[Respiratory disorders during sleep in Duchenne muscular dystrophy]

Respiratory disorders during sleep were studied in 42 patients with Duchenne muscular dystrophy (DMD) (mean age 18.4 years). Chest and abdominal movement, nasal airflow, snoring sounds, eye movement, and oxygen saturation were monitored during sleep. Three patterns of disorders were found: obstructive apnea, central apnea, and paradoxical respiration without upper airway obstruction (non-obstructive paradoxical respiration). Of these three patterns, obstructive apnea was the most common. Hypertrophy of the tongue and collapsibility of the upper airway seemed to be responsible for the obstructive apnea in these patients. The relationships between PaCO2 while breathing room air and the various indices of respiratory disorders were studied. The index of central apnea differed significantly between patients in whom PaCO2 was less than 50 Torr (early disease, n = 22) and those in whom PaCO2 was greater than or equal to 50 Torr (advanced disease, n = 20), but the indices of obstructive apnea and non-obstructive paradoxical respiration did not differ between those two groups. In conclusion, sleep disorders were common in patients with DMD, and the most common was obstructive apnea. In the patients with advanced DMD, blood gas analysis showed hypercapnia, and the index of central sleep apnea was high, probably because of respiratory muscle weakness or abnormalities in the respiratory center.