Increased kidney xanthine oxidoreductase activity in salt-induced experimental hypertension

OBJECTIVES: To assess the efficacy and safety of low molecular weight heparin (LMWH) as deep venous thrombosis (DVT) prophylaxis following total knee arthroplasty. DATA SOURCES: Medline 1986 to June 1997, Embase, and manufacturers were used to identify randomized controlled trials. REVIEW METHODS: Trials included were randomized studies of LMWH with routine radiological screening for DVT. Placebo or active controls were included. Two reviewers independently screened trials for inclusion, and assessed their quality. Pooled relative risk estimates of DVT and proximal DVT rates were calculated using a DerSimonian and Laird random effects model. Sensitivity of the results to the type of control used and the quality of the trial was assessed. RESULTS: The relative risk of DVT for a patient given LMWH is 0.73 (95% CI 0.66 to 0.80) when compared with patients treated with adjusted dose heparin or warfarin controls. The relative risk for proximal DVT is 0.58 (95% CI 0.38 to 0.90). The relative risk of pulmonary emboli in the LMWH group was 0.55 (95% C.I. 0.20 to 1.57). No excess of bleeding was recorded in the LMWH group. CONCLUSIONS: Low molecular weight heparin is more efficacious than either adjusted dose heparin or adjusted dose warfarin, when used to prevent DVT and proximal DVT following total knee arthroplasty.     

Alterations in fibrinolytic and protein C pathways in gynaecological surgery: low molecular weight heparin prophylaxis

Several parameters of fibrinolytic and protein C pathways were evaluated in three groups of patients with high (HR), moderate (MR) and low (LR) postoperative thrombotic risk undergoing major gynaecological surgery. The HR and MR groups were subjected to low molecular weight heparin (LMW) prophylaxis. A significant increase in plasminogen activator inhibitor type 1 (PAI-1) antigen and activity levels was observed in the HR patient group in comparison with the MR and LR groups in the preoperative and early postoperative period. In all the groups studied, the maximum increase in the levels of PAI-1 was seen on day 1 after surgery. However, the D-dimeric levels reached the highest level on day 7. A significant increase in activated protein C:alpha 1 antitrypsin (APC:alpha 1AT) complex levels was observed in the HR group in comparison with the LR group, and a strong decrease in protein C inhibitor in the early postoperative period was detected in all the groups. In spite of heparin prophylaxis, 2 HR patients were diagnosed as deep vein thrombosis (DVT) during the postoperative period. Both patients showed pre-operative levels of PAI-1 antigen or activity and APC:alpha 1AT complexes above the mean + 1 SD of the pre-operative levels in the HR group. In conclusion, in HR patients a hypofibrinolytic and hypercoagulable state was detected in the pre-operative and early postoperative periods. The prophylactic LMW heparin dose used in the present report (20 mg/day x 7) was insufficient to prevent DVT in the HR group. At present our HR patients are given higher doses of LMW heparin (40 mg/day x 7).     

A phase II study of paclitaxel in heavily pretreated patients with small-cell lung cancer

Deep vein thrombosis (DVT) and pulmonary embolism (PE) are major complications associated with total knee arthroplasty. The American College of Chest Physicians recommends twice-daily, fixed-dose low-molecular-weight heparin (LMWH) as routine prophylaxis in this patient population. This study represents a cost analysis of ardeparin and enoxaparin, the two LMWHs currently available for this indication in the United States. Costs for treating DVT, PE, and major bleeding episodes were derived from values reported in the literature. Both ardeparin and enoxaparin were found to produce significant cost savings when used routinely as DVT prophylaxis after knee replacement surgery compared with no prophylaxis. Based on the currently available data, enoxaparin 40 mg once daily appears to be the least costly LMWH for routine pharmacoprophylaxis of DVT in patients undergoing knee replacement surgery.     

Low dose heparin in major surgery: clinical relevance of plasma heparin concentrations

56 patients undergoing elective major surgery received low dose heparin prophylaxis, 5,000 IU 2 h before surgery and every 8 h for 7 days. The patients were tested by the 125I-fibrinogen uptake test, which, if positive, was controlled by venography. The heparin concentrations were measured by the method of DENSON and BONNAR and by the chromogenic method of TEIEN et al. in blood samples drained immediately before and after surgery and on the 1st and 5th postoperative day 2 and 4h after the injection of heparin. The values were found higher when estimated by the method of DENSON and BONNAR than by the chromogenic method. Deep vein thrombosis (DVT) developed in 11 patients, and in 10 of them within the first 48 after the operative procedure, in 1 after 4 days. The preoperative values were not lower in the patients who developed DVT, and the heparin concentrations found on the 1st and 5th postoperative day were at the same level as in those who did not develop DVT.     

Experimental transplantation of size-reduced, adult kidneys into pediatric recipients

BACKGROUND: Renal transplantation in infants is frequently complicated by graft thrombosis and accelerated rejection reactions. We herein tested the hypothesis that the amount of blood required to sustain normal perfusion of an adult renal allograft transplanted into a pediatric recipient would surpass the cardiac output and aortic blood flow of the recipient and that the ensuing low flow in full-size grafts (FSG) would induce a release of thrombogenic substances. METHODS: In a porcine renal transplant model, adult FSG were transplanted into pediatric recipients. Macro- and microhemodynamic as well as metabolic data were recorded. Surgically size-reduced grafts (RSG) served as controls. RESULTS: Donor weight was 55.1+/-4.8 kg and 9.6+/-0.9 kg for recipients. FSG weight was 122+/-16 g and 65+/-14 g for RSG. Blood flow in donor kidneys was 20% higher than the infrarenal aortic blood flow of recipients. After reperfusion, mean arterial pressure in recipients of FSG but not RSG dropped to 64 mmHg, despite an increase in cardiac output by 60%. FSG but not RSG were polyuric and proteinuric. The release of endothelin and thromboxane B2 into the circulation was higher from FSG when compared with RSG (P<0.05 for endothelin after 60 min; NS for thromboxane B2). CONCLUSIONS: After transplantation of FSG into pediatric recipients, the macrohemodynamic limitations of the recipient cause microcirculatory disturbances in the graft, which contribute to the release of vasoconstrictive and prothrombotic substances and an impaired early graft function. Some of those effects can be ameliorated by surgically size reducing the renal graft.     

Prophylaxis for venous thromboembolism in head and neck surgery: the practice of otolaryngologists

Deep venous thrombosis (DVT) and pulmonary embolism (PE) are an important cause of morbidity and mortality in the surgical patient. The first guideline produced by the Scottish Intercollegiate Guidelines Network was for the prophylaxis of venous thromboembolism. Patients undergoing major head and neck cancer surgery commonly exhibit risk factors for venous thromboembolism. Currently, however, there are no data on its incidence in these patients. A questionnaire survey was performed to assess the current practice of consultant otolaryngologists regarding DVT prophylaxis in patients undergoing head and neck cancer surgery. Of those respondents who managed these patients, 57 per cent did not use routine DVT prophylaxis while 43 per cent did. A wide variety of techniques were employed among those practising DVT prophylaxis. A consensus is needed concerning the use of thromboembolism prophylaxis in head and neck surgery patients.     

Prognosis after primary renal transplant failure and the beneficial effects of repeat transplantation: multivariate analyses from the United States Renal Data System

BACKGROUND: Survival of transplant recipients after primary renal allograft failure has not been well studied. METHODS: A cohort of 19,208 renal transplant recipients with primary allograft failure between 1985 and 1995 were followed from the date of allograft loss until death, repeat transplantation, or December 31, 1996. The mortality, wait-listing, and repeat transplantation rates were assessed. The mortality risks associated with repeat transplantation were estimated with a time-dependent survival model. RESULTS: In total, 34.5% (n=6,631) of patients died during follow-up. Of these deaths, 82.9% (n=5,498) occurred in patients not wait-listed for repeat transplantation, 11.9% (n=789) occurred in wait-listed patients, and 5.2% (n=344) occurred in second transplant recipients. Before repeat transplantation, the adjusted 5-year patient survival was 36%, 49%, and 65% for type I diabetes mellitus (DM), type II DM, and nondiabetic end-stage renal disease, respectively (P<0.001; DM vs. nondiabetics). The adjusted 5-year patient survival was lower in Caucasians (57%, P<0.001) compared with African-Americans (67%) and other races (64%). The 5-yr repeat transplantation rate was 29%, 15%, and 19%, whereas the median waiting time for a second transplant was 32, 90, and 81 months for Caucasians, African-Americans, and other races, respectively (P<0.0001 each). Repeat transplantation was associated with 45% and 23% reduction in 5-year mortality for type I DM and nondiabetic end-stage renal disease, respectively, when compared with their wait-listed dialysis counterparts with prior transplant failure. CONCLUSIONS: The loss of a primary renal allograft was associated with significant mortality, especially in recipients with type I DM. Repeat transplantation was associated with a substantial improvement in 5-year patient survival. Recipients with type I DM achieved the greatest proportional benefit from repeat transplantation.     

The great success of Asian kidney transplant recipients

BACKGROUND: Little has been written about allograft survival in non-African-American minority groups. We examine the success of kidney transplantation in 1900 Asian recipients. METHODS: Data from 42,252 cadaveric and 16,115 live donor kidney transplant recipients were monitored from the United Network for Organ Sharing Scientific Renal Transplant Registry from 1991 through 1996. RESULTS: Asian recipients exhibited the highest cadaveric allograft survival rates (89% 1-year and 83% 3-year survival) and the longest mean allograft half-life (18 years). Asian women had the highest mean graft half-life (23 years). Asians were less likely to be broadly sensitized and had a high incidence of IgA nephropathy causing end-stage renal disease. Although it has been suggested that their low body weights may help explain the excellent allograft outcome, Asians exhibited superior graft survival rates even when compared with low body weight recipients of other races. CONCLUSION: Asian renal allograft recipients, particularly Asian females, have the highest allograft survival rates of all racial groups.     

A PIL for every ill? Patient information leaflets (PILs): a review of past, present and future use

PURPOSE: The necessity of effective prevention of DVT is generally accepted. However, attitudes and beliefs concerning prophylaxis vary greatly in terms of the risk groups receiving prophylaxis and the prophylactic methodology. This paper reviews current research on the subject and seeks to provide recommendations. RESULTS: Known clinical risk factors allow the classification of patients according to high, medium and low risk of developing thromboembolism. Basic forms of prophylaxis are physiotherapy and early mobilisation. However, there are no data on the safety and efficacy of these methods. Mechanical devices used include external intermittent pneumatic compression and graduated compression stockings. Used in isolation, these methods reduce the incidence of deep vein thrombosis in low and moderate risk patients by one half or one third. There is no distinction between mechanical and pharmacological methods in terms of safety and efficacy. Furthermore, secondary effects are extremely rare. Moderate and high risk category patients should receive combined modes of mechanical and pharmacological treatment. A direct comparison of safety in moderate risk patients fixed doses of standard heparin vs. low molecular weight heparin revealed no significant differences. In the case of high risk patients, adjusted dose heparin administered subcutaneously or fixed dose low molecular heparin is recommended. A severe secondary effect of heparin-prophylaxis is heparin-induced thrombocytopenie. The optimum duration of pharmacological prophylaxis is not yet clear. CONCLUSION: The methods and duration of prophylaxis remain subject to an individual medical assessment of the clinically significant benefits in relation to the risk secondary effects of the treatment. On major questions there are significant variations in the specialist literature. This means that standards cannot be formulated, although recommendations can be given.     

Deep vein thrombosis after thoracotomy

In a prospective study of 183 patients undergoing lateral thoracotomy the 125 I fibrinogen uptake test and perioperative heparin prophylaxis for deep-vein thrombosis were investigated. There was an incidence of deep vein thrombosis in 51% in untreated control patients. The heparin prophylaxis effectively reduced the incidence of deep venous thrombosis to 28% (P less than 0.005) without increasing postoperative blood loss. Unilateral thrombosis was found to be significantly more frequent in the leg opposite the side of the thoracotomy (P less than 0.005). The 125I fibrinogen test is essential in assessing methods of prophylaxis but is not recommended as a routine.     

Treatment of venous thromboembolism

This review provides meta-analytic data of studies aiming at improved treatment of deep vein thrombosis and pulmonary embolism. The introduction of low molecular weight heparin has considerably ameliorated the initial treatment of deep vein thrombosis, and should now be regarded as the treatment of choice for most patients with deep vein thrombosis. Oral anticoagulant treatment is presently considered safe and effective for the long-term treatment of venous thromboembolism, provided that the INR is maintained at 2.0-3.0. However, the optimal duration as well as the optimal intensity of anticoagulation have still to be determined. Patients with submassive pulmonary embolism should presently be treated with adjusted dose unfractionated heparin and coumarins. Studies determining the efficacy and safety of low molecular weight heparin in this condition deserve priority. Thrombolytic therapy should be restricted to patients with massive pulmonary embolism, unless safer methods of thrombolysis have been developed. Surgical embolectomy and catheter fragmentation of emboli seem alternative options but deserve further investigations.     

Clinical utility of prothrombin fragment 1+2, thrombin antithrombin III complexes and D-dimer measurements in the diagnosis of deep vein thrombosis following total hip replacement

BACKGROUND: Measurements of prothrombin fragment 1+2 (F1+2), thrombin antithrombin III complexes (TAT) and D-dimer plasma levels have been proposed as non-invasive screening tests to exclude postoperative deep venous thrombosis (DVT). We investigated the diagnostic efficacy of these coagulation activation markers to rule out postoperative DVT in patients undergoing hip surgery under antithrombotic prophylaxis. METHODS: In this substudy of a randomized double-blind thrombosis prophylaxis trial comparing three doses of desirudin (10, 15 or 20 mg b.i.d.) with unfractionated heparin (5000 IU t.i.d.) we used ELISA procedures to measure F1+2, TAT and D-dimer in 159 patients undergoing total hip replacement at baseline (day 0) and on postoperative days 1, 3 and 6. Bilateral venography was performed in all cases 8-11 days after surgery. RESULTS: For the F1+2 assay sensitivity ranged from 73 to 83% in the three postoperative days investigated, and negative predictive value (NPV) from 68 to 74%. For TAT and D-dimer sensitivity ranged from 71 to 73% and from 71 to 83% and NPV from 61 to 65% and from 61 to 74% respectively. INTERPRETATION: In terms of sensitivity and NPV F1+2 and D-dimer are equivalent and are superior to TAT. However, their accuracy is too low to rule out the presence of DVT after hip surgery under antithrombotic prophylaxis.     

Outpatient management of deep vein thrombosis

OBJECTIVE: To assess whether patients with deep vein thrombosis (DVT) could be satisfactorily treated on an outpatient basis with low molecular weight (LMW) heparin and warfarin. DESIGN: A 22 month prospective study of adults attending St Peter's Hospital accident and emergency department with DVT. RESULTS: 1093 patients were referred and assessed; 160 were venogram positive, of which 159 patients between the ages of 22 and 89 years of age have now been treated with LMW heparin as outpatients. Direct liaison with community nurses has minimised the impact on general practitioner workload. CONCLUSIONS: 1272 bed days were saved during this period (an estimated 320,000 pounds). The outpatient treatment of thromboembolism has been shown to be effective and safe.     

Prevention of the extension of distal deep venous thrombosis. A randomized controlled trial with a 6-month follow-up

BACKGROUND: Deep venous thrombosis (DVT) of distal veins of the legs is important for its frequency and its potential proximal extension. The incidence of embolization in distal DVT is limited and treatment still undefined. METHODS: After diagnosing with duplex scanning a distal DVT patients were included in a 24-week follow-up. All subjects used elastic compression (stockings TED = thromboembolic deterrent) for 24 weeks after DVT. In the 4 groups the following prophylaxis for 8 weeks were used: A: oral anticoagulant (INR 2.5). B: subcutaneous calcium heparin 0.2 ml bid (8.00 and 20.00). C: subcutaneous calcium heparin (0.5 ml at 20.00). D was the control group (only elastic TED stockings). heparin 0.2 ml bid (5000 IU) and 0.5 ml once daily (12.500 IU) were used for individuals with weight range between 65 and 90 kg. No patient was admitted into hospitals. Initially 106 patients were included. There were 17 (9.6%) drop outs and after 8 weeks 177 patients completed the study. No pulmonary embolisation or side effects were observed. In one patient (control group) an important extension of the thrombus to the femoral and iliac veins was observed. RESULTS: The percentage of thrombus reduction was higher in the treatment groups than in controls (p < 0.05). No significant differences were found among the 3 treatment groups. At 8 weeks 88.6% of patients treated with oral anticoagulant showed improvement (stability/reduction in size of the thrombus; the percentage was 88.4% in subjects treated with subcutaneous heparin bid and 93.2% in those treated with a single dosage). In the control group thrombus increase was observed in 78.3% of patients (this difference was significant in comparison with the treatment groups; p < 0.05). At the 24-week control in 97.6% of patients in group A thrombosis was reduced/stable. This percentage was 97.7% in the ca-heparin double-dose group (B) and 100% in the single dose group (C), significantly lower than in group D (75%; p < 0.05). CONCLUSIONS: Results indicate that untreated subjects with distal DVT are at risk of thrombus extension. In this study treatments were clinically equivalent. However one single dose of subcutaneous heparin is as effective as the double dose, is better tolerated, does not require haematological monitoring and has a lower cost.     

Transplantation of pediatric en bloc cadaver kidneys into adult recipients

BACKGROUND: To maximize the renal donor pool, cadaveric pediatric en bloc kidneys have been transplanted as a dual unit by some transplant centers. We compared the short- and long-term outcomes of adult recipients of cadaveric pediatric en bloc renal transplants versus those of matched recipients of cadaveric adult kidneys. METHODS: Thirty-three adults who received pediatric en bloc kidney transplants between April 1990 and September 1997 were retrospectively identified and were compared with 33 matched adults who received adult cadaveric kidney transplants. The groups were identical for transplantation era, immunosuppression, recipient sex, race, cause of renal failure, mean weight, and follow-up duration (37.8 vs. 37.5 months). The mean recipient age study versus control was lower (36.3 vs. 48.9 years, P=0.0003). Results. There was no difference between the en bloc and adult donor groups in the 3-year patient survival rates (95% vs. 87%, P=0.16) or the 3-year graft survival rates (87.3% vs. 84.2%, P=0.35). Further, there was no difference in en bloc patient or en bloc graft survival time stratified by recipient age (14-44 vs. >45 years, P=0.11), en bloc donor age (<24 vs. >24 months, P=0.39), or recipient weight (<60, 61-75, >75 kg; P=0.60). Differences in serum creatinine (mg/dl) for the en bloc versus the control group at the time of discharge (3.0 vs. 7.8 mg/dl, P=0.06), at 1 year (1.4 vs. 2.0 mg/dl, P=0.06), and at 2 years (1.1 vs. 1.6 mg/dl, P=0.14) had dissipated by the time of the 5-year follow-up examination (1.1 vs. 1.6 mg/dl, P=0.14). Vascular complications were more prevalent in the en bloc group: renal vein thrombosis (one case), thrombosis of donor aorta (two cases), arterial thrombosis of one renal moiety (two cases), and renal artery stenosis (two cases). There were no differences between groups in delayed graft function, acute or chronic rejection, posttransplant hypertension, posttransplant protein-uria, or long-term graft function. CONCLUSIONS: Collectively, these data indicate that transplanting pediatric en bloc kidneys into adult recipients results in equivalent patient and graft survival compared with adult cadaveric kidneys. Further, the data also suggest that pediatric en bloc kidneys need not be strictly allocated based on recipient weight or age criteria.     

Preoperative prediction of postoperative deep vein thrombosis

A range of clinical data was obtained from 124 patients about to undergo operation and several coagulation tests were performed. No patient received prophylaxis for deep vein thrombosis, and isotopic scanning after operation showed that 20 patients had developed thrombosis. a simiple prognostic index for predicting which patients would develop postoperative deep vein thrombosis was constructed using the clinical and coagulation data obtained before operation. The five variables with the best predictive power-euglobulin lysis time, age, presence of varicose veins, fibrin related antigen, and percentage overweight-produced an equation that identfied 95% of those who developed deep vein thrombosis and misallocated only 28% of those who did not develop thrombosis. In view of the complications that low-dose heparin and dextran can cause, giving prophylaxis to under a third of the patients who will not develop deep vein thrombosis is clearly better than giving it to all.     

A randomized prospective controlled trial of oral acyclovir versus oral ganciclovir for cytomegalovirus prophylaxis in high-risk kidney transplant recipients

BACKGROUND: Posttransplantation cytomegalovirus (CMV) infection remains a significant cause of morbidity in kidney transplant recipients. We performed a randomized prospective controlled trial of oral acyclovir versus oral ganciclovir for CMV prophylaxis in a group of renal allograft recipients considered at high risk for CMV disease due to the use of OKT3 induction therapy. METHODS: A total of 101 recipients of cadaveric (83) and zero haplotype-matched live donor (18) kidney transplants were entered into the trial. A total of 22 D-R- patients received no prophylaxis. Twenty-seven D+R-, 29 D+R+, and 23 D-R+ patients were randomized to receive 3 months of either oral acyclovir (800 mg q.i.d.) or oral ganciclovir (1000 mg t.i.d.). Doses were adjusted according to the level of renal function. The D+R- patients were also given CMV immune globulin biweekly for 16 weeks. Surveillance blood cultures were obtained at transplantation, at months 1, 2, 3, and 6, and when clinically indicated. The primary study end points were time to CMV infection and disease the first 6 months after transplantation. RESULTS: The mean follow up was 14.4 months. Both agents were well tolerated, and no drug interruptions for toxicity occurred. CMV was isolated in 14 of 39 (35.9%) acyclovir-treated and 1 of 40 (2.5%) ganciclovir-treated recipients by 6 months (P=0.0001). Symptomatic CMV disease occurred in 9 of 14 (64%) of the acyclovir patients, two with tissue-invasive disease. Infection rates for acyclovir vs. ganciclovir, respectively, stratified by CMV serology were: D+R-, 54 vs. 0%, P=0.0008; D+R+, 43 vs. 6.6%, P=0.01; D-R+, 8.3 vs. 0%, P=NS. No patient developed CMV infection while taking oral ganciclovir, however three delayed infections occurred 2-7 months after finishing therapy. Each patient had been previously treated for acute rejection. CONCLUSIONS: Oral acyclovir provides effective CMV prophylaxis only for recipients of seronegative donor kidneys. Oral ganciclovir is a superior agent providing effective CMV prophylaxis for recipients of seropositive donor kidneys. Recipients who are treated for acute rejection are at risk for delayed CMV infection during the first posttransplantation year.     

Deep venous thrombosis: incidence on admission to a brain injury rehabilitation program

OBJECTIVE: To determine the incidence of deep venous thrombosis (DVT) in brain injured individuals at time of admission to a brain injury (BI) rehabilitation program. DESIGN: Prospective study, sequential case series. SETTING: University tertiary care BI rehabilitation center. DATA SET: Eighty-two traumatic brain injury (TBI) and 71 atraumatic brain injury (ABI) patients were consecutively admitted to our BI unit over a 12-month period and screened within 24 hours of admission for a lower extremity DVT with color flow duplex Doppler ultrasonography. All patients had been prophylaxed with either subcutaneous heparin anticoagulation therapy or intermittent compression devices, and all patients were within 2 months of the original BI. MAIN OUTCOME MEASURES: Evidence of intrinsic venous occlusion by duplex Doppler. RESULTS: DVTs were detected and treated prior to rehabilitation admission in three patients (2%), and these persisted at rehabilitation admission. New DVTs were detected at time of rehabilitation admission in 17 patients (11%). All were occult DVTs; none of the 17 patients had clinical findings indicative of acute DVT. No significant differences were noted in the TBI group when age, highest 24-hour Glasgow Coma Scale score, length of acute hospitalization, type of DVT prophylaxis, or presence of an extremity fracture were compared for individuals with and without DVT. No significant differences were noted in the ABI group when age, length of acute hospitalization, and type of DVT prophylaxis were compared for individuals with and without DVT. CONCLUSION: The overall incidence of DVTs was 13% and the incidence of occult DVT was 11%. Individuals with TBI had an overall incidence of DVTs of 20% and an occult DVT incidence of 18%. Individuals with ABI had an overall incidence of DVT's of 6% and an occult DVT incidence of 4%. These findings indicate the importance of baseline screening for DVT in this patient population.     

Incidence and prevention of deep venous thrombosis occurring late after general surgery: randomised controlled study of prolonged thromboprophylaxis

OBJECTIVE: To study the incidence of late deep venous thrombosis (DVT), and to evaluate a regimen of prolonged thromboprophylaxis after general surgery. DESIGN: Randomised, controlled, open trial, with blinded evaluation. SETTING: University hospital, Denmark. SUBJECTS: 176 consecutive patients undergoing major elective abdominal or non-cardiac thoracic operations, of whom 118 were eligible for evaluation. INTERVENTIONS: Thromboprophylaxis with a low-molecular-weight heparin, tinzaparin, given for four weeks (n = 58), compared with one week (control group, n = 60). MAIN OUTCOME MEASURES: Presence of DVT established by bilateral venography four weeks after the operation. RESULTS: The incidence of late DVT in the control group was 6/60 (10%, 95% confidence interval (CI) 4% to 21%). In the prophylaxis group it was 3/58 (5.2%, 95% CI 1% to 14%) (p = 0.49). CONCLUSION: Prolonged thromboprophylaxis had no significant effect on the incidence of DVT occurring late after general surgery.     

Low molecular weight heparins. Implications in anesthesia and resuscitation

Low molecular weight heparins are a group of drugs that have only recently been introduced in clinical practice. The are widely used for prophylaxis in thromboembolic disease and are being employed increasingly to treat established venous thrombosis. One way in which these drugs are often used is for prophylaxis in the perioperative period for patients at high risk of developing venous thromboembolism, and the anesthesiologist must therefore be familiar with the main aspects of this application. We review pharmacological characteristics of these drugs as well as the literature on low molecular weight heparins, stressing points of main interest to the anesthesiologist and intensive care recovery unit specialist, namely adverse effects (mainly bleeding) and the implications that use of low molecular weight heparin will have on choice of anesthetic (in particular the dilemma of whether to use local/regional anesthesia).