Respiratory function will be assessed by a qualified and certified evaluator in each hospital. This is typically a respiratory therapist or physiotherapist. The participating boys will be instructed on the use of the hospital-based spirometer and a handheld nmd-1 device.
Boys will be asked to use the nmd-1 device, an easy to use device that monitors respiratory function at home, once a week. The home device is used to have more data points, and a more sensitive measure, of respiratory function decline.
At each study visit, the evaluator will download the data from the home device. The boy also will be asked to repeat the respiratory function test with the home device during each study visit.
Respiratory function measurements will include: