A standardized method for the evaluation of respiratory muscle endurance in patients with Duchenne muscular dystrophy

The aim of the study was to develop a standardized method using controlled breathing to quantify respiratory muscle endurance in children with Duchenn e muscular dystrophy (DMD) and to test its reproducibility, In 10 DMD patie nts, all between 10 and 14 years (mean age, 11.5 +/- 1.5 years), except for two patients of 20 and 22 years, and 10 healthy children (mean age, 12 +/- 1 years), we measured the maximal time (T-lim) that a threshold load fixed at 35% of the individual maximal inspiratory pressure (Pi(max)) could be t olerated. We asked the children to maintain their rest breathing pattern un til exhaustion using visual feedback and an auditory signal. The mean T-lim in the DMD children was 4.45 +/- 1.45 min and values were reproducible. Al l healthy children were able to obtain T-lim values greater than 30 min. Th e respiratory muscles of DMD children are more susceptible to fatigue than those of healthy subjects. This method should be satisfactory for estimatin g the effect of treatment and for the specific training of respiratory musc les in DMD patients without significant learning disability. (C) 2001 Elsev ier Science Ireland Ltd. All rights reserved.