BACKGROUND: Duchenne muscular dystrophy (DMD) is a rapidly progressive and highly lethal hereditary muscle disease. Cardiopulmonary failure is the leading cause of death. Early standardized cardiopulmonary management can slow disease progression and prolong life. This study collected pulmonary function-related parameters of DMD patients aged 6-18 years to investigate respiratory impairment characteristics.
OBJECTIVES: A retrospective, cross-sectional study was conducted at West China Second Hospital of Sichuan University between July 2023 and January 2024. 144 DMD patients aged 6-18 years were included. Clinical phenotypes, pulmonary function parameters, anthropometrics, and end-expiratory carbon dioxide (EtCO2) were collected, and differences in respiratory function and related factors among different age groups were analyzed using t-test, analysis of variance, and Pearson correlation analysis.
RESULTS: 1) Out of the 144 patients, 30% exhibited abnormal pulmonary ventilation function, with restrictive ventilation dysfunction (48.94%) and/or small airway dysfunction (40.48%) being the most prevalent. 2) The FVC% and FVE1% showed an increasing trend and reached a plateau before the age of 10 years, followed by a decreasing trend after the age of 10 years. In contrast, PEF% (p < 0.001) and FEF25% (p = 0.001) have already shown a decreasing trend after the age of 7 years. 3) Maximal expiratory pressure (MEP) and maximal inspiratory pressure (MIP) both increase with age, but the rate of increase slows down significantly from 6 years onwards. The inspiratory function is more affected than the expiratory function (MIP% IQ2=37.8%, IQ1-IQ3=30.8%-47.2%, MEP% IQ2=40%, IQ1- IQ3=40%-51.6%). 4) EtCO2 showed a significant positive correlation with age (r=0.221, p=0.009).
CONCLUSION: Different changing patterns in various stages of the disease were identified for various pulmonary function parameters in 6 to 18-year-old patients with DMD, which provides references for the respiratory management of pediatric DMD patients. PEF% and FEF25% were found to be more sensitive than FVC% and FEV1% in responding to early respiratory impairment in DMD and can be used as novel monitoring markers for early respiratory impairment.