Relationship of Nocturnal Desaturations and Daytime Pulmonary Functions in Duchenne Muscular Dystrophy

Duchenne muscular dystrophy is a progressive, hereditary neuromuscular disease with the cause of death usually occurring because of respiratory failure. The development of respiratory failure during wakefulness usually preceded by hypoventilation during sleep. The aim of this study were to assess the presence and severity of nocturnal desaturations and to determine the parameter of daytime lung function associated with nocturnal desaturations in patients with DMD. Material and method: The monitoring of overnight oxygen saturation is widely used for sleep apnoea-hypopnea screening. As our method we choosed aprospective comparison of wakeful respiratory function tests (spirometry, maximum voluntary ventilation, maximal mouth pressures, arterial blood gases) with outcomes of overnight oxymetry. Fourteen clinically stable patients with DMD, mean age (±SD) 13,83 ± 1,86 were studied. Results: The lowest oxygen saturation < 85% was present in 9 (64%) patients and oxygen desaturation index > 5 was found in 10 subjects (71%). Desaturation index was significantly related to maximum inspiratory pressure (r= -0,633, p<0,05), FVC (r= -0,730, p<0,01) and FEV1 (r= 0,664, p<0,05). However logistic regression analysis showed that overnight desaturations could not be reliably predicted from the daytime pulmonary function test results. Conclusion: Sleep-related desaturations are freguently present in clinically stable patients with DMD. Overnight desaturations can not be predicted from daytime respiratory function tests. Even in the absence of sleep-related symptomatology (headache, somnolence, etc.), sleep related respiratory disturbances should be suspected and searchhed in DMD patients.