Assessment of Ventilation-perfusion Abnormalities in Patients With Stable Smoking-related Airways Disease

Subjects undergo history, examination, lung function assessment after informed consent has been obtained. All subjects will undergo ventilation-perfusion scans. If there first scan is normal they will undergo a second and final scan four weeks later. If abnormal they will undergo two further scans with either nebulized bronchodilator or nebulized saline prior to their second and third scans. Each time they will have repeat lung function tests prior to scanning. We will examine the regional changes in ventilation and perfusion and there relationship to lung function.

As in Brief description