Subtle symptoms of night-time respiratory difficulty caninclude daytime somnolence or morning headache as well as lab-oratory data including polycythemia or elevated CO2. Of adultswith Pompe disease, roughly 33% require mechanical ventilatorsupport, and respiratory-related problems (e.g. pneumonia, bron-chitis) are prevalent (Hagemans et al., 2005). Hypoventilationduring sleep may occur even if the patient is still fully mobileand commonly precedes daytime respiratory failure. Respiratory-related symptoms also include restrictive alveolar disease andimpaired cough. Impaired cough results in retained secretionsand an inability to clear both the normal volume of pulmonarysecretions as well as those associated with acute infections. Manyadult patients present initially with respiratory insufficiency, andacute respiratory failure is often precipitated by pulmonary infec-tions.