Terese T. Horlocker

Regional anesthesia in the patient receiving antithrombotic or thrombolytic therapy: American Society of Regional Anesthesia and Pain Medicine Evidence-Based Guidelines (Third Edition).

The actual incidence of neurologic dysfunction resulting from hemorrhagic complications associated with neuraxial blockade is unknown. Although the incidence cited in the literature is estimated to be less than 1 in 150,000 epidural and less than 1 in 220,000 spinal anesthetics, recent epidemiologic surveys suggest that the frequency is increasing and may be as high as 1 in 3000 in some patient populations. Overall, the risk of clinically significant bleeding increase with age, associated abnormalities of the spinal cord or vertebral column, the presence of an underlying coagulopathy, difficulty during needle placement, and an indwelling neuraxial catheter during sustained anticoagulation (particularly with standard heparin or low-molecular weight heparin). The need for prompt diagnosis and intervention to optimize is also consistently reported. In response to these patient safety issues, the American Society of Regional Anesthesia and Pain Medicine (ASRA) convened its Third Consensus Conference on Regional Anesthesia and Anticoagulation. Practice guidelines or recommendations summarize evidence-based reviews. However, the rarity of spinal hematoma defies a prospective randomized study, and there is no current laboratory model. As a result, the ASRA consensus statements represent the collective experience of recognized experts in the field of neuraxial anesthesia and anticoagulation. These are based on case reports, clinical series, pharmacology, hematology, and risk factors for surgical bleeding. An understanding of the complexity of this issue is essential to patient management.

Regional anesthesia in the anticoagulated patient: Defining the risks (the second ASRA Consensus Conference on Neuraxial Anesthesia and Anticoagulation)

Neuraxial anesthesia and analgesia provide several advantages over systemic opioids, including superior analgesia, reduced blood loss and need for transfusion, decreased incidence of graft occlusion, and improved joint mobility following major knee surgery. 1-4 New challenges in the management of patients undergoing neuraxial block have arisen over the last 2 decades, as medical standards for the prevention of perioperative venous thromboembolism were established. 5,6 Concern for patient safety in the presence of potent antithrombotic drugs has resulted in avoidance of regional anesthesia. Indeed, perioperative anesthesia and analgesia are often determined by the antithrombotic agent. 7 Conversely, although the anesthesia community is well aware of the potential for spinal bleeding, other specialties have only recently become cognizant of the risk, as documented by case reports

Clinical outcome of patients undergoing non-cardiac surgery in the two months following coronary stenting

OBJECTIVES We sought to determine the frequency and timing of complications at our institution when surgery was performed within two months of coronary stent placement. BACKGROUND The optimal delay following coronary stent placement prior to non-cardiac surgery is unknown. METHODS We analyzed the Mayo Clinic Percutaneous Coronary Intervention and Surgical databases between 1990 and 2000 and identified 207 patients who underwent surgery in the two months following successful coronary stent placement. RESULTS Eight patients (4.0%) died or suffered a myocardial infarction or stent thrombosis. All 8 patients were among the 168 patients (4.8%, 95% confidence interval [CI] 2.1 to 9.2) undergoing surgery six weeks after stent placement; the frequency of these events ranged from 3.8% to 7.1% per week during each of the six weeks. No events occurred in the 39 patients undergoing surgery seven to nine weeks after stent placement (0%, 95% CI 0.0 to 9.0). CONCLUSIONS These data suggest that, whenever possible, non-cardiac surgery should be delayed six weeks after stent placement, by which time stents are generally endothelialized, and a course of antiplatelet therapy to prevent stent thrombosis has been completed.

Frequency of myocardial infarction, pulmonary embolism, deep venous thrombosis, and death following primary hip or knee arthroplasty

Background There is limited information about the frequency of perioperative complications after elective primary orthopedic total hip and knee arthroplasty in contemporary practice. The purpose of this study was to determine the frequency of clinically relevant myocardial infarction, pulmonary embolism, deep venous thrombosis, and death within 30 days after elective primary hip or knee arthroplasty treated according to contemporary perioperative management. Methods The authors examined the medical records of consecutive patients undergoing hip or knee arthroplasty at their institution in a 10-yr period. Prospectively collected databases were used to identify patients with the diagnosis of myocardial infarction, pulmonary embolism, deep venous thrombosis, or death using strict validation criteria and diagnostic-certainty categories. Results A total of 10,244 patients underwent primary total hip or knee arthroplasty in the period of study. Of these, 224 patients had one or more adverse events (overall event rate: 2.2%; myocardial infarction: 0.4%; pulmonary embolism: 0.7%; deep venous thrombosis: 1.5%; death: 0.5%). Most adverse events (myocardial infarction, pulmonary embolism, and death) increased in frequency with older age, particularly for patients aged 70 yr or older. Myocardial infarction occurred more frequently in male patients. There were no differences in the overall event frequency between types of procedure. However, pulmonary embolism was highest in patients undergoing bilateral knee operations. Conclusions The overall frequency of serious complications within 30 days after primary total hip or knee arthroplasty with contemporary practice was 2.2%. Accurate knowledge of the perioperative risks associated with widely performed elective operations can be used to implement management strategies that may further improve patient outcomes and decrease cost.

Preoperative antiplatelet therapy does not increase the risk of spinal hematoma associated with regional anesthesia

One thousand orthopedic procedures in 924 patients given spinal or epidural anesthesia were prospectively studied to determine the risk of hemorrhagic complications associated with regional anesthesia.A history of excessive bruising or bleeding was elicited in 115 (12%) patients. Preoperative antiplatelet medications were taken by 386 (39%) patients. Aspirin was the most frequently reported antiplatelet drug and was taken by 193 patients. Subcutaneous heparin was administered to 22 patients before surgery on the operative day. One patient of 774 tested had a preoperative platelet count less than 100,000/mm.3 In addition, 26 of 171 preoperative prothrombin times and 10 of 115 preoperative activated partial thromboplastin times were longer than normal. Only 31 preoperative bleeding times were performed; five were prolonged. There were no documented spinal hematomas (major hemorrhagic complications). Blood was noted during needle or catheter placement (minor hemorrhagic complication) in 223 (22%) patients, including 73 patients with frank blood in the needle or catheter. Preoperative antiplatelet therapy did not increase the incidence of minor hemorrhagic complications. However, female gender, increased age, a history of excessive bruising/bleeding, surgery to the hip, continuous catheter anesthetic technique, large needle gauge, multiple needle passes, and moderate or difficult needle placement were all significant risk factors. The lack of correlation between antiplatelet medications and bloody needle or catheter placement (producing clinically insignificant collections of blood in the spinal canal or epidural space) is strong evidence that preoperative antiplatelet therapy is not a significant risk factor for the development of neurologic dysfunction from spinal hematoma in patients who undergo spinal or epidural anesthesia while receiving these medications. (Anesth Analg 1995;80:303-9)

Low molecular weight heparin: biochemistry, pharmacology, perioperative prophylaxis regimens, and guidelines for regional anesthetic management.

M ultiple randomized clinical trials have established the efficacy of standard heparin (SH) anticoagulation for venous thromboembolism prophylaxis. However, for high-risk populations, such as patients undergoing total hip or knee replacement, SH is relatively ineffective and may be associated with significant bleeding complications (1). Initial animal model studies suggested that low molecular weight fractions of heparin, when administered at equivalent antithrombotic doses, caused less bleeding than SH (2). These early studies raised the exciting possibility of separating the antithrombotic from the bleeding effects of heparin. The efficacy and safety of low molecular weight heparins (LMWH) as postoperative venous thromboembolism prophylaxis subsequently has been demonstrated in more than 60 clinical trials including more than 20,000 patients (3). However, reports of spinal hematoma occurring spontaneously and in association with regional anesthesia (4,5) have generated concern regarding the safety of spinal or epidural anesthesia in patients receiving LMWH. In this review, we focus on the biochemistry and pharmacology of LMWH compared with SH, current LMWH prophylaxis regimens, and the implications of perioperative LMWH prophylaxis for anesthesia, particularly among patients receiving regional anesthesia and analgesia. Guidelines will be provided for minimizing the risk of spinal hematoma in patients undergoing regional anesthesia while receiving perioperative anticoagulant-based prophylaxis.

A retrospective review of 4767 consecutive spinal anesthetics: Central nervous system complications

Serious neurologic complications rarely occur after spinal anesthesia.Historically, the reported frequency of persistent sensory or motor deficits has ranged from 0.005% to 0.7%. However, the introduction of small-gauge needles and new local anesthetics and intrathecal adjuvants makes it necessary to reevaluate the frequency of neurologic complications after spinal anesthesia. This study is a retrospective review of 4767 consecutive spinal anesthetics performed between June 1987 and June 1990. Mean patient age was 65 +/- 15 yrs. There were 3560 (74.7%) men and 1207 (25.3%) women. A preexisting neurologic condition was present in 481 (10.1%) cases. The surgical procedures were genitourinary and lower extremity orthopedic in 4348 (91.2%) cases. A paresthesia was elicited during needle placement in 298 (6.3%) cases. Six patients reported pain upon resolution of the spinal anesthetic (persistent paresthesia). Four persistent paresthesias resolved within 1 wk; the remaining two resolved in 18-24 mo. The presence of a paresthesia during needle placement significantly increased the risk of persistent paresthesia (P < 0.001). There were also two infectious complications. One patient with recent (treated) urosepsis underwent a urologic procedure under spinal anesthesia and subsequently developed a disc space infection. The second patient developed a paraspinal abscess. Both were treated with surgical drainage and antibiotics and remained neurologically intact. There were 62 (1.3%) patients with a postdural puncture headache, including 23 (0.5%) who underwent an epidural blood patch. These results are similar to those of previously published reviews and demonstrate the continued safety of spinal anesthesia. (Anesth Analg 1997;84:578-84)

ASRA Practice Advisory on Neurologic Complications in Regional Anesthesia and Pain Medicine

Neurologic complications associated with regional anesthesia and pain medicine practice are extremely rare. The ASRA Practice Advisory on Neurologic Complications in Regional Anesthesia and Pain Medicine addresses the etiology, differential diagnosis, prevention, and treatment of these complications. This Advisory does not focus on hemorrhagic and infectious complications, because they have been addressed by other recent ASRA Practice Advisories. The current Practice Advisory offers recommendations to aid in the understanding and potential limitation of neurologic complications that may arise during the practice of regional anesthesia and pain medicine.

Regional anesthesia in the anticoagulated patient: Defining the risks

umerous studies have documented the safety of neuraxial anesthesia and analgesia in the anticoagulated patient. Patient management is based on ppropriate timing of needle placement and catheter removal relative to the iming of anticoagulant drug administration. Familiarity with the pharmacology f hemostasis-altering drugs, the clinical studies involving patients undergoing euraxial blockade while receiving these medications, as well as the case reports f spinal hematoma will guide the clinician in management decisions. New challenges in the management of the anticoagulated patient undergoing euraxial blockade have arisen as medical standards for the prevention of periperative venous thromboembolism were established. Likewise, as more efficaious anticoagulants and antiplatelet agents have been introduced, patient mangement has become more complex. In response to these patient safety issues, the merican Society of Regional Anesthesia and Pain Medicine (ASRA) convened its econd Consensus Conference on Neuraxial Anesthesia and Anticoagulation. It is mportant to note that although the consensus statements are based on a thorugh evaluation of the available information, in some cases, data are sparse. ariances from recommendations contained in this document may be acceptable ased on the judgment of the responsible anesthesiologist. The consensus stateents are designed to encourage safe and quality patient care, but cannot guarntee a specific outcome. They are also subject to timely revision as justified by volution of information and practice. Finally, the current information focuses on

Risk factors for clinically relevant pulmonary embolism and deep venous thrombosis in patients undergoing primary hip or knee arthroplasty.

Background Prevention of thromboembolic complications after elective lower extremity arthroplasty has increasingly relied on routine thromboprophylaxis in all patients. Not all patients are at equal risk, however, and prophylaxis is not devoid of complications. The aim of this study was to examine the risk factors for clinically relevant pulmonary embolism and deep venous thrombosis after elective primary hip or knee arthroplasty in a large patient population. Methods During the 10-yr study period, 116 of 9,791 patients undergoing primary hip or knee arthroplasty at the authors’ institution who experienced pulmonary embolism or deep venous thrombosis within 30 days of surgery were matched at a 1:1 ratio with patients undergoing the same surgery with the same surgeon who did not experience an adverse event. Medical records were reviewed, with data abstracted using a standardized data collection form. Results Increased body mass index (P = 0.031; odds ratio = 1.5 for each 5-kg/m2 increase) and American Society of Anesthesiologists physical status classification of 3 or greater (P = 0.005; odds ratio = 2.6) were found to independently increase the likelihood of pulmonary embolism or deep venous thrombosis. In addition, use of antithrombotic prophylaxis was found to decrease the likelihood of these thromboembolic events (P = 0.050; odds ratio = 0.2 for aspirin or subcutaneous heparin, and odds ratio = 0.4 for warfarin or low-molecular-weight heparin). Conclusions In patients undergoing primary elective lower extremity arthroplasty, obesity, poor American Society of Anesthesiologists physical status classification, and lack of thromboprophylaxis are independent risk factors for clinically relevant thromboembolic events.