Introduction to the Anatomy and Physiology of Pulmonary Circulation.

In the United States, venous thromboembolism is associated with high mortality and morbidity affecting as many as 900 000 people (1-2 per 1000) each year. Estimates suggest that 60 000 to 100 000 Americans die of deep venous thrombosis/pulmonary embolism and 10% to 30% die within 1 month of diagnosis, with sudden death being the first symptom in approximately 25% of population with pulmonary embolism. One-half of the patients with deep venous thrombosis will have postthrombotic syndrome, which includes swelling, pain, discoloration, and scaling in the affected limb. Approximately 33% of patients will have a recurrence within 10 years. It is important to understand the anatomy of the pulmonary circulation and the pathophysiology of the disease as it leads to understanding of the potential devastating clinical consequences.

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.

Clinical Presentation and Risk Factors of Venous Thromboembolic Disease.

Venous thromboembolism (VTE) has a wide range of clinical presentations. Deep venous thrombosis may occur in upper or lower extremities or in visceral veins. Extremity deep venous thrombosis usually manifests with unilateral painful swelling in the limb, while visceral deep venous thrombosis manifestations vary on the basis of the involved organ. Pulmonary embolism classically manifests with sudden pleuritic chest pain and unexplained dyspnea. Superficial thrombophlebitis usually presents with acute inflammation around a palpable thrombosed superficial vein. Risk factors of VTE are either inherited or acquired. The inherited causes of VTE tend to be familial and more common in younger patients. The common acquired risk factors of VTE include previous history of venous thrombosis, immobilization, recent surgery or trauma, malignancy, and pregnancy. Identifying high-risk patients for VTE based on these risk factors is the cornerstone to provide the prophylactic treatment to prevent thrombotic events.

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.

Deep Venous Thrombosis of the Upper and Lower Extremity.

Upper and lower extremity deep venous thrombosis (DVT) is defined as a blood clot within the deep veins of the affected extremities. These blood clots can either occur spontaneously or be associated with specific risk factors. Regardless of the cause, DVT is associated with significant morbidity and mortality and has the potential for lethal complications. The most notable complication is the potential for development of pulmonary embolism from a lower extremity DVT. As studies have reported, more than 90% of acute pulmonary emboli arise from the proximal veins. Venous thromboembolism is also associated with a significant economic burden on the health care system and the individual patient. In this article, we review DVT of the upper and lower extremity including risk factors, signs and symptoms, diagnosis, and management.

Venous Thromboembolism and Pulmonary Embolism Response Teams: An Overview.

Venous thromboembolism is a common disease with a wide array of signs and symptoms. It has been cited as the third leading cause of cardiovascular death, and if left untreated, it leads to death in 1 in 4 patients. Sophisticated diagnostic tools have allowed physician to become more accurate in diagnosing pulmonary embolism and deep vein thrombosis. The advent of new oral anticoagulants, the emergence of pulmonary embolism response teams, and protocols demonstrate recent achievements in the management of venous thromboembolism. The focus of this article is to discuss the treatment of venous thromboembolism.

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.

Prophylaxis for Venous Thromboembolism.

Venous thromboembolisms are major risk factors for many of our hospitalized patients. These events, however, can be prevented with prophylactic measurements when administered appropriately and on a timely basis. As patients are admitted, discharged, transferred, and scheduled for procedures on an hourly basis, anticoagulation and deep vein thrombosis prophylaxis are held or discontinued in anticipation for possible procedures. This results in delay of care and intervals where patients may not be covered with any prophylactic measurements. Similarly, alterations in clinical status can quickly change such as an increase in creatinine levels or the development of a new bleed, thus requiring a revision in their deep vein thrombosis prophylaxis. Nurses, therefore, play an integral role in not only administering the medicine but also routinely assessing the patients' clinical status and, therefore, their deep vein thrombosis prophylactic regimens as well. This article will review the indications, scoring systems, common prophylactic methods, and special populations at increased risks for venous thromboembolisms.

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.

Prognosis and Monitoring of VTE.

Venous thromboembolism (VTE) can present in a variety of different clinical settings and in a diverse, comorbid patient population, both of which will guide the clinician toward the appropriate therapeutic response. Patients who present with pulmonary embolism are at risk for hemodynamic instability, recurrence of VTE, cardiac comorbidities, and increased risk of overall mortality. Prognostication models have been clinically validated for risk stratification and prediction of mortality. Similar to pulmonary embolism, patients with deep vein thrombosis carry a higher risk of VTE recurrence and cardiac comorbidities. Consequently, VTE can be treated by a variety of methods such as anticoagulants or inferior vena cava filters, which bear their own risks and benefits. It is imperative that clinicians monitor patients for complications from VTE and the chosen therapy.

Pathophysiology and Classification of Respiratory Failure.

Respiratory failure is a condition in which the respiratory system fails in one or both of its gas exchange functions. It is a major cause of morbidity and mortality in patients admitted to intensive care units. It is a result of either lung failure, resulting in hypoxemia, or pump failure, resulting in alveolar hypoventilation and hypercapnia. This article covers the basic lung anatomy, pathophysiology, and classification of respiratory failure.

Management of Respiratory Failure.

The management of acute respiratory failure varies according to the etiology. A clear understanding of physiology of respiration and pathophysiological mechanisms of respiratory failure is mandatory for managing these patients. The extent of abnormality in arterial blood gas values is a result of the balance between the severity of disease and the degree of compensation by cardiopulmonary system. Normal blood gases do not mean that there is an absence of disease because the homeostatic system can compensate. However, an abnormal arterial blood gas value reflects uncompensated disease that might be life threatening.

Asthma.

Asthma is one of the most frequent chronic respiratory diseases worldwide, with an increase in its prevalence in the last decade. Ongoing studies continue to search for better diagnostic tools and advanced treatment options in an effort to decrease the morbidity and mortality associated with it. Unfortunately, many asthmatic patients still suffer from poorly controlled asthma, which may lead to life-threatening situations. This article reviews the basics of asthma and highlights the current guidelines in making accurate diagnosis and initiating therapeutic plan.

Chronic Obstructive Pulmonary Disease.

Chronic obstructive pulmonary disease (COPD) is a chronic smoking-related lung disease associated with significant mortality and morbidity. It carries an enormous economic burden on the health care system. This results in a significant social impact on affected patients and their families. In this article, we review COPD in general, critical care management of patients presenting with acute exacerbation of COPD, and methods of prevention.

Acute Pneumonia.

Acute pneumonia is an active infection of the lungs that results when an individual at risk gets exposed to a particular microbiological pathogen. Acute pneumonia is the leading cause of death in the United States that is attributable to an infection. The risk factors, pathogenesis, and microbiological organisms involved differ if the pneumonia develops in the community versus health care-associated environment. The development of concise and comprehensive guidelines has led to an improvement in the management of the problem. However, the emergence of multidrug-resistant organisms and the increase in the percentage of elderly population keep mortality risk very substantial.

Acute Pneumothorax.

Pneumothorax is defined as the abnormal presence of air within the pleural space (cavity) that results in the partial or complete collapse of a lung. It can occur spontaneously or due to a traumatic event. Symptoms can vary from a nondescriptive complaint of shortness of breath or chest pain to complete cardiopulmonary collapse. Diagnosis is based on a combination of clinical suspicion along with supporting imaging studies. Treatment often involves surgical or nonsurgical approaches with goal to alleviate symptoms and prevent recurrence.

Opportunistic Pulmonary Infections in Immunocompromised Hosts.

Infections that are typically innocuous in immunocompetent persons may cause significant disease states in immunocompromised hosts. These individuals may be immunosuppressed secondary to many different causes such as drugs, malignancy, solid-organ or hematopoietic stem cell transplantation, HIV/AIDS, or anatomic reasons (asplenia). These immunocompromised hosts are at high risk for developing opportunistic infections. Here, we discuss some of these infections caused by bacteria, fungi, viruses, and parasites. Clinicians should be aware of the risk factors, common clinical presentations, diagnostic modalities, and treatment options for these potentially fatal illnesses.