Heparin, deep venous thrombosis, and trauma patients

Venous Thromboembolism in Trauma: The Role of Anticoagulation and Inferior Vena Cava Filters

Venous thromboembolism (VTE) is a significant contributor to morbidity and mortality among patients with severe trauma. Historically, prophylactic inferior vena cava filters (IVCFs) were used in high-risk trauma patients with suspected risk factors for VTE, including prolonged immobilization, and concurrent contraindication to anticoagulation. Mounting data regarding the efficacy of IVCF in this cohort, as well as concerns regarding morbidity of an in situ IVCF, have challenged this practice paradigm. In this review, we discuss the comanagement of VTE and trauma, including anticoagulation and the use of IVCF.

The Effectiveness and Safety of Direct Oral Anticoagulants Following Lower Limb Fracture Surgery: A Systematic Review and Meta-analysis

OBJECTIVES

Venous thromboembolism (VTE) is a well-established complication after many orthopaedic injuries, such as hip and lower limb fractures. The use of direct oral anticoagulants (DOACs, previously termed novel oral anticoagulants) is well-established as thromboprophylaxis after major elective orthopaedic surgery, but not in the nonelective setting. The aim of this study was to investigate the effectiveness and safety of DOACs after nonelective lower limb fracture surgery.

DATA SOURCES

A systematic literature search of the MEDLINE, EMBASE, CINAHL, and CENTRAL databases was conducted. No limitation was placed on publication date, with only manuscripts printed in English were eligible.

STUDY SELECTION

Included studies were either randomized controlled trials or prospective and retrospective comparative studies. Included studies compared DOACs to conventional methods of thromboprophylaxis in the postoperative period after surgical management of lower limb fractures.

DATA EXTRACTION

Outcomes included VTE, bleeding, wound complications, mortality, and adverse events. Eight studies met inclusion criteria, of which 7 compared direct factor Xa inhibitors (XaIs) with conventional VTE prophylaxis and one study compared a direct thrombin inhibitor with conventional VTE prophylaxis.

DATA SYNTHESIS

Revman 5.3 (Nordic Cochrane Centre, Denmark) was used to complete the meta-analysis and generate forest plots.

CONCLUSIONS

XaIs were shown to have lower rates of deep vein thrombosis (Odds ratio 0.59; 95% confidence interval, 0.46-0.76; P < 0.0001) and less pharmacologically attributable adverse events (Odds ratio 0.62; 95% confidence interval, 0.46-0.82; P = 0.0007). There was difference between DOACs and conventional VTE prophylaxis regarding mortality, PE, symptomatic deep vein thrombosis, or bleeding events. The results generally support the use of DOACs for VTE prophylaxis after nonelective lower limb fracture surgery, such after hip fracture. The results more strongly support the use of XaIs; however, more evidence is needed to fully assess DOACs' role in clinical practice.

LEVEL OF EVIDENCE

Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.

Venous Thromboembolism Prophylaxis: A Narrative Review With a Focus on the High-Risk Critically Ill Patient

Venous thromboembolism (VTE) is a major health concern associated with significant morbidity and mortality. Critically ill patients are at an increased risk of VTE compared to general medical patients due to unique risk factors: prolonged immobilization, invasive lines and devices, certain medications, and acquired thrombophilia. Furthermore, VTE in the critically ill is associated with increased duration of mechanical ventilation, increased length of intensive care unit and hospital stay, and a trend toward increased mortality. Clinical practice guidelines therefore recommend VTE prophylaxis with either subcutaneous heparin or low-molecular-weight heparin for all critically ill patients without contraindication. Yet, many patients will develop VTE despite appropriate pharmacologic prophylaxis, which has led to interest in risk-stratifying critically ill patients for more aggressive prophylaxis strategies. Recent research identified patients at highest risk of failure of thromboprophylaxis and provided insight into the pathophysiologic mechanisms. Obesity and the receipt of vasopressors are 2 risk factors consistently identified in observational studies; further clinical data support decreased absorption of anticoagulant administered via the subcutaneous route as the likely mechanism behind thromboprophylaxis failure in these patient populations. Several studies have investigated novel thromboprophylaxis strategies to circumvent pharmacokinetic limitations in patients who are obese or on vasopressors: increased fixed-dose, weight-based subcutaneous, or continuous intravenous infusion of a prophylactic dose of anticoagulant has shown promise in limited studies; however, the results have yet to demonstrate superiority compared to current standard-of-care. This review discusses observational studies identifying patients at risk of thromboprophylaxis failure and critiques clinical studies evaluating novel thromboprophylaxis strategies in high-risk, critically ill patients with a focus on their limitations. Future studies are currently being conducted that will provide further guidance into the appropriate use of individualized thromboprophylaxis.

Methods and Guidelines for Venous Thromboembolism Prevention in Polytrauma Patients with Pelvic and Acetabular Fractures

Sequential compression devices and chemical prophylaxis are the standard venous thromboembolism (VTE) prevention for trauma patients with acetabular and pelvic fractures. Current chemical pharmacological contemplates the use of heparins or fondaparinux. Other anticoagulants include coumarins and aspirin, however these oral agents can be challenging to administer and may need monitoring. When contraindications to anticoagulation in high-risk patients are present, prophylactic inferior vena cava filters can be an option to prevent pulmonary emboli. Unfortunately strong evidence about the most effective method, and the timing of their commencement, in patients with pelvic and acetabular fractures remains controversial.

Heparin and related drugs for venous thromboembolism prophylaxis: subcutaneous or intravenous continuous infusion?

In this article, the most evidenced approaches of unfractionated heparin administration for prevention of venous thromboembolism in medical and surgical hospitalized patients will be reviewed. Present data were collected by searching Scopus, PubMed, MEDLINE, Science direct, Clinical trials and Cochrane database systematic reviews. Subcutaneous low doses of unfractionated heparin (10000–15000 IU) in two or three divided doses per day are commonly administrated for venous thromboembolism prevention in different medical and surgical populations. In some populations such as obese surgical and critically ill patients, due to altered pharmacokinetics behavior of unfractionated heparin, continuous intravenous infusion of the low doses of unfractionated heparin has been proposed.

Deep vein thrombosis prophylaxis in trauma patients

Deep vein thrombosis (DVT) and pulmonary embolism (PE) are known collectively as venous thromboembolism (VTE). Venous thromboembolic events are common and potentially life-threatening complications following trauma with an incidence of 5 to 63%. DVT prophylaxis is essential in the management of trauma patients. Currently, the optimal VTE prophylaxis strategy for trauma patients is unknown. Traditionally, pelvic and lower extremity fractures, head injury, and prolonged immobilization have been considered risk factors for VTE; however it is unclear which combination of risk factors defines a high-risk group. Modalities available for trauma patient thromboprophylaxis are classified into pharmacologic anticoagulation, mechanical prophylaxis, and inferior vena cava (IVC) filters. The available pharmacologic agents include low-dose heparin (LDH), low molecular weight heparin (LMWH), and factor Xa inhibitors. Mechanical prophylaxis methods include graduated compression stockings (GCSs), pneumatic compression devices (PCDs), and A-V foot pumps. IVCs are traditionally used in high risk patients in whom pharmacological prophylaxis is contraindicated. Both EAST and ACCP guidelines recommend primary use of LMWHs in trauma patients; however there are still controversies regarding the definitive VTE prophylaxis in trauma patients. Large randomized prospective clinical studies would be required to provide level I evidence to define the optimal VTE prophylaxis in trauma patients.

Is routine thromboprophylaxis justified among Indian patients sustaining major orthopedic trauma? A systematic review

Venous thromboembolism (VTE) is one of the most common preventable cause of morbidity and mortality after trauma. Though most of the western countries have their guidelines for thromboprophylaxis in these patients, India still does not have these. The increasing detection of VTE among Indian population, lack of awareness, underestimation of the risk, and fear of bleeding complications after chemical prophylaxis have made deep vein thrombosis (DVT) a serious problem, hence a standard guideline for thromboprophylaxis after trauma is essential. The present review article discusses the incidence of DVT and role of thromboprophylaxis in Indian patients who have sustained major orthopedic trauma. A thorough search of 'PubMed' and 'Google Scholar' revealed 10 studies regarding venous thromboembolism in Indian patients after major orthopedic trauma surgery (hip or proximal femur fracture and spine injury). Most of these studies have evaluated venous thromboembolism in patients of arthroplasty and trauma. The incidence, risk factors, diagnosis and management of VTE in the subgroup of trauma patients (1049 patients) were separately evaluated after segregating them from the arthroplasty patients. Except two studies, which were based on spinal injury, all other studies recommended screening/ thromboprophylaxis in posttraumatic conditions in the Indian population. Color Doppler was used as common diagnostic or screening tool in most of the studies (eight studies, 722 patients). The incidence of VTE among thromboprophylaxis-receiving group was found to be 8% (10/125), whereas it was much higher (14.49%, 40/276) in patients not receiving any form of prophylaxis. Indian patients have definite risk of venous thromboembolism after major orthopedic trauma (except spinal injury), and thromboprophylaxis either by chemical or mechanical methods seems to be justified in them.

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.

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.

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.

Inpatient multitrauma rehabilitation in a U.S. military hospital

Rehabilitation serves a vital role in the care of multiply injured patients in the military, from diagnosis of occult injuries to gaining functional independence. Optimal rehabilitative care of the war casualties is predicated on diligent and rigorous training and evaluation of similar care during peacetime.

Prevention of venous thromboembolism in trauma and long bone fractures

Patients sustaining traumatic injuries are at high risk for the development of venous thromboembolism. The reported incidence of deep venous thrombosis in trauma patients ranges from 20 to 90%. The reported incidence of pulmonary embolism in trauma patients varies between 2.3 and 22%. The aging population and the survival of more severely injured patients may suggest an increasing risk of thromboembolism in the trauma patient population. There have been few randomized prospective studies assessing methods of thromboembolism prophylaxis in trauma patients. Controversy exists as to the optimal method of prophylaxis in this high-risk population. Contraindications arising from associated injuries often limit the potential options for prophylaxis in patients with trauma. Large prospective randomized studies are needed to determine the most effective means of prophylaxis in trauma patients, who have a wide range of both isolated and combined injuries. Future studies should also address the duration of prophylaxis because many trauma patients remain immobile for an extended time.

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

BACKGROUND

Trauma surgeons use a variety of methods to prevent venous thromboembolism (VT). The rationale for their use frequently is based on conclusions from research on nontrauma populations. Existing recommendations are based on expert opinion and consensus statements rather than systematic analysis of the existing literature and synthesis of available data. The objective is to produce an evidence-based report on the methods of prevention of VT after injury.

METHODS

A panel of 17 national authorities from the academic, private, and managed care sectors helped design and review the project. We searched three electronic databases (MEDLINE, EM-BASE, and Cochrane Controlled Trial Register) to identify articles relevant to four key questions: methods of prophylaxis, methods of screening, risk factors for VT, and the role of vena caval filters. The initial 4,093 titles yielded 73 articles for meta-analysis. A random-effects model was used for all pooled results. Study quality was evaluated by previously published quality scores. In this article (part I), we report on the question ranked by the experts as the most important, i.e., Which is the best method to prevent VT?, and also on the incidence of deep venous thrombosis and pulmonary embolism in trauma patients.

RESULTS

The incidence of deep venous thrombosis and pulmonary embolism reported in different studies varies widely. The pooled rates are 11.8% for deep venous thrombosis and 1.5% for pulmonary embolism. Only a few randomized controlled trials have evaluated the methods of VT prophylaxis among trauma patients, and combining their data is difficult because of different designs and preventive methods used. The quality of most studies is low. Meta-analysis shows no evidence that low-dose heparin, mechanical prophylaxis, or low-molecular-weight heparin are more effective than no prophylaxis or each other. However, the 95% confidence intervals of many of the comparisons are wide; therefore, a clinically important difference may exist.

CONCLUSION

The trauma literature on VT prophylaxis provides inconsistent data. There is no evidence that any existing method of VT prophylaxis is clearly superior to the other methods or even to no prophylaxis. Our results cast serious doubt on the existing policies on VT prophylaxis, and we call for a large, high-quality, multicenter trial that can provide definitive answers.

Prophylactic inferior vena cava filters in trauma patients at high risk: follow-up examination and risk/benefit assessment

PURPOSE

The efficacy of prophylactic inferior vena cava filters in selected trauma patients at high risk has come into question in relation to risk/benefit assessment. To evaluate the usefulness of prophylactic inferior vena cava filters, we reviewed our experience and overall complication rate.

METHODS

From February 1991 to April 1998, the trauma registry identified 7333 admissions. One hundred eighty-seven prophylactic inferior vena cava filters were inserted. After the exclusion of 27 trauma-related deaths (none caused by thromboembolism), 160 patients were eligible for the study. The eligible patients were contacted and asked to complete a survey and return for a follow-up examination to include physical examination, Doppler scan study, vena cava duplex scanning, and fluoroscopic examination. The patients' hospital charts were reviewed in detail. The indications for prophylactic inferior vena cava filter insertion included prolonged immobilization with multiple injuries, closed head injury, pelvic fracture, spine fracture, multiple long bone fracture, and attending discretion.

RESULTS

Of the 160 eligible patients, 127 were men, the mean age was 40.3 years, and the mean injury severity score was 26.1. The mean day of insertion was hospital day 6. Seventy-five patients (47%) returned for evaluation, with a mean follow-up period of 19.4 months after implantation (range, 7 to 60 months). On survey, patients had leg swelling (n = 27), lower extremity numbness (n = 14), shortness of breath (n = 9), chest pain (n = 7), and skin changes (n = 4). All the survey symptoms appeared to be attributable to patient injuries and not related to prophylactic inferior vena cava filter. Physical examination results revealed edema (n = 12) and skin changes (n = 2). Ten Doppler scan studies had results that were suggestive of venous insufficiency, nine of which had histories of deep vein thrombosis. With duplex scanning, 93% (70 of 75) of the vena cavas were visualized, and all were patent. Only 52% (39 of 75) of the prophylactic inferior vena cava filters were visualized with duplex scanning. All the prophylactic inferior vena cava filters were visualized with fluoroscopy, with no evidence of filter migration. Of the total 187 patients, 24 (12.8%) had deep vein thrombosis develop after prophylactic inferior vena cava filter insertion, including 10 of 75 (13.3%) in the follow-up group, and one patient had a nonfatal pulmonary embolism despite filter placement. Filter insertion complications occurred in 1.6% (three of 187) of patients and included one groin hematoma, one arteriovenous fistula, and one misplacement in the common iliac vein.

CONCLUSION

This study's results show that prophylactic inferior vena cava filters can be placed safely with low morbidity and no attributable long-term disabilities. In this patient population with a high risk of pulmonary embolism, prophylactic inferior vena cava filters offered a 99.5% protection rate, with only one of 187 patients having a nonfatal pulmonary embolism.

Duplex ultrasound insertion of inferior vena cava filters in multitrauma patients

BACKGROUND

Techniques for placement of inferior vena cava (IVC) filters have undergone continued evolution from open surgical exposure of the venous insertion site to percutaneous insertion in most cases today. However, the required transport either to an operating room or interventional suite can be complex and potentially hazardous for the multiply injured trauma patient who may require ventilator support, controlled intravenous infusions, or skeletal immobilization. Increased experience with color-flow duplex scanning for routine IVC imaging and portability of ultrasound equipment have suggested the usefulness of duplex-guided IVC filter insertion (DGFI) in critically ill trauma and intensive care unit (ICU) patients.

METHODS

A total of 25 multitrauma/ICU patients were considered for DGIF. Screening color-flow duplex scans were performed on all patients, and obesity or bowel gas prevented ultrasound imaging in 2 cases, leaving 23 patients suitable for DGFI. In each case, the IVC was imaged in the transverse and longitudinal planes. The right renal artery was identified as it passed posterior to the IVC and was used as a landmark of the infrarenal segment of the IVC. All procedures were performed at the bedside in a monitored ICU setting using percutaneous placement of titanium Greenfield filters. Duplex scanning after insertion was used to document proper placement, and circumferential engagement of the filter struts in the IVC wall. An abdominal radiograph was also obtained in each case to confirm proper filter location. Duplex ultrasound imaging was repeated within 1 week of insertion to assess IVC and insertion site patency.

RESULTS

DGFI was successful in all cases. The filter was deployed at a suprarenal level in one case, as was recognized at the time of postprocedural scanning. Three patients died as a result of their injuries but there were no pulmonary embolism deaths. Repeat duplex scanning was obtained in 17 patients, and revealed no case of IVC or insertion site thrombosis.

CONCLUSIONS

Vena caval interruption can be safely performed under ultrasound guidance in a monitored, ICU environment. In selected multiply injured trauma patients, this will reduce the risk, complexity and cost of transport for these critically ill patients. DGFI also reduces procedural costs compared with an operating room or interventional suite, and eliminates intravenous contrast exposure. Preprocedural scanning is essential to identify patients suitable for DGFI, and careful attention must be paid to the known ultrasonographic anatomical landmarks.

Duplex directed caval filter insertion in multi-trauma and critically ill patients

This study was undertaken to determine the safety and feasibility of inferior vena cava (IVC) filter insertion at the bedside using duplex imaging in multi-trauma and/or critically ill patients. From February 1996 to August 1997, 53 multi-trauma and/or critically ill patients, who were in the intensive care unit and referred for an IVC filter, were prospectively evaluated for possible duplex directed caval filter (DDCF) insertion. Screening IVC duplex scans were performed in all patients. Satisfactory ultrasound visualization in 46 patients (87%) allowed attempted DDCF insertion. All procedures were percutaneously performed at the bedside using Vena Tech IVC filters. The results from this series showed that DDCF insertion can be safely and rapidly performed at the bedside in multi-trauma or critically ill patients. The procedure is dependent on satisfactory visualization of the IVC by duplex ultrasonography, which was possible in 45 out of 53 (85%) patients. Insertion at the bedside substantially reduces the procedural cost and avoids the need for transport, radiation exposure, and intravenous contrast.

Screening for major deep vein thrombosis in seriously injured patients: a prospective study

The purpose of the study is to determine the prevalence of acute deep venous thrombosis (DVT) in severely injured trauma patients, to investigate the cost effectiveness of a noninvasive surveillance program, and to assess the merit of current methods of prophylaxis against DVT. One hundred and forty-eight patients (295 limbs) with a mean age of 36.5 years, mean trauma score of 13.3, mean injury severity score of 22.4 with predominantly blunt injuries (88.5%), were part of the study. The mean length of stay was 17.6 days. Venous duplex scans (VDS) were performed on inpatients on days 2-5, day 11, and day 30 following admission. Sequential compression device and/or subcutaneous heparin was used in 99% of patients with compliance being monitored by trauma nurse clinicians. A total of 272 VDS were performed with total charges of $111,520. DVT was found by VDS or venography in eight limbs (2.7%) of six patients (4%), our of the limbs being symptomatic. Two additional patients had pulmonary embolism, both with normal VDS. Routine serial VDS in severely injured patients who undergo aggressive prophylaxis against DVT is not cost effective and therefore not justified.

Practical management of venous thromboembolism following pelvic fractures

The management of thromboembolic complications remains one of the most controversial issues in the care of patients with pelvic and acetabular fractures. Recent studies have indicated that the incidence of proximal deep vein thrombosis is much higher than was previously believed. These patients should be managed with a formal institutional protocol that includes universal prophylaxis, supplemented in some cases by screening for deep vein thrombosis.

Efficacy of prophylactic vena cava filters in high-risk trauma patients

Severely injured trauma patients are at increased risk of pulmonary embolism (PE). Certain injuries may preclude the use of standard prophylactic measures, and even when used, these measures may be ineffective in the trauma population. We defined a group of trauma patients who are at statistically elevated risk of venous thromboembolic events. We then adopted an aggressive approach to the placement of prophylactic inferior vena cava (IVC) filters in these high-risk patients. Between January 1994 and January 1996 we treated 250 trauma patients who met our high-risk criteria. Prophylactic IVC filters were placed in 99 of these patients, and 151 received deep venous thrombosis prophylaxis with either heparin, sequential compression stockings, or a combination of these modalities. High-risk patients did not receive filters if they were unlikely to survive or showed rapid clinical improvement and were felt to not remain at high risk. The incidence of pulmonary embolism in this high-risk population was 1.6%. This is a significant reduction (p = 0.045, Fisher exact test) from the 4.8% incidence of PE in high-risk historical control patients with similar injury profiles. No patient with a prophylactic IVC filter suffered a clinically evident PE and there were no complications associated with placement of these filters. We conclude that the placement of prophylactic IVC filters in high-risk trauma patients is a safe and effective method of reducing the incidence of pulmonary embolism.

Use of low molecular weight heparin in preventing thromboembolism in trauma patients

OBJECTIVE

To investigate the safety and effectiveness of low molecular weight heparin (LMWH) in preventing deep venous thrombosis (DVT) in high-risk trauma patients, compared with mechanical methods of prophylaxis.

DESIGN

A prospective randomized trial conducted over a 19-month period in an urban, academic trauma center.

METHODS

All trauma patients with the following risk factors for the development of DVT were considered for enrollment in this study: any injury with an Abbreviated Injury Scale score > or = 3; major head injury (Glasgow Coma Scale score < or = 8); spine, pelvic, or lower extremity fractures; acute venous injury; or age > 50 years. After a screening venous duplex examination, the patients were assigned to a Heparin versus No-Heparin group, depending upon the presence of injuries precluding the use of heparin. In the Heparin group, the patients were then randomized to receive either LMWH or optimal mechanical compression (defined as bilateral sequential gradient pneumatic compression (SCD) or, in the presence of lower extremity injuries precluding the use of the SCD, the arteriovenous impulse (AVI) compression system). All the patients in the No-Heparin group received optimal compression. Enrolled patients underwent sequential duplex examinations every 5 to 7 days until discharge.

RESULTS

Of the 487 consecutive patients initially enrolled in this study, 372 were available for at least the first two duplex examinations and comprise the study population. Only nine (2.4%) patients developed DVT, compared with the predicted 9.1% rate in high-risk trauma patients receiving no prophylaxis (p = 0.037). Of the 120 patients who were randomized to receive LMWH, only one (0.8%) developed DVT. In the SCD group, there were 5 of 199 patients (2.5%) with DVT, and 3 of 53 (5.7%) in the AVI group. One patient with DVT also had clinical symptoms of pulmonary embolism, but there were no deaths secondary to pulmonary embolism. There was one major bleeding complication potentially associated with the use of LMWH.

CONCLUSIONS

The administration of LMWH is a safe and extremely effective method of preventing DVT in high-risk trauma patients. When heparin is contraindicated, aggressive attempts at mechanical compression are warranted.

Effect of critical injury on plasma antithrombin activity: low antithrombin levels are associated with thromboembolic complications

OBJECTIVE

Determine whether severe injury results in decreased plasma antithrombin (AT) activity and whether this decreased AT activity is associated with thromboembolic complications.

DESIGN

Prospective observational.

SUBJECTS

A total of 157 critically injured trauma patients.

METHODS

Each patient underwent laboratory analysis on arrival to the emergency room at hours 8, 16, 24, and 48, and days 3, 4, 5, and 6. Laboratory analyses included AT, tissue factor pathway inhibitor, protein C, prothrombin fragment 1.2, thrombin-antithrombin complex, and D-dimer. Patients were followed for thromboembolic complications including: deep venous thrombosis (DVT), pulmonary embolus, disseminated intravascular coagulation (DIC) and adult respiratory distress syndrome (ARDS).

RESULTS

Mean Injury Severity Score was 23 (+/-11). AT activity fell below normal in 95 (61%) patients; AT activity rose to greater than normal in 51 (32%) patients. Nine (6%) patients developed DVT, two (1%) pulmonary embolus, 13 (8%) DIC and 26 (17%) ARDS. Using logistic regression analysis, low AT levels were a significant predictor of DVT, DIC, and ARDS (p < 0.05). Supranormal At levels were associated with closed head injury (p < 0.05). D-dimer levels were inversely correlated with AT (p < 0.05).

CONCLUSIONS

AT activity was depressed in critically injured patients. Patients with head injury developed supranormal AT activity. The risk factors for AT deficiency mimicked those for thromboembolism. Patients with decreased AT activity were at increased risk for thromboembolic complications. Given heparin's dependence on AT, these data call into question the use of unmonitored heparin thromboembolism prophylaxis.

Thromboembolic complications in patients with pelvic trauma

Patients with pelvic trauma are known to be at increased risk for the development of thromboembolic complications. The incidence of deep venous thrombosis in patients with pelvic fractures is 35% to 60%. Proximal deep venous thrombosis, which is most likely to result in pulmonary embolism, occurs in 25% to 35% of these patients, and almost 1/2 of all proximal thrombi will be in the pelvic veins. The incidence of symptomatic pulmonary embolism in the pelvic trauma population is 2% to 10% whereas a greater proportion of patients will have clinically silent pulmonary embolism. Fatal pulmonary embolism occurs in 0.5% to 2% of patients with pelvic trauma. The cornerstone of effective management is prophylaxis and the most commonly used forms include low dose heparin, low molecular weight heparin, mechanical devices, and in some studies, inferior vena caval filters. Based on a critical review of the literature, in algorithm is proposed for the management of thromboprophylaxis in this trauma subgroup. This includes prophylaxis, screening, and treatment when proximal thrombosis is identified. Such a systematic approach to this potentially catastrophic problem may decrease the morbidity and mortality associated with thromboembolic complications in these patients.

Thromboembolic prophylaxis in orthopaedic trauma patients: a comparison between a fixed dose and an individually adjusted dose of a low molecular weight heparin (nadroparin calcium)

In a prospective, randomized multicentre trial the safety and efficacy of two regimens of a low molecular weight heparin (nadroparin calcium) were compared for the prevention of deep vein thrombosis (DVT) and pulmonary embolism (PE) in orthopaedic trauma patients. Two hundred and eighty-three patients with a spinal fracture, a pelvic fracture, or a lower limb injury were randomized to receive either a fixed dose (7500 anti-Xa IC units = 3075 anti-Xa IU) or a variable dose depending on body weight and time since operation (100 to 150 anti-Xa IC units/kg approximately equal to 40 to 60 anti-Xa IU/kg). The patients continued the prophylactic regimen for 6 weeks, but were withdrawn from the study medication in the presence of a major complication or if they were completely cured from their injury. To assess the rate of DVT, a B-mode ultrasound scan of both legs was performed. Positive results were confirmed by phlebography. If signs or symptoms of PE were present, a ventilation-perfusion scan was performed. Both prophylactic regimens were equally safe. In each group, five patients developed major haemorrhagic complications. In each group, one case of reversible thrombocytopenia was seen. DVT was confirmed by phlebography in one patient given the fixed dose and in four patients given the variable dose. PE was confirmed by ventilation-perfusion scans in one patient with the fixed dose and in two patients with the variable dose. An intention-to-treat analysis was performed on the overall randomized population, with the assumption that all patients who were lost to follow-up had DVT. A therapeutic efficacy analysis was performed on those patients, who completed the course of the prophylactic regimen and in whom B-mode ultrasound scanning was performed 10 days and also 6 weeks after injury. These two modes of analysis showed no significant differences in the incidence of DVT or PE between both prophylactic regimens. In conclusion, both regimens were equally safe following a spinal fracture, a pelvic fracture or a lower limb injury. The risk of DVT and PE was similar with both regimens.

Asymptomatic deep venous thrombosis in the trauma patient: is an aggressive screening protocol justified?

The incidence and sequelae of deep venous thrombosis (DVT) in trauma patients are unclear because the majority of patients who develop DVT are asymptomatic. This study evaluated the incidence, risk factors, and efficacy of prophylaxis for DVT in trauma patients over a 5-year period. Trauma patients at high risk for DVT were evaluated biweekly with lower extremity venous duplex scans. The DVT prophylaxis was instituted on admission with low-dose heparin therapy and pneumatic compression. The incidence of asymptomatic DVT identified by duplex screening was 10% (45 of 458); one pulmonary embolus occurred. Five variables were significant from bivariate and multiple logistic regression analysis: age (p = 0.005), Injury Severity Score (p = 0.005), length of stay (p = 0.004), Trauma and Injury Severity Score (p = 0.01), and spinal injury (p = 0.014). This analysis documents that trauma patients with these risk factors are at increased risk for the development of asymptomatic DVT, despite prophylaxis, and warrant surveillance with venous duplex sonography.

Prophylactic Greenfield filter placement in selected high-risk trauma patients

PURPOSE

Pulmonary embolus (PE) remains a major factor in morbidity and death in severely injured patients, especially those in specific high-risk groups. PEs have been documented to occur despite routine deep venous thrombosis prophylaxis. The purpose of this study was to evaluate the safety and efficacy of prophylactic Greenfield filter (PGF) placement in patients who have multiple trauma with known high-risk injuries for PE.

METHODS

From January 1992 to June 1994, PGF were prospectively placed in 108 patients who had an injury severity score greater than 9 and met one of the following criteria: (1) severe head injury with prolonged ventilator dependence, (2) severe head injury with multiple lower extremity fractures, (3) spinal cord injury with or without paralysis, (4) major abdominal or pelvic penetrating venous injury, (5) pelvic fracture with lower extremity fractures. These patients were compared with 216 patients, historically matched for age, sex, mechanism of injury, injury severity score, and days in the intensive care unit. Data analysis was done with chi-squared and Student's t testing.

RESULT

There were no statistical differences between the PGF and control group with regard to age (35.9 +/- 1.5 vs 38.3 +/- 1.4), sex (male 76% vs 75.5%), days in the intensive care unit (21.2 +/- 1.4 vs 18.1 +/- 1.5), ISS (28.0 +/- 1.0 vs 25.4 +/- 0.8) and mechanism of injury (blunt 85% vs 81%). None of the patients in the PGF group had a PE. In the control group, however, 13 patients had a PE, nine of which were fatal. These differences were statistically significant for both PE (p < 0.009) and PE-related death (p < 0.03). The overall mortality rate was reduced in the PGF group (18 of 108, 16%) versus the control group (47 of 216, 22%); however, this did not achieve statistical significance.

CONCLUSION

PGF insertion in selected patients at high risk who had trauma effectively prevented both fatal and nonfatal PE. The lower incidence of fatal PE in the PGF group may have contributed to a reduction in the overall mortality rate. Patients who have trauma with high risk for PE should be considered for PGF placement.

Venous thromboembolism in trauma patients

Venous thromboembolism is common in patients with multiple injuries. In addition to having endothelial injury, trauma patients are hypercoagulable and are often confined to bed, thus placing them at high risk for venous thromboembolic events. Duplex ultrasonography and impedance plethysmography are the most practical modalities to screen trauma patients for the presence of DVT. At present, there do not appear to be any effective means of preventing DVT in trauma patients, although low molecular weight heparin appears promising. In particularly high-risk patients vena cava filters have been used safely and effectively to prevent PE.

Prevention of postoperative venous thromboembolism: an update

BACKGROUND

Perioperative venous thromboembolism remains a major health problem. Each year, approximately 260,000 cases are diagnosed clinically, and the incidence of asymptomatic and undiagnosed cases is far greater. Despite the availability of effective strategies to prevent venous thromboembolism, prophylaxis is underutilized. According to recent epidemiologic surveys, approximately two thirds of hospitalized patients with clinical risk factors for venous thromboembolism do not receive adequate prophylaxis.

METHODS

A comprehensive review of the English language literature was carried out to define effective antithrombotic regimens to prevent venous thromboembolism in discrete surgical patient populations. Reliable data are available for every group with the exception of patients with multiple trauma and spinal cord injury.

CONCLUSIONS

A wide variety of effective prophylactic methods are available to prevent venous thromboembolism. Individual patients can be assigned a level of risk based on clinical risk factors. The choice of prophylactic method is based on the level of risk, potential for complications, and costs. With the wide availability of proven methods, no patient at risk for venous thromboembolism should be left unprotected.

Medical consultation in the patient with multiple trauma

Medical consultation is frequently requested to assist the trauma team in the management of the patient with multiple traumatic injuries. Four areas are commonly encountered as problems for management in this patient population. In this article, myocardial contusion, stress ulceration, seizure prophylaxis, and deep vein thrombosis prevention are addressed with respect to incidence, assessment, and management.