<qa>  What is the most common healthcare-associated infection in severely injured patients?This proposal investigates the utility of exhaled breath condensate fluid EBCF collected from heat moisture exchange HME filters connected to patients endotracheal tubes for early, non-invasive detection of ventilator-associated pneumonia VAP in critically ill or injured ICU patients. The development of pneumonia during mechanical ventilation is the most common healthcare-associated infection in severely injured patients, accounting for substantial morbidity, excess ICU and hospital stay, additional cost and increased mortality. 