03-02-2009, 05:39 PM
A 40-year-old woman with muscular dystrophy is evaluated for daytime sleepiness, disturbed sleep, and morning headaches. Physical examination shows decreased air movement bilaterally. In the supine position, her abdomen moved inward with inspiration. Pulmonary function testing shows a reduction in the forced expiratory volume in one second (FEV1) and a low forced vital capacity (FVC). The ratio of FEV1/FVC is normal. In the supine position, the vital capacity fell by 30% compared to the upright position (normal