Effort-independent respiratory monitoring in Duchenne muscular dystrophy: clinical value of impulse oscillometry.

Duchenne muscular dystrophy (DMD) is a progressive neuromuscular disorder characterized by muscle weakness and respiratory decline due to impaired dystrophin production. Traditional spirometry, while valuable and reproducible, may pose difficulties for patients with significant muscle weakness. IOS can thus serve as a complementary, effort-independent approach, measuring respiratory system impedance, including resistance (R) and reactance (X) at various frequencies. This study aimed to evaluate IOS parameters in DMD patients, compare them with spirometry metrics, and explore their associations with clinical status, including ventilatory support use, ambulatory function, and scoliosis severity. This is a retrospective study. Clinical data, including ambulatory status (Vignos scale), bilevel positive airway pressure (BiPAP) use, the degree of Cobb angle, and spirometry and IOS measurements, were extracted from electronic medical records. Quantitative analyses included Student's t-tests, Mann-Whitney U test, and Spearman's rank correlation coefficients. A total of 42 DMD patients (mean age 14.3 ± 5.2 years) were included. Spirometry showed decreased forced vital capacity (FVC) in 52% and reduced FEV1/FVC in 12%. IOS revealed elevated mean R5 (120.9 ± 47.8%) and R20 (121.1 ± 33.1%) values, with significant correlations between IOS parameters (Z5Hz, R5Hz, R20Hz) and spirometry indices (FVC, FEV1, PEF, FEF25-75) (all p < 0.05). R5-R20 was positively correlated with FVC and PEF but negatively correlated with FEV1/FVC. Non-ambulatory patients and those requiring BiPAP support showed a higher R20% predicted values; however, these differences did not reach statistical significance (p = 0.068 and p = 0.123, respectively).

conclusionIOS is a feasible and valuable tool for respiratory assessment in pediatric DMD patients. The moderate correlations observed between IOS and spirometric indices suggest that IOS can provide supplementary information, enhancing the comprehensive evaluation of respiratory function in this population. WHAT IS KNOWN: ∙ Spirometry is commonly used to assess respiratory function in DMD but requires patient effort, which can be challenging. ∙ Impulse oscillometry (IOS) offers an effort-independent method to evaluate respiratory mechanics. WHAT IS NEW: ∙ Moderate correlations between IOS and spirometric indices can provide clinically relevant supplementary information for respiratory assessment in pediatric DMD. ∙ Combining IOS with spirometry provides a more comprehensive assessment of respiratory function in DMD.