Prevention of venous thromboembolism after injury: an evidence-based report--part I: analysis of risk factors and evaluation of the role of vena caval filters

Venous thromboembolism as a marker of quality of care in trauma

BACKGROUND

Venous thromboembolism (VTE) is reported to occur among 7% to 58% of trauma patients. Variability in VTE rates might reflect differences in case mix and quality of care, but also screening practices or data capture. We explored the variation in VTE rates across trauma centers to determine its use as a measure of the quality of patient care.

STUDY DESIGN

The National Trauma Data Bank (version 7.1, admission year 2006) was used to capture a cohort at risk for VTE. Crude and adjusted rates of VTE were determined, and the observed and expected rates were compared across centers. Outlier hospitals were defined as those with considerably more (or fewer) patients than expected. We then assessed the level of concordance between outlier status for deep vein thrombosis (DVT) and pulmonary embolism (PE). Intraclass correlation coefficients (ICC) were calculated to evaluate for the presence of a "center" effect using multilevel modeling.

RESULTS

The 22,421 patients met inclusion criteria from 30 trauma centers. There was marked variability in the rate of VTE across centers, ranging from 0.2% to 13.3%, which was more pronounced for DVT (0.2% to 13.1%) than for PE (0% to 1.7%). There was poor concordance for DVT and PE outlier status. Intraclass correlation coefficient was four times greater for DVT (0.23) than for PE (0.06).

CONCLUSIONS

There was substantial variation in rates of VTE across trauma centers. There was no relationship between DVT and PE outlier status, which is counter to the understanding of the biologic relationship between the two. Lastly, the very low Intraclass correlation coefficient for PE compared with DVT suggests that to a large extent, practice variation has very little impact on PE rates. In light of these findings and concerns about patient ascertainment of DVT, VTE rates might not be a useful measure of quality of care.

Thromboprophylaxis in patients with lower limb immobilisation - review of current status

The risk for venous thromboembolism (VTE) associated with lower limb immobilisation is unclear, owing to of a lack of evidence from studies in this patient group. However, six small, randomised control trials (RCTs), totalling 1536 patients, compared low molecular weight heparin (LMWH) with controls and showed a significant reduction in asymptomatic deep vein thrombosis (DVT) from 17.1% to 9.8%, with very low bleeding rates. This is likely to be an underestimate of the real risk reduction as most trials excluded high-risk patients from randomisation. There have been no other controlled trials in cast-immobilised patients using alternative prophylactic measures. Together with the RCTs, other cohort studies have identified risk factors that increase the risk for VTE in lower limb immobilisation. In summary, patients in lower limb cast (or brace) immobilisation should be risk assessed and those deemed high risk for VTE should receive prophylactic LMWH for at least the duration of cast immobilisation.

Retrievable Inferior Vena Cava Filters Are Rarely Removed

There has been an increasing nationwide trend of inferior vena cava (IVC) filter placement over the past 3 years. Most of these have been the newer, removable variety. Although these are marketed as retrievable, few are removed. The purpose of this study was to examine the practice pattern of IVC filter placement at Huntington Hospital. This study is a retrospective chart review of all IVC filter placements and removals between January 1, 2004, and December 31, 2006. The primary data points include indication for placement, major complications (migration, caval thrombosis, pulmonary embolus [PE]), attempted removal, and successful removal. Three hundred ten patients received IVC filters at our institution during this period. Eighty-four were placed in 2004, 95 in 2005, and 131 in 2006. Of those, only 12 (3.9%) were documented permanent filters, whereas the remainder (298) were removable. Of the retrievable filters placed, only 11 (3.7%) underwent successful removal. There were four (1.3%) instances in which the filter could not be removed as a result of thrombus present within the filter and two (0.67%) in which removal was aborted as a result of technical difficulty. Our use of IVC filters has increased steadily over the last 3 years. Despite the rise in use of “removable” filter devices, few are ever retrieved. Although IVC filter insertion appears an effective method of PE prevention, it comes at a cost, both physiological and monetary. It would be wise to devise more stringent criteria to identify those patients in the various populations who truly require filter placement and to be cautious in altering our indications for placement.

Guidelines and the use of inferior vena cava filters: a review of an institutional experience

BACKGROUND AND OBJECTIVES

Based on the American College of Chest Physicians 2004 antithrombotic therapy for venous thromboembolism (VTE) and the Eastern Association for the Surgery of Trauma 2002 guidelines, placement of an inferior vena cava (IVC) filter is indicated in patients who either have, or are at high risk for, VTE, but have a contraindication or failure of anticoagulation. Our aim is to compare clinical characteristics and outcomes of patients receiving IVC filters within-guidelines (WG) and outside-of-guidelines (OOG).

METHODS

The 558 patients who received an IVC filter were divided into two groups called WG or OOG. The WG group met the criteria described above and the OOG group did not have a contraindication to or a failure of anticoagulation.

RESULTS

The WG group had 362 patients and the OOG group had 196 patients. The OOG group had one (0.5%) patient with post-filter pulmonary embolism (PE), two (1%) with IVC thrombosis, and seven (3.6%) with deep vein thrombosis (DVT). The WG group had five (1.4%) patients with post-filter PE, 13 (3.6%) with IVC thrombosis, and 34 (9.4%) with DVT. All patients who developed post-filter PE had a DVT before filter placement, and patients who did not have a prior VTE event were at a significantly lower risk of developing post-filter IVC thrombosis and PE.

CONCLUSION

Our data do not support the use of an IVC filter outside of guidelines in patients without prior VTE who can tolerate anticoagulation because of the low risk of developing PE.

Variation in DVT prophylaxis for adolescent trauma patients: a survey of the Society of Trauma Nurses

We performed a survey of the Society of Trauma Nurses to explore current practice patterns for deep venous thrombosis prophylaxis in adolescent trauma patients and analyzed responses from 133 institutions. The majority of adult prophylaxis protocols include older adolescents. Only 41% of adult programs identified patient age as "very" important in prophylaxis decision making. Pelvic fracture, spinal cord injury, and expected immobilization were rated most important. Pharmacologic prophylaxis in 11- to 15-year-olds was infrequent, with 60% of centers using never or rarely. Use was much higher but variable among older adolescents. No consensus on deep venous thrombosis prophylaxis in adolescent trauma emerged from our survey.

Four years of an aggressive prophylaxis and screening protocol for venous thromboembolism in a large trauma population

BACKGROUND

This retrospective review of a prospectively collected database was conducted to analyze the efficacy of 4 years of aggressive prophylaxis and screening protocols for venous thromboembolism (VTE) in a large population of trauma patients.

METHODS

Trauma patients at a Level I Trauma Center found to be nonambulatory or otherwise high risk were placed on a protocol of lower-extremity (LE) compression devices and subcutaneous enoxaparin as soon as feasible after admission. Duplex scans of LEs were conducted weekly.

RESULTS

During 4 years, 2,939 patients were admitted to trauma with length of stay >2 days. There was a 3.2% incidence of VTE in the length of stay >2 days population, 2.5% rate of deep venous thrombosis (DVT), and 0.7% pulmonary embolism. All VTE patients had factors known to increase risk of VTE and were included in our prophylaxis and screening protocol. Twenty-one percent of these received pharmacologic prophylaxis within the first 2 days of admission; 62% received enoxaparin at some point before diagnosis of VTE. Duplex scans were conducted in 982 patients. Notably, 86% of LE DVTs were found on routine screening duplex.

CONCLUSION

To our knowledge, this is the largest population of trauma patients followed by screening duplexes. All patients with VTEs were identified as high risk, and screening revealed multiple patients with an asymptomatic DVT. We conclude our aggressive prophylaxis regimen lead to low rates of VTE and think screening duplex is a critical component for identifying unsuspected DVT.

Critical care medicine at Walter Reed Army Medical Center in support of the global war on terrorism

BACKGROUND

The military medical experience during wartime is unique and distinct from civilian medical practice. Historically, the military has produced innovations resulting in both civilian and military medical care advances, and our current conflict is no different. In this article, we provide a description of the medical and surgical intensive care units at Walter Reed, their history, and approach to new issues encountered in the care of Operation Iraqi Freedom and Operation Enduring Freedom soldiers. Additionally, descriptive statistics regarding the number of Operation Iraqi Freedom and Operation Enduring Freedom soldiers admitted to the critical care service, basic demographics, general category of injury, and discussion of intensive care unit issues unique to this patient population, such as Acinetobacter and traumatic brain injury, are presented.

DISCUSSION

We intend to provide a general description of our Operation Iraqi Freedom/Operation Enduring Freedom trauma population cared for by the critical care service at Walter Reed Army Medical Center, as well as a discussion of our approach to caring for some of their unique issues, to detail experiences that could translate into improvements for civilian trauma centers.

A 10-year analysis of venous thromboembolism on the surgical service: the effect of practice guidelines for prophylaxis

BACKGROUND

There is a national effort to decrease the incidence of venous thromboembolism (VTE) in surgical patients by encouraging compliance with established guidelines for prophylaxis. Reported compliance with these guidelines has been poor. The outcome of noncompliance in terms of morbidity and mortality in surgical patients is unknown. We sought to determine if there has been a decrease in the incidence of symptomatic VTE since implementation of the guidelines and whether there has been compliance with the guidelines in individual patients; we also analyzed the outcome of a cohort with VTE.

METHODS

We reviewed the records of all patients with symptomatic VTE on 3 surgery services over the 10-year period since initial publication of the guidelines. We determined in each patient whether there was compliance with the guidelines. We weighted the morbidity of each episode of VTE based on the likelihood of short-term mortality and long-term morbidity to determine the disease burden.

RESULTS

Of 37,615 patients, 172 developed a VTE (0.46%), and the incidence increased gradually over the years of the study. There was partial or complete compliance with the guidelines in 84% of the patients, but 37% of the VTEs were considered to be preventable. The disease burden was greatest in the higher-risk patients-there were 20 deaths (6%), 4 of which were caused by a pulmonary embolus.

CONCLUSIONS

Despite one of the highest published rates of compliance with the guidelines for prophylaxis, the rate of symptomatic VTE is increasing.

Medication-related complications in the trauma patient

Trauma patients are twice as likely to have adverse reactions to medication as nontrauma patients. The need for medication in trauma patients is high. Surgery is often necessary, and immunosuppression and hypercoagulability may be present. Adverse drug events can be caused in part by altered pharmacokinetics, drug interactions, and polypharmacy. Medications may also have serious long-term adverse effects, which must be considered. It is not the purpose of this review article to discuss all adverse effects of all medications. This article will discuss the more common adverse effects of medications for trauma patients in the acute care setting, in the following categories: pain control, sedation, antibiotics, seizure prophylaxis in head trauma, atrial fibrillation, deep vein thrombosis and pulmonary embolism prophylaxis, hemodynamic support, adrenal insufficiency, factor VIIa.

Early Placement of Optional Vena Cava Filter in High-Risk Patients with Traumatic Brain Injury

OBJECTIVES

Patients sustaining severe trauma are at high risk for the development of venous thromboembolic events (VTE). Pharmacologic VTE prophylaxis may be contraindicated early after trauma due to potential bleeding complications. The purpose of this study was to evaluate safety and feasibility of early prophylactic vena cava filter (VCF) placement and subsequent retrieval in multiple injured patients with traumatic brain injury (TBI).

METHODS

Analysis of single-institution case series of consecutive patients who received a prophylactic VCF after severe TBI (Abbreviated Injury Scale, AiS ≥ 3) between August 2003 and October 2006.

RESULTS

A total of 34 optional VCF were prophylactically placed with a median delay of 1 day after trauma (range, 0-7 days). All patients had sustained multiple injuries (median Injury Severity Score 41, range, 18-59) with severe TBI (median AiS 4, range 3-5). Median age was 41 years (range, 17-67 years). Two patients had succumbed before potential filter retrieval. Of the remaining patients, 27 (84%) had their filters uneventfully retrieved between 11 and 32 days (median, 18 days) after placement with no retrieval-related morbidity. Five VCF (16%) were left permanently. In one patient (3%) early inferior vena cava occlusion and deep venous thrombosis occurred 14 days after VCF placement. Symptomatic pulmonary embolism was observed in one patient (3%) 5 days after VCF retrieval. Overall trauma-related mortality was 9%.

CONCLUSIONS

Early VCF placement may be of benefit for multiple injured patients with TBI when pharmacologic VTE prophylaxis is contraindicated. VCF retrieval is safe and feasible. Filter placement- and retrieval-related morbidity is low.

Acute trauma with multiple injuries

Trauma with multiple injuries is a leading cause of death. It presents a diversity of challenges and requires many healthcare workers to care for its victims. Advances continue in the organization of pre-hospital care, the techniques of trauma surgery and critical care, and understanding the pathophysiology of traumatic injuries.

The Practice of Venous Thromboembolism Prophylaxis in the Major Trauma Patient

BACKGROUND

The incidence of venous thromboembolism (VTE) without prophylaxis is as high as 80% after major trauma. Initiation of prophylaxis is often delayed because of concerns of injury-associated bleeding. As the effect of delays in the initiation of prophylaxis on VTE rates is unknown, we set out to evaluate the relationship between late initiation of prophylaxis and VTE.

METHODS

Data were derived from a multicenter prospective cohort study evaluating clinical outcomes in adults with hemorrhagic shock after injury. Analyses were limited to patients with an Intensive Care Unit length of stay >or=7 days. The rate of VTE was estimated as a function of the time to initiation of pharmacologic prophylaxis. A multivariate stepwise logistic regression model was used to evaluate factors associated with late initiation.

RESULTS

There were 315 subjects who met inclusion criteria; 34 patients (11%) experienced a VTE within the first 28 days. Prophylaxis was initiated within 48 hours of injury in 25% of patients, and another one-quarter had no prophylaxis for at least 7 days after injury. Early prophylaxis was associated with a 5% risk of VTE, whereas delay beyond 4 days was associated with three times that risk (risk ratio, 3.0, 95% CI [1.4-6.5]). Factors associated with late (>4 days) initiation of prophylaxis included severe head injury, absence of comorbidities, and massive transfusion, whereas the presence of a severe lower extremity fracture was associated with early prophylaxis.

CONCLUSIONS

Clinicians are reticent to begin timely VTE prophylaxis in critically injured patients. Patients are without VTE prophylaxis for half of all days within the first week of admission and this delay in the initiation of prophylaxis is associated with a threefold greater risk of VTE. The relative risks and benefits of early VTE prophylaxis need to be defined to better direct practice in this high-risk population.

Utility of once-daily dose of low-molecular-weight heparin to prevent venous thromboembolism in multisystem trauma patients

INTRODUCTION

Venous thromboembolism is a preventable cause of death in the severely injured patient. Low-molecular-weight heparins (LMWHs) have been recommended as effective, safe prophylactic agents. However, LMWH use remains controversial in patients at risk for bleeding, those with traumatic brain injury, and those undergoing multiple invasive or operative procedures. We hypothesized that a protocol utilizing once-daily LMWH prophylaxis in high-risk trauma patients, regardless of the need for invasive procedures, is feasible, safe, and effective.

METHODS

From August 1998 to August 2000, all patients admitted to our American College of Surgeons-verified Level I trauma facility following injury were evaluated for deep venous thrombosis (DVT) risk and prospectively followed. Patients at high risk for DVT, including those with stable intracranial injuries, were placed on our institutional protocol and prospectively followed. Patients on the protocol received daily injections of the LMWH, dalteparin; DVT screening was performed with duplex ultrasonography within 48 hours of admission and after 7 to 10 days after injury. Regimen compliance, bleeding complications, DVT rates, and pulmonary embolus (PE) rates were analyzed.

RESULTS

During the 2-year study period, 6247 trauma patients were admitted; 743 were considered at high risk for DVT. Most of the patients were men (72%), with a mean age of 38.7 years (range 15-89 years) and a mean injury severity score (ISS) of 19.5. Compliance with the daily regimen was maintained in 74% of patients. DVT was detected in 3.9% and PE in 0.8%. The wound complications rate was 2.7%, and the need for unexplained transfusions was 3%. There were no exacerbations of head injury following dalteparin initiation due to bleeding. There were 16 patient deaths; none was caused by PE or late hemorrhage.

CONCLUSIONS

Once-daily dosing of prophylactic LMWH dalteparin is feasible, safe, and effective in high-risk trauma patients. Our protocol allows one to "operate through" systemic prophylaxis and ensures timely prophylaxis for brain-injured and multisystem trauma patients.

Extended interval for retrieval of vena cava filters is safe and may maximize protection against pulmonary embolism

BACKGROUND

Retrieval of optional vena cava filters (VCF) has been demonstrated to be safe and feasible in injured patients in 4 recent studies. However, 2 pulmonary emboli PE were reported in these studies with mean implant durations less than 19 days. In light of these occurrences, we changed our practice for VCF retrieval when patients had recovered from their injuries and at least 30 days after their discharge, or had been stable on therapeutic anticoagulation for deep venous thrombosis (DVT) or PE for at least 2 weeks. The aim of the current study was to assess the safety of this approach.

METHODS

A review of prospectively collected data on optional VCF over a 16-month period. The filters were inserted prophylactically per an institutional practice guideline or for the presence of DVT or PE with a contraindication and/or complication to anticoagulation. All patients underwent duplex imaging of the lower extremities and had pre- and post- retrieval cavagrams. Demographics, duration of implantation, and complications were recorded.

RESULTS

Eighty-three patients had optional VCF inserted since the change in our clinical practice. Indications included prophylaxis for high-risk trauma patients (n = 58), DVT or PE with acute contraindication to therapeutic anticoagulation (n = 22), or complications of anticoagulation (n = 3). Two patients developed lower extremity DVT after filter insertion and 1 patient developed a vena cava thrombosis. Retrieval was successful in 47 of 54 cases (87%) attempted. Median implantation duration was 142 days (range 17-475). A filter strut fracture occurred during retrieval without further consequences. No post-insertion or post-retrieval PE occurred in this study.

CONCLUSION

Extended intervals for retrieval of VCF are safe and may maximize protection against pulmonary embolism.

Nine-year experience with insertion of vena cava filters in the intensive care unit

BACKGROUND

Vena cava filter insertion (VCF) is traditionally performed in a radiology suite or in the operating room. We reviewed our experience of bedside VCF insertion in the intensive care unit (ICU) performed by general surgeons.

METHODS

A prospective, observational study of bedside VCF insertion in the ICU was performed by general surgeons between February 1996 and June 2005. Demographic data and procedural complications were recorded.

RESULTS

Four hundred three patients underwent bedside VCF insertion. Complications included 1 groin hematoma, 2 misplacements, and a right ventricular perforation from a dilator requiring surgical repair. DVT occurred in 38 patients (8.5%); 14 occurred at the insertion site. There were 2 pulmonary embolisms (<1%) after VCF. Contrast-related renal failure occurred in 2 of the first 35 patients; carbon dioxide gas is now used for contrast in high-risk patients.

CONCLUSIONS

Bedside insertion of VCF in the ICU by surgeons is safe and effective.

Pilot study on the comprehensive economic costs of major trauma: Consequential costs are well in excess of medical costs

BACKGROUND

Trauma care is expensive. However, reliable data on the exact lifelong costs incurred by a major trauma patient are lacking. Discussion usually focuses on direct medical costs--underestimating consequential costs resulting from absence from work and permanent disability.

METHODS

Direct medical costs and consequential costs of 63 major trauma survivors (ISS >13) at a Swiss trauma center from 1995 to 1996 were assessed 5 years posttrauma. The following cost evaluation methods were used: correction cost method (direct cost of restoring an original state), human capital method (indirect cost of lost productivity), contingent valuation method (human cost as the lost quality of life), and macroeconomic estimates.

RESULTS

Mean ISS (Injury Severity Score) was 26.8 +/- 9.5 (mean +/- SD). In all, 22 patients (35%) were disabled, causing discounted average lifelong total costs of USD 1,293,800, compared with 41 patients (65%) who recovered without any disabilities with incurred costs of USD 147,200 (average of both groups USD 547,800). Two thirds of these costs were attributable to a loss of production whereas only one third was a result of the cost of correction. Primary hospital treatment (USD 27,800 +/- 37,800) was only a minor fraction of the total cost--less than the estimated cost of police and the judiciary. Loss of quality of life led to considerable intangible human costs similar to real costs.

CONCLUSIONS

Trauma costs are commonly underestimated. Direct medical costs make up only a small part of the total costs. Consequential costs, such as lost productivity, are well in excess of the usual medical costs. Mere cost averages give a false estimate of the costs incurred by patients with/without disabilities.

Posttraumatic thromboprophylaxis revisited: an argument against the current methods of DVT and PE prophylaxis after injury

BACKGROUND

Thromboprophylaxis after injury is a controversial issue. Practices and outcomes vary widely.

METHODS

Review of selected trauma literature on venous thromboprophylaxis after injury.

RESULTS

Multiple trauma articles suggest that the efficacy of different methods of thromboprophylaxis is unproven. Most of the practices on this issue are extrapolated from studies which were performed in non-trauma patients and therefore, may not be applicable in the unique trauma population.

CONCLUSIONS

In the absence of undisputable evidence, none of the current methods of venous thromboprophylaxis after injury should be considered as standard of care. There is a need to discover new methods of thromboprophylaxis for the Trauma patient.

The Current Status of Thromboprophylaxis after Trauma: A Story of Confusion and Uncertainty

It is difficult to support a standard of care for venous thromboprophylaxis after trauma when there is no convincing research that any of the currently used methods is consistently effective. Because many conclusions from the nontrauma literature have been misleadingly extrapolated to trauma patients, this review focuses exclusively on trauma articles. These articles present variable results. The rates of deep venous thrombosis and pulmonary embolism are widely different even among similar trauma populations. The heparin-unfractionated or low-molecular-weight and calf compression methods fail to show a reproducible effect in decreasing venous thromboembolic events. The current methods of venous thromboprophylaxis after trauma are inadequate and further research in this area is direly needed.

Prophylaxis against deep-vein thrombosis following trauma: a prospective, randomized comparison of mechanical and pharmacologic prophylaxis

BACKGROUND

Deep-vein thrombosis following skeletal trauma is an important yet poorly studied issue. The purpose of the present study was to evaluate the efficacy of two different strategies for prophylaxis against deep-vein thrombosis and pulmonary embolus following blunt skeletal trauma.

METHODS

Two hundred and twenty-four inpatients were enrolled in a prospective, randomized study investigating venous thromboembolic disease following trauma. Two hundred patients completed the study, which compared two different regimens of prophylaxis. The patients in Group A received enoxaparin (30 mg, administered subcutaneously twice a day) starting twenty-four to forty-eight hours after blunt trauma. The patients in Group B were managed with pulsatile foot pumps at the time of admission combined with enoxaparin on a delayed basis. All patients were screened with magnetic resonance venography and ultrasonography before discharge.

RESULTS

There were ninety-seven patients in Group A and 103 patients in Group B. Twenty-two patients (including thirteen in Group A and nine in Group B) had development of deep-vein thrombosis, with two (both in Group A) also having development of pulmonary embolism. The prevalence of deep-vein thrombosis was 11% for the whole series, 13.4% for Group A, and 8.7% for Group B; the difference between Groups A and B was not significant. There were eleven large or occlusive clots (prevalence, 11.3%) in Group A, compared with only three (prevalence, 2.9%) in Group B (p = 0.025). The prevalence of pulmonary embolism was 2.1% in Group A and 0% in Group B. Wound complications occurred in twenty-one patients in Group A, compared with twenty patients in Group B. Patients who had development of deep-vein thrombosis during the inpatient portion of the study required a mean of 7.4 units of blood during hospitalization, compared with 3.9 units of blood for those who did not (p < 0.05).

CONCLUSIONS

Our results indicate that early mechanical prophylaxis with foot pumps and the addition of enoxaparin on a delayed basis is a very successful strategy for prophylaxis against venous thromboembolic disease following serious musculoskeletal injury. The prevalence of large or occlusive deep-vein thromboses among patients who had been managed with this protocol was significantly less than that among patients who had been managed with enoxaparin alone.

The (Absence of a) Role of Venous Duplex Scan in the Diagnosis of Pulmonary Embolism after Severe Trauma

Venous duplex scan (VDS) has been used for interim bedside diagnosis of pulmonary embolism (PE) in severely injured patients deemed to be at risk if transported out of the intensive care unit. In combination with the level of clinical suspicion for PE, VDS helps select patients for temporary treatment until definitive diagnosis is made. We evaluate the sensitivity and specificity of VDS in critically injured patients with a high level of clinical suspicion for PE. We performed a prospective observational cohort study at the surgical intensive care unit of an academic level 1 trauma center. Patients were 59 critically injured patients suspected to have PE over a 30-month period. The level of clinical suspicion for PE was classified as low or high according to preset criteria. Interventions were VDS and a PE outcome test (conventional or computed tomographic pulmonary angiography). The sensitivity and specificity of VDS to detect PE in all patients and in patients with high level of clinical suspicion was calculated against the results of the outcome test. PE was diagnosed in 21 patients (35.5%). The sensitivity and specificity of VDS was 33 per cent and 89 per cent, respectively. Among the 28 patients who had a high level of clinical suspicion for PE, the sensitivity of VDS was 23 per cent and the specificity 93 per cent. In this latter population, 1 of the 4 (25%) positive VDS was of a patient without PE and 10 of the 24 (42%) negative VDS were of patients who had PE. VDS does not accurately predict PE in severely injured patients, even in the presence of a high level of clinical suspicion.

Retrievable Vena Cava Filters for Preventing Pulmonary Embolism in Trauma Patients: A Cautionary Tale

BACKGROUND

Retrievable vena cava filters (RFs) offer the appeal of short-term prophylaxis for trauma patients temporarily at risk for pulmonary embolism (PE) without the long-term risks of permanent vena cava filters (PFs). However, the evidence that RFs and PFs reduce the risks of PE and death in trauma patients is not conclusive. RFs were introduced at our trauma center in August 2002. The purpose of this study was to evaluate the effects of RFs on our strategy to prevent PE in trauma patients.

METHODS

We reviewed our trauma registry to compare rates of filter placement, filter-related complications (FRCs), and PE before (Group I: January 2000 to August 15, 2002) and after (Group II: August 16, 2002 through December 2004) RF introduction. Indication for filter placement, filter retrieval, FRCs, and incidence of PE were compared.

RESULTS

There were 5,042 patients in Group I and 5,038 patients in Group II. There was a threefold increase in filter placement in Group II compared with Group I (55 [1.1%] versus 161 [3.2%]; p < 0.001). There were no significant differences between the rates of PE (0.2% versus 0.2%, p = 0.636) or major FRCs (1.8% versus 2.5%, p = 0.777). Major FRCs included two filter infections with sepsis, one vena cava thrombotic occlusion, one filter lodged in the jugular vein during retrieval, and one PE after filter placement. RF removal was attempted in 43 (27%) patients and successful in 33 (21%).

CONCLUSION

The advent of RFs was associated with a threefold increase in vena cava filter placement in our trauma center. Major FRCs were encountered and a very low incidence of PE was not altered by their use. Successful removal could be verified in only 21% of RFs. The results of this study lead us to question the rationale for a more liberal use of vena cava filters in trauma patients.

Prevention of Venous Thromboembolism in High-Risk Patients

The prevention of venous thromboembolism (VTE) in patients recovering from major trauma, spinal cord injury (SCI), or other critical illness is often challenging. These patient groups share a high risk for VTE, they often have at least a temporary high bleeding risk, and there are relatively few thromboprophylaxis trials specific to these populations. A systematic literature review has been conducted to summarize the risks and prevention of VTE in these three groups. It is concluded that routine thromboprophylaxis should be provided to major trauma, SCI and critical care patients based on an individual assessment of their thrombosis and bleeding risks. For patients at high risk for VTE, including those recovering from major trauma and SCI, prophylaxis with a low molecular weight heparin (LMWH) should commence as soon as hemostasis has been demonstrated. For critical care patients at lower thrombosis risk, either LMWH or low-dose heparin is recommended. For those with a very high risk of bleeding, mechanical prophylaxis should be instituted as early as possible and continued until pharmacologic prophylaxis can be initiated. The use of prophylactic inferior vena caval filters is strongly discouraged because their potential benefit has not been shown to outweigh the risks or substantial costs. Implementation of thromboprophylaxis in these patients requires a local commitment to this important patient safety priority as well as a highly functional delivery system, based on the use of pre-printed orders, computer prompts, regular audit and feedback, and ongoing quality improvement efforts.

Thrombosis and Coagulation: Deep Vein Thrombosis and Pulmonary Embolism Prophylaxis

Venous thromboembolism (deep venous thrombosis and pulmonary embolism, VTE) is a common complication in surgical patients and is the primary cause of preventable deaths in hospitalized patients. Despite well-known risk factors, VTE prophylaxis is frequently not practiced according to recommended guidelines. Patients can readily be stratified according to their risk of perioperative VTE, and mechanical and pharmacologic prophylactic regimens can be tailored to their individual risk. Pharmacologic VTEprophylaxis should be the standard of care in most clinical settings given its ease of administration, low risk, and cost-effectiveness.

The prophylactic use of inferior vena cava filters in patients undergoing high-risk spinal surgery

Prophylactic inferior vena cava filter (IVCF) placement is advocated in some high-risk groups. We sought data regarding safety and efficacy for prophylactic IVCF placement in patients at high risk for venous thromboembolism (VTE) following major spinal reconstruction. Seventy-four spine surgery patients with contraindication to anticoagulation (44 females, 30 males; mean age 56.2) received prophylactic IVCFs. Criteria were (1) history of thromboembolism, (2) diagnosed thrombophilia, (3) malignancy, (4) bedridden >2 weeks prior to surgery, (5) staged procedures or multiple levels, (6) combined anterior/posterior approaches, (7) expected need for significant iliocaval manipulation during exposure, and (8) single-stage anesthetic time >8 hr. Seventy patients had at least two risk factors. All received IVCFs prior to the first stage of spine reconstruction. Patients were evaluated for filter complications, deep vein thrombosis (DVT), and pulmonary embolism (PE). Patients' lower extremity veins from groin to ankle were imaged weekly until discharge using duplex ultrasound (DUS). One-third also underwent thoracic and pelvic computed tomography scans, and the pelvic veins, IVC, and pulmonary vasculature were evaluated for VTE. Multiple DUS (n = 198, mean 2.6 studies per patient) were performed in 68 patients. At a mean follow-up of 11 months, one of the patients developed PE. Twenty-seven limbs in 23 patients developed DVT. Five limbs had isolated calf DVT, and 22 had proximal vein involvement. Insertion site DVT accounted for nearly one-third of the DVTs. Six patients died from unrelated complications. There was one technical error with an IVCF deployed in the iliac vein. Despite a high incidence of DVT following high-risk spinal surgery, prophylactic IVCF placement appears to protect patients from PE.

Deep-vein thrombosis in high-energy skeletal trauma despite thromboprophylaxis

We report the incidence and location of deep-vein thrombosis in 312 patients who had sustained high-energy, skeletal trauma. They were investigated using magnetic resonance venography and Duplex ultrasound.

Despite thromboprophylaxis, 36 (11.5%) developed venous thromboembolic disease with an incidence of 10% in those with non-pelvic trauma and 12.2% in the group with pelvic trauma. Of patients who developed deep-vein thrombosis, 13 of 27 in the pelvic group (48%) and only one of nine in the non-pelvic group (11%) had a definite pelvic deep-vein thrombosis. When compared with magnetic resonance venography, ultrasound had a false-negative rate of 77% in diagnosing pelvic deep-vein thrombosis. Its value in the pelvis was limited, although it was more accurate than magnetic resonance venography in diagnosing clots in the lower limbs. Additional screening may be needed to detect pelvic deep-vein thrombosis in patients with pelvic or acetabular fractures.

Electrostimulation for the prevention of deep venous thrombosis in patients with major trauma: a prospective randomized study

BACKGROUND

Current methods of posttraumatic thromboprophylaxis (heparins and sequential compression devices) are inadequate. New methods should be tested. Muscle electrostimulation (MEST) has been used over the years with mixed-but predominantly encouraging-results for a variety of conditions, including prevention of deep venous thrombosis (DVT). It has not been tested in multiple trauma patients.

METHODS

Trauma patients with Injury Severity Score higher than 9 who were admitted to the intensive care unit and had a contraindication for prophylactic heparinization were randomized to groups MEST and control. MEST patients received 30-minute MEST sessions twice daily for 7 to 14 days. Venous flow velocity and venous diameter were measured by duplex venous scan. Venography-or, if not available, duplex-was used to evaluate the presence of proximal and peripheral DVT between days 7 and 15.

RESULTS

After exclusions, 26 MEST and 21 control patients completed the study and received outcome evaluation by venography (25) or duplex (22). Three patients in each group developed proximal DVT (11.5% vs 14%, P = .79), and an additional 4 (15%) MEST group and 3 (14%) control group patients developed peripheral DVT ( P = .96). There was no difference in venous flow velocity or venous diameter between the groups.

CONCLUSIONS

MEST was not effective in decreasing DVT rates in major trauma patients.

Deep Venous Thrombosis and Pulmonary Embolism in Trauma Patients: An Overstatement of the Problem?

Deep venous thrombosis (DVT) and pulmonary embolism (PE) affect high-risk trauma patients (HRTP). Accurate incidence and clinical importance of DVT and PE in HRPT may be overstated. We performed a ten-year retrospective analysis of HRTP of the Pennsylvania Trauma Outcome Study. High-risk factors (HRF) included pelvic fracture (PFx), lower extremity fracture (LEFx), severe head injury (CHI) (AIS – head ≥3), and spinal cord injury. HRF alone or in combination, age, Injury Severity Score (ISS), and Glasgow Coma Score (GCS) were examined for association with DVT/PE. A total of 73,419 HRTP were included: 1377 (1.9%) had DVT, 365 (0.5%) had PE. The incidence of DVT in level I trauma centers was 2.2 per cent and was 1.5 per cent in level II centers. The lowest incidence of DVT was 1.3 per cent for isolated LEFx; highest was 5.4% for combined PFx, LEFx, and CHI. Variables associated with DVT included age, ISS, and GCS (all P < 0.001). In logistic regression analysis, only ISS was consistently predictive for DVT and PE. Though increased during the past decade, the overall incidence of DVT in HRTP remains below 3 per cent. Only the combination of multiple injuries or an ISS >30 result in DVT incidence of ≥5 per cent. We believe that current guidelines for screening for DVT may need to be reevaluated.

Thromboprophylaxis in pelvic and acetabular trauma surgery

We prospectively studied the outcome of a protocol of prophylaxis for deep vein thrombosis (DVT) in 103 consecutive patients undergoing surgical stabilisation of pelvic and acetabular fractures. Low-molecular-weight heparin (LMWH) was administered within 24 hours of injury or on achieving haemodynamic stability. Patients were screened for proximal DVT by duplex ultrasonography performed ten to 14 days after surgery.

The incidence of proximal DVT was 10% and of pulmonary embolus 5%. Proximal DVT developed in two of 64 patients (3%) who had received LMWH within 24 hours of injury, but in eight of 36 patients (22%) who received LMWH more than 24 hours after the injury (p < 0.01). We conclude that LMWH, when begun without delay, is a safe and effective method of thromboprophylaxis in high-risk patients with major pelvic or acetabular fractures.

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).

Thromboprophylaxis Does Not Protect Severely Injured Patients against Pulmonary Embolism

The existing evidence on the effectiveness of thromboprophylaxis after trauma is conflicting. Although prophylaxis with heparin and/or sequential compression devices is practiced widely, many studies failed to document a clear benefit. A recent meta-analysis suggests that prophylaxis does not reduce posttraumatic deep venous thrombosis rates compared to no prophylaxis. The objective of this prospective study is to examine if the use of thromboprophylaxis prevents posttraumatic pulmonary embolism (PE). Sixty-four critically injured patients with clinical evidence of PE were studied by computed tomographic pulmonary angiography and/or conventional pulmonary angiography. PE was diagnosed in 24 (37.5%) patients. Patients with PE were similar to patients without PE with regard to demographics, injury type and severity, operations, and mortality. Thromboprophylaxis was used with equal frequency between PE and no-PE patients (71% vs 80%, P = 0.4). The type of prophylaxis used was similar between patients with PE (17% heparin, 71% sequential compression devices, 17% combination) and patients without PE (32%, 57%, and 10%, respectively; P = 0.16, 0.28, 0.69, respectively). Current methods of posttraumatic thromboprophylaxis may be inadequate. Practices from nontrauma populations have been erroneously extrapolated to the unique trauma population. To reduce the rate of PE after trauma, new methods of thromboprophylaxis should be considered.

Thromboembolism after trauma: an analysis of 1602 episodes from the American College of Surgeons National Trauma Data Bank

OBJECTIVE

Venous thromboembolic events (VTE) are potentially preventable causes of morbidity and mortality after injury. We hypothesized that the current clinical incidence of VTE is relatively low and that VTE risk factors could be identified.

METHODS

We queried the ACS National Trauma Data Bank for episodes of deep venous thrombosis (DVT) and/or pulmonary embolism (PE). We examined demographic data, VTE risk factors, outcomes, and VTE prophylaxis measures in patients admitted to the 131 contributing trauma centers.

RESULTS

From a total of 450,375 patients, 1602 (0.36%) had a VTE (998 DVT, 522 PE, 82 both), for an incidence of 0.36%. Ninety percent of patients with VTE had 1 of the 9 risk factors commonly associated with VTE. Six risk factors found to be independently significant in multivariate logistic regression for VTE were age > or = 40 years (odds ratio [OR] 2.01; 95% confidence interval [CI] 1.74 to 2.32), lower extremity fracture with AIS > or = 3 (OR 1.92; 95% CI 1.64 to 2.26), head injury with AIS > or = 3 (OR 1.24; 95% CI 1.05 to 1.46), ventilator days >3 (OR 8.08; 95% CI 6.86 to 9.52), venous injury (OR 3.56; 95% CI 2.22 to 5.72), and a major operative procedure (OR 1.53; 95% CI 1.30 to 1.80). Vena cava filters were placed in 3,883 patients, 86% as PE prophylaxis, including in 410 patients without an identifiable risk factor for VTE.

CONCLUSIONS

Patients who need VTE prophylaxis after trauma can be identified based on risk factors. The use of prophylactic vena cava filters should be re-examined.

Can We Rely on Computed Tomographic Scanning to Diagnose Pulmonary Embolism in Critically Ill Surgical Patients?

BACKGROUND

Spiral computed tomographic pulmonary angiography (CTPA) is gaining an increasing role in pulmonary embolism (PE) diagnosis because it is more convenient and less invasive than conventional pulmonary angiography (PA). Encouraging reports on the reliability of CTPA for medical patients have prompted widespread use despite the fact that its value in critically ill surgical patients has been inadequately explored. Hemodynamic and respiratory issues of critical illness may interfere with CTPA's diagnostic accuracy. The objective of this study was to compare CTPA with PA for the diagnosis of PE in critically ill surgical patients.

METHODS

Over 30 months (August 1999-February 2002), 37 critically ill surgical patients (28 trauma and 9 non-trauma patients) wiith clinical suspicion of PE were enrolled prospectively. CTPA and PA were independently interpreted by four radiologists (two for each test) blinded to each other's interpretation. Clinical suspicion for PE was classified as high, intermediate,or low on the basis of predetermined criteria. PA was considered as the standard of reference for the diagnosis of PE.

RESULTS

PE was found in 15 (40%) patients by: central PE in 8 and peripheral PE in 7. CTPA and PA findings were different in 11 patients (30%): CTPA was false-negative in 9 patients and false-positive in 2. Its sensitivity and specificity were PE 50% and 100%, respectively, for central PE; 28% and 93% for peripheral PE; and 40% and 91% for all PE. There were no differences in risk factors or clinical characteristics between patients with and without PE. The level of clinical suspicion was identical in the two groups. The independent reviewers disagreed on CTPA or PA interpretations in 11% and 16% of the readings, respectively.

CONCLUSION

PA remains the "gold standard" for diagnosis of PE in critically ill surgical patients. CTPA should be explored further before being universally accepted. Clinical criteria are unreliable for detecting PE in this population and therefore a high index of suspicion should be maintained.

Management of brain and spine injuries

For both SCI and TBI, physicians are unable to affect reversal of the cellular injuries suffered at the time of trauma directly. Unfortunately, understanding such processes is just on the horizon. Physicians do, however, have significant influence on recovery through the avoidance of secondary insults to the injured nervous system. In keeping with trauma in general, the mechanism for this is focused and coordinated multi-disciplinary care originating at the earliest contact and continuing through acute care. Aggressive and pre-emptive attention to the ABC(D)s with attention to the needs of the injured nervous system, appropriate monitoring in all patients, meticulous medical management, and prompt surgical intervention when indicated have made marked improvements in outcome, particularly in TBI. Focusing on the basics and strict attention to detail appear to be the major roles played in the care of CNS trauma.

Bleeding Manifestations after Early Use of Low-Molecular-Weight Heparins in Blunt Splenic Injuries

Low-molecular-weight heparins (LMWHs) have emerged as an effective method for deep venous thrombosis (DVT) prophylaxis after major trauma. The early use of LMWH in patients with splenic injuries may result in increased rates of blood transfusions and failure of nonoperative management. A retrospective review of the records of all patients ≥18 years old that sustained blunt splenic injuries from April 2000 to July 2002 was performed. Patients were divided in two groups based on whether they received LMWH during the first 48 hours (early group) or not (late group). A total of 188 patients were evaluated. One hundred fourteen patients had their splenic injuries managed nonoperatively and were included in the study. Fifty patients were assigned to the early group and 64 to the late group. There was no statistical difference between groups regarding basic demographic data, initial laboratory results, and severity of their splenic injuries. In the early group, two (4%) patients failed nonoperative management compared with four (6%) patients in the late group ( P = 0.593). The number of patients requiring blood transfusions within the first 5 days after admission was 25 (50.0%) in the early group and 36 (56.2%) in the late group ( P = 0.507). The average number of blood units given per patient within the first 5 days after admission were 3.2 ± 1.5 in the early group and 3.0 ± 1.8 in the late group ( P = 0.782). This study suggests that the early use of LMWH in trauma patients with splenic injuries is not associated with an increased rate of blood transfusion requirements or an increased rate of failure of non-operative management.

The Impact of Pelvic and Lower Extremity Fractures on the Incidence of Lower Extremity Deep Vein Thrombosis in High-Risk Trauma Patients

Lower extremity fractures (LEFx) and pelvic fractures (PFx) are believed to increase the risk of lower extremity deep vein thrombosis (LEDVT). We studied trauma patients at high risk for LEDVT to determine whether an increased incidence of LEDVT was associated with LEFx and/or PFx. From January 1995 through December 1997 4163 trauma patients were admitted to our Level I trauma center. One thousand ninety-three patients at high risk for LEDVT were screened with serial lower extremity venous duplex ultrasound. Their medical records were retrospectively reviewed for demographics, mechanism of injury, and fracture data. The occurrence of LEDVT, pulmonary embolus, and LEDVT prophylaxis and treatment were noted. The incidence of LEDVT in the fracture group (Fx) was compared with that in the nonfracture group (NFx) using chi-square analysis and logistic regression. Statistical significance was set at ≤0.05. Complete data were available for 1059 of 1093 patients. Five hundred sixty-nine (53.73%) patients had PFx and/or LEFx, 151 (14.26%) patients had PFx only, 317 (29.3%) patients had LEFx only, and 101 (9.54%) patients had both PFx and LEFx. Four hundred ninety (46.27%) patients had NFx. In 1059 patients LEDVT was detected in 125 (11.8%). Sixty-three patients in the Fx groups developed LEDVT (50.4%): 19 (15.2%) PFx patients, 15 (12.0%) PFx/LEFx patients, and 29 (23.2%) LEFx patients. Sixty-two (49.6%) NFx patients developed LEDVT. LEDVT incidence was not significantly different between the Fx and NFx groups or among the PFx, LEFx, and PFx/LEFx groups ( P = 0.317). Nine patients developed pulmonary embolism: four NFx patients, two LEFx patients, two PFx patients, and one PFx/LEFx patient. Significant predictors of LEDVT were age and hospital length of stay. Mean age in patients with LEDVT was 47.58 years and in patients without LEDVT it was 40.89 years ( P < 0.001). Mean hospital length of stay in patients with LEDVT was 29.81 days and in patients without LEDVT it was 16.84 days. The power of this study to detect differences representing medium effect sizes was greater than 90 per cent. We conclude that LEFx and/or PFx was not associated with an increased incidence of LEDVT in trauma patients at high risk for LEDVT. Lower extremity venous duplex ultrasound needs to be performed in both Fx and NFx groups to detect LEDVTs.

Medical literature and vena cava filters: so far so weak

STUDY OBJECTIVE

With the development of percutaneous inferior vena cava (IVC) filters, IVC interruption has become a widely used procedure in patients with or at risk for venous thromboembolism. In an attempt at clarifying the indications for filter placement, a systematic literature review was undertaken.

DESIGN

Bibliographic search and analysis.

MEASUREMENTS AND RESULTS

A systematic MEDLINE search about vena cava filters produced a total of 568 references with abstracts between 1975 and 2000 inclusively. Each reference was analyzed according to predetermined criteria. Nearly two thirds (65.0%) of these publications were retrospective studies or case reports (33.3 and 31.7%, respectively), 12.9% were animal or in vitro studies, 7.4% were prospective studies, 6.7% were reviews, and 8.1% reported on miscellaneous related topics. Among the prospective studies, only 16 studies included > or = 100 patients, only 1 study was a randomized controlled trial (0.02% of 568 references), and heterogeneity among series precluded any relevant comparison. In a similar search about heparin and venous thromboembolism, 47.4% of 531 references were randomized controlled trials.

CONCLUSIONS

Until more relevant data become available, literature reviews about vena cava filters will remain narrative, and many if not most indications for filter placement will remain a matter of opinion.