What is the cause of frequent respiratory infections in children with duchenne muscular dystrophy ?

Impaired muscles: When dmd affects the muscles of breathing, patients have difficulty clearing secretions which can lead to increased infections. Chest pt can be useful to break the secretions up and allow them to be cleared. If there is an issue with scoliosis, this should be addressed early to prevent further repiratory compromise later in the disease course.

Reduced muscle stren: the most likely cause is the weakness of the intercoastal muscles, that reduces the expansion of the chest. Also, scoliosis will reduce the available chest expansion on one side.