The purpose of this study is to examine the appropriate setting pressure of MI-E for Duchenne muscular dystrophy which is a model disease of neuromuscular disease and to ascertain the influence on cough function. Furthermore, we investigated the effect of NPPV and manual and mechanical assisted coughing on rate of oral intake and respiratory complications.Chapter 1 : Duchenne muscular dystrophy In Duchenne muscular dystrophy, Epidemiology, pathology of respiratory insufficiency, changes in respiratory management in recent noninvasive ventilation and life prolonging effect were described based as a review based on previous research and our study.Chapter2 : Decreased cough function, use and effect of manual and mechanical assisted coughing in Duchenne muscular dystrophy. Position of MI-E in various airway clearance techniques will be explained based on the airway clearance guidelines in Europe and the United States. In addition, we summarized the outline, adaptation, effect and risk of cough function evaluation and manual and mechanical assisted coughing in Duchenne muscular dystrophy based on previous studies. Chapter3 : Validation of optimum setting condition pressure in MI-E use by cough peak flow We examined the appropriate pressure setting condition of MI-E for Duchenne muscular dystrophy by cough peak flow and maximum insufflation capacity. As a result, the pressure of MI-E showed a tendency higher than 270 L/min, which is said to be effective for excretion of secretions even at ±40cmH2O, which was recommended as in the past. However, in order to more effectively perform airway clearance and to obtain a value close to 360 L/min which is a normal value of CPF, it is necessary to consider the use of MI-E at ±50cmH2O to 60cmH2O pressure. Chapter4 : Rate of oral intake and effects of mechanical insufflation-exsufflation on pulmonary complications in patients with Duchenne muscular dystrophy[Purpose] In Duchenne muscular dystrophy, it increases risks of difficulties of expectoration of secretion, asphyxia, aspiration pneumonia because of decreased cough function.The aim of this study is to prove that manually assisted coughing or mechanical insufflation-exsufflation prevents pulmonary complication and contribute to continue oral intake safely and continue rate of oral intake in Duchenne muscular dystrophy.[Subjects and Methods] We investigated the status of using ventilator, manually assisted coughing or mechanical insufflation-exsufflation , and oral intake or not. In addition, we inspected the frequency of fever (over 37℃) needed antibiotics from medical records for index of respiratory tract infection, and compared with every period of using mechanical insufflation-exsufflation from respiratory evaluation on cough peak flow .[Results] 58 patients participated in this study. There were 45 Full-time noninvasive positive pressure ventilation patients. 43 in 45 Full-time noninvasive positive pressure ventilation patients (95.6%) avoided tracheostomy and continued noninvasive positive pressure ventilation because they continued oral intake without tracheal intubation due to the respiratory acute exacerbation by asphyxia or aspiration pneumonia.[Conclusion]Duchenne muscular dystrophy patients can continue oral intake safely while preventing pulmonary complication by using manually assisted coughing or mechanical insufflation-exsufflation.