- Pulmonary embolism (PE) is common, underdiagnosed, and lethal, yet readily treatable.
- Prophylaxis and accurate diagnosis are essential to improving outcome.
- The cause of death in PE is most often circulatory failure (acute cor pulmonale) due to right heart ischemia.
- There is no perfect diagnostic test for PE; accurate diagnosis requires both an informed clinical pretest probability and a stepwise application of tests including D-dimer, helical CT angiography, and lower extremity duplex.
- A careful risk assessment may identify patients ideal for outpatient therapy. Conversely, patients with hypotension, cancer, heart failure, hypoxemia, and present or prior deep vein thrombosis are at significantly higher risk for death, recurrence, or major bleeding from PE, and are best managed in an appropriately monitored setting.
- Low molecular weight heparin (LMWH) is approved and recommended as the initial therapy for PE, and should be used in most patients unless there exists a compelling reason to do otherwise. When LMWH is not used, unfractionated heparin is typically used to maintain the partial thromboplastin time at 1.5 to 2.5 times control. Numerous new anticoagulants are being tested and may soon be approved for the treatment of PE.
- Critically ill patients may especially benefit from aggressive use of vena caval interruption.
- Thrombolytic therapy is life-saving in patients with massive embolism and circulatory instability.
- Air and fat embolism usually present as acute respiratory distress syndrome, and are managed with mechanical ventilation, oxygen, and positive end-expiratory pressure.
This chapter will cover diseases involving embolism to the pulmonary circulation, including pulmonary thromboembolism, as well as the less common conditions of venous air embolism and fat embolism. Thromboembolism is predominantly an acute circulatory insult, with important but less dramatic consequences for gas exchange. In contrast, both air and fat embolism usually present as acute hypoxemic respiratory failure (AHRF). All three of these forms of embolism may cause acute right heart failure, which is more fully discussed in Chap. 26.
Pulmonary embolism (PE) is a dramatic and life-threatening complication of underlying deep venous thrombosis (DVT). Therefore, much of the management of PE is grounded in the prophylaxis, diagnosis, and treatment of DVT. Much of our knowledge about DVT and PE is derived from patients who are not critically ill. When generalizations regarding clinical manifestations, utility of diagnostic tests, and efficacy of therapeutic approaches are extrapolated to the critically ill population, it is with some risk.
Pulmonary thromboembolism is a common yet underdiagnosed illness which accounts for substantial morbidity and mortality. It was estimated nearly 25 years ago that 630,000 persons each year suffer PE in the United States alone, with nearly 200,000 deaths (Fig. 27-1).1 The incidence of PE over the past two decades may be decreasing2 but this is controversial.3,4 Recent hospital-based studies estimate an incidence of 1 case per 1000 persons per year, with 200,000 to 300,000 annual hospitalizations.5,6 Data on mortality from PE are less problematic; a recent analysis ...