PE is the second leading cause of sudden, unexpected death in the United States. In 90% of the cases, it is caused by deep vein thrombosis: a blood clot forms in a vein, travels through the bloodstream, and lodges in the lungs. PE symptoms vary, and can include cough, shortness of breath, chest pain, rapid breathing, or increased heart rate. Some medical procedures and diseases activate inflammation and blood coagulation, thereby making individuals more vulnerable to PE. Surgery, kidney dialysis, cancer, connective tissue diseases, infectious diseases, and being over 70 years old put individuals at increased risk for developing PEs. A common screening test for PE is the D-dimer blood test, which measures the level of a specific protein that is released following a PE. This test, however, has proven to be an unreliable diagnostic tool for individuals who are at high risk for PE. A more reliable diagnostic tool is needed. The Carboximeter is a new device that measures the ratio of CO2/O2 pressure in an individual's expired breath. By monitoring these components, researchers may be able to accurately diagnose PEs in high risk individuals. The purpose of this study is to evaluate the effectiveness of the Carboximeter at diagnosing PE in individuals at risk for developing PEs.~This study will be conducted in two phases. In Phase I, CO2/O2 ratio and D-dimer levels will be measured prior to and following orthopedic or cancer-related surgery in 100 individuals at risk for developing PEs. In Phase II, the same measurements will be carried out on 350 high risk individuals who are experiencing PE symptoms. These individuals will also undergo computed tomography (CT) angiography and venography, in which blood flow will be visualized using x-rays. A follow-up evaluation will occur 30 days later. If any participant from Phase I or II experiences a PE or a medical condition that affects their lungs, such as asthma or chronic obstructive pulmonary disease (COPD), researchers may schedule a follow-up evaluation to obtain repeat measurements.
A pulmonary embolism (PE) is a blockage in one of the arteries of the lungs, and is usually caused by a traveling blood clot. The D-dimer blood test is currently used to diagnose PEs, but it is not always accurate for individuals who have recently undergone surgery or who have inflammatory-provoking diseases. The purpose of this study is to evaluate the effectiveness of the Carboximeter, a new PE diagnostic device that measures carbon dioxide (CO2) and oxygen (O2) output, in individuals at risk for developing PEs.