Pilot Study to Evaluate the Role of EBUS in the Diagnosis of Acute PE in Critically Ill Patients

Acute pulmonary embolism (PE) in critically ill patients is common and often life threatening. The diagnosis of acute PE is often entertained in intensive care unit patients who develop unexplained hypotension or hypoxemia. Obtaining diagnostic confirmation of acute PE with a contrast-enhanced computed tomography of the chest (CT angiogram) may be difficult as patients are often too unstable for transport to the CT scanner or have renal insufficiency limiting the ability to receive intravenous contrast agents. Making or excluding the diagnosis of acute PE in these patients is critically important, as hemodynamic instability or right heart dysfunction, if due to PE, puts patients in the massive or submassive category and increased mortality risk. More aggressive therapies such as thrombolysis, extracorporeal membrane oxygenation or surgical embolectomy are often entertained. The investigators have previously described a case where endobronchial ultrasound (EBUS) was employed in the diagnostic algorithm of suspected acute PE and significantly affected treatment recommendations. The investigators believe that, in these patients, use of EBUS to assess for thrombotic occlusion of the central pulmonary vasculature can fill a critical gap in the decision tree for management of these patients. EBUS has become part of the diagnostic approach in a number of clinical situations, including the workup and staging of suspected malignancy, unexplained lymphadenopathy, and diagnosis of mediastinal and parabronchial masses. There is strong evidence that EBUS is equivalent to mediastinoscopy in the mediastinal staging of lung cancer. The number of physicians skilled and experienced in performance of EBUS has increased dramatically, and training in the procedure is frequently obtained in a pulmonary fellowship. To our knowledge, there have been no prospective studies that investigate the use of EBUS as a tool for the diagnosis of acute central pulmonary embolism in critically ill patients where obtaining diagnostic confirmation of this diagnosis with a contrast-enhanced computed tomography of the chest is not safe or feasible.