 Lung and heart-lung recipients at the University of Texas Medical Branch who have participated in the Assessment of Cough Reflex in Lung Transplant Recipients study who meet the specific study inclusionexclusion criteria will have one study visit where they will undergo lung volume measurements, followed by high resolution CT scan of the lungs within 2 hours. After the initial CT scan, patients will be given a standard dose of Atrovent, followed thirty minutes later by repeat lung volume measurements and CT scan. 