Deep venous thrombosis in postoperative vascular surgical patients: a frequent finding without prophylaxis

Incidence of venous thromboembolism in patients with peripheral arterial disease after endovascular intervention

OBJECTIVE

Venous thromboembolism (VTE) is a well-known postoperative complication; however, the incidence of VTE after peripheral vascular intervention (PVI) has not been well described. Despite the minimally invasive nature of these procedures, the patients undergoing PVI have significant risk factors for the development of VTE. In the present study, our objective was to describe the short-term incidence of VTE after PVI, identify differences between sexes, and examine the periprocedural antiplatelet and anticoagulation regimens.

METHODS

We identified adults (age >66 years) who had undergone PVI from January 1, 2008 to September 30, 2015 from the inpatient Medicare claims data. The patients were followed for 365 days after the procedure. VTE events during follow-up were identified using the International Classification of Diseases, 9th revision, diagnosis codes. The covariate-standardized 30- and 90-day cumulative incidence of VTE events, overall and stratified by sex, were estimated using Aalen-Johansen estimators, accounting for death as a competing risk. Differences in sex between females and males were identified using Gray's test. Any antiplatelet or anticoagulant prescription fill was defined as any fill from 14 days before the endovascular intervention through the date of the VTE event. Persistence with antiplatelet and anticoagulant therapy was assessed by creating daily logs of antiplatelet and anticoagulant coverage using the dispensing dates and days of supply. Over-the-counter medications (ie, aspirin) were not evaluated.

RESULTS

We identified 31,593 qualifying patients with a mean age of 76.8 ± 7.4 years. Of the 31,593 patients, 46% were male, and 12% had a history of VTE. After the procedure, deep vein thrombosis (DVT) was a commonly diagnosed complication (3.8% and 4.8% at 30 and 90 days, respectively). The cumulative incidence of pulmonary embolism was 0.9% and 1.2% at 30 and 90 days after the procedure, respectively. Throughout the 90-day postoperative period, females had had a slightly increased risk of DVT compared with males (30-day risk difference, 0.007; P < .01; 90-day risk difference, 0.008; P = .02). We found no sex-based differences in the risk of pulmonary embolism. Of the patients who had developed VTE at 90 days, 970 (55%) had had no prescription fill for an antiplatelet or anticoagulant. Assuming all the patients had been taking aspirin, only 15% of the patients who had developed VTE had been taking prescribed dual antiplatelet medication persistently after PVI. In addition, among the patients who had developed VTE at 90 days, females were less likely to have had a prescription fill for an anticoagulant.

CONCLUSIONS

The findings from our study have demonstrated that the incidence of VTE after PVI is high, with an increased risk of deep vein thrombosis for females. We also found that females were less likely to have been prescribed an anticoagulant after PVI. Future studies are needed to characterize the variables associated with an increased risk of VTE after PVI and to identify strategies to increase dual antiplatelet therapy or anticoagulant prescription adherence to reduce the risk of VTE.

Risk Factors for Venous Thromboembolism after Vascular Surgery and Implications for Chemoprophylaxis Strategies

OBJECTIVE

Venous thromboembolism (VTE) is an important cause of postoperative morbidity and mortality, but the reported incidence after major vascular surgery ranges from as low as 1% to upwards of 10%. Further, little is known about optimal chemoprophylaxis regimens or rates of post-discharge VTE in this population. This study aimed to better characterize in-hospital and post-discharge VTE after major vascular surgery, the role of chemoprophylaxis timing, and the association of VTE with mortality.

METHODS

A single center retrospective study of 1,449 major vascular operations (2013-2020) was performed, and included 189 EVARs (13%), 169 TEVARs (12%), 318 open aortic operations (22%), 640 lower extremity bypasses (44%), and 133 femoral endarterectomies (9%). Baseline characteristics, anticoagulant/antiplatelet medications, and outcomes were abstracted from an electronic data warehouse with medical chart auditing. Post-operative VTE (pulmonary embolism [PE] and deep vein thrombosis [DVT]) within 90-days of surgery was classified based on location, symptoms, and treatment. Cut point analysis using Youden's index identified the most VTE discriminating timing of chemoprophylaxis (including therapeutic/prophylactic anticoagulant and antiplatelet medications) and Caprini score. Multivariable logistic regression tested the association of VTE with chemoprophylaxis timing, Caprini score, and additional risk factors. Cox proportional hazard modeling measured the association between VTE and mortality.

RESULTS

Overall VTE incidence was 3.4% (65% DVTs, 25% PEs, 10% both) and 37% were post-discharge. The rate of symptomatic VTE was 2.4%, which was lowest for EVAR (0.0%) and highest for open aortic operations (4.1%, p=0.02). Individuals who developed VTE had longer length of stay, higher rates of end-stage renal disease, prior VTE, and higher Caprini scores (8 vs 5 points) (all p<0.01). Individuals who developed VTE were also more likely to receive >2 units of blood postoperatively, have an unplanned return to the operating room, have delayed chemoprophylaxis/anticoagulation/antiplatelet initiation >4 days postoperatively, and had increased 90-day mortality (all p<0.01). Caprini score >7 (29% of patients) was associated with post-discharge VTE (2.6% vs 0.7%, p=0.01), and chemoprophylaxis/anticoagulation/antiplatelet timing >4 days was associated with increased adjusted odds of VTE (odds ratio 2.4 [1.1-4.9]). Although no fatal VTEs were identified, VTE was an independent predictor of 90-day mortality (adjusted hazard ratio 2.7 [1.3-5.9]).

CONCLUSIONS

These data highlight that patients undergoing major vascular surgery are particularly prone to VTE with frequent hypercoagulable comorbidities and earlier initiation of chemoprophylaxis is associated with reduced risk of development of VTE. Furthermore, post-discharge VTE rates may reach thresholds warranting post-discharge chemoprophylaxis, particularly for patients with Caprini scores >7.

A meta-analysis and systematic review of venous thromboembolism prophylaxis in patients undergoing vascular surgery procedures

OBJECTIVE

Perioperative venous thromboembolism (VTE) is generally considered preventable. Whereas the non-vascular surgery literature is rich in providing data about the impact of VTE prophylaxis on VTE outcomes, vascular surgery data are relatively sparse on this topic. This study sought to evaluate the evidence for VTE prophylaxis specifically for the population of vascular surgery patients.

METHODS

A systematic search was conducted in MEDLINE, Cochrane, and Embase databases in December 2018. Included were studies reporting primary and secondary outcomes for common vascular surgery procedures (open aortic operation, endovascular aneurysm repair [EVAR], peripheral artery bypass, amputation, venous reflux operation). A meta-analysis was performed comparing the patients who did not receive VTE prophylaxis and had VTE complications with patients who developed VTE despite receiving prophylaxis.

RESULTS

From 3757 uniquely identified articles, 42 publications met the criteria for inclusion in this review (1 for the category of all vascular operations, 5 for open aortic reconstructions, 2 for EVAR, 1 for open aortic surgery or EVAR, 3 for abdominal or bypass surgery, 2 for peripheral bypass surgery, 2 for amputations, 1 for vascular trauma, and 25 for surgical treatment of superficial venous disease). Five studies met the criteria for inclusion in the meta-analysis. The results demonstrated slightly lower relative risk for development of VTE among patients receiving VTE prophylaxis (relative risk, 0.70; 95% confidence interval, 0.26-1.87). After open aortic reconstruction, the risk of VTE is 13% to 18% and is not reduced by VTE prophylaxis. For EVAR patients, the risk of VTE without prophylaxis is 6%. For patients undergoing peripheral bypass surgery and not receiving therapeutic or prophylactic anticoagulation, the risk of VTE is <2%. For patients undergoing amputations, VTE prophylaxis reduces the risk of VTE. For patients undergoing surgical treatment of superficial venous disease, there is an abundance of literature exploring the utility of VTE prophylaxis, but the evidence is conflicting; some studies demonstrated a benefit, whereas others showed no reduction of VTE with prophylaxis.

CONCLUSIONS

Overall, there is a paucity of literature that addresses the effectiveness of VTE prophylaxis specifically in the population of vascular surgery patients. Our meta-analysis of the literature does not demonstrate a statistically significant benefit of VTE prophylaxis among the vascular surgery patients evaluated; however, it does suggest a low incidence of VTE among patients who receive VTE prophylaxis. Clinicians should identify the patients at high risk for development of postoperative VTE as the risk-benefit ratio may favor VTE prophylaxis in a selected group of patients. Clinicians should use their judgment and established VTE risk prediction models to assess VTE risk for patients. Vascular surgeons should consider reporting VTE incidence as a secondary outcome in publications.

Postoperative Venous Thromboembolism after Neurotologic Surgery

Objective  This study aimed to determine the incidence of postoperative venous thromboembolism (VTE) in adults undergoing neurotologic surgery at a single center. Methods  The records of adults undergoing neurotologic surgery from August 2009 to December 2016 at a tertiary care hospital were reviewed for VTE within 30 postoperative days. Particular attention was focused on postoperative diagnosis codes, imaging, and a keyword search of postoperative notes. Caprini risk scores were calculated. Results  Among 387 patients, 5 experienced postoperative VTE including 3 cases of pulmonary embolism (PE) and 2 cases of isolated deep vein thrombosis (DVT). All patients were given sequential compression devices perioperatively, and none received preoperative chemoprophylaxis. Patients with Caprini score > 8 had a significantly higher rate of VTE compared with those < 8 (12.5 vs. 1%, p  = 0.004). Receiver operating characteristic analysis revealed the Caprini risk assessment model to be a fair predictor of VTE, with a C-statistic of 0.70 (95% confidence interval [CI]: 0.49-0.92). Conclusion  While no specific validated VTE risk stratification scheme has been widely accepted for patients undergoing neurotologic surgery, the Caprini score appears to be a useful predictor of risk. The benefits of chemoprophylaxis should be balanced with the risks of intraoperative bleeding, as well as the potential for postoperative intracranial hemorrhage.

Postoperative Venous Thromboembolism after Extracranial Otologic Surgery

OBJECTIVE

To determine the incidence of postoperative venous thromboembolism (VTE) in adults undergoing otologic surgery.

STUDY DESIGN

Cross-sectional retrospective study.

SETTING

Single tertiary academic center.

SUBJECTS AND METHODS

Adults undergoing nononcologic, extracranial otologic surgery from August 2009 to December 2016. Patients with postoperative diagnosis VTE codes were identified. Imaging and clinical documents were searched for VTE evidence within the first 30 postoperative days. Methods of thromboprophylaxis were documented, and Caprini risk scores were calculated.

RESULTS

In total, 1213 otologic surgeries were evaluated. No postoperative VTE events were identified (0/1268). Mean age was 51.0 ± 17.3 years (range, 18.1-93.4 years). Average length of surgery was 136.0 ± 79.0 minutes (range, 5-768 minutes). The average Caprini score in all patients was 4.0 ± 1.7 (range, 1-15). Eighty-five percent of patients had a Caprini score ≥3, the threshold at which chemoprophylaxis has been recommended in general surgery patients by the American College of Chest Physicians 2012 guidelines. Six patients had documented preoperative chemoprophylaxis and a Caprini score of 4.8 ± 1.7. This was not significantly different from that of patients who did not receive preoperative chemoprophylaxis (t test, P = .3). The literature would estimate a rate of 3.7% VTE in adults with similar Caprini scores undergoing general surgery procedures with no VTE prophylaxis.

CONCLUSION

The Caprini risk assessment model may overestimate VTE risk in patients undergoing extracranial otologic surgery. Postoperative VTE following otologic surgery is rare, even in patients traditionally considered moderate or high risk. Chemoprophylaxis guidelines in this group should be balanced against the potential risk of increased intraoperative bleeding and its associated effects on surgical visualization and morbidity.

The association of venous thromboembolism chemoprophylaxis timing on venous thromboembolism after major vascular surgery

OBJECTIVE

Venous thromboembolism (VTE) is reported to occur in up to 33% of patients undergoing major vascular surgery. Despite this high incidence, patients inconsistently receive timely VTE chemoprophylaxis. The true incidence of VTE among patients receiving delayed VTE chemoprophylaxis is unknown. We sought to identify the association of VTE chemoprophylaxis timing on VTE risk, postoperative transfusion rates, and 30-day mortality and morbidity in patients undergoing major open vascular surgery.

METHODS

Patients undergoing major open vascular surgery (open abdominal aortic aneurysm [oAAA] repair, aortofemoral bypass, and lower extremity infrainguinal bypass [LEB]) were identified using the Michigan Surgical Quality Collaborative (MSQC) between July 2012 and June 2015. The VTE rate was compared between patients receiving early versus delayed VTE chemoprophylaxis. VTE chemoprophylaxis delay was defined as therapy initiation more than 24 hours after surgery. The risk-adjusted association of the chemoprophylaxis timing and VTE development was determined using multivariable logistic regression. Blood transfusion rates, 30-day mortality, and postoperative complications were compared across groups.

RESULTS

A total of 2421 patients underwent major open vascular surgery, including 196 oAAA repair, 259 aortofemoral bypass, and 1966 LEB. The overall incidence of 30-day VTE was 1.40%, ranging from 1.12% for LEB to 3.57% for oAAA repair. Among patients receiving early VTE chemoprophylaxis, the rate of VTE was 0.78% versus 2.26% among those with a delay in VTE chemoprophylaxis (P = .002). When accounting for the preoperative risk of VTE, delayed chemoprophylaxis was associated with a significantly higher risk of VTE (odds ratio, 2.38; 95% confidence interval, 1.12-5.06; P = .024). The early VTE chemoprophylaxis group was associated with a significantly decreased risk of bleeding compared with those with a delay (14.31% vs 18.90%; P = .002). Overall 30-day mortality and postoperative complications were similar with the exception of an associated higher rate of infectious complications in the delayed VTE chemoprophylaxis group, including superficial surgical site infection (6.00% vs 4.06%; P = .028), pneumonia (3.25% vs 1.85%; P = .028), urinary tract infection (2.95% vs 1.57%; P = .020), and severe sepsis (3.05% vs 1.71%; P = .029).

CONCLUSIONS

Although patients undergoing major open vascular surgery have a low risk of VTE at baseline, there is a significantly greater risk of developing VTE among patients who have a delay in the administration of VTE chemoprophylaxis. Postoperative transfusion rates were significantly lower among patients receiving early chemoprophylaxis. There were no differences in the 30-day mortality and postoperative complications, except for infectious complications. Given these findings, surgeons should consider early chemoprophylaxis in the postoperative setting after major open vascular surgery without contraindication.

Post-operative Venous Thromboembolism in Patients Operated on for Aorto-iliac Obstruction and Abdominal Aortic Aneurysm, and the Application of Pharmacological Thromboprophylaxis

OBJECTIVE/BACKGROUND

In light of the methods generally used to assess the risk of venous thromboembolism (VTE), major vascular operations should be regarded as high risk procedures. Nevertheless, no principles for implementing and maintaining thromboprophylaxis have so far been developed. The aim of this study was to determine the frequency and nature of VTE occurrence in patients routinely applying pharmacological thromboprophylaxis following implantation of an aorto-bifemoral prosthesis.

METHODS

The prospective non-randomized study included 105 patients with aortoiliac obstruction and 119 patients with abdominal aortic aneurysm (AAA) treated surgically. During hospitalization pharmacological thromboprophylactic procedures were observed. A duplex test was performed on the day before surgery, on the day of discharge, and 30 days after the patients had left the hospital.

RESULTS

VTE was detected in 18.1% of the patients with aortoiliac obstruction (9.5% of patients during hospitalization and 8.6% of patients after discharge). VTE was diagnosed in 21.0% of patients with AAA (15.1% of patients during hospitalization and 5.9% of patients after discharge). The incidence of VTE was comparable in both groups, both during hospitalization (p = .51) and in the 30 day period following the end of hospitalization (p = .48). It is advisable that before hospital discharge routine duplex ultrasonography tests should be conducted on the venous systems of all patients who have undergone major vascular operations.

CONCLUSIONS

It is likewise advisable to consider whether thromboprophylaxis for vascular patients should be extended beyond their discharge from hospital.

Incidence of deep vein thrombosis and quality of venous thromboembolism prophylaxis

OBJECTIVE

to determine the incidence of deep vein thrombosis and prophylaxis quality in hospitalized patients undergoing vascular and orthopedic surgical procedures.

METHODS

we evaluated 296 patients, whose incidence of deep venous thrombosis was studied by vascular ultrasonography. Risk factors for venous thrombosis were stratified according the Caprini model. To assess the quality of prophylaxis we compared the adopted measures with the prophylaxis guidelines of the American College of Chest Physicians.

RESULTS

the overall incidence of deep venous thrombosis was 7.5%. As for the risk groups, 10.8% were considered low risk, 14.9%moderate risk, 24.3% high risk and 50.5% very high risk. Prophylaxis of deep venous thrombosis was correct in 57.7%. In groups of high and very high risk, adequate prophylaxis rates were 72.2% and 71.6%, respectively. Excessive use of chemoprophylaxis was seen in 68.7% and 61.4% in the low and moderate-risk groups, respectively.

CONCLUSION

although most patients are deemed to be at high and very high risk for deep vein thrombosis, deficiency in the application of prophylaxis persists in medical practice.

Incidence of deep venous thrombosis and stratification of risk groups in a university hospital vascular surgery unit

BACKGROUND: There is a knowledge gap with relation to the true incidence of deep vein thrombosis among patients undergoing vascular surgery procedures in Brazil. This study is designed to support the implementation of a surveillance system to control the quality of venous thromboembolism prophylaxis in our country. Investigations in specific institutions have determined the true incidence of deep vein thrombosis and identified risk groups, to enable measures to be taken to ensure adequate prophylaxis and treatment to prevent the condition.OBJECTIVE: To study the incidence of deep venous thrombosis in patients admitted to hospital for non-venous vascular surgery procedures and stratify them into risk groups.METHOD: This was a cross-sectional observational study that evaluated 202 patients from a university hospital vascular surgery clinic between March 2011 and July 2012. The incidence of deep venous thrombosis was determined using vascular ultrasound examinations and the Caprini scale.RESULTS: The mean incidence of deep venous thrombosis in vascular surgery patients was 8.5%. The frequency distribution of patients by venous thromboembolism risk groups was as follows: 8.4% were considered low risk, 17.3% moderate risk, 29.7% high risk and 44.6% were classified as very high risk.CONCLUSION: The incidence of deep venous thrombosis in vascular surgery patients was 8.5%, which is similar to figures reported in the international literature. Most vascular surgery patients were stratified into the high and very high risk for deep venous thrombosis groups.

Incidence of acute lower extremity venous thrombosis after percutaneous endovascular aneurysm repair

BACKGROUND

Improvements in endovascular aortic aneurysm repair (EVAR) have led many physicians to embrace a purely percutaneous approach using the suture-mediated "preclose" technique. Whereas there are a number of theoretical benefits, the rate of periprocedural iatrogenic acute deep venous thrombosis (DVT) is unknown. We sought to determine the incidence of acute DVT after percutaneous EVAR (PEVAR).

METHODS

This was a single-center, retrospective review of 52 consecutive patients undergoing elective PEVAR. Demographics, procedural data, and postprocedure lower extremity venous duplex ultrasound data were analyzed by univariate statistical analysis.

RESULTS

Among the 52 patients, the average age was 73 years, and the majority were men (n = 44). Only 6% (n = 3) had a prior history of DVT. The majority of procedures were performed under general anesthesia (n = 51 [98%]) with systemic intravenous heparin. Protamine was used in only 13 cases (25%). Sheath sizes ranged from 9F to 20F, with an average of 16F, and closure was achieved using the preclose technique. Postprocedure chemoprophylaxis was administered to 85% of patients (n = 44) during their hospitalization. Median length of stay was 1 day. Acute DVT was identified in 8% of patients (n = 4) on postoperative day 1. Among the 4 DVTs, 25% were femoropopliteal (n = 1) and 75% were calf vein DVTs (n = 3). On follow-up imaging 2 weeks later, 75% of DVTs were resolved. Among the four patients with acute DVT on postoperative day 1, three had associated risk factors: history of DVT (n = 2), active smokers (n = 1), and obesity (body mass index >30; n = 3). The remaining patient had no risk factors but developed an ipsilateral calf vein DVT.

CONCLUSIONS

The risk of acute DVT after PEVAR is low. Lower extremity venous duplex ultrasound screening is not necessary unless there exist preclinical risk factors or postprocedural clinical indications suggestive of DVT.

Nephrotic syndrome complicated with deep venous thrombosis in the upper extremities

Deep venous thrombosis (DVT) in the upper extremities is a rare but important clinical illness, which leads to severe complications such as pulmonary embolism. Unlike DVT in the lower extremities, which is mainly induced by a hypercoagulable state, DVT in the upper extremities is usually caused by mechanical obstruction or anatomical stenosis in the venous system. We herein report a case in which DVT developed in the left upper limb during treatment of nephrotic syndrome. This is the first case report of upper-extremity DVT in association with nephrotic syndrome in the literature. Our patient was a 56-year-old male with nephrotic syndrome due to idiopathic membranous nephropathy who was treated with 40 mg/day of prednisolone. During corticosteroid therapy, he developed a swelling of the left upper limb. Computed tomography revealed thrombi in the left internal jugular vein and the left subclavian vein without anatomical abnormalities in his venous system. Thus, he was diagnosed with DVT of the upper extremities. After the initiation of warfarin treatment and subsequent regression of nephrotic syndrome, the swelling disappeared and the thrombi significantly diminished. DVT should be considered when upper-extremity edema is observed in patients with nephrotic syndrome.

Epidemiology, risk factors and sequelae of venous thromboembolism

The aim of this review was to discuss the epidemiology, risk factors and sequelae of venous thromboembolism (VTE). VTE has an incidence of 1-2 per 1000 people annually. The risk of VTE increases with age and is highest in Caucasians and African Americans. Combined oral contraceptives (COC), especially the third-generation COCs, have been strongly implicated in VTE. Hospitalized patients, especially patients with underlying malignancy and undergoing surgery, have a host of risk factors for VTE. Thrombophilia can predispose an individual to VTE but indiscriminate testing for thrombophilia in patients presenting with VTE is not indicated. VTE can have serious chronic sequelae in the form of post-thrombotic syndrome (PTS) and chronic thromboembolic pulmonary hypertension (CTPH). The risk of PTS and CTPH is increased with recurrent deep vein thrombosis and pulmonary embolism, respectively. Mortality from VTE can be as high as 21.6% at one year. Patients who had an episode of VTE have a high risk of subsequent VTE and this risk is highest in patients who had a first VTE event associated with malignancy. A good understanding of the epidemiology and risk factors of VTE will enable the treating medical practitioners to identify patients at risk and administer appropriate VTE prophylaxis to prevent the long-term consequences of VTE.

Effectiveness of instituting a specific bed protocol in reducing complications associated with bed rest

Pressure ulceration, deep venous thromboembolism, and hospital-acquired pneumonia are well-known complications of bed rest. This retrospective, single-center, observational cohort study evaluated the effectiveness of instituting bed rest protocol that included specific positioning, continuous heel off-loading, recumbent upper and lower body bed exercises, scheduled incentive spirometry, frequent position changes, and thromboprophylaxis (chemical, mechanical, or both), in reducing the incidence of pressure ulceration, deep venous thromboembolism, and hospital-acquired pneumonia in consecutive patients admitted for at least 7 days. A total of 29 patients (24 males, 5 females) were included in this study, with a mean age of 62.5 (median 63, range 17 to 84) years. The mean length of bed rest was 13.1 (median 10, range 7 to 31) days; and, the mean length of hospital stay was 21.1 (median 17, range 8 to 72) days. During hospitalization, 2 (6.9%) patients developed one or more of the complications measured, with 1 developing a posterior heel pressure ulcer that resolved with local care and another who developed deep venous thrombosis without pulmonary embolism, managed with therapeutic anticoagulation, and hospital-acquired pneumonia treated with antibiotic therapy. The results of this analysis were favorable in comparison with previously reported incidence rates for pressure ulcer, deep venous thrombosis, and hospital-acquired pulmonary complications in patients with similar risk factors, and suggested that a prescribed bed protocol reduces complications associated with bed rest.

Interventions for preventing venous thromboembolism following abdominal aortic surgery

BACKGROUND

Deep vein thrombosis (DVT) is one of the most common, preventable complications of surgery. Although the relationship between surgery and DVT is well established in general surgical operations and most other subspecialties, the same cannot be said about arterial surgery. Deep vein thrombosis is believed to be less common in aortic surgery where its management is rather controversial with a reported incidence of DVT from 2% to 18%.Intra-operative heparin is believed to provide protection during the period when DVT is most likely to develop. However, the practice of using intra-operative heparin could increase the risk of haemorrhagic complications if further heparin is used during the recovery period. This can significantly limit the use of such prophylactic measures especially with the low perceived risk of venous thromboembolism (DVT or pulmonary embolism (PE)) following abdominal aortic surgery. However, vascular patients are usually older, with more co-morbidity and are subject to prolonged immobility, all of which increase the likelihood of developing venous thromboembolism.

OBJECTIVES

To determine the efficacy of anticoagulant prophylaxis (with or without mechanical devices) in patients undergoing surgery for abdominal aortic aneurysm.

SEARCH STRATEGY

The Cochrane Peripheral Vascular Diseases Group searched their trials register (last searched 8 August 2007) and the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library, (last searched Issue 3, 2007). The authors searched for additional trials through reference lists of retrieved studies and conference proceedings.

SELECTION CRITERIA

Randomised controlled trials comparing the use of anticoagulants (with or without mechanical devices) with control or no intervention in preventing DVT or PE after abdominal aortic operations.

DATA COLLECTION AND ANALYSIS

Three authors independently selected potential trials and assessed trial quality.

MAIN RESULTS

Two studies (n=147) were included. Both studies had methodological limitations. There were no data to indicate that post operative anticoagulation, with or without the use of mechanical devices, can safely reduce the incidence of DVT after aortic surgery. Neither study reported a significant effect of anticoagulants on the incidence of PE or related mortality. One study was terminated before recruiting sufficient participants due to a higher incidence of bleeding with the use of anticoagulants. The incidence of minor bleeding events was also slightly higher with anticoagulants.

AUTHORS' CONCLUSIONS

There is not enough evidence to make a definitive conclusion about the use of anticoagulant drugs (with or without mechanical devices) for DVT prophylaxis in patients undergoing abdominal aortic surgery.

The Significant Negative Impact of In-Hospital Venous Thromboembolism after Cardiovascular Procedures

Our objective was to assess the impact of venous thromboembolism (VTE) on common postoperative cardiovascular surgical patients. An administrative database, the Nationwide Inpatient Sample (NIS, a sampling of 20% of all inpatients across the United States), from 1998 to 2001, was queried for all patients who were hospitalized for primary procedural diagnosis of abdominal aortic aneurysm repair (AAA), amputation (AMP), coronary artery bypass grafting (CABG), carotid endarterectomy (CEA), lower extremity revascularization (LE), and aortic or mitral valve repair (VALV) and for secondary diagnosis of VTE, using standard ICD-9-CM codes. To validate these findings for specificity, the same patient procedure groups with a secondary code of VTE and the same hospitalization procedural code for inferior vena cava (IVC) filter were also analyzed. Factors relating to VTE and the outcomes of death, length of stay (LOS), and unfavorable discharge were analyzed by logistical regression, with odds ratios (ORs) reported as well as analysis of covariance for cost and LOS determinations. A total of 191,666 patients were identified from the NIS, with a mean age of 68 years, 65% men, 85% white race, and a mean VTE incidence of 0.68%. VTE incidence varied with primary procedure: AAA = 1.2%, AMP = 1.1%, CABG = 0.54%, CEA = 0.26%, LE = 0.78%, VALV = 0.63%. VTE was more likely with AAA (OR = 3.9), AMP (3.1), LE (2.8), VALV (2.0), and CABG (1.9) (all compared with CEA, P < 0.0001) and female gender (1.14, P =0.03) but not race or age. Mortality was associated with increased age (1.05), female gender (1.2), and VTE (3.4) (all P < 0.0001). Inpatient costs were 14% higher (P < 0.001), and LOS was increased by 68% compared with those patients not having a VTE (P < 0.0001). Unfavorable discharge status was associated with increased age (1.05), female gender (1.4), and VTE (2.2), among others. A similar magnitude of effect was observed with the subgroup analysis (n = 150) of those undergoing the index procedures who received an IVC filter during the same hospitalization as VTE diagnosis, including increased risk of death, cost, LOS, and unfavorable discharge (all P < 0.001). The occurrence of VTE is not common and varies with the cardiovascular procedure but significantly increases the risk of in-hospital death, cost, LOS, and unfavorable discharge. Process variables should be examined to identify practice patterns that might better prevent this complication.

Mechanical and pharmacological methods to prevent venous thromboembolism

Today, it is possible to define certain risk groups for the development of venous thromboembolism, most studies having been conducted on post-operative venous thromboembolism. Nonetheless, the risk classification is rather inexact, resulting in many patients receiving prophylaxis who would not have gone on to develop the complication. However, the current prophylactic methods are safe and can therefore also be used in the post-operative situation. The dominating pharmacological substances are unfractionated heparin, low-molecular-weight heparins and the pentasaccharide fondaparinux. In some situations (such as elective hip surgery and likely hip fracture surgery, and in many cases where malignant diseases in the abdomen/pelvis have been operated upon), extended prophylaxis for 1 month should be considered.

Profilaxia para tromboembolismo venoso em um hospital de ensino

OBJETIVO: Verificar se a profilaxia da trombose venosa profunda está sendo utilizada de maneira correta e rotineira em um hospital de ensino. MÉTODOS E CASUÍSTICA: Foi realizado um estudo transversal de pacientes internados em sete setores (enfermarias) do Conjunto Hospitalar de Sorocaba (Hospital de Ensino), no período de agosto de 2004 a agosto de 2005. Para estratificação do risco de trombose venosa profunda de cada paciente, foram pesquisados fatores clínicos e cirúrgicos, segundo o protocolo preconizado pela Sociedade Brasileira de Angiologia e Cirurgia Vascular. No período estudado, foram analisados 216 prontuários, dos quais 30 eram da cirurgia abdominal, 30 da cirurgia vascular, 30 da urologia, 31 da clínica médica, 31 da unidade de terapia intensiva, 31 da ortopedia e 33 da ginecologia/obstetrícia. RESULTADOS: Do total de pacientes, foi efetuada profilaxia para trombose venosa profunda em 57 (26%), sendo que, em 51 (89%), a execução foi de maneira correta e, em 6 (11%), não-preconizada. O método profilático mais utilizado foi o medicamentoso; 49 de 57 pacientes fizeram uso de heparina de baixo peso molecular. Também foi verificada a utilização de meias elásticas em cinco pacientes e deambulação precoce em sete. Já a compressão pneumática intermitente não foi utilizada em nenhum deles. CONCLUSÃO: De acordo com os resultados e com base no protocolo, concluiu-se que, no período da pesquisa, a profilaxia para trombose venosa profunda, no Conjunto Hospitalar de Sorocaba, foi executada rotineiramente e de forma adequada em apenas 23,6% (51 do total de 216 pacientes).

Update in the prevention and treatment of deep vein thrombosis and pulmonary embolism

PURPOSE OF REVIEW

Thromboembolic events have a major impact on outcome of surgical and medical patients. This review is focused on standards and recent advances in antithrombotic strategies for prevention and therapy of venous thromboembolism and pulmonary embolism.

RECENT FINDINGS

Alert programs improve prophylactic strategies to prevent venous thromboembolism. Evidenced-based guidelines are available on antithrombotic and thrombolytic therapy outweighing the benefits, risks, burdens and costs. Selective factor Xa and direct thrombin inhibitors are at least as effective as low-molecular-weight heparin in prevention of venous thromboembolism and treatment of pulmonary embolism, but have fewer side effects and will not need routine monitoring. In high-risk orthopaedic patients but not in general surgery patients fondaparinux is superior to low-molecular-weight heparin in the prevention of thromboembolic disease. Ximelagatran, the first oral direct thrombin inhibitor, is as effective and well tolerated as warfarin. Long-term treatment is uncertain, however, because of elevation in alanine transaminase levels. In high-risk patients with contraindication for anticoagulation, retrievable vena cava filters may be an option to prevent pulmonary embolism. Permanent cava filters do not improve long-term survival and are associated with relevant side effects. Thrombolytics should be reserved for deep venous thrombosis complicated by limb gangrene and for life threatening pulmonary embolism.

SUMMARY

There is currently sufficient information based on guidelines available on preventive and therapeutic strategies for venous thromboembolism and pulmonary embolism. Antithrombotics are the therapeutic backbone. In high-risk orthopedic surgery and venous thromboembolism the new antithrombotics fondaparinux, idraparinux and ximelagatran are superior to standard treatment. Temporary caval filters may be a therapeutic option in high-risk patients with contraindication for antithrombotics.

[Prevention of venous thromboembolism following cardiac, vascular or thoracic surgery]

In the absence of thromboprophylaxis, coronary artery bypass graft surgery (CABG), intrathoracic surgery (thoracotomy or video-assisted thoracoscopy), abdominal aortic surgery and infrainguinal vascular surgery are high-risk surgeries for the development of venous thromboembolic events (VTE). The incidence of VTE following surgery of the intrathoracic aorta, carotid endarterectomy or mediastinoscopy is unknown. Data from the litterature are lacking to draw evidence-based recommandations for venous thromboprophylaxis after these three types of surgeries, and the following guidelines are but experts'opinions (Grade D recommendations). Thromboprophylaxis is recommended after CABG (Grade D), with either subcutaneous (SC) low molecular weight heparin (LMWH) or SC or intravenous (i.v.) unfractioned heparin (UH) (PTT target = 1.1-1.5 time control value) (both grade D). This may be combined with the use of intermittent pneumatic compression device (Grade B). After valve surgery. The anticoagulation recommended to prevent valve thrombosis is sufficient in order to prevent VTE. We recommend thromboprophylaxis with either LMWH or low dose UH to prevent VTE after aortic or lower limbs infrainguinal vascular surgery (both grade B and D). Vitamine K antagonists (VKA) are not recommended in this indication (Grade D). We recommend thromprophylaxis following intrathoracic surgery via thoracotomy or videoassisted thoracoscopy (grade C). Either subcutaneous LMWH or subcutaneous or i.v. low dose UH may be used (Grade C). Efficacy of intermittent pneumatic compression device has been demonstrated in a study (grade C). VKA are not recommended (grade D). No further recommendation regarding the duration of thromboprophylaxis after these three types of surgeries can be made.

Prevention of venous thromboembolism in surgical patients

Venous thromboembolism (VTE) is a common complication of surgical procedures. The risk for VTE in surgical patients is determined by the combination of individual predisposing factors and the specific type of surgery. Prophylaxis with mechanical and pharmacological methods has been shown to be effective and safe in most types of surgery and should be routinely implemented. For patients undergoing general, gynecologic, vascular, and major urologic surgery, low-dose unfractionated heparin or low-molecular-weight heparin (LMWH) are the options of choice. For low-risk urologic surgery, early postoperative mobilization of patients is the only intervention warranted. For higher-risk patients, including those undergoing elective hip or knee replacement and surgery for hip fracture, vitamin K antagonists, LMWH, or fondaparinux are recommended. For patients undergoing neurosurgery, graduated elastic stockings are effective and safe and may be combined with LMWH to further reduce the risk of VTE. The role of prophylaxis is less defined in patients undergoing elective spine surgery, as well as laparoscopic and arthroscopic surgery. A number of issues related to prophylaxis of VTE after surgery deserve further clarification, including the role of screening for asymptomatic deep vein thrombosis, the best timing for initiation of pharmacological prophylaxis, and the optimal duration of prophylaxis in high-risk patients.

Prevention of venous thromboembolism: the Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy

This article discusses the prevention of venous thromboembolism (VTE) and is part of the Seventh American College of Chest Physicians Conference on Antithrombotic and Thrombolytic Therapy: Evidence-Based Guidelines. Grade 1 recommendations are strong and indicate that the benefits do, or do not, outweigh risks, burden, and costs. Grade 2 suggests that individual patients' values may lead to different choices (for a full understanding of the grading see Guyatt et al, CHEST 2004; 126:179S-187S). Among the key recommendations in this chapter are the following. We recommend against the use of aspirin alone as thromboprophylaxis for any patient group (Grade 1A). For moderate-risk general surgery patients, we recommend prophylaxis with low-dose unfractionated heparin (LDUH) (5,000 U bid) or low-molecular-weight heparin (LMWH) [< or = 3,400 U once daily] (both Grade 1A). For higher risk general surgery patients, we recommend thromboprophylaxis with LDUH (5,000 U tid) or LMWH (> 3,400 U daily) [both Grade 1A]. For high-risk general surgery patients with multiple risk factors, we recommend combining pharmacologic methods (LDUH three times daily or LMWH, > 3,400 U daily) with the use of graduated compression stockings and/or intermittent pneumatic compression devices (Grade 1C+). We recommend that thromboprophylaxis be used in all patients undergoing major gynecologic surgery (Grade 1A) or major, open urologic procedures, and we recommend prophylaxis with LDUH two times or three times daily (Grade 1A). For patients undergoing elective total hip or knee arthroplasty, we recommend one of the following three anticoagulant agents: LMWH, fondaparinux, or adjusted-dose vitamin K antagonist (VKA) [international normalized ratio (INR) target, 2.5; range, 2.0 to 3.0] (all Grade 1A). For patients undergoing hip fracture surgery (HFS), we recommend the routine use of fondaparinux (Grade 1A), LMWH (Grade 1C+), VKA (target INR, 2.5; range, 2.0 to 3.0) [Grade 2B], or LDUH (Grade 1B). We recommend that patients undergoing hip or knee arthroplasty, or HFS receive thromboprophylaxis for at least 10 days (Grade 1A). We recommend that all trauma patients with at least one risk factor for VTE receive thromboprophylaxis (Grade 1A). In acutely ill medical patients who have been admitted to the hospital with congestive heart failure or severe respiratory disease, or who are confined to bed and have one or more additional risk factors, we recommend prophylaxis with LDUH (Grade 1A) or LMWH (Grade 1A). We recommend, on admission to the intensive care unit, all patients be assessed for their risk of VTE. Accordingly, most patients should receive thromboprophylaxis (Grade 1A).