary approach is obligatory in these imminent conditions to proceed with either interventional or surgical revascularization. Co-existing malignancies and disorders which must be treated surgically should be excluded before PCI. Furthermore, DES and dual anti-platelet therapy produce unanswered forensic questions. On legal grounds it is not possible to proceed with surgery in cases of medication with anti-platelet therapy. Therefore, it is mandatory to discuss the possible answers to this problem with health care lawyers. The patient must be informed about this complex of problems.

Perioperative management of antiplatelet agents in noncardiac surgery

It is common that patients who are scheduled for surgery are treated with antiplatelet agents (APAs) due to their wide indications. The management of these APAs in the perioperative period (acetylsalicylic acid alone, a thienopyridine alone or, in most cases, a combination of them) has a dual perspective: the risk of bleeding when the patient is operated under the effect of the APA against the risk of thrombosis if it has been withdrawn. The main challenges for the anaesthesiologist and the surgeon include patients with a coronary stent (mainly, new drug-eluting coronary stents), those undergoing urgent surgery and those undergoing high bleeding risk surgery. We review current protocols and discuss the most recent proposals for the management of APAs in patients undergoing noncardiac surgery. Current recommendations include the maintenance of aspirin if possible throughout the perioperative period, in order to limit the risks of cardiological, vascular or neurological postoperative events, although this makes it necessary to assume a small risk for haemorrhagic complications in some patients. Nevertheless, there are many circumstances that are not clear yet and, in this situation, it is crucial that patients are treated with a multidisciplinary approach (anaesthesiologists, surgeons, cardiologists and haematologists).

Operative delay for orthopedic patients on clopidogrel (plavix): a complete lack of consensus

BACKGROUND

: Because of its irreversible nature, Plavix (clopidogrel) has become a double edged sword in the care of some of our sickest patients, particularly when surgical intervention is required. Platelets exposed to a single dose of clopidogrel are affected for the remainder of their lifespan and recover normal platelet function at a rate consistent with platelet turnover, which is within 5 days to 7 days (1-3) with the generation of new platelets not influenced by the drug; however, delay of surgical fixation for orthopedic patients, particularly patients with hip fractures may lead to increased morbidity and mortality.

METHODS

: A Web-based survey was created and administered to the program directors of academic orthopedic surgery programs.

RESULTS

: Seventy-three percent of orthopedic residency programs responded that waiting 3 days or less for urgent but nonemergent operative interventions on patients on clopidogrel is acceptable with 23% feeling that no delay at all is necessary. For emergent surgery, the vast majority of programs 66 (89%) reported no delay to the operating room for patients on clopidogrel.

CONCLUSIONS

: The majority of orthopedic surgery residency programs who responded to the survey wait less than 3 days for urgent surgery and do not delay surgery for emergency cases for patients on clopidogrel. At this point we feel that an early intervention that occurs within approximately 2 days, with the acceptance of the possibility of increased blood loss is in the patient's best interest. Based on the reviewed physiology, a perioperative platelet transfusion may be of some benefit as the transfused platelets would be effective in forming a viable plug.

Anticlotting drugs and regional anaesthetic and analgesic techniques

The wide use of anticlotting drugs by patients scheduled for surgery is a challenge for the anaesthesiologist when considering a regional anaesthesia technique. This practice seems safe if there is an appropriate management based on safety intervals established according to the pharmacology of the drug and the regional technique. Some anaesthesiology societies have published recommendations for the safe practice of regional anaesthesia with the simultaneous use of anticoagulants (heparin, low molecular weight heparins, oral anticoagulants (OA), fondaparinux and others) and antiplatelet agents (aspirin, clopidogrel, ticlopidine, argatroban and others). One of the most recent guidelines has been published by the Spanish Society of Anaesthesia and Critical Care. This article reviews these recommendations and compares them with others published in the last years. The recommendations are similar, but some interesting differences can be observed and need to be considered. A European consensus in this setting would probably be necessary.

Regional Anesthesia and Anticoagulation in Patients undergoing Cardiothoracic and Vascular Surgery

Spinal hematoma is a rare and potentially catastrophic complication of spinal or epidural anesthesia. The decision to perform spinal or epidural anesthesia or analgesia and the timing of catheter removal in a patient receiving antithrombotic therapy should be made on an individual basis, weighing the small, though definite risk of spinal hematoma with the benefits of regional anesthesia for a specific patient. Alternative anesthetic and analgesic techniques exist for patients considered an unacceptable risk. The patient's coagulation status should be optimized at the time the spinal or epidural needle or catheter is placed, and the level of anticoagulation must be carefully monitored during the period of epidural catheterization. Indwelling catheters should not be removed in the presence of therapeutic anticoagulation, as this appears to significantly increase the risk of spinal hematoma. Vigilance in monitoring is critical to allow early evaluation of neurologic dysfunction and prompt intervention.

Thromboprophylaxis and neuraxial anesthesia

Spinal hematoma is a rare and potentially catastrophic complication of spinal or epidural anesthesia. Risk factors include traumatic needle/catheter placement, sustained anticoagulation in an indwelling neuraxial catheter, and catheter removal during therapeutic levels of anticoagulation. Generally, a patient's coagulation status should be optimized at the time of spinal or epidural needle/catheter placement, and the level of anticoagulation should be monitored during epidural catheterization. Signs of cord compression, such as severe back pain, progression of numbness or weakness, and bowel and bladder dysfunction, warrant immediate radiographic evaluation. A delay in diagnosis and intervention of spinal hematoma may lead to irreversible cord ischemia.

The effects of perioperatively administered colloids and crystalloids on primary platelet-mediated hemostasis and clot formation

To explore whether routinely administered colloids and crystalloids influence the hemostatic system, we studied 60 patients undergoing knee replacement surgery during randomized intravascular fluid administration using 6% hydroxyethyl starch 200/0.5 (HES) or 4% modified gelatin (GEL) in addition to a basal infusion of lactated Ringer's solution (RL), or exclusively RL. In addition to routine coagulation tests, measurements of coagulation factors were performed. Also, functional measurements of the in vitro bleeding time by use of the platelet function analyzer (PFA-100 and ROTEG analysis (ROTEG(R); extrinsically and intrinsically [Ex; In] activated measurements of clotting time, CT [s]; clot formation time, CFT [s]; clot strength, A20 [mm]; fibrinogen component of the clot, FibA20 [mm]; and maximal clot elasticity) were used. Time dependency of variables was analyzed with a repeated-measures analysis of variance (all groups pooled); differences between groups were detected by comparing the calculated area under the curve (AUC(A-D)). For all variables, except ExCT, ExCFT, and InCFT, a significant time dependency was demonstrated, indicating that impaired platelet-mediated hemostasis and clot formation occurred with IV administration of fluids. Total clot strength, fibrinogen part, and clot elasticity decreased significantly more in the colloid groups than in the RL group (InA20: HES, -13.0 mm; GEL, -11.5 mm; RL, -1.3 mm; P = 0.042; FibA20: HES, -10.5 mm; GEL, -6.0 mm; RL, -1.3 mm: P < 0.0001; MCE: HES, -48; GEL, -35; RL, -15.8; P < 0.0001). The decrease in fibronectin concentrations was significantly smaller with GEL as compared with HES, whereas a weak trend toward a larger decrease in fibrinogen concentrations was observed with both colloids. Results show that colloid administration reduces final clot strength more than does RL alone, which also exhibited effects, albeit minor, on the coagulation system. The reduction in total clot strength was due to impaired fibrinogen polymerization, resulting in a decreased fibrinogen part of the clot and reduced clot elasticity.

IMPLICATIONS

Our data suggest that during deliberate colloid administration, critically impaired fibrinogen polymerization and reduced fibrinogen concentrations might be reached earlier than expected. Therefore, maintaining fibrinogen concentrations seems essential when continuing blood loss is bridged by colloid infusion until transfusion triggers are reached, especially in patients already exhibiting borderline fibrinogen levels at baseline.