In this study, no difference in the rate of CVC-related VTE was detected between patients receiving enoxaparin and patients receiving placebo. The dose of enoxaparin used in this study proved to be safe. Clinical trials evaluating higher enoxaparin doses could optimize the efficacy of this agent for this indication.

SummaryRecent epidemiological studies have suggested that psoriasis represents a risk factor for thrombotic vascular diseases. In order to evaluate the possible role of hemostatic changes in the development of thrombotic episodes in psoriasis, some parameters of the hemostatic “balance” were investigated in 22 male psoriatic patients and compared to those of 22 male control subjects. Incidence of known risk factors for vascular diseases (diabetes, hypertension, smoking, dyslipidemia) was comparable in the two study groups. There were no statistically significant differences in platelet count, circulating platelet aggregates, platelet production of malondialdehyde (MDA), total plasma anti thrombin and fibrinolytic activities. In patients with psoriasis the incidence of spontaneous platelet hyperaggregability and plasma levels of β-thromboglobulin were significantly higher than in control subjects. Platelet regeneration time, measured as MDA recovery after aspirin ingestion, was significantly shorter in psoriatic patients. These data suggest that an in vivo platelet activation occurs in patients with psoriasis and could contribute to the development of thrombotic complications. The release of mitogenic and inflammatory substances by activated platelets may play a role in the histogenesis of psoriatic lesions.

SummaryA high incidence of post-discharge venous thromboembolism in orthopaedic surgery patients has been recently reported drawing further attention to the unresolved issue of the optimal duration of the pharmacological prophylaxis. We performed an overview analysis in order to evaluate the incidence of late occurring clinically overt venous thromboembolism in major orthopaedic surgery patients discharged from the hospital with a negative venography and without further pharmacological prophylaxis. We selected the studies published from January 1974 to December 1995 on the prophylaxis of venous thromboembolism after major orthopaedic surgery fulfilling the following criteria: 1) adoption of pharmacological prophylaxis, 2) performing of a bilateral venography before discharge, 3) interruption of pharmacological prophylaxis at discharge in patients with negative venography, and 4) post-discharge follow-up of the patients for at least four weeks. Out of 31 identified studies, 13 fulfilled the overview criteria. The total number of evaluated patients was 4120. An adequate venography was obtained in 3469 patients (84.1%). In the 2361 patients with negative venography (68.1%), 30 episodes of symptomatic venous thromboembolism after hospital discharge were reported with a resulting cumulative incidence of 1.27% (95% C.I. 0.82-1.72) and a weighted mean incidence of 1.52% (95% C.I. 1.05-1.95). Six cases of pulmonary embolism were reported. Our overview showed a low incidence of clinically overt venous thromboembolism at follow-up in major orthopaedic surgery patients discharged with negative venography. Extending pharmacological prophylaxis in these patients does not appear to be justified. Venous thrombi leading to hospital re-admission are likely to be present but asymptomatic at the time of discharge. Future research should be directed toward improving the accuracy of non invasive diagnostic methods in order to replace venography in the screening of asymptomatic post-operative deep vein thrombosis.

SummaryVenous thromboembolism is a leading cause of in-hospital postoperative morbidity and mortality. Postoperative deep vein thrombosis (DVT) is usually asymptomatic. A number of studies have consistently shown that the non invasive diagnostic methods are inaccurate in the screening of asymptomatic DVT. Failure of non invasive diagnostic methods to detect thrombi in asymptomatic patients has been suggested to be due to the features of thrombi in these patients. The aim of this study was to assess the distribution and the occlusiveness of thrombi in a series of 321 asymptomatic hip surgery patients with adequate bilateral venography of the lower limbs.Venography was performed 10 ± 1 days after hip surgery. DVT was found in 180 limbs (28.0%). The distribution of thrombi was as follows: 26 (14.4%) isolated proximal thrombi, 55 (30.6%) proximal and distal thrombi, 99 (55.0%) isolated calf thrombi. We found that 14 of the 81 proximal trombi (17.3%) involved the superficial femoral vein either as exclusive location or in association with calf veins. An involvement of common femoral, superficial femoral and popliteal vein was observed in 37 (45.7%), 39 (48.1%) and 44 (54.3%) cases of the 91 proximal DVT. These thrombi were non occlusive in 25 (67.6%), 22 (56.4%) and 26 (59.1%) limbs, respectively. An involvement of at least one peroneal, anterior tibial and posterior tibial veins was observed in 118,13 and 89 cases of the 220 distal thrombi. These thrombi were non occlusive in 61 (51.7%), 10 (76.9%) and 30 (33.7%) of the cases.We conclude that the majority of thrombi found in asymptomatic hip surgery patients are non occlusive. In view of this, non invasive diagnostic methods based upon venous flow measurement will be unlikely to improve the diagnosis of asymptomatic DVT. The high incidence of isolated superficial femoral vein thrombosis necessitates that real-time B-mode ultrasonography should be performed examining the entire proximal venous system.

Quantitation of the thrombocytopathy of uraemics may be one useful way of evaluating forms of therapy. 24 patients treated by haemodialysis and peritoneal dialysis at two different times had platelet aggregation studies whose parameters were compared with those of 24 normal persons, 5 successful transplants or 13 untreated uraemics. Renal transplantation and peritoneal dialysis improved platelet function. The haemodialysis procedure itself impaired platelet function: this was not due to heparin.