Heparin-based treatment to prevent symptomatic deep venous thrombosis, pulmonary embolism or death in general medical inpatients is not supported by best evidence

Reassessment of venous thromboembolism and bleeding risk in medical patients receiving VTE prophylaxis

RATIONALE, AIMS, AND OBJECTIVES

The majority of hospitalized nonsurgical medical patients receive pharmacological prophylaxis for venous thromboembolism (VTE), and reassessment of changes in thrombosis and bleeding risk factors during hospital admission may represent an opportunity to discontinue unnecessary or unsafe therapy. The use of validated, clinically derived risk assessment models (RAMs) represents a shift towards an individualized, patient-centred approach to VTE prophylaxis. We are interested in using these tools to assess whether risk categories for VTE and bleeding change during admission and to assess whether such changes result in discontinuation of prophylaxis. Our primary objective was to determine whether VTE and bleed risk categories changed during the course of admission to warrant discontinuation of VTE prophylaxis, using the International Medical Prevention Registry on Venous Thromboembolism (IMPROVE) VTE and Bleed RAMs, respectively. Secondary objectives were to determine the number of patients whose risk categorizations for VTE and bleeding warranted discontinuation of VTE prophylaxis and to survey whether prophylaxis was continued or discontinued.

METHODS

A retrospective review was undertaken for a cross-sectional, randomly selected sample of patients who received VTE prophylaxis while admitted to medical wards in a collection of regional hospitals.

RESULTS

Of the 351 medical records reviewed, only eight patients (2.3%) changed their VTE risk category and six (1.7%) changed their bleed risk category to warrant discontinuation of VTE prophylaxis. Ninety patients (26%) were at high risk of VTE and low risk of bleed throughout admission, warranting continued VTE prophylaxis. The majority of patients remained at low risk of VTE throughout admission but remained on VTE prophylaxis until discharge.

CONCLUSIONS

Risk categories for VTE and bleeding for medical patients did not appreciably change throughout hospital admission. Use of VTE RAMs at admission and prior to initiation of therapy should reduce unnecessary prophylaxis in the majority of medical patients who are at low risk of VTE.

Effects of Low Molecular Weight Heparin on Alveolar Bone Loss in Wistar Rats

This study aimed to assess the effects of low molecular weight heparin (LMWH) on alveolar bone loss (ABL), blood count, and counting of megakaryocytes and adipocytes in male Wistar rats. Forty male 60-day Wistar rats were randomly divided into four groups: Control (C), Periodontal Disease (PD), Heparin (Hp) and Heparin + Periodontal Disease (Hp+PD). LMWH was applied for 60 days at doses of 1 ml/kg/day. Blood samples were collected at baseline, 30 and 60. On day-49, PD and Hp+PD groups were subjected to ligature-induced periodontitis around second upper right molar. The left side was assessed as spontaneous alveolar bone loss. Mean ABL in the side with ligature showed significantly different between C (0.35±0.07 mm) and Hp+DP (0.49±0.09 mm) groups (p<0.001), between PD (0.55±0.11 mm) and Hp (0.32±0.06 mm) groups (p<0.001) and between Hp and Hp+DP groups (p<0.001). No significant differences were found among groups for ABL in the side without ligature. Animal weight, food intake, and water consumption showed no statistically significant difference among groups. Megakaryocytes and adipocytes were counted using optical microscopy and no statistically significant differences were found. Within-groups, there were an increase and a decrease, respectively, in the counting of lymphocytes (p=0.005 for C and p=0.009 for Hp+PD groups only) and leukocytes (p=0.003 for C, p=0.001 for PD, p=0.002 for Hp, and p<0.001 for Hp+PD groups). There was no decrease in the number of platelets in the three collection periods. LMWH was not able to affect ABL, but it may change the blood counting, especially increasing lymphocytes.

New paradigms in venous thromboprophylaxis of medically ill patients

Acutelly-ill hospitalised medical patients are at risk of venous thromboembolism (VTE), both in-hospital and in the immediate post-discharge period, and mortality from VTE is thought to be particularly high in this patient population. However, despite previous mandates from international antithrombotic guidelines such as those of the American College of Chest Physicians (ACCP) for the "universal" use of thromboprophylaxis in hospitalised medical patients, global audits suggest that implementation of thromboprophylaxis continues to be challenging because of the perceived higher risk of bleeding and lower risk of VTE than that reported in clinical trials. Recent population-based studies also reveal that a "universal" hospital-only thromboprophylactic strategy does not reduce the community burden of VTE from this population, which may constitute nearly one quarter of the attributable risk of VTE. Lastly, four large randomised placebo-controlled trials of extended thromboprophylaxis have failed to show a definitive net clinical benefit in hospitalised medical patients. Recent large-scale efforts in deriving and validating scored VTE and bleed risk assessment models (RAMs) have been completed in the medically-ill population. In addition, an elevated D-dimer as a new biomarker to identify at-VTE risk medically ill patients has also undergone prospective evaluation. This paper will review current concepts of VTE and bleed risk in hospitalised medical patients, both in the hospital as well as the post-hospital discharge period, and will discuss new paradigms of thromboprophylaxis in this population using an individualised, patient-centered approach.

Inhaled Heparin: Therapeutic Efficacy and Recent Formulations

Heparin is well known for its anticoagulant and anti-inflammatory properties. Inhaled heparin regimens are increasingly being used to manage lung disease. It has been used to treat cystic fibrosis, thromboembolism, and pulmonary fibrosis, as well as bronchial asthma and asthma-induced airway hypersensitivity. Several preclinical studies attained some useful effects of heparin-administered, parenterally and through inhalation, treatment of lung disease. Besides, recent clinical trials suggest that inhaled heparin for lung diseases is beneficial and safe, but such data remain to be limited. In 2005, the orphan designation was granted by the European Commission for heparin sodium (inhalation use) for the treatment of cystic fibrosis. The positive results of heparin in the pulmonary route necessitate a focus on the preparation and evaluation of heparin in advanced drug delivery systems, namely nano/microparticles and liposomes. Through this pulmonary delivery, heparin is protected from enzymatic degradation within the airway. Heparin is thus passively targeted into the lungs, and long-lasting localized treatment is achieved. On the other hand, these systems have encountered several problems as follows: (1) polymers, such as poly-L-lactide-glycolic acid, poly (lactic acid), and chitosan, used to prepare heparin-loaded microparticle/nanoparticle (MP/NP) systems have not been granted approval for lung application by the FDA and (2) liposomal and NP formulation stability is the main problem of formulation design. We propose that additional in vitro and in vivo research is necessary to assess the clinical applicability of this treatment strategy. The present article discusses heparin treatments for lung diseases and the use of heparin and/or heparin-loaded drugs in advanced delivery systems through the pulmonary route.

Surgical retrieval of a guide wire lost during central venous catheterization in a dog

OBJECTIVE

To report a case of successful surgical removal of a guide wire lost during central venous catheterization.

CASE SUMMARY

A 28 kg, 4-year-old female neutered mixed breed dog presented to the primary care veterinarian with diabetic ketosis. During the process of central venous catheterization, the guide wire was accidently released and the entire length of the guide wire slipped into the jugular vein. Due to the absence of nearby interventional radiology facilities, surgical intervention was proposed. An ultrasound was used to determine that the guide wire was located in the caudal vena cava extending caudally into the right internal iliac vein. Rommel tourniquets were placed around the iliac vein cranial to the bifurcation of the common iliac vein into the external and internal iliac veins. A venotomy was performed in the right common iliac vein and the guide wire was grasped with hemostats and gently removed while alternately relaxing the cranial then caudal tourniquets. During anesthesia, ventricular premature contractions were noted that varied in frequency with the dog's positioning. Postoperative color flow Doppler ultrasound evaluation of the caudal vena cava, right common, internal and external iliac veins, and right femoral vein was normal with no evidence of thrombosis. Several days postoperative the dog's diabetic ketosis and ventricular premature contractions had resolved and color flow Doppler ultrasound evaluation was normal with no evidence of thrombosis.

NEW OR UNIQUE INFORMATION PROVIDED

To the authors' knowledge, this is the first reported veterinary case of loss and subsequent surgical retrieval of a central venous catheter guide wire.

Deep Vein Thrombosis in the Lower Extremities in Comatose Elderly Patients with Acute Neurological Diseases

PURPOSE

Comatose elderly patients with acute neurological illness have a great risk of deep vein thrombosis (DVT). In this study, the incidence of DVT and the effectiveness of early initiation of treatment were evaluated in those patients.

MATERIALS AND METHODS

Total 323 patients were admitted to our ward due to neurological diseases in one year, and 43 patients, whose Glasgow Coma Scale was ≤ 11 and who was older than ≥ 60 years, were included in this study. D-dimer was measured on admission and day 7, and lower-extremity ultrasonography was performed on day 7. When DVT was positive, heparin treatment was initiated, and further evaluation of pulmonary embolism (PE) was conducted. Vena cava filter protection was inserted in PE-positive patients. Incidence of DVT and PE, alteration of D-dimer value, and effect of heparin treatment were analyzed.

RESULTS

DVT was positive in 19 (44.2%) patients, and PE was in 4 (9.3%). D-dimer was significantly higher in DVT-positive group on day 7 (p<0.01). No DVT were identified in patients with ischemic disease, while 66.7% of intracerebral hemorrhage and 53.3% of brain contusion patients were DVT positive. Surgery was a definite risk factor for DVT, with an odds ratio of 5.25. DVT and PE disappeared by treatment in all cases, and no patients were succumbed to the thrombosis.

CONCLUSION

Patients with hemorrhagic diseases or who undergo operation possess high risk of DVT, and initiation of heparin treatment in 7 days after admission is an effective prophylaxis for DVT in comatose elderly patients without causing bleeding.

Effect of medical thromboprophylaxis on mortality from pulmonary embolus and major bleedingy

BACKGROUND

Several studies have failed to discover a beneficial effect of medical thromboprophylaxis on mortality.

AIMS

To examine the relative influence of acute fatal pulmonary embolism (PE) and fatal major haemorrhage on overall mortality in medical patients treated with low molecular weight heparin (LMWP) for prophylaxis.

METHODS

The author compared deaths from the above factors using data from a recent Cochrane Collaboration meta-analysis. Data from trials satisfying the criteria of the Cochrane analysis plus additional exclusions to avoid bias were pooled to produce point estimates of mortality from PE and major bleeds to estimate net mortality benefit. Estimates were then subject to limited sensitivity analysis based on reported epidemiological data.

RESULTS

Reported PE and major bleeds were 0.44 per cent and 0.27 per cent, respectively. The corresponding case-specific mortality rates were 30.8 per cent and 12.8 per cent and the relative risk reduction (RRR) for PE was 23.2 per cent. Estimated deaths from major bleeds exceeded PE deaths avoided by a small margin (3/100,000 patients given prophylaxis). This excess increased to 30/100,000 when more plausible literature values for PE case fatality rates were applied.

CONCLUSION

Medical thromboprophylaxis has a finely balanced effect on mortality but may increase it. Such an effect would explain the failure to discover a mortality benefit from medical thromboprophylaxis. Further work, including a formal meta-analysis and additional clinical studies, is required to confirm this picture.