Management of Venous Thromboembolic Disease in the Chronically Critically Ill Patient

Venous thromboembolism (VTE) is a spectrum of diseases that can be classified into two categories—deep venous thrombosis (DVT) and pulmonary embolism (PE). The prevalence of VTE is estimated to be 600,000 cases per year, and the mortality rate is 50,000 to 100,000 cases occurring secondary to PE and accounting for 5% to 10% of all hospital deaths in the United States. 5 Although better diagnostic tools have improved the knowledge of the natural history and clinical manifestations of VTE, more than 50% of all cases remain undiagnosed. 5 This occurrence is most likely because of the nonspecificity of signs and symptoms of this disease and the fact that both DVT and PE commonly are unsuspected on clinical grounds and only can be diagnosed with objective testing. 101 In addition, despite many studies that demonstrate the efficacy of preventing DVT and, subsequently, PE, many physicians do not incorporate prophylactic therapy into their daily practice. 6 The specific problems of diagnosis and management of VTE in the ventilated patient in the post acute phase of a severe illness are compounded by several additional factors. Comorbid events contributing to a patient's respiratory symptoms or failure (e.g., exacerbation of chronic obstructive lung disease, pneumonia, or congestive heart failure) frequently can mask the manifestations of VTE. In addition, the nonspecificity of symptoms (e.g., chest pain or dyspnea) and signs (e.g., tachycardia) of a patient on assisted ventilation further contributes to delaying the diagnostic workup for DVT or PE. Finally, the possibility of poor communication between an ill, ventilated patient and the nursing, respiratory, and medical staff caring for this patient can be an additional source of diagnostic confusion. Aside from potential delay in initiating the diagnostic workup for these patients, testing for VTE may be less specific in this context (e.g., perfusion/ventilation scanning in a patient with significant underlying lung disease or pulmonary infiltrates) or technically difficult because of the patient's overall clinical condition. Furthermore, preventive therapy in these patients can be problematic if, for example, there is associated blood dyscrasia or a condition (e.g., gastrointestinal bleed) that prevents anticoagulation. For all of the reasons just mentioned, diagnosis and management of VTE can be challenging particularly in the chronically critically ill patient compared with the patient encountered in an ambulatory setting. This article reviews the general approach to the diagnosis, management, and prevention of VTE, with a focus on the post acute, mechanically ventilated patient. Because of the paucity or absence of specific information derived from clinical trials and related to DVT and PE in this group, recommendations reflect the authors' personal experience and bias, which are derived from working in settings dedicated to treatment of these patients. In discussing the various methods used for the diagnosis of VTE in this patient population, several factors are taken into consideration, including the patient's clinical condition and the availability, feasibility, and cost of a specific test.