Prophylaxis against postoperative pulmonary embolism and deep-vein thrombosis by low-dose heparin

Efficacy and Safety of a Biosimilar Versus Branded Enoxaparin in the Prevention of Venous Thromboembolism Following Major Abdominal Surgery: A Randomized, Prospective, Single-Blinded, Multicenter Clinical Trial

Several biosimilar versions of enoxaparin are already approved and in use globally. Analytical characterization can establish good quality control in manufacturing, but they may not assure similarity in clinical outcomes between biosimilar and branded enoxaparin. This study evaluated the efficacy and safety of biosimilar Cristália versus branded Sanofi enoxaparin in venous thromboembolism (VTE) prevention in patients undergoing major abdominal surgery at risk for VTE. In this randomized, prospective single-blind study, we compared Cristália enoxaparin (Ce), a biosimilar version, versus branded Sanofi enoxaparin (Se; at a dose of 40 mg subcutaneously per day postoperatively from 7 to 10 days) in 243 patients submitted to major abdominal surgery at risk for VTE for VTE prevention. The primary efficacy outcome was occurrence of VTE or death related to VTE. The principal safety outcomes were a combination of major bleeding and clinically relevant non-major bleeding. Bilateral duplex scanning of the legs was performed from days 10 to 14, and follow-ups were performed up to 60 days after surgery. The incidence of VTE was 4.9% in the Cristália group and 1.1% in the Sanofi group (absolute risk difference = 3.80%, 95% confidence interval [CI]: −1.4%-9.0%) yielding noninferiority since the 95% CI does not reach the prespecified value Δ = 20%. Clinically significant bleeding occurred in 9.9% in the Cristália group and in 5.5% in the Sanofi group (n.s. ). In conclusion, this study suggests that 40 mg once daily of Ce, a biosimilar enoxaparin, is as effective and safe as the branded Sanofi enoxaparin in the prophylaxis of VTE in patients submitted to major abdominal surgery at risk for VTE.

Different combination strategies for prophylaxis of venous thromboembolism in patients: A prospective multicenter randomized controlled study

The aim was to evaluate the efficacy and safety of different combination strategies for prophylaxis of venous thromboembolism (VTE) after gynecologic surgery in patients at different levels of risk. This was a prospective multicenter randomized controlled study, in which 625 women who would undergo pelvic surgery for gynecologic diseases were stratified into three risk groups and then randomized into four groups to receive graduated compression stockings (GCS) alone (group A), GCS + low molecular weight heparin (LMWH) (group B), GCS + intermittent pneumatic compression (IPC) (group C), and GCS + IPC + LMWH (group C), respectively. The overall incidence of DVT was 5.1%. Group A had the highest incidence of DVT (8.8%), followed by group C (5.2%), group B (3.8%), and group D (2.6%). There was a significant difference in the incidence of DVT between groups A and D. The incidence of DVT was significantly lower in LMWH-treated patients (group B + group D) than in non-LMWH-treated patients (group A + group C). In conclusion, combination prophylaxis, especially LMWH-containing strategies, is better than monoprophylaxis in reducing VTE after gynecologic surgery. Risk-stratified prophylactic strategies should be implemented in patients undergoing gynecologic surgery, with LMWH-containing strategies being recommended for high-risk and very-high-risk patients.

The inflammatory reflex and neural tourniquet: harnessing the healing power of the vagus nerve

The CNS helps protect against tissue injury. The most important priorities include limiting blood loss and systemic inflammation. We elucidated two endogenous neural pathways that rapidly and specifically improve hemostasis and decrease inflammation through vagus nerve signaling. Activation of the neural tourniquet or inflammatory reflex via electrical vagus nerve stimulation (VNS) significantly improves outcomes in preclinical disease models. Currently, VNS is clinically approved for the treatment of medically refractory epilepsy and depression. The growing field of bioelectronic medicine will help physicians harness the Neural Tourniquet™ and inflammatory reflex for clinical use as well. Considering the substantial harm caused by uncontrolled bleeding and inflammation, electrical VNS may dramatically improve the care of millions of patients.

Thromboembolism prevention in surgery of digestive cancer

BACKGROUND

The venous thromboembolism is a common complication after surgical treatment in general and, in particular, on the therapeutic management on cancer. Surgery of the digestive tract has been reported to induce this complication. Patients with digestive cancer have substantial increased risk of initial or recurrent thromboembolism.

AIM

To provide to surgeons working in digestive surgery and general surgery guidance on how to make safe thromboprophylaxis for patients requiring operations in the treatment of their gastrointestinal malignancies.

METHODS

The guideline was based on 15 relevant clinical issues and related to the risk factors, treatment and prognosis of the patient undergoing surgical treatment of cancer on digestive tract. They focused thromboembolic events associated with operations and thromboprophylaxis. The questions were structured using the PICO (Patient, Intervention or Indicator, Comparison and Outcome), allowing strategies to generate evidence on the main primary bases of scientific information (Medline / Pubmed, Embase, Lilacs / Scielo, Cochrane Library, PreMedline via OVID). Evidence manual search was also conducted (BDTD and IBICT). The evidence was recovered from the selected critical evaluation using discriminatory instruments (scores) according to the category of the question: risk, prognosis and therapy (JADAD Randomized Clinical Trials and New Castle Ottawa Scale for studies not randomized). After defining potential studies to support the recommendations, they were selected by the strength of evidence and grade of recommendation according to the classification of Oxford, including the available evidence of greater strength.

RESULTS

A total of 53,555 papers by title and / or abstract related to issue were found. Of this total were selected (1st selection) 478 studies that were evaluated as full-text. From them to support the recommendations were included in the consensus 132 papers. The 15 questions could be answered with evidence grade of articles with 31 A, 130 B, 1 C and 0 D.

CONCLUSION

It was possible to prepare safe recommendations as guidance for thromboembolism prophylaxis in operations on the digestive tract malignancies, addressing the most frequent topics of everyday work of digestive and general surgeons.

Engineered virus-like nanoparticle heparin antagonists

Virus nanoparticles provide a self-assembling, reproducible multivalent platform that can be chemically and genetically manipulated for the presentation of a wide array of epitopes. Presented herein are engineered bacteriophage Qβ nanoparticles that function as potent heparin antagonists. Three successful approaches have been used: 1) chemically appending poly-Arg peptides; 2) point mutations to Arg on the virus capsid; 3) incorporation of heparin-binding peptides displayed externally on the virus surface. Each approach generates particles with good heparin antagonist activity with none of the toxic side effects of protamine, the only drug currently FDA-approved for clinical use as a heparin antagonist.

Heparin antagonism by polyvalent display of cationic motifs on virus-like particles

Particles to the rescue! The construction of cationic amino acid motifs on the surface of bacteriophage Qbeta by genetic engineering or chemical conjugation gives particles that are potent inhibitors of the anticoagulant action of heparin, which is a common anticlotting agent subject to clinical overdose.Polyvalent interactions allow biological structures to exploit low-affinity ligand-receptor binding events to affect physiological responses. We describe here the use of bacteriophage Qbeta as a multivalent platform for the display of polycationic motifs that act as heparin antagonists. Point mutations to the coat protein allowed us to generate capsids bearing the K16M, T18R, N10R, or D14R mutations; because 180 coat proteins form the capsid, the mutants provide a spectrum of particles differing in surface charge by as much as +540 units (K16M vs. D14R). Whereas larger poly-Arg insertions (for example, C-terminal Arg(8)) did not yield intact virions, it was possible to append chemically synthesized oligo-Arg peptides to stable wild-type (WT) and K16M platforms. Heparin antagonism by the particles was evaluated by using the activated partial thrombin time (aPTT) clotting assay; this revealed that T18R, D14R, and WT-(R(8)G(2))(95) were the most effective at disrupting heparin-mediated anticoagulation (>95 % inhibition). This activity agreed with measurements of zeta potential (ZP) and retention time on cation exchange chromatography for the genetic constructs, which distribute their added positive charge over the capsid surface (+180 and +360 for T18R and D14R relative to WT). The potent activity of WT-(R(8)G(2))(95), despite its relatively diminished overall surface charge is likely a consequence of the particle's presentation of locally concentrated regions with high positive charge density that interact with heparin's extensively sulfated domains. The engineered cationic capsids retained their ability to inhibit heparin at high concentrations and showed no anticlotting activity of the kind that limits the utility of antiheparin polycationic agents that are currently in clinical use.

Prolonged thromboprophylaxis with low molecular weight heparin for abdominal or pelvic surgery

BACKGROUND

Major abdominal and pelvic surgery carries a high risk of venous thromboembolism (VTE). The efficacy of thromboprophylaxis with low-molecular weight heparin (LMWH) administered during the in-hospital period is well documented, but the optimal duration of thromboprophylaxis after surgery remains controversial. Some studies suggest that patients undergoing major abdominal surgery benefit from prolongation of the thromboprophylaxis to 1 month after surgery. No systematic review on prolonged thromboprophylaxis after major abdominal or pelvic surgery has been published.

OBJECTIVES

To evaluate the efficacy and safety of prolonged thromboprophylaxis with LMWH for at least 1 month after abdominal or pelvic surgery with thromboprophylaxis administered during the in-hospital period only in preventing late VTE.

SEARCH STRATEGY

Electronic searches were performed January 2008 in the Medline, Embase, Lilacs, and the Cochrane Central Register of Controlled Trials. Abstract books from major congresses addressing thromboembolism were hand searched, as were reference lists from studies of relevance.

SELECTION CRITERIA

We assessed both randomised and non-randomised controlled clinical trials comparing prolonged thromboprophylaxis with any anti-thrombotic agent with placebo and/or thromboprophylaxis during the admission period only. The patient population in the trials were patients undergoing abdominal or pelvic surgery. The outcome measures included VTE (deep venous thrombosis (DVT) or pulmonary embolism (PE)) as assessed by objective means (ascending bilateral venography, ultrasonography, pulmonary ventilation/perfusion scintigraphy, spiral CT scan or autopsy). Studies exclusively reporting on clinical diagnosis of VTE, without objective confirmation were excluded.

DATA COLLECTION AND ANALYSIS

The identification of studies and data extraction were performed by the authors. Outcomes were VTE (DVT or PE) assessed by objective means. Safety outcome were defined as bleeding complications and mortality within 3 months after surgery.

MAIN RESULTS

The search exclusively detected trials evaluating prolonged thromboprophylaxis with LMWH as compared to control or placebo. 133 studies were found in the searches, of which only 4 were found eligible for inclusion, and 129 were excluded. The incidence of overall VTE after major abdominal or pelvic surgery was 14.3% (95% confidence interval 11.2% - 17.8%) in the control group as compared to 6.1% (95% CI 4.0% - 8.7%) in the patients receiving out-of-hospital LMWH. This difference was statistically significant, Peto Odds Ratio 0.41 (95% CI 0.26 -0.63), P < 0.0005. Prolonged thromboprophylaxis with LMWH was also associated with a statistically significant reduction of even the incidence of symptomatic VTE from 1.7% (95% CI 0.8% - 3.4%) in the control group to 0.2 % (95% CI 0.0% - 1.2%) in patients receiving prolonged thromboprophylaxis, Peto Odds ratio 0.22 (95% CI 0.06 -0.80), P = 0.02. The respective incidence of bleeding in the control and LMWH group were 3.7% (95% CI 2.4% -5.5%) and 4.1% (95% CI 2.7% - 6.0%), Peto Odds ratio 1.11 (95% CI 0.62 - 1.97), P = 0.73. There was no significant heterogeneity detected as regards to outcome parameters reported in the included trials.

AUTHORS' CONCLUSIONS

Prolonged thromboprophylaxis with LMWH significantly reduces the risk of VTE compared to thromboprophylaxis during hospital admittance only, without increasing bleeding complications after major abdominal or pelvic surgery.

Prolonged thromboprophylaxis with low molecular weight heparin after major abdominal surgery

PURPOSE OF REVIEW

To analyze the effect of prolonged thromboprophylaxis with low molecular weight heparin in patients undergoing major abdominal surgery.

RECENT FINDINGS

Literature searches in PubMed, EMBASE and Cochrane Database between 1990 and 2006 were conducted to identify trials concerning prolonged thromboprophylaxis in major abdominal surgery. Three randomized controlled trials met the search criteria. They showed that low molecular weight heparin is effective and safe to use as prolonged thromboprophylaxis after major abdominal surgery.

SUMMARY

Three published randomized studies all show a 50-60% relative risk reduction of late occurring deep venous thrombosis after major abdominal surgery. Evidence for the use of prolonged thromboprophylaxis after major abdominal surgery is emerging, and seems justified in selected high-risk patients, including patients operated on for cancer.

Prolonged prophylaxis with dalteparin to prevent late thromboembolic complications in patients undergoing major abdominal surgery: a multicenter randomized open-label study

BACKGROUND

Patients undergoing major abdominal surgery carry a high risk of venous thromboembolism (VTE), but the optimal duration of postoperative thromboprophylaxis is unknown.

OBJECTIVES

To evaluate the efficacy and safety of thromboprophylaxis with the low molecular weight heparin (dalteparin), administered for 28 days after major abdominal surgery compared to 7 days' treatment.

PATIENTS/METHODS

A multicenter, prospective, assessor-blinded, open-label, randomized trial was performed in order to evaluate prolonged thromboprophylaxis after major abdominal surgery. In total, 590 patients were recruited, of whom 427 were randomized and received at least 1 day of study medication, and 343 reached an evaluable endpoint. The primary efficacy endpoint was objectively verified VTE occurring between 7 and 28 days after surgery. All patients underwent bilateral venography at day 28.

RESULTS

The cumulative incidence of VTE was reduced from 16.3% with short-term thromboprophylaxis (29/178 patients) to 7.3% after prolonged thromboprophylaxis (12/165) (relative risk reduction 55%; 95% confidence interval 15-76; P=0.012). The number that needed to be treated to prevent one case of VTE was 12 (95% confidence interval 7-44). Bleeding events were not increased with prolonged compared with short-term thromboprophylaxis.

CONCLUSIONS

Four-week administration of dalteparin, 5000 IU once daily, after major abdominal surgery significantly reduces the rate of VTE, without increasing the risk of bleeding, compared with 1 week of thromboprophylaxis.

Perioperative complications of radical retropubic prostatectomy

The opinions and assertions contained herein are the private views of the authors and are not to be construed as reflective of the views of the US Army or the Department of Defense. Radical retropubic prostatectomy has long been considered one of the most difficult procedures in the urologist's armamentarium. Therefore, we performed a thorough review of recent literature regarding intraoperative and postoperative complications. The intent of this effort is to review established data regarding the most frequently seen complications and to highlight recent developments regarding the prevention or treatment of such complications.

Prevention of venous thromboembolism

Venous thromboembolism is the most common cause of preventable death among hospitalised patients. Systematic prophylaxis with antithrombotic agents in patients at risk for venous thromboembolism is the most effective approach to reduce morbidity and mortality. Despite this evidence, antithrombotic prophylaxis is still underused, due to the underestimation of incidence of venous thromboembolism and to the unjustified fear of bleeding complications. Both the characteristics of the individual patient and the clinical setting contribute to the definition of the risk for venous thromboembolism. Patient-related risk factors include clinical and molecular abnormalities. The grade of risk for venous thromboembolism is defined better by the clinical setting than by the patient characteristics. Prophylactic studies have been extensively carried out in surgical patients and, only more recently, in medical patients. Prophylactic methods include pharmacological agents, such as heparin, low molecular weight heparins, warfarin, and hirudin, as well as mechanical methods such as compression stockings and intermittent pneumatic compression.

Risk reduction in the intensive care unit

Many potentially preventable complications occur in patients who receive intensive care. We have reviewed the epidemiology of three important complications (venous thromboembolism, stress-related upper gastrointestinal bleeding, and vascular catheter-related infection) and evaluated common preventive treatments to provide evidence-based recommendations for prevention. We used English language articles located by MEDLINE or cross-citation, giving preference to articles published in the last 10 years, meta-analyses, and clinical trials that were randomized, double-blinded, and used intention-to-treat analysis. We recommend prophylaxis against venous thromboembolism in most patients, whereas those without respiratory failure or coagulopathy may not require prophylaxis against stress-related upper gastrointestinal hemorrhage. Chlorhexidine gluconate is the preferred antiseptic for disinfecting the skin prior to and during intravascular catheterization. Central venous catheters impregnated with antibacterial or antiseptic agents should be considered in patients at high risk for vascular catheter-related infection. Finally, central venous, pulmonary arterial, and systemic arterial catheters should be changed only when clinically indicated.

Complications of subcutaneous low-dose heparin therapy in neurosurgical patients

BACKGROUND

Venous thromboembolism is a major cause of postoperative morbidity and mortality in neurosurgery. The use of low-dose unfractionated heparin therapy perioperatively for prophylaxis against deep vein thromboses and pulmonary embolism has been well demonstrated in many other surgical specialties but is less commonly used in neurosurgery because of fears of devastating postoperative hematomas.

METHODS

The safety of such therapy has been analyzed in 950 patients undergoing an inpatient neurosurgical procedure. 872 patients (152 cranial procedures) completed treatment with 5000 U sodium heparin subcutaneously twice a day, commencing before surgery and continuing till patients were ambulatory.

RESULTS

There were three minor hemorrhagic complications-two superficial wound hematomas (one requiring treatment) and one gastrointestinal hemorrhage-identified. Three clinically significant major complications developed, two epidural hematomas after spinal surgery requiring evacuation and one intraventricular hemorrhage after brain biopsy.

CONCLUSION

This report, along with an analysis of previously published reports of low-dose perioperative heparin therapy in neurosurgical patients, suggests that such therapy is unlikely to be associated with increased morbidity. Given the known efficacy of low-dose heparin in reducing venous thromboembolism in other surgical patients, such therapy may reduce mortality and morbidity from thromboembolic complications in neurosurgical patients with minimal risk.

Prophylactically equivalent doses of Enoxaparin and unfractionated heparin inhibit in vivo coagulation to the same extent

This study compared how Enoxaparin and unfractionated (UF) heparin influenced in vivo coagulation in patients randomized to receive, by twice daily subcutaneous injections, either 30 mg of Enoxaparin or 7500 I.U. of UF heparin after elective hip surgery. These two regimens were equally effective in reducing the incidence of post-operative deep vein thrombosis DVT. We compared the concentrations of endogenous thrombin-antithrombin III in pre- and post-surgical plasmas to determine how each prophylactic regimen influenced prothrombinase activity in vivo, and found the same concentrations of endogenous thrombin-antithrombin III in post-heparin and post-Enoxaparin plasmas. However, significantly higher concentrations of endogenous thrombin-antithrombin III were found in pre- and post-surgical plasmas of patients who developed post-operative DVT than the levels found in comparable plasmas of patients who remained DVT-negative, regardless of the drug received for prophylaxis. Human factor Xa was added to an equal volume of each patient's plasmas and the amount of added enzyme inactivated by antithrombin III measured using an enzyme-linked immunosorbent assay for factor Xa-antithrombin III. Post-heparin and post-Enoxaparin plasmas inactivated approximately 4 times more factor Xa than the pre-surgical plasmas, regardless of the clinical outcome. Thus, before and after surgery, a higher than normal in vivo prothrombinase activity may be a significant risk factor for developing post-operative DVT.

Prophylaxis of venous thromboembolism

The objective of prophylaxis in venous thromboembolism is, first, to prevent fatal pulmonary embolism and, second, to reduce the morbidity associated with deep vein thrombosis (DVT) and the postphlebitic limb. This should now be standard practice for most patients over 40 years of age undergoing major surgery and for younger patients with a history of venous thromboembolism. Particularly high-risk groups include patients over 60 years of age undergoing major surgery, those with malignancy, and those requiring hip operations. Low-dose subcutaneous heparin 5,000 IU commencing 2 hours preoperatively and continuing 12 hourly until the patient is fully mobile is unequivocally effective in preventing DVT in medical and surgical patients and, most importantly, significantly reduces the incidence of fatal postoperative pulmonary embolism and total mortality. Such prophylaxis, in the presence of established DVT, also limits proximal clot propagation, which is the precursor of major pulmonary embolism. Low-dose heparin prophylaxis is associated with a small risk of bleeding complications, evidenced mostly by an increased frequency of wound hematoma rather than major clinical hemorrhage. Low molecular weight heparin fragments (e.g., Fragmin, Choay, Enoxaparine) are emerging as useful alternative agents, having the advantage of once daily administration and yet providing similar efficacy in the prevention of DVT. Mechanical methods of prevention which counteract venous stasis, such as graduated elastic compression stockings, are also useful in protecting against DVT but have not been shown to prevent fatal postoperative pulmonary embolism. They are recommended particularly for patients in whom heparin prophylaxis is best avoided (e.g., neurosurgery) and possibly in combination with heparin in very high-risk patients.

Anticoagulants in the prevention of venous thromboembolism

For 50 years, the key to successfully preventing venous thrombosis (VT) or pulmonary embolism (PE) among high-risk patients has been the judicious use of anticoagulants: first through full doses of oral anticoagulants and more recently through low-dose heparin prophylaxis. Low-dose heparin has become the standard of comparison for other preventive methods, since it is relatively safe and simple, its ability to prevent approximately 65% of the subclinical VT found by leg scanning after elective general surgery is well known, and recent meta-analysis of the many pertinent published clinical trials (large and small) strongly suggests a much greater benefit: a 65% reduction in the risk of postoperative death from major PE. In addition, there are trials that have also found low-dose heparin to be effective in general medical patients, although its value in this clinical setting is much less well documented. Although several effective approaches other than low-dose heparin are available, many of these tend to be either more cumbersome (intermittent external leg compression) or probably less powerful (graded pressure elastic stockings). There are situations where low-dose heparin prophylaxis fails, most obviously after orthopaedic surgery where the use of more complex regimens, including adjusted-dose heparin treatment and various schedules of warfarin prophylaxis, becomes appropriate. Recent progress has come from the intensive clinical exploration of various low molecular weight heparin fractions or fragments which appear to be effective after once daily administration to general surgical patients and show great promise of effectiveness and safety after hip surgery. The level of warfarin effect needed for VT prophylaxis has also been reinvestigated, with trials suggesting a need for less warfarin and a lower prothrombin time effect than was previously thought to be appropriate. Given that any attempts to minimize mortality from PE in hospital patients must rely on the widespread and systematic use of simple, safe, and cost-effective preventive methods, it is hoped that these advances will help move anticoagulant prophylaxis further out of the realm of clinical research and into that of common clinical practice.

Double-blind multicenter trial on a new medium molecular weight glycosaminoglycan. Current therapeutic effects and perspectives for clinical use

The ability of glycosaminoglycans to bind to a wide number of biologically active macromolecules has already been investigated. Recent clinical trials on the possible therapeutic benefits of glycosaminoglycans must be placed in perspective, even if they appear to be particularly encouraging, especially as regards the glycosaminoglycan effects on certain coagulation factors. A multicenter, medium-term, double-blind, crossover trial was performed by several Italian Lipid Clinics to determine whether administration of a medium molecular weight glycosaminoglycan (Sulodexide) has a significant clinical effect. Patients affected by peripheral vascular disease and/or hyperlipidemia (type IIa, IIb and IV) were submitted to a 4-week wash-out period, followed by parenteral Sulodexide (S) or placebo (P) administration for 2 weeks, another 2 week wash-out period, parenteral crossover drug or P administration for 2 weeks and, finally, oral S administration for 6 months. Sulodexide lowered plasma viscosity and plasma fibrinogen in all patients. There was also a drop in triglycerides together with a rise in apo A-I and HDL-C in type IV hyperlipoproteinemics, whereas there was no significant effect on total or LDL-plasma cholesterol in type IIa and IIb patients. Moreover, there was a percent increase in peak flow and rest flow in the lower limbs of peripheral vascular disease patients. No side effects or intolerance phenomena were detected. The results indicate that Sulodexide administration may be useful in long-term treatment of patients with peripheral vascular disease and a concomitant increase in plasma triglycerides and/or fibrinogen and/or viscosity.

Prevention of venous thrombosis and pulmonary embolism

Deep vein thrombosis (DVT) leads to hospitalization for up to 600,000 persons each year in the United States. Venous thrombosis in itself may be benign, but the condition can lead to dangerous complications and has a high recurrence rate. Strategies to prevent DVT involve prevention of stasis and reversal of changes in blood coagulability that allow thrombi to form. Pharmacologic agents have been effective in reducing the incidence of DVT and pulmonary embolism. Low-dose subcutaneous heparin is considered a nearly ideal DVT preventative for surgically treated patients. The risk of hemorrhage is the main limitation to routine use of subcutaneous anticoagulants for DVT, but careful patient selection can minimize that risk. After anticoagulant therapy with heparin, generally for 7 to 10 days, oral warfarin is the drug of choice for maintenance anticoagulation to prevent DVT recurrence. Therapy for pulmonary embolism is the same as for DVT--immediate anticoagulation with heparin followed by maintenance with warfarin.

Low dose heparin versus low molecular weight heparin (Kabi 2165, Fragmin) in the prophylaxis of thromboembolic complications of abdominal oncological surgery

Eighty patients undergoing pelvic or abdominal surgery for cancer were randomized in two groups for prevention of postoperative thromboembolism: 40 patients received a 15,000 IU day-1 Calciparine prophylaxis and 40 patients a 5000 anti-Xa U/d Fragmin prophylaxis for 10 days. In the Calciparine group, two patients (5%) developed postoperative pulmonary embolism but none developed it in the Fragmin group. Two patients in the Fragmin group (5%) developed isotopic DVT, which was not confirmed by phlebography. There was no deep vein thrombosis of the lower limbs in the two groups. Important postoperative bleeding (one patient in the Calciparine group and two patients in the Fragmin group) was similar in both groups. Moderate and minor bleeding were significantly lower in the Fragmin group. Haemoglobin and haematocrit changes, total blood loss and transfusion requirements were not different in both groups. It is concluded that, over a 10-day period, one daily 5000 U Fragmin prophylaxis was as effective and safe as three daily 5000 IU Calciparine injections.

Prevention of venous thromboembolism in general surgical patients. Results of meta-analysis

The results of randomized clinical trials evaluating commonly used methods of deep vein thrombosis (DVT) prophylaxis in moderate- and high-risk general surgery patients were pooled to obtain an unbiased estimate of efficacy and risks. Low-dose heparin (LDH), dextran, heparin-dihydroergotamine (HDHE), intermittent pneumatic compression (IPC), and graded elastic stockings significantly reduced the incidence of DVT; aspirin was ineffective. In contrast to other methods, elastic stockings have not been adequately studied to determine their value in reducing DVT in high-risk patients, such as those with malignancy. Only LDH and dextran were studied in numbers of patients sufficient for demonstrating a clear reduction in pulmonary embolism (PE). In comparison studies, LDH was superior to dextran in preventing DVT, but the two agents were equivalent in protecting against PE. Although HDHE was marginally better than LDH in preventing DVT, it appeared to have no advantage in preventing PE--at least in moderate-risk patients. The incidence of major hemorrhage was not increased with any of the prophylactic agents. However, wound hematomas occurred significantly more frequently with LDH, an effect noted in the pooled data from double-blind and open trials. In comparison trials with LDH, both dextran and HDHE had significantly fewer wound hematomas. LDH administered every 8 hours appeared more effective in reducing DVT than LDH administered every 12 hours; the incidence of wound hematomas was equivalent with both regimens.

Thromboembolic problems in colorectal cancer surgery

The problem of thromboembolic complication in patients undergoing surgery for colorectal malignancies has been evaluated based on data from the literature and own experiences. One problem is the few studies dealing exclusively with this group of patients or presenting separate data on these patients. Deep vein thrombosis is somewhat more common than that seen after other types of abdominal surgery. No difference between patients operated on for colonic or rectal cancer have been found. The number of fatal or contributory pulmonary emboli is higher than the average number among other operated patients. Low dose heparin, low molecular weight heparin and mechanical methods, especially when combined with heparin or dextran, reduce the frequency of deep vein thrombosis. Fatal pulmonary embolism can effectively be prevented by low dose heparin with or without dihydroergotamine or by dextran.

Current recommendations in prevention of thrombosis in surgery

Fatal pulmonary embolism is a major cause of postoperative death. When no prophylaxis is given in general surgery, it has a frequency of about 1%. Apart from the immediate risk to life, one must also consider the late sequelae of extensive deep vein thrombosis--swelling of the legs, varicose veins, ulceration and other trophic changes which represent an equally distressing situation. Recently, three large-scale surveys have been published, where the data of over 100 randomized controlled clinical trials of prophylaxis against venous thromboembolism has been analysed. The purpose of this talk is to provide an overview of the currently available prophylactic methods analysed in these surveys, with an aim to define a policy for preventing venous thromboembolism, with particular emphasis on the surgical patients. There is evidence suggesting that the frequency of fatal pulmonary embolism can be reduced by such prophylactic remedies as low-dose heparin, dextran, the combination of dihydroergotamine plus heparin, and low molecular weight heparin.

Preventive and therapeutic approach to venous thromboembolic disease and pulmonary embolism--can death from pulmonary embolism be prevented?

Venous thromboembolism produces chronic sequelae in the legs and occasional immediate mortality due to pulmonary embolism. Because it occurs in certain high risk situations (for example, after surgery) its prevention is a practical proposition. This has been attempted using many different approaches. Administration of low dose heparin with or without dihydroergotamine to enhance venous return has been one of the most widely tested regimens. There is little doubt that this can prevent, in many patient groups, postoperative deep venous thrombosis and fatal pulmonary embolism, with a low incidence of adverse reactions. Some particularly high risk postoperative patient groups (for example, those undergoing hip surgery) warrant more aggressive measures to prevent thrombosis. Surveys have shown that increasing use is being made of this approach, and it is hoped that all surgeons will adopt a policy that will reduce postoperative venous thrombosis and pulmonary embolism. A reduction in the incidence of venous thromboembolism in large acute myocardial infarction is achieved by low dose heparin, although early mobilization is important. In addition, many of the patients at risk merit full dose anticoagulation to prevent intracardiac thromboembolism. Established venous thrombosis is treated effectively by intravenous heparin, followed by warfarin to keep the prothrombin time at 1.2 to 1.5 times control, as assessed using rabbit thromboplastin; most patients need three months of treatment. Anticoagulation is warranted for pulmonary embolism, with fibrinolytic therapy reserved for patients with massive embolism and hemodynamic compromise. Embolectomy is a heroic measure, which may occasionally be lifesaving.

A 30-year survey of pulmonary embolism verified at autopsy: an analysis of 1274 surgical patients

A retrospective study was undertaken of all surgical patients in Malmö, Sweden, during the period 1951-1980, in whom pulmonary emboli were found at autopsy. The autopsy rate was high throughout the period, ranging from 73 to 100 per cent. Of 5477 patients who died during the period, 1274 had pulmonary emboli (23.6 per cent), 349 of which were considered fatal, 353 contributory to death and 572 incidental. Fifty-one per cent of the patients were not operated upon. The number of contributory and incidental emboli increased over the period, to some extent probably reflecting greater thoroughness in postmortems. The frequency of fatal pulmonary emboli decreased in the last 5 year period. Pulmonary embolism was more rare in patients under 50 years of age. The proportion of females increased. In 24 cases major embolism emanated from thrombi around central venous catheters. This retrospective analysis of a large number of patients shows that pulmonary embolism continues to be a major cause of death in surgical patients, and in Malmö as common a cause of death in operated as in nonoperated patients.

Deep-vein thrombosis after major non-cardiovascular thoracic surgery

The incidence of deep-vein thrombosis (DVT) verified by fibrinogen test was studied in 44 high-risk patients after major non-cardiovascular thoracic surgery. In eight patients (18%) a total of ten DVT appeared within the first postoperative week. Four thrombi were located at or above knee level. More extensive surgery was associated with higher DVT incidence than lesser operations (32% v. 8%). In patients belonging to blood groups B and AB, DVT was more common than in other blood groups. Five of the six unilateral DVT were detected on the same side as the thoracotomy. The findings suggest that DVT incidence after this kind of surgery may be of the same order as after major general surgery, indicating a need for thromboprophylactic measures.

The effect of low-dose heparin on blood loss at abdominal hysterectomy

In a double blind trial, the effect of prophylactic low-dose subcutaneous heparin or saline on peri-operative blood loss was studied in 100 women undergoing abdominal hysterectomy. Mean blood loss was 401 (SEM 75) ml and 246 (SEM 15) ml in the women who received heparin or saline, respectively. Coagulation studies were carried out during the pre- and post-operative phases in order to assess the contribution of any coagulation abnormalities to operative blood loss. In identifying patients at risk, platelet function tests were of some value.

[Thromboembolism prevention in surgical medicine: heparin or heparin-dihydroergotamine?]

This review summarizes clinical studies on prevention of venous thromboembolism by heparin or heparin and dihydroergotamine. Advantages and disadvantages of both drugs are described. The value of low-dose-heparin can no longer be seriously disputed. Up to now, however, there is no clear evidence that heparin-dihydroergotamine improves the efficacy and reduces the frequency of complications. The later drug is a new approach still under investigation.

The effect of prophylactic heparinization on the venous blood flow using the Doppler ultrasonic flowmeter

The effect of prophylactic heparinization on the postoperative venous blood flow was prospectively studied in 100 lower limbs of 50 patients. Patients were randomized into two groups of 25 patients each: a control group and a heparin group. Changes in the venous blood flow were monitored using the Doppler ultrasonic flowmeter. The study illustrated the protective role of prophylactic heparinization in maintaining a near normal venous blood flow after surgery. The postoperative reduction in venous blood flow in heparinized patients was significantly less than the decrease in blood flow in non-heparinized patients during the same postoperative period. This significant difference between the two groups of patients applied to the steady and the augmented blood flow rates. The beneficial role of prophylactic heparinization was shown to act significantly in patients undergoing minor surgery, in obese subjects and in those suffering malignant disease. Patients undergoing major surgery also benefited significantly from prophylactic heparinization apart from their steady venous blood flow during the first postoperative day.