Project Summary/Abstract The proposed effort addresses an unmet need for early detection of pulmonary edema (PE). PE is a cardiovascular disorder and is the underlying cause of acute respiratory distress syndrome and acute heart failure, projected to affect more than 8 million Americans by 2030. PE is caused by abnormally high capillary leakage into the alveolar cavities leading to accumulation of extravascular lung water (EVLW). It can be life-threatening, but effective therapy is available to save patients from harmful consequences of this lung fluid imbalance if detected early. However, delays and missed diagnosis are common in PE due to unavailability of effective tools outside of hospitals. Tools such as echocardiography and chest radiography are best performed in patients with acute heart failure in the hospital setting. This highlights the need for a simple, inexpensive, noninvasive detection method that can be used to routinely screen those at risk for PE, including patients with vascular or blood disorders or patients having undergone hematopoietic stem cell transplantation (HSCT). In the proposed study, we intend to demonstrate a technology and methodology that will enable the use of endogenous exhaled gases as probes to assess presence and amount of excessive EVLW. There are indications that simultaneous detection of the rate at which two or more gas molecules permeate the blood-air barrier into the exhaled breath can provide a strong link to the amount of extravascular lung water. In this SBIR Phase I study, Exhalix will collaborate with the University of Cincinnati College of Engineering to perform simulated gas exchange laboratory experiments to demonstrate the merits of this technique for detection of trace amount of water. By teaming with the University of New Mexico School of Medicine, we intend to perform animal studies in which isolated lungs from male Sprague-Dawley rats will be used to evaluate feasibility in detection of EVLW under stimulated PE conditions. We anticipate that these studies will last 12 months and success in feasibility demonstration is expected to lead to a Phase II effort for development of prototypes for human studies in clinical environments.