Pathogenesis and Epidemiology of Venous Thromboembolic Disease.

Venous thromboembolism is the formation of a blood clot in the vein. It mainly consists of 2 life-threatening conditions-deep venous thrombosis and pulmonary embolism. Deep venous thrombosis is a potentially dangerous condition with grave sequelae, the worst of which is pulmonary embolism. Venous thromboembolism can also lead to multiple other conditions with significant morbidity and mortality that include extension of thrombi, pulmonary hypertension, recurrence, and postthrombotic syndrome. An update on the epidemiology, etiology, and pathogenesis of venous thromboembolism will be reviewed in this article.

Diagnostic Considerations of Venous Thromboembolic Disease.

Venous thromboembolism (VTE) includes deep venous thrombosis (DVT) and pulmonary embolism (PE). The clinical presentation of VTE is nonspecific and requires confirmatory testing. The most common diagnostic tool for DVT is duplex ultrasonography since it is a noninvasive test with high accuracy. Contrast venography is considered the gold standard modality to diagnose DVT, but it is an invasive test. Magnetic resonance venography and computed tomography venography are alternative diagnostic methods for DVT, which can be helpful in certain circumstances. Pulmonary embolism is commonly diagnosed by computed tomography pulmonary angiography. Ventilation perfusion scanning is an alternative imaging to diagnose PE in patients who cannot receive intravenous contrast. Pulmonary angiography is still the gold standard in the diagnosis of PE and is usually needed in specific conditions. D-dimer assay can be utilized in ruling VTE out in low-risk patients. Estimating the pretest clinical probability for having VTE is the key step in guiding the clinicians and nurses to the appropriate diagnostic method for patients with suspected DVT or PE.

Consequences of Venous Thromboembolism, Including Chronic Thromboembolic Pulmonary Hypertension.

Venous thromboembolism includes both deep vein thrombosis and pulmonary embolism. They pose a significant risk for morbidity and mortality. In an appropriate clinical setting, invasive interventions, including administration of thrombolytics, anticoagulation, and placement of vena cava filter, are warranted. Bleeding, postthrombotic syndrome, recurrence, and filter-associated complications are few of the complications of this disease. More recently, chronic thromboembolic pulmonary hypertension has gained clinical interest in patients with pulmonary embolism and has warranted close follow-up.

Advanced Therapies in Venous Thromboembolism.

Advanced therapies are available for both deep venous thrombosis and pulmonary embolism when anticoagulation alone is not sufficient to improve clinical outcomes. In some cases, clinical deterioration ensues despite anticoagulation, and this requires unique techniques that can ameliorate the clinical course. Such advancements are described in this upcoming article.

Controversies in Venous Thromboembolism.

Numerous controversies exist in the diagnosis of venous thromboembolism despite all the guidelines that are currently available. Screening of malignancy in venous thromboembolism has been a debated issue, as it has not been shown to change mortality. Calf vein thrombosis is also a controversial topic, but evidence points to risk stratifying those patients. Overdiagnosis, most notably from the finding of subsegmental pulmonary embolism, ultimately requires evaluating the risk and benefit for each patient. In addition, treatment of upper extremity deep vein thrombosis is a challenging scenario that is quite common in clinical practice. Finally, postthrombotic syndrome may be reduced by graduated compression stockings, but their use has not been validated for preventive use at this time and is still being discussed.

Acute Respiratory Distress Syndrome.

Acute respiratory distress syndrome (ARDS) is a serious inflammatory disorder with high mortality. Its main pathologic mechanism seems to result from increased alveolar permeability. Its definition has also changed since first being described according to the Berlin definition, which now classifies ARDS on a severity scale based on PaO2 (partial pressure of oxygen, arterial)/FIO2 (fraction of inspired oxygen) ratio. The cornerstone of therapy was found to be a low tidal volume strategy featuring volumes of 6 to 8 mL per kg of ideal body weight that has been shown to have decreased mortality as proven by the ARDSnet trials. There are other areas of treatment right now that include extracorporeal membrane oxygenation, as well for severe refractory hypoxemia. Other methods that include prone positioning for ventilation have also shown improvements in oxygenation. Positive end-expiratory pressure with lung recruitment maneuvers has also been found to be helpful. Other therapies that include vasodilators and neuromuscular agents are still being explored and need further studies to define their role in ARDS.