PROJECT SUMMARY Bronchopulmonary dysplasia (BPD) is the most common morbidity of prematurity with over 10,000 infants diagnosed each year in the United States. Underdeveloped lungs at birth, the need for ventilatory support, which may result in ventilator-induced lung injury, and other factors result in significant structural and functional pulmonary abnormalities associated with short- and long-term lung disease. Effective management includes an individualized approach to choosing the right ventilation strategy and medications. Two important techniques include the use of a long i-time ventilatory strategy and administration of bronchodilators. However, each of these treatments has some associated risk, and there is currently no real-time method to assess their effectiveness on improving ventilation and perfusion. Electrical impedance tomography (EIT) is a noninvasive, non-ionizing real-time functional imaging technique with no harmful side effects, suitable for patients of any age. We hypothesize that EIT images and derived measures can provide real-time, actionable information to guide the clinician's treatment strategy in infants with BPD, and satisfy this unmet need. In this proposal we will carry out the following specific aims: (1) Build a new Adaptive Current Tomography system designed for 3D imaging of very young intubated infants including novel 3-D reconstruction algorithms to provide real-time images of regional ventilation, pulsatile perfusion and quantitative EIT-derived measures. (2) Assess the ability of EIT images and derived measures to determine the effectiveness of long i-time ventilation strategies while they are being applied. An EIT Visualization Platform will be developed to enable the clinician to visualize the images and output measures to assess treatment effectiveness. (3) Determine what combination of EIT- derived measures provides the best assessment of bronchodilator responsiveness (BDR) in infants with or at risk of BPD after the first administration of bronchodilator therapy. We will evaluate the efficacy in Aims 2 and 3 in a study with infants enrolled from the Level IV NICU at Stanford University Medical Center and the University of Colorado Hospital Neonatal Intensive Care Unit.