Low-molecular-weight heparin prophylaxis: preoperative versus postoperative initiation in patients undergoing elective hip surgery

Thrombosis and Thromboprophylaxis in Gynecology Surgery

Gynecologic surgery offers unique challenges, as pelvic surgery places patients at an increased risk of venous thromboembolism (VTE). Prevention of VTE is a goal of patients, policy makers, and surgeons. In this review, we address the current research and recommendations for VTE prophylaxis.

High energy injury is a risk factor for preoperative venous thromboembolism in the patients with hip fractures: A prospective observational study

BACKGROUND

The purpose of this study was to identify the incidence of preoperative venous thromboembolism (VTE), and determine if high energy hip fracture affects preoperative VTE occurrence.

METHODS

Three-hundred nine patients (244 low and 61 high energy injuries) treated between March 2015 and March 2017 were included in this study. Indirect multidetector computed tomographic venography for the detection of preoperative VTE was performed at admission. The incidence of preoperative VTE was compared between high and low energy injury hip fractures. Logistic regression analysis was used to identify independent risk factors for preoperative VTE.

RESULTS

The overall incidence of preoperative VTE was 18.4% (56 of 305 patients). Preoperative VTE was identified in 17 (27.9%) and 39 (16.0%) patients in the high and low energy injury groups, respectively (p = 0.034). Multivariate logistic regression analysis showed that high energy injury, history of VTE, and myeloproliferative disease were significant predictive factors of preoperative VTE (OR = 2.451; 95% CI = 1.227-4.896, OR = 11.174; 95% CI = 3.500-35.673, OR = 6.936; 95% CI = 1.641-29.321, respectively) CONCLUSION: Because high energy hip fracture is significantly associated with preoperative VTE occurrence, preoperative evaluation and proper thromboprophylaxis should be performed for patients with a high-energy hip fracture.

Comparative effectiveness of venous thromboembolism prophylaxis options for the patient undergoing total hip and knee replacement: a network meta-analysis

Essentials Despite trial data, guidelines have not endorsed direct oral Xa inhibitors above other options. We provide profiles of venous thromboembolism and hemorrhage risk for 12 options. Direct oral Xa inhibitors had a favorable profile compared with low-molecular-weight heparin. Other options did not have favorable profiles compared with low-molecular-weight heparin.

SUMMARY

Background There are numerous trials and several meta-analyses comparing venous thromboembolism (VTE) prophylaxis options after total hip and knee replacement (THR and TKR). None have included simultaneous comparison of new with older options. Objective To measure simultaneously the relative risk of VTE and hemorrhage for 12 prophylaxis options. Methods We abstracted VTE and hemorrhage information from randomized controlled trials published between January 1990 and June 2016 comparing 12 prophylaxis options. We then constructed networks to compute the relative risk for each option, relative to once-daily dosing with low-molecular-weight heparin (LMWH) Low. Results Main: Relative to LMWH Low, direct oral Xa inhibitors had the lowest risk of total deep vein thrombosis (DVT)-asymptomatic and symptomatic- (odds ratio [OR], 0.45; 95% confidence interval [CI], 0.35-0.57), translating to 53-139 fewer DVTs per 1000 patients. Vitamin K antagonists (VKAs) titrated to International Normalized Ratio [INR] 2-3 predicted 56% more DVT events (OR, 1.56; 95% CI, 1.14-2.14). Aspirin performed similarly (OR, 0.80; 95% CI, 0.34-1.86), although small numbers prohibit firm conclusions. Direct oral Xa inhibitors did not lead to significantly more bleeding (OR, 1.21; 95% CI, 0.79-1.90). Secondary: Relative to LMWH Low, direct oral Xa inhibitors prevented 4-fold more symptomatic DVTs (OR, 0.25; 95% CI, 0.13-0.47). Conclusions Relative to LMWH Low, direct oral Xa inhibitors had a more favorable profile of VTE and hemorrhage risk, whereas VKAs had a less favorable profile. The profile of other agents was not more or less favorable. Clinicians should consider these profiles when selecting prophylaxis options.

Incidence of venous thromboembolism and hemorrhage related safety studies of preoperative anticoagulation therapy in hip fracture patients undergoing surgical treatment: a case-control study

Background

Venous thromboembolism is a common postoperative complication following orthopedic surgeries, with morbid and potentially fatal consequences. Perioperative low-molecular-weight heparin (LMWH) therapy can reduce the incidence of venous thromboembolism, but may also increase the risk of bleeding complications. Current literature reflects the need to balance the improved efficacy of early initiating prophylaxis with increased risk of perioperative bleeding. The purpose of this study was to compare the effectiveness and hemorrhage related safety of preoperative versus postoperative LMWH therapy for prevention of deep venous thrombosis (DVT) and pulmonary embolism (PE) in hip fracture patients.

Methods

We retrospectively evaluated 222 patients who underwent surgical treatment at Peking University People's Hospital between January 2009 and December 2010. Patients were allocated to two groups, receiving either preoperative or postoperative initiation of LMWH therapy for venous thromboembolism prophylaxis. Preoperative anticoagulation therapy was initiated 1–12 days prior to surgery (133 patients), and postoperative anticoagulation therapy was initiated 12 h after completion of surgery (89 patients). The preoperative group was further subdivided into four subgroups according to the time of initiation of therapy: 1–3 days before surgery (group A, 54 patients), 4–6 days before surgery (group B, 57 patients), 7–9 days before surgery (group C, 15 patients), and 10–12 days before surgery (group D, 7 patients). Occurrences of DVT, PE, adverse drug effects, intraoperative and postoperative bleeding were recorded, along with concentrations of preoperative and postoperative hemoglobin and length of hospital stay. The above parameters were compared between groups.

Results

Among recipients of preoperative anticoagulation therapy, two patients developed postoperative PE (1.5 %), one patient developed DVT (0.75 %). In the group receiving postoperative initiation of anticoagulation therapy, one patient each developed PE and DVT (1.1 %, 1.1 %). There was no difference in the occurrence of PE and DVT between the two groups (P>0.05, Chi-square tests). We identified the incidences of major bleeding, minor bleeding, and intraspinal hematoma after spinal anesthesia, which were 0 %/0 %, 3.76 %/3.37 %, and 0 %/0 %, respectively in preoperative and postoperative anticoagulation groups. There was no significant difference in the incidence of bleeding complications between patients receiving preoperatively initiated LMWH with patients receiving postoperatively initiated LMWH. Spinal anesthesia was administered to 168 patients, with no cases of postoperative intraspinal hematoma.

Conclusions

Preoperative anticoagulation therapy with LMWH may not increase intraoperative or postoperative blood loss, or the rate of intraspinal hematoma after spinal anesthesia, but also does not significantly reduce the risk of postoperative DVT or PE, compared to postoperative initiation.

Thromboembolic disease in patients with rheumatoid arthritis undergoing joint arthroplasty: Update on prophylaxes

The risk of venous thromboembolism (VTE) in rheumatoid arthritis (RA) and the higher incidence of RA patients undergoing major orthopedic surgery is well recognized. The objective of the present study is to describe the incidence of VTE and discuss the correct prophylaxis in RA patients undergoing knee or hip replacement. A systematic review of studies on thromboprophylaxis in RA patients undergoing major orthopedic surgery was performed. Detailed information was extracted to calculate the rate of VTE in RA orthopedic patients and analyze the thromboprophylaxis performed and bleeding complications. Eight articles were eligible for full review. No difference in the overall rate of VTE was observed between RA patients and controls. No significant differences were found in RA patients in terms of bleeding complications. The data on the optimal prophylaxis to be used in RA patients were insufficient to recommend any of the several options available. In the absence of dedicated guidelines for the care of RA patients undergoing orthopedic surgery, management must be individualized to obtain favorable patient outcome, weighing up all the factors that might put the patient at risk for higher bleeding and thrombotic events.

The Influence of NSAIDs on Coumarin Sensitivity in Patients with CYP2C9 Polymorphism After Total Hip Replacement Surgery

OBJECTIVE

To determine the influence of NSAIDs on the international normalized ratio (INR) in patients with cytochrome P450 (CYP)-2C9 enzyme variants starting acenocoumarol (an oral coumarin) therapy during the first 7 days after total hip replacement surgery.

METHODS

In this prospective study, an age-dependent protocol was used for the initiation of the acenocoumarol dose. Low-molecular-weight heparin was given for 5 days. The study included 100 patients undergoing total hip replacement surgery. After the inclusion of the last patient, polymerase chain reaction CYP2C9 mutation testing was performed for all patients. Drug-use evaluation of NSAIDs and other potential coumarin-drug interactions was also performed.

RESULTS

Eleven patients had an INR on 1 or more days >4.9. There were 52 patients who were using NSAIDs. Patients with a CYP2C9 mutation had a mean INR curve similar to patients without the mutation when NSAIDs were not coadministered. Within the group of patients heterozygous for a CYP2C9 mutation (n=30) only concomitant use of a NSAID resulted in an INR >4.9 (0% vs 38.9%, p<0.05).

CONCLUSION

In the group of patients with a CYP2C9 variant (*2 or *3 alleles), only concomitant use of a NSAID resulted in INRs >4.9. The cost effectiveness of CYP2C9 screening before elective surgery has yet to be determined.

Adverse effects of heparin

All the adverse effects of heparins are related to their wide variety of biological activities, with bleeding being the most important safety issue, resulting directly from the potency of heparin as an anticoagulant. However, it is hard to define the bleeding risk, since it depends on numerous parameters including the indication, dosage, method, and duration of heparin application, the clinical study design and definition of bleeding as well as patient characteristics and determinants of bleeding such as type of surgery and co-medication. Nonbleeding complications of heparins are caused by binding of heparin molecules to proteins other than antithrombin and to cells, which is generally more pronounced with unfractionated heparin than with low-molecular-weight heparins. Accordingly, heparin-induced thrombocytopenia, the most severe nonbleeding adverse reaction, occurs about 10 times less with low-molecular-weight heparins than with unfractionated heparin. Frequent and therefore important adverse reactions of heparins are skin lesions resulting from delayed-type hypersensitivity reactions. All the other undesirable effects are discussed as well, but they are mostly clinically irrelevant.

Thromboembolism prophylaxis with dabigatran leads to lower perioperative blood loss than with dalteparin in primary knee arthroplasty

INTRODUCTION

Low-molecular-weight heparins (LMWH) are commonly used in thrombosis prophylaxis after total knee arthroplasty. In contrast to LMWH, dabigatran etexilate is an oral and direct acting anticoagulant. The hypothesis of the present study was that blood loss occurring in total knee arthroplasty (TKA) is not greater after dabigatran etexilate than after dalteparin.

METHOD

All patients suffering from primary arthrosis of knee joint that had received a total knee arthroplasty were included in this retrospective case-control study. Two groups were formed (dalteparin versus dabigatran etexilate) and the perioperative blood loss was compared using the formula of Nadler (V = EBV × ln (Hct(0)/Hct(1)) [V = blood loss (l); EBV = blood volume (l); Hct(0) = preoperative haematocrit; Hct(1) = haematocrit on the first postoperative day].

PATIENTS

A total of 155 patients, 61 men and 94 women, were included. The calculated blood loss differed significantly between the two groups. The blood loss was on average 1.5 ± 0.58 l [0.32-2.9 l] in the dalteparin group, compared with 1.3 ± 0.63 l [0.29-4.31 l] in the dabigatran etexilate group (p < 0.01). None of the patients of both observed groups showed clinical signs of thrombosis or pulmonary artery embolism.

RESULTS

Dabigatran etexilate showed a lower perioperative blood loss than dalteparin by comparable safety of both drugs.

CONCLUSION

Whether the timing of administration or pharmacological factors were responsible for this cannot be explained by our study.

Preoperative versus postoperative initiation of thromboprophylaxis following major orthopedic surgery: safety and efficacy of postoperative administration supported by recent trials of new oral anticoagulants

In European countries, low-molecular-weight heparin is generally initiated preoperatively for thromboprophylaxis in hip or knee replacement surgery. The objective of this review is to compare pre- and postoperative thromboprophylaxis strategies using available evidence, and discuss the challenges and issues that arise. Surgery is the first step in the process of thrombus formation, but thrombosis is not an instant process and the formation and growth of the thrombus can take several days or weeks. Hence, it may be possible to stop this process if thromboprophylaxis is initiated after surgery. Meta-analyses or systematic reviews comparing pre- and postoperative initiation of therapy have found no consistent differences in efficacy and similar safety (bleeding rates) between the two strategies. The recently available oral anticoagulant dabigatran etexilate provides thromboprophylaxis when administered postoperatively and is as safe as preoperative enoxaparin. Further support for the use of postoperative oral thromboprophylaxis in hip or knee replacement surgery has been provided by the phase III clinical trials of rivaroxaban and apixaban versus preoperative enoxaparin. Postoperative thromboprophylaxis offers the opportunity to change management practices in Europe. As postoperative initiation may have a clinical benefit in some settings (e.g. for neuraxial anesthesia) and practical advantages (e.g. allowing same-day admission), it is a worthwhile thromboprophylactic strategy for hip or knee replacement surgery.

[Recommendations for the administration of conventional and new antithrombotic agents from the perspective of anesthesiology]

Neuraxial blockade confers benefits to surgical patients not only due to the high analgesic quality but also through a reduction in postoperative complications, such as respiratory insufficiency and a shortening of postoperative paralytic ileus. In orthopedic surgery peripheral and neuraxial blockades are extensively used to enhance postoperative mobilization. The most serious complication of neuraxial blockade is spinal epidural hematoma, which may lead to permanent paraplegia if left untreated. The risk is enhanced in patients receiving thromboembolism prophylaxis. Most national societies have issued guidelines with specific time intervals between application of antithrombotic drugs and subsequent neuraxial blockade to minimize this risk. From the viewpoint of an anesthesiologist it is preferable to start with chemical thromboembolism prophylaxis postoperatively as opposed to preoperatively, to administer all drugs in the evening and to limit the number of available drugs at each site. The safety of neuraxial blockade in the presence of the new oral anticoagulant rivaroxaban is currently unknown due to limited experience and dabigatran is considered contraindicated with indwelling epidural catheters according to the manufacturer.

Preoperative versus postoperative initiation of dalteparin thromboprophylaxis in THA

Chemical thromboprophylaxis in total hip arthroplasty (THA) may increase surgical site bleeding. The drug dose and timing of such therapy is therefore important. We studied two cohorts of 298 and 301 patients undergoing THA. The first group received their first dose of dalteparin sodium 5000 IU subcutaneously the evening before surgery and the second group a half dose six hours postoperatively, followed by 5000 units daily in both groups. Blood loss was reduced by 146 ml from 1230 ml to 1084 ml (p<0.001) with postoperative prophylaxis alone. The number of patients receiving blood transfusion decreased from 53% to 35% (p=0.001), and the use of transfused packed red blood cells was reduced from 1.25 to 0.83 units per patient (p=0.001). The overall rates of non-vascular complications 6 months after surgery were 12% and 11%, bleeding related events 6.0% and 4.0%, and thromboembolic related events were 2.0% and 2.3% in the preoperative and the postoperative cohorts. Two patients died in the preoperative group and one in the postoperative group due to venous and arterial thromboembolism. This study show that 2500 IU dose of dalteparin started 6 hours after surgery significantly reduced blood loss and transfusions compared to 5000 IU dalteparin injected 12 hours before surgery. Few thromboembolic events occurred, and these were equally distributed.

Prevention of acute hematoma after face-lifts

Acute hematoma remains one of the most frequently encountered complications after face-lift surgery. Several risk factors inherent to the patient and omission of certain intraoperative regimens are considered to cause hematoma. Significant risk factors include high blood pressure and male gender. Possible intraoperative regimens for the prevention of hematoma include tumescence infiltration without adrenaline, clotting of raw surfaces with fibrin glue, usage of drains, and application of compression bandages. However, little attention has been paid to postoperative measures. To examine whether different regimens in the postoperative phase can influence the incidence of hematoma, all face-lift patients who underwent surgery by a single surgeon in two different clinics (n = 376) with two different postoperative regimens were evaluated over the course of 3 years. In group 1 (n = 308), all postoperative medication was administered on request including medication for pain control, blood pressure stabilization, and prevention of nausea and vomiting as well as postoperative restlessness and agitation. In group 2 (n = 68), this medication was administered prophylactically at the end of the operation before extubation. The hematoma rate was 7% in group 1 and 0% in group 2. This study showed that the prophylactic use of medications (e.g., analgesics, antihypertonics, antiemetics, and sedatives) during the postoperative phase is superior to making drugs available to patients on request and can decrease the occurrence of acute hematoma in face-lift patients.

Defining practice patterns in Gynecologic Oncology to prevent pulmonary embolism and deep venous thrombosis

OBJECTIVE

The goal of venous thromboembolism (VTE) prophylaxis is to reduce the morbidity and mortality associated with the development of a deep venous thrombosis (DVT) or pulmonary embolism (PE). Because women with gynecologic cancers are at high risk to develop VTE, we sought to determine the present practice patterns of gynecologic oncologists regarding their use of VTE prophylaxis.

METHODS

1073 members of the Society of Gynecologic Oncologists (SGO) were mailed surveys that asked about preferred methods to prevent the development of VTE after gynecologic oncology surgery. Data were collected by online member entry and return mail. Frequency distributions were calculated and nonparametric test used for comparisons.

RESULTS

343/1073 (34%) of SGO members and fellows responded. 142/343 (42%) preferred double prophylaxis consisting of external pneumatic compression (EPC) and an anticoagulant while 41% (n=141) preferred EPC with no additional anticoagulation. Of respondents choosing any anticoagulant, 40% preferred Enoxaparin pre- and/or postoperatively. Ovarian cancer patients were perceived by respondents to have the highest risk of developing a postoperative PE.

CONCLUSIONS

Most respondents agree that women with gynecologic cancers undergoing major surgery should receive VTE prophylaxis, though there is not agreement as to which method is optimal. While 42% of members preferred double prophylaxis, 41% chose no additional measures other than EPC. Randomized studies in gynecologic oncology should be initiated in the United States to determine the optimal practice pattern.

Neuraxial Anesthesia and Low-Molecular-Weight Heparin Prophylaxis in Major Orthopedic Surgery in the Wake of the Latest American Society of Regional Anesthesia Guidelines

In May 2003, the Second American Society of Regional Anesthesia Consensus Conference statement was issued partly in response to continued safety concerns over the use of regional anesthesia--in particular, neuraxial techniques--with low-molecular-weight heparin (LMWH) prophylaxis in major orthopedic surgery. As the 2003 Consensus statement makes clear, regional anesthesia may be used safely with LMWH prophylaxis. The key to optimizing patient safety, however, depends on a careful calibration of the total daily dose and the timing of the first and subsequent doses of the LMWH drug with the timing and management of the regional anesthetic procedure. Because the challenge of successfully providing regional anesthesia in the presence of LMWH thromboprophylaxis is a clinical one, anesthesiologists should do what they can to ensure that every member of the surgical team has an understanding of current literature and practice guidelines such as those recently published by the American Society of Regional Anesthesia.

Prevention of venous thromboembolism in spinal surgery

Deep vein thrombosis (DVT), and its most feared complication, pulmonary embolism (PE), still have a high incidence with high risk for patients' health. Proven prophylactic measures are available but are generally underused, and DVT is still considered the most common cause of preventable death among hospitalized patients. The rationale for prophylaxis of venous thromboembolism is based on the clinically silent nature of the disease, the relatively high prevalence among hospitalized patients and the potentially tragic consequences of a missed diagnosis. During the last 15-20 years, spine surgery has changed radically, developing into a well-defined area of specialist surgery, and some attention is now being given to DVT events in spine surgery. The incidence of DVT during spine surgery is not documented in the literature, because only case reports or retrospective studies are reported. It would therefore be very helpful to initiate a multicenter study in order to understand this problem better and to develop, if possible, some guidelines on prophylactic measures in spine surgery. In doing so, we need to consider each patient's pattern, any risk factors and every kind of surgical technique related to DVT, in order to improve the outcome of the patient and to reduce any medicolegal problems that could arise from a thrombotic complication or an epidural hematoma, with its high potential for irreversible consequences.