Epidemiology of venous thromboembolic disease

Venous Thromboembolism Subsequent to the Management of Panfacial Fracture- A Clinical Paper and Review

Background

Venous thromboembolism (VTE) is a major factor responsible for death in patients suffering from prolonged immobilisation due to various causes like old age, pregnancy, stroke, and prolonged surgical procedures to mention a few. Long-duration surgeries as in fixation and reconstruction in panfacial fractures and facial orthognathic surgeries can be potential cases predisposed for VTE in maxillofacial surgery.

Method

A fifty-eight-year-old patient suffered from pulmonary thromboembolism following long-duration surgery for panfacial fracture fixation and reconstruction under general anaesthesia. He was promptly managed via medical management and recovered well.

Discussion

Pulmonary thromboembolism is a severe complication that can lead to severe morbidity or even death. Owing to the characteristics of venous thrombosis, all collaborating healthcare team members should be trained to assess risk factors for efficient diagnosis which can facilitate specialised intervention that can result in better patient outcomes.

Conclusion

Maxillofacial surgeons need to evaluate the risk of thromboembolism in patients and institute efficient diagnosis whenever required to deliver optimised and better patient care. Although thromboembolism is a preventable disease state, the key is to keep a close eye on the patient's clinical features to identify and treat them at the right time for better patient care and survival.

Anticoagulation in Deep Venous Thrombosis: Current Trends in the Era of Non- Vitamin K Antagonists Oral Anticoagulants

Anticoagulation therapy is the cornerstone of treatment in acute vein thrombosis (DVT) and it aims to reduce symptoms, thrombus extension, DVT recurrences, and mortality. The treatment for DVT depends on its anatomical extent, among other factors. Anticoagulation therapy for proximal DVT is clearly recommended (at least for 3 months), while AT for isolated distal DVT should be considered, especially in the presence of high thromboembolic risk factors. The optimal anticoagulant and duration of therapy are determined by the clinical assessment, taking into account the thromboembolic and bleeding risk in each patient in a case-by-case decision making. Non-Vitamin K antagonists oral anticoagulants (NOACs) were a revolution in the anticoagulation management of DVT. Nowadays, NOACs are considered as first-line therapy in the anticoagulation therapy for DVT and are recommended as the preferred anticoagulant agents by most scientific societies. NOACs offer a simple route of administration (oral agents), a rapid onset-offset of their action along with a good efficacy and safety profile in comparison with Vitamin K Antagonists (VKAs). However, there are issues about their efficacy and safety profile in specific populations with high thromboembolic and bleeding risks, such as renal failure patients, active-cancer patients, and pregnant women, in which VKAs and heparins were the standard care of treatment. Since the available data are promising for the use of NOACs in end-stage chronic kidney disease and cancer patients, several ongoing randomized trials are currently trying to solve that issues and give evidence about the safety and efficacy of NOACs in these populations.

Chronic leg pain in athletes

Chronic leg pain is commonly treated by orthopaedic surgeons who take care of athletes. The sources are varied and include the more commonly encountered medial tibial stress syndrome, chronic exertional compartment syndrome, stress fracture, popliteal artery entrapment syndrome, nerve entrapment, Achilles tightness, deep vein thrombosis, and complex regional pain syndrome. Owing to overlapping physical examination findings, an assortment of imaging and other diagnostic modalities are employed to distinguish among the diagnoses to guide the appropriate management. Although most of these chronic problems are treated nonsurgically, some patients require operative intervention. For each condition listed above, the pathophysiology, diagnosis, management option, and outcomes are discussed in turn.

Complex Interaction between Obesity and Trauma

Trauma and obesity are large-scale epidemics that can be associated with significant morbidity and mortality. In few studies, it has noted that there is the ‘obesity paradox’ (obesity has been found to be protective against mortality) due to certain causes, i.e. heart failure or cardiovascular disease. Subcutaneous fat can show great variability between individuals and increased subcutaneous fat may be protective against injuries by cushioning the internal abdominal organs against injurious forces in road traffic accidents. Many factors including the body fat distribution, body shape, and center of gravity may play an important role in the different injury patterns and severity of injury between men and women. A better understanding of how obesity influences trauma related injuries not only will help to improve the outcome but also foster the development of interventions to address the most salient and modifiable risk factors to reduce obesity related morbidity and mortality. In present article, we review the relevant literature with special considerations to understand the interactions of obesity and trauma with their impact on patient management and outcomes.

How to cite this article

Agrawal A. Complex Interaction between Obesity and Trauma. Panam J Trauma Crit Care Emerg Surg 2014;3(3):109-113.

Pulmonary embolism

Pulmonary embolism (PE) remains one of the most challenging medical diseases in the emergency department. PE is a potentially life threatening diagnosis that is seen in patients with chest pain and/or dyspnea but can span the clinical spectrum of medical presentations. In addition, it does not have any particular clinical feature, laboratory test, or diagnostic modality that can independently and confidently exclude its possibility. This article offers a review of PE in the emergency department. It emphasizes the appropriate determination of pretest probability, the approach to diagnosis and management, and special considerations related to pregnancy and radiation exposure.

Concomitant and antecedent deep venous thrombosis and cancer survival in male US veterans

Survival is reportedly worse in patients with cancer concurrently diagnosed with deep venous thrombosis. However, information on specific malignancies is limited. From a cohort study of male US veterans we identified incident cancer cases (n = 412,008) and compared survival patterns among those with versus without a history of deep venous thrombosis. Using Cox proportional hazard models, we estimated hazard ratios (HRs) and 95% confidence intervals as measures of the relative risk of dying. Individuals with (versus without) a concomitant deep venous thrombosis and cancer diagnosis had a higher risk of dying (HR = 1.38; 1.28-1.49). The most prominent excess mortality (HR = 1.29-2.55) was observed among patients diagnosed with deep venous thrombosis at the time of diagnosis of lung, gastric, prostate, bladder, or kidney cancer. Increased risk of dying was also found among cancer patients diagnosed with deep venous thrombosis 1 year (HR = 1.14; 1.07-1.22), 1-5 years (HR = 1.14; 1.10-1.19), and >5 years (HR = 1.27; 1.23-1.31) before cancer; this was true for most cancer sites (HR = 1.17-1.64). In summary, antecedent deep venous thrombosis confers a worse prognosis upon cancer patients. Advanced stage at diagnosis, treatment effects, lifestyle factors, and comorbidity could explain differences by cancer site and time frame between a prior deep venous thrombosis diagnosis and cancer outcome.

Difficulties in managing the surgical patient who is morbidly obese

Managing patients who are morbidly obese in the intensive care unit is associated with a variety of problems uncommonly experienced with the those who are not morbidly obese. Clinicians experience a myriad of unique problems and circumstances, from the need for special beds and lifts to unusual and unknown volumes of distribution resulting in unclear drug dosing. This review examines several issues including sedation, invasive monitoring, venous thromboembolism prophylaxis, surgical infections, nutritional support, and other complications that may be of particular importance to the critically ill patient who is morbidly obese. In many cases, care is altered based on the complicating issues surrounding morbid obesity. In other cases, the presence of obesity suggests no alterations in our routine critical care delivery. A comprehensive review of the literature is undertaken, data are critically considered, and overall opinion is rendered based on the available peer-reviewed literature. In many cases, data are not available that address the specific patient population in question, so related papers (like gastric bypass data) are considered. Many issues do not have definitive answers based on randomized controlled trials, and much is left to treating clinician opinion and local practice patterns. Where good data exist, however, one should consider carefully and individually deviation from the evidence-based approach.

A cohort study investigating patient expectations and satisfaction outcomes in men undergoing robotic assisted radical prostatectomy

INTRODUCTION

Robotic assisted radical prostatectomy (RARP) is gaining widespread acceptance for the management of localized prostate cancer. However, data regarding patient expectations and satisfaction outcomes after RARP are scarce.

METHODS

We developed a structured program for preoperative education and evidence-based counseling using a multi-disciplinary team approach and measured its impact on patient satisfaction in a cohort of 377 consecutive patients who underwent RARP at our institution. Responses regarding overall, sexual, and continence satisfaction were assessed.

RESULTS

Fifty percent of our patient cohort replied to the questionnaire assessments. Ninety-three percent of responding patients expressed overall satisfaction after RARP with only 0.5% expressing regret at having had the operation. Biochemical recurrence and lack of continence correlated significantly with low levels of satisfaction, though sexual function was not significantly different among those satisfied and those not. Most patients (97%) valued oncologic outcome as their top priority, with regaining of urinary control being the commonest second priority (60%).

CONCLUSIONS

RARP appears to be associated with a high degree of patient satisfaction in a cohort of patients subjected to a structured preoperative education and counseling program. Oncologic outcomes are most important to these patients and have the largest influence on satisfaction scores.

Prevalence of thrombophilias in patients presenting for bariatric surgery

BACKGROUND

The rise in bariatric surgery has driven an increased number of complications from venous thromboembolism (VTE). Evidence supports obesity as an independent risk factor for VTE, but the specific derangements underlying the hypercoagulability of obesity are not well defined. To better characterize VTE risk for the purpose of tailoring prophylactic strategies, we developed a protocol for thrombophilia screening in patients presenting for bariatric surgery at our institution.

METHODS

Between April 2004 and April 2006, 180 bariatric surgery candidates underwent serologic screening for inherited thrombophilias (Factor V-Leiden mutation, low Protein C activity, low Protein S activity, Free Protein S deficiency) and acquired thrombophilias (D-Dimer elevation, Fibrinogen elevation, elevation of coagulation factors VIII, IX, and XI, elevation of Lupus anticoagulants and homocysteine level, and Antithrombin III deficiency). Prevalence rate of each thrombophilia in the subject group was compared to the actual prevalence rate of the general population.

RESULTS

Most plasma markers of both inherited and acquired thrombophilias were identified in higher than expected proportions, including D-Dimer elevation in 31%, Fibrinogen elevation in 40%, Factor VIII elevation in 50%, Factor IX elevation in 64%, Factor XI elevation in 50%, and Lupus anticoagulant in 13%.

CONCLUSIONS

Obesity is a well-described demographic risk factor for VTE. In bariatric surgery candidates routinely screened for serologic markers, both inherited and acquired thrombophilias occurred more frequently than in the general population, and may therefore prove to be useful for individualized VTE risk assessment and prophylaxis.

[Venous interventions--part 1: techniques and lower torso thromboses]

Venous thrombosis is one of the most common vascular diseases. Without treatment, pulmonary embolism is a potentially life-threatening complication. Long-term complications are chronic venous insufficiency and post-thrombotic syndrome. Medical anticoagulation is currently the standard therapy, since it prevents appositional thrombus growth although it usually can not prevent the development of post-thrombotic syndrome. The structure of the thrombotic material often leads to partial recanalisation with residual stenosis. Early and sufficient systemic thrombolysis with adequate concentration may achieve disintegration of the thrombus and preservation of venous valve function. Supplementary to conservative therapy, local catheter thrombolysis is possible even in cases with contraindications for a systemic thrombolysis therapy. Additional interventional techniques reduce the required concentration of the thrombolytic. Venous stenosis can be treated by balloon angioplasty and stent implantation. This article reviews the different percutaneous treatment options as well as their application and usefulness in thrombosis of the lower torso.

Arterial thrombosis associated with factor V Leiden and methylenetetrahydrofolate reductase C677T mutation in childhood membranous glomerulonephritis

Acquired abnormalities of coagulation and fibrinolysis in nephrotic syndrome have been implicated in the pathogenesis of deep-vein and arterial thrombosis. A mutation in the factor V and methylenetetrahydrofolate reductase (MTHFR) gene, the commonest inherited risk factor for venous thrombosis, may contribute to the risk of both arterial and deep-vein thrombosis in patients with nephrotic syndrome. Here, we report on an arterial thrombosis in a young girl with idiopathic membranous glomerulonephritis associated with heterozygous factor V Leiden and homozygous MTHFR C677T mutation. We postulate that screening for factors such as factor V Leiden and MTHFR C677T mutation may be beneficial to patients associated with thromboembolism and idiopathic nephrotic syndrome.

High Incidence of Venous Thromboembolic Events in Lung Transplant Recipients

BACKGROUND

Previous studies have reported a 12% incidence of venous thromboembolic events (VTEs) in lung transplant recipients (LTRs). Characterization of risk factors for VTEs in LTRs is lacking. We identified the incidence and risk factors associated with post-transplant VTEs.

METHODS

A retrospective review of 153 LTRs from 1994 to 2006 was performed. Patients were categorized by age, race, gender, weight, underlying diagnosis, procedure, ischemic time, length of stay (LOS), cardiopulmonary bypass (CPB), location and number of VTEs, mobility, immunosuppression, renal, hepatic, hematologic and coagulation profiles and nutritional status.

RESULTS

A single VTE occurred in 29% of LTRs within the study period. Fifty-eight percent had multiple VTEs and 7% had a radiologically confirmed pulmonary embolism. Median time from transplant to first VTE was 69 days. Sixty percent of VTEs occurred within 1 year, 20% of which occurred within the first month, 19% between 2 and 5 years, and 13% at beyond 5 years post-transplant. Seventy-six percent of VTEs occurred during hospitalization, 19% during outpatient status. Forty-eight percent were of the upper extremity and 47% were of the lower extremity. Sixty-one percent of LTRs were taking cyclosporine and 39% tacrolimus. VTE and non-VTE groups were similar in age, weight, body mass index (BMI), ischemic time, procedure or underlying diagnosis precipitating the need for transplant. Univariate analysis revealed LOS and CPB as significant predictors of a single VTE (p = 0.036, hazard ratio [HR] 1.006 and p = 0.045, HR 1.91, respectively). Multivariate analysis revealed only CPB as a significant predictor (p = 0.047, HR 1.929).

CONCLUSIONS

Analysis of a cohort of LTRs for a median period of 1.5 years revealed a VTE incidence much higher than previously reported, especially within the first month after transplantation.

Management of the obese trauma patient

Obese persons are more likely to be involved in vehicle accidents, probably because of the presence of sleep apnea. They are more likely to suffer chest, pelvis, and extremity fractures. Mildly overweight persons are less prone to intra-abdominal injury because of the protective effect of the abdominal fat, known as the cushion effect. Obese trauma patients are far more likely to develop in-hospital complications, especially pulmonary, renal, and thromboembolic complications. The BMI is an independent risk factor for morbidity and mortality after trauma. Because only limited data exist about the right clinical approach to obese trauma patients, it is necessary to rely on general knowledge about treating obese patients in the ICU. More research is needed to improve the treatment of obese trauma patients.

Retrievable vena cava filters: clinical experience

PURPOSE OF REVIEW

To summarize currently available literature regarding indications for inferior vena cava filters, potential problems associated with the different filters available, and the efficacy and safety of retrievable inferior vena cava filters.

RECENT FINDINGS

The placement of permanent filters may present a number of long-term complications such as filter occlusion and an increased risk of recurrent deep vein thrombosis. Furthermore, patients who require inferior vena cava interruption often have short-term contraindications to anticoagulant therapy, and thus only require filters for temporary indications. Four different retrievable filters have recently received approval for temporary insertion, and preliminary data suggest that the use of these filters is associated with a low rate of pulmonary embolism and complications related to filter insertion. Retrieval was uneventful in almost all patients. No randomized clinical trials have yet been performed, and available information is based on the results of either retrospective or prospective cohort studies.

SUMMARY

Retrievable filters are a very attractive alternative to either permanent or temporary filters when inferior vena cava interruption becomes necessary, thanks to the advantages of very easy management and the possibility of their being left in place for a long time and removed when they become unnecessary.

The treatment of venous thromboembolism in special populations

Anticoagulant therapy for the typical venous thromboembolism patient is straightforward with predictably favorable outcomes. However, for certain patients with venous thromboembolism, there remains uncertainty and controversy about optimal treatment. These controversial areas include venous thromboembolism patients with: heparin resistance, renal insufficiency, morbid obesity, cancer, antiphospholipid antibody syndrome, recurrent thrombosis despite appropriate anticoagulation, and patients with unprovoked VTE who may or may not benefit from thrombophilia testing. This review summarizes the current data for these special patient populations with venous thromboembolism and provides our recommendations for management.

Pathophysiology of venous thrombosis, thrombophilia, and the diagnosis of deep vein thrombosis-pulmonary embolism in the elderly

This article reviews Virchow's triad to provide clinicians with the pathophysiologic basis for the development of venous thromboembolism (VTE). Armed with these data physicians should be vigilant of the development of VTE when these factors are present. The second clinical point is the appropriate need to evaluate elderly patients for primary or secondary thrombophilia. By using statistical probability and clinical history selected geriatric patients with VTE should be assessed for the etiology of their hypercoagulable state. Finally, evaluating symptomatic patients for VTE should be structured to use the appropriate testing to confirm the diagnosis.

Inferior vena cava thrombosis causing acute cauda equina syndrome

The authors report a case of a 16-year-old girl who presented with a 1-week history of progressive low-back pain, buttock paresthesias, and bilateral lower extremity pain and weakness. Magnetic resonance (MR) imaging and MR venography studies of her lumbar spine revealed engorgement of the epidural venous plexus and mild compression of the cauda equina. A lower extremity and pelvic venogram revealed occlusive thrombosis of the femoral and iliac veins as well as of the inferior vena cava (IVC). The patient required an IVC thrombectomy due to progressive symptoms, after which she improved and returned to baseline status in 1 week. Imaging studies afterwards showed resolution of the venous engorgement and decompression of the cauda equina. This is the second published report of an association between IVC thrombosis and cauda equina syndrome.

Incidence and risk factors of venous thromboembolism (VTD) in patients with amyloidosis

Background

Coagulation problems in amyloidosis are historically associated with bleeding tendencies (mostly Factor X abnormalities). Increased clotting was observed in isolated cases diagnosed with low-grade disseminated intravascular coagulation (DIC). Problem of venous thromboembolic disaease (VTD) in amyloidosis was not systematically investigated.

Methods

We evaluated frequency of VTD and risk factors for VTD in 56 consecutive amyloidosis patients with a documented disease evaluated and followed up at our Center from 1991–2001. Data was collected in 5 categories: (a) demographics, (b) disease and treatment, (c) thrombosis case information, (d) major risk factors for thrombosis and (e) baseline laboratory data. Univariable correlates of VTD were assessed using Kaplan-Meier analysis and Cox proportional hazards analysis.

Results

Mean age of the patients was 67 (years range 21 – 83). Male/female percentage ratio was 70/30. 29 % of the patients had high creatinine level (> 1.4 mg/dl). Personal or family history of VTD was recorded in 2 and 0 % of patients, respectively. Known hypercoagulable state was present in 1 patient (2%). 8 % of patients were smokers. Of 56 patients, 6 developed VTD (11%). Median time from diagnosis of amyloidosis to VTD was 12.5 month (range 1–107). Treatment was given within a median of 1 month (range 0–4) from the development of thrombosis. Only sites of VTD were lower extremities. No cases were associated with I.V. line. 1 case (17 %) was identified postoperatively. We identified several univariable correlates of VTD in amyloid patients, including greater age at diagnosis (HR-2.99, P = .041), personal history of DVT (HR-47.7, P = .006) and immobility (HR-11.78, P = .006). Presence of circulating serum M-protein had protective role in our analysis (HR-.08, P = .031). There was no correlation with the type of treatment patients were receiving.

Conclusion

Risk for thromboembolic diseases in patients with amyloidosis is similar to one previously described for multiple myeloma. Additional studies with higher number of thromboembolic events could help to further elucidate risk factors for VTD in this population of patients.

From genetics to genomics: using gene-based medicine to prevent disease and promote health in children

The remarkable achievements of the Human Genome Project promise great opportunities for disease prediction, treatment, and prevention. In this paper, we discuss the continuum of genetic variation as medical practice begins to shift focus from the study of single genes (genetics) to the study of the entire genome (genomics). Pediatricians should anticipate an influx of genetic information and will need to become as facile in interpreting this type of predictive information as they are with other types of medical data, while recognizing the unique ethical, legal, and social implications of genetic testing in children. We discuss an approach to assist pediatricians in decision-making that emphasizes the need for knowledge about the analytic performance of genetic tests, their validity in predicting health outcomes, and the utility of the genetic information in improving health and preventing disease.

Epidemiology of acute deep vein thrombosis

Although the factors leading to venous thrombosis have been known for over a century, Virchow's initial model of thrombosis has been extensively refined. Activated coagulation is now recognized to be of primary importance in venous thrombogenesis; the concept of venous injury has been expanded to include molecular changes in the endothelium; and stasis has been redefined as a largely permissive factor. Furthermore, it is now clear that venous thrombi undergo a dynamic evolution beginning early after their formation. The natural history of acute deep venous thrombosis (DVT) is a balance between recurrent thrombotic events and processes that restore the venous lumen, both of which have important implications for the development of complications. Although pulmonary embolism (PE) is clearly the most life threatening complication of acute DVT, the long term socio-economic consequences of the post thrombotic syndrome (PTS) have perhaps been underemphasized in clinical trials. The development of post-thrombotic manifestations is related to both residual venous obstruction and valvular incompetence. Recognition of the factors contributing to a poor outcome, including recurrent thrombotic events, the rate of recanalization, the global extent of venous reflux, and the anatomic distribution of reflux and obstruction is important, as there may be therapeutic alternatives to alter the natural history of acute DVT. The treatment alternatives will continue to expand with the introduction of new therapeutic drugs, for both systemic and catheter-directed therapy, and mechanical thrombectomy devices. The primary care physician is challenged with the task of correctly evaluating deep vein thrombosis and providing his patient with access to the most clinically appropriate, and cost-effective, diagnostic and management options available. This article will review the epidemiology of DVT, its risk factors and major complications.

Pulmonary embolism: an unsuspected killer

The presentation of PE is often subtle and may mimic other diseases. Many pulmonary emboli invariably preclude diagnosis by their occult nature or by leading to rapid death from cardiopulmonary arrest. In patients who do manifest symptoms from PE, accurate diagnosis is essential. Often it is difficult to distinguish the vague symptoms of PE from other diagnoses, such as acute coronary syndrome, pneumonia, COPD, CHF,aortic dissection, myocarditis or pericarditis, pneumothorax, and musculo-skeletal or gastrointestinal causes. Regardless of the presentation, the most fundamental step in making the diagnosis of PE is first to consider it. Historical clues and risk factors should raise the clinician's suspicion.PE is an unsuspected killer with a nebulous presentation and high mortality. In all likelihood, PE will remain an elusive diagnosis despite advances in technology and a wealth of research. A high index of suspicion is required, but no amount of suspicion would eliminate all missed cases. Patients with significant underlying cardiopulmonary disease seem to be the most challenging. Patients with significant comorbidity have poor reserve and are likely to have poor outcomes, especially if the diagnosis is not made and anticoagulation is not initiated early. Controversy exists over the best diagnostic approach to PE. A battery of diagnostic studies is available, with few providing definitive answers. Studies such as CT may be helpful at some institutions but offer poor predictive value at others. Other diagnostic tests are not universally available. It is hoped that further research and improvements in current diagnostic modalities will clear some of the current confusion and controversy of this ubiquitous and deadly disease.

Postmenopausal HRT is not independent risk factor for dural sinus thrombosis

While a dural sinus thrombosis (DST), is a well-known consequence of the use of oral contraceptives, the role of hormone replacement therapy (HRT) in DST was not previously evaluated. We report two postmenopausal women, presenting with DST under HRT. Antiphospholipid antibodies in one case and borderline protein S deficiency in another were diagnosed. Only five cases of DST under HRT were previously reported and in two of them additional prothrombotic risk factors were found. According to these and previous cases, HRT is not an independent risk factor for DST.

A prospective registry of 5,451 patients with ultrasound-confirmed deep vein thrombosis

We enrolled 5,451 patients with ultrasound-confirmed deep vein thrombosis (DVT), including 2,892 women and 2,559 men, from 183 United States sites in our prospective registry. The 5 most frequent co-morbidities were hypertension (50%), surgery within 3 months (38%), immobility within 30 days (34%), cancer (32%), and obesity (27%). Of the 2,726 patients who had their DVT diagnosed while in the hospital, only 1,147 (42%) received prophylaxis within 30 days before diagnosis.

Provider Volume of Total Knee Arthroplasties and Patient Outcomes in the HCUP-Nationwide Inpatient Sample

BACKGROUND

The relationship between volume and outcome of total knee arthroplasties has never been evaluated in a nationally representative sample, to our knowledge. We hypothesized that surgeons and hospitals with higher patient volumes would have better outcomes, as defined by lower mortality rates, shorter hospital stays, and lower postoperative complication rates.

METHODS

The 1997 Healthcare Cost and Utilization Project (HCUP) Nationwide Inpatient Sample, Release 6, provided discharge abstracts of patients undergoing total knee arthroplasty from a national stratified probability sample. Logistic and multiple regression models were used to estimate the adjusted association of surgeon or hospital volume with rates of in-hospital mortality, pulmonary thromboembolism, deep venous thrombosis in the lower extremity, and postoperative wound infection as well as length of hospital stay. Estimates were calculated for a target population of 277,550 patients. Models were adjusted for comorbidity, age, gender, race, household income, and procedure (primary or revision arthroplasty).

RESULTS

The patients were mostly white (70.2%) and female (62.7%), with a mean age of 68.9 years. The overall in-hospital mortality rate for the target population was 0.2%, and the average length of stay was 4.6 days for the primary total knee arthroplasties and 4.9 days for the revision procedures. Surgeon volumes of at least fifteen procedures per year and hospital volumes of at least eighty-five per year were significantly and linearly associated with lower mortality rates (odds ratio = 0.56 [0.24 to 1.31] for surgeon volume of > or = 60). No other association demonstrated a significant and directionally consistent linear trend for improved outcomes.

CONCLUSION

Patients treated by providers with lower caseload volumes had higher rates of mortality following total knee arthroplasty in 1997. Proposing volume standards could decrease patient mortality following this procedure.

Pulmonary embolism

PE is one of the great challenges in medicine. It is a disease that carries with it a high mortality rate, yet no historical piece of information, physical examination finding, or diagnostic modality is perfect at excluding its possibility. Emergency physicians must be vigilant about considering PE in the differential diagnosis of a variety of presenting complaints and must use a variety of diagnostic and therapeutic options as they manage patients with suspected or confirmed PE. The diagnostic options range from bedside diagnostic tests to highly specialized imaging available at only specialized institutions. Knowing the advantages and disadvantages of each of the diagnostic modalities assists the physician in employing the best test. Therapeutic options also vary widely and include anticoagulation, vena caval interruption, systemic thrombolysis, embolectomy, and other therapeutic adjuncts, such as ECMO and inhaled nitric oxide. Similarly, awareness of the indications and contraindications to the varied therapeutic agents ensures appropriate therapy when the diagnosis is made.

Venous thromboembolism prophylaxis in the medically ill patient

All general medical patients should be assessed for clinical risk factors for VTE. The ACCP has recommended that general medical patients with clinical risk factors receive either LDUH twice or three times daily or once-daily LMWH. Current evidence suggests that twice-daily LDUH may not be efficacious enough in the acutely ill medical inpatient. LDUH three times daily may be efficacious in most medical patients; however, it is associated with an increased risk for bleeding. The preferred strategy for prevention in the medically ill population at high to very high risk for VTE is LMWH. For patients who have a high to very high risk for bleeding, nonpharmacologic strategies such as ES or IPC devices are recommended.

Obesity increases prostanoid-mediated vasoconstriction and vascular thromboxane receptor gene expression

OBJECTIVES

Vasoconstrictor prostanoids have been implicated in abnormal vasomotion in atherosclerosis and hypertension.

METHOD

Using lean and diet-induced obese mice, we investigated whether obesity affects vascular function or expression of genes involved in prostanoid action.

RESULTS

In lean C57BL/6J mice, at high concentrations acetylcholine caused endothelium-dependent contractions in the carotid artery but not in the aorta. Endothelium-dependent contractions to acetylcholine were blocked by the non-selective cyclooxygenase (COX) inhibitors indomethacin and meclofenamate, or a prostaglandin H2/thromboxane A2 receptor antagonist, but not by inhibitors of COX-2, thromboxane synthase or cytochrome P450 monooxygenase. Obesity increased endothelium-dependent contractions to acetylcholine in the carotid artery, and prostanoid-mediated vasoconstriction was now present in the aorta. Similarly, contractions to endothelin-1 were largely blocked by meclofenamate and were increased in the aorta of obese mice. Real-time quantitative polymerase chain reaction analysis of the thromboxane receptor gene in the carotid artery revealed a robust upregulation in obese animals (18-fold, 0.05); in comparison, obesity had a less pronounced effect on thromboxane synthase (2.1-fold increase, 0.05), or preproendothelin-1 gene expression (4.2-fold increase, 0.05).

CONCLUSIONS

These data demonstrate that obesity augments prostanoid-dependent vasoconstriction and markedly increases vascular thromboxane receptor gene expression. These changes are likely to promote the development of vascular disease, hypertension and thrombosis associated with obesity.