An 11-year-old boy complains of wheezing and difficulty getting enough air. Notices it more when he is playing baseball and symptoms improve when exercise activity stops. He says that the symptoms are getting worse and the symptoms are even occurring at rest. The mother says the child is allergic to cat dander and his next-door neighbor in their apartment building recently began sheltering cats for the local humane society. Auscultation demonstrates wheezes on forced expiration throughout all lung fields