Congenital muscular dystrophy (CMD) secondary to collagen VI deficiency is a distinct genetic neuromuscular disorder presenting from birth with progressive loss of motor function, skeletal deformities and debilitating contractures. Respiratory failure is the principal cause of morbidity and mortality from the disease. As CMD has no existing treatment, the majority of affected children develop respiratory failure and require non-invasive ventilation between the first and second decades of life. There is evidence that in muscular dystrophy the progressive decrease in lung volume is disproportionally greater than anticipated for the degree of respiratory muscle weakness. Chest wall stiffness and decreased lung elasticity which collectively diminish compliance of the respiratory system are believed to be important contributors to the disproportionate decrease in lung volume.
Our research aims at testing the hypothesis that in subjects with CMD, daily passive stretch of the chest wall through lung hyperinsufflation therapy could slow down the annual rate of decline in lung volume, delay the onset of respiratory failure and improve quality of life. We will demonstrate that 1) By measuring in each subject the respiratory pressure volume relationship, maximum lung inflation by hyperinsufflation could be attained and the corresponding pressure estimated, 2) Subjects with CMD will be able to adhere to a twice-a-day 15 minute hyperinsufflation regimen over a period of 5 months and 3) Demonstrate that by studying for a period of one year 17 subjects enrolled in the intervention group and 17 in the observational group, the difference in the rate of decline of vital capacity between the 2 groups will yield an effect size of >0.5. The results of this application will pave the way for the development of a future randomized control trial of daily passive stretch of the chest wall through lung hyperinsuflation in patients with neuromuscular disorders.
The development of respiratory failure in children with neuromuscular disorders is due in part to progressive stiffness of the chest wall and the lungs. In this application and in future research, we intend to test the feasibility and efficacy of passie stretch of the chest wall by lung hyperinsuflation on the onset of respiratory failure and the quality of life of patients and their care givers. (End of Abstract)