Current concepts review: heparin-induced thrombocytopenia

Routine monitoring for heparin-induced thrombocytopenia following lower limb arthroplasty: Is it necessary? A prospective study in a UK district general hospital

INTRODUCTION

Heparin-induced thrombocytopenia (HIT) is a potentially life-threatening condition associated with heparin administration. Many orthopaedic units routinely prescribe low-molecular-weight heparins as thromboprophylaxis after hip and knee arthroplasty.

HYPOTHESIS

We postulated that routine platelet monitoring following heparin administration is of no clinical benefit. We therefore asked: firstly, what was the rate of thrombocytopenia in a large population of patients undergoing lower limb arthroplasty? Secondly, did this rate justify routine platelet monitoring?

MATERIALS AND METHODS

Unless contraindicated, all patients (n=1999, 53.05% female, mean age 69.23 years) at a UK district general hospital undergoing hip and knee arthroplasty were given daily prophylactic enoxaparin. Platelet counts were obtained between the 8th and 10th postoperative days and compared to preoperative baseline. A > 50% fall in platelet count was classified as "possible HIT". The minimal acceptable risk of thrombocytopenia was defined using The American College of Chest Physicians (ACCP) 2012 guidelines, which recommend monitoring platelet counts in patients receiving heparin where the expected risk of HIT is>1% and by descriptive cost-benefit analysis based on the cost of routine platelet monitoring in the clinical setting.

RESULTS

Complete results were available for 1361 (68.1%) patients, comprising: 653 primary hips, 22 revision hips, 1 hip resurfacing, 665 primary knees, 19 revision knees and 1 unicompartmental knee replacement. Mean platelet level was 281.9×109/L preoperatively and 527.83×109/L postoperatively. Forty-four patients (3.2%) experienced a postoperative fall in platelet levels. However, no patient experienced a drop in platelets to less than 50% of the preoperative value.

DISCUSSION

The incidence of HIT in the elective arthroplasty population is low. Therefore, routine postoperative monitoring of platelets is not necessary in this population of patients.

LEVEL OF EVIDENCE

II, prospective study.

Symptomatic venous thromboembolism after non-operatively treated foot or ankle injury

The purpose was to assess the incidence and risk factors associated with symptomatic venous thromboembolism in patients undergoing below knee immobilization for non-operative foot or ankle injury. We included all foot and ankle patients between January 2005 and May 2016 who underwent non-operative management using below knee immobilization with cast, splint, brace, and/or boot. The primary outcome was the development of a venous thromboembolism within 90 days of immobilization initiation. Of 6,088 patients, twenty-three (0.38%) developed a venous thromboembolism. Risk factors for venous thromboembolism were age>50 years, unremovable immobilization, Achilles tendon rupture, Modified Charlson Comorbidity Index>2, patients on chemoprophylaxis, varicose veins, history of venous thromboembolism, known hypercoagulability disorder, and rheumatoid arthritis. Routine thromboprophylaxis after below-knee immobilization for non-operative foot or ankle injury may be beneficial in these specific subpopulations. These data can facilitate more substantive shared decision-making between providers and patients with respect to use of thromboprophylaxis. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

Venous Thromboembolism Disease Prophylaxis in Foot and Ankle Surgery

There are limited data to guide the use of venous thromboembolism disease (VTED) prophylaxis after foot and ankle surgery. Although there is general consensus that the overall risk is lower than after hip or knee replacement, subpopulations of patients may be at relatively heightened risk. Furthermore, existing data are often conflicting regarding the efficacy of prophylaxis, with little acknowledgment of the tradeoffs between VTED prophylaxis and potential complications associated with the use of such medications. This article provides an overview of currently available evidence to guide decision making regarding VTED prophylaxis in patients who undergo foot and ankle surgery.

Drug-Immune Thrombocytopenia with Thrombosis versus Heparin-Induced Thrombocytopenia: A Critical Clinical Controversy

Heparin-induced thrombocytopenia (HIT) is a type of drug-induced immune thrombocytopenia (DITP). DITP is a rare and challenging clinical issue, especially when it is associated with thrombosis. A 62-year-old woman was admitted to our institution with end-stage renal failure. She received heparin for hemodialysis. Six days later, she became febrile and was treated with vancomycin and amikacin antibiotics. Two days after starting the vancomycin, she developed severe thrombocytopenia with extensive gangrenous deep vein thrombosis in her right leg, which required a below-the-knee amputation. The HIT test yielded positive results when heparin was already stopped, but her platelet count did not regenerate even after 3 months of heparin-free treatment. Courses of vancomycin treatment were given during several febrile episodes over the long period of severe thrombocytopenia. The patient was given both anti-immune thrombocytopenia and anticoagulant treatments because of both severe persistent thrombocytopenia and recurrent thrombotic episodes. The patient died as a result of severe thrombocytopenia, recurrent infection, and blood loss from the amputation site. Vancomycin is known to cause DITP, thrombosis, and immune complexes. DITP is a bleeding disorder, whereas HIT is a controversial thrombotic disorder. HIT tests can be influenced by cross-reacting antibodies and many other factors. Thus, there is no single method that can be considered 100% effective in confirming the HIT diagnosis. Anticoagulants must be used with great caution in patients with suspected DITP. Treatment of HIT-positive cases requires both clinical correlation and experience rather than reliance on HIT tests alone.

Evaluation of thromboprophylaxis in medium-sized general hospital

CONTEXT: Deep vein thrombosis (DVT) is a serious, common disease whose complications include pulmonary thromboembolism (PTE) and postthrombotic syndrome. The importance and benefits of correct and effective pharmacological prophylaxis for DVT are well documented. OBJECTIVES: The aims of this study were to evaluate adequacy of prophylaxis for DVT and PTE at the Santa Casa de Misericórdia de Ponta Grossa (SCMPG), Paraná, Brazil, and determine risk stratification for patients hospitalized in this institution. METHODS: A cohort study was conducted to assess DVT prophylaxis of patients hospitalized on May 15th, 2009. The study population consisted of a sample of 104 patients, subdivided into clinical and surgical groups and stratified into different specialties. Correct use of DVT prophylaxis was evaluated according to recommendations published by The Brazilian Society for Angiology and Vascular Surgery and took into account prophylactic methods specified explicitly in information found in each patient's medical chart. RESULTS: Of the 104 patients interviewed, 51 (49.04%) were clinical patients and 53 (50.96%) surgical. Based on risk stratification, 17 (16.35%) were classified as low risk, 37 (35.58%) as moderate risk, 46 (44.23%) as high risk and 4 (3.85%) as extremely high risk for DVT/PTE. A total of 68 patients (65.38%) received prophylaxis, but of these only 56 (53.85%) received the correct prophylaxis, and 36 (34.62%) did not receive any prophylaxis. CONCLUSION: The rates of prophylaxis use for DVT and PTE in this service are higher than rates published in the literature.

Venous thromboembolism and foot and ankle surgery: current updates 2012

Significant patient morbidity and mortality is associated with the development of venous thromboembolism (VTE) following orthopedic surgery. The majority of the literature supports proper prophylaxis following major orthopedic surgery involving hip and knee procedures. Foot and ankle surgery, however, is starkly contrasted because of the lack of recommendations. This article provides a comprehensive overview of the risk factors and incidence of VTE in foot and ankle surgery while also outlining the newest literature guidelines for prophylaxis.

Perioperative management of chronic anticoagulation in orthopaedic surgery

The orthopaedic patient on chronic anticoagulation therapy is at risk of thromboembolism and hemorrhage in the perioperative period. To establish the most effective anticoagulation regimen, patients should be stratified according to the risk of arterial or venous thromboembolism. Timing of surgery, thromboembolic risk, and bleeding risk should be considered when developing an anticoagulation protocol. Retrievable inferior vena cava filters may be a viable alternative to bridging therapy in patients at high risk of venous thromboembolism and/or bleeding.