We have shown previously that recurrent episodes of central hypopnea and/or apnea with accompanying hypoxemia are common in subjects with advanced Duchenne muscular dystrophy (MD) during rapid eye movement (REM) sleep. There are, however, few reports quantifying the breathing pattern during wakefulness and sleep in patients with respiratory muscle weakness; such data can be obtained noninvasively using respiratory inductance plethysmography (RIP) that should help to characterize further the disordered breathing in sleep seen in subjects with Duchenne MD. In addition, the analysis of rib cage and abdominal contributions to breathing during wakefulness and sleep may shed light on the role of diaphragm dysfunction in the mechanism of REM-related oxygen desaturation in Duchenne MD. Acpurate and stable quantification of RIP data requires the subject to maintain a single posture and the equipment to be recalibrated following body movement. During sleep, therefore, reliable quantification is possible only for stationary or paralyzed subjects. Patients with advanced Duchenne MD are capable of only minimal body movement and require assistance to change their sleeping posture; they are thus ideally suited to RIP data analysis. We present ventilatory data obtained during overnight polysomnography from six acclimatized subjects with Duchenne MD randomized to air or oxygen on two consecutive nights. buy mircette birth control
Patients and Methods
Six patients aged 16 to 22 years (mean, 19.2 years) were studied. The diagnosis of Duchenne MD was based on clinical, electrophy-siologic, and muscle biopsy criteria. None had reported abnormal daytime sleep symptoms and all were free from respiratory tract infection; any scoliosis was either minimal or controlled by segmental spinal surgery. Approval for the studies on air and oxygen had been obtained from the local hospital ethical committee. Pulmonary function measurements made included sitting and lying vital capacity (water spirometer), lung volume estimation (helium dilution technique), maximum inspiratory (M1P) and expiratory (MEP) static mouth pressures (method of Black and Hyatt), and daytime blood gas tensions.
The subjects slept for three nights in the laboratory, the first serving to acclimatize them to the equipment and during which no measurements were made. On the following two nights the subjects were randomized either to room air or nasal oxygen (2 L min). Standard overnight polysomnography methods were followed as detailed previously. The variables monitored continuously were electroencephalogram (C4/A2), electro-oculograms (E1/A2, E2/A2), submental electromyogram, electrocardiogram, oxygen saturation (Ohmeda Biox III), oronasal airflow detected by thermistor, and chest and abdominal movement with a combined “sum” signal using RIP (Respitrace).