Domiciliary investigation of sleep-related hypoxaemia in Duchenne muscular dystrophy.

In Duchenne muscular dystrophy (DMD) nocturnal oxygen desaturation occurs during rapid eye movement (REM) sleep. Polysomnography, which requires hospital admission, will detect sleep-related breathing abnormalities. In order to avoid the inconvenience of hospital admission for the disabled patient, we investigated overnight oxygenation in ten boys with DMD by domiciliary oximetry. In four boys the results of oximetry were compared with those of a polysomnographic recording. The "repeatability" of domiciliary oximetry was assessed in six boys by performing oximetry on two non-consecutive nights. Older boys with DMD may develop a cardiomyopathy. In order to assess cardiac rhythm and ST segment changes we performed simultaneous Holter monitoring and oximetry in seven boys with overnight hypoxaemia. Six of the initial ten boys studied demonstrated episodic nocturnal hypoxaemia and there was a strong correlation between minimum oxygen saturation overnight and daytime arterial oxygen and carbon dioxide tensions (PaO2 r = 0.89; PaCO2 r = -0.87). Despite adequate REM time during polysomnography, greater oxygen desaturation was found during domiciliary oximetry. No difference was found in the severity of desaturation recorded in the boys who were studied on two separate occasions. Five boys demonstrated marked heart rate variation during hypoxaemic episodes and more serious arrhythmias occurred overnight in the three most hypoxaemic boys. Domiciliary oximetry is a simple, repeatable method of assessing overnight oxygenation and compares well with polysomnography. In boys with advanced DMD and severe nocturnal hypoxaemia, 24 h electrocardiographic monitoring may detect potentially life-threatening arrhythmias.