Association between thoracic ultrasound findings and respiratory function in children with Duchenne muscular...

Duchenne muscular dystrophy (DMD) is characterized by progressive muscle weakness, atrophy, and respiratory failure. As the primary inspiratory muscle, the diaphragm plays a crucial role in the respiratory progression of DMD. Therefore, this study aimed to evaluate diaphragmatic function and structure in children with DMD. This study included 60 children with DMD who underwent diaphragmatic evaluation with B-mode thoracic ultrasonography (USG) and pulmonary functional testing. The same pediatric pulmonologist (P1) and pediatric radiologist (P2) performed all USG scans. The participants were divided into ambulant (n = 39) and non-ambulant (n = 21) groups. The Pediatric Sleep Questionnaire (PSQ) was used to assess the risk of sleep-related breathing disorders. The participants' mean age was 10.2 ± 2.8 years. The forced vital capacity (FVC) and forced expiratory volume in one second (FEV₁) z-scores were significantly lower in the non-ambulant group (p = 0.001 and 0.004, respectively). The USG measurements of P1 and P2 were significantly correlated (p = < 0.001). The left end-expiratory and left end-inspiratory diaphragmatic thickness (DT) were significantly higher in the non-ambulant group (p = 0.006 and 0.014, respectively). Diaphragmatic thickening fractions were nonsignificantly lower in the non-ambulant group. Maximal inspiratory pressure correlated positively with FVC (r = 0.429, p = 0.006), and maximal expiratory pressure correlated positively with the FVC z-scores (r = 0.386, p = 0.014) and FEV₁ z-scores (r = 0.432, p = 0.008). PSQ scores correlated positively with P1's right end-inspiratory DT (r = 0.268, p = 0.042) and P1's left end-expiratory DT (r = 0.262, p = 0.047).

Thoracic USG, alongside spirometry and MIP/MEP measurements, provides a simple and noninvasive means to evaluate respiratory function in children with DMD, revealing diaphragmatic changes associated with functional decline and the risk of sleep-related breathing disorders.

• DMD causes progressive respiratory muscle weakness due to diaphragmatic involvement. • Spirometry and maximal inspiratory and expiratory pressures (MIP/MEP) are commonly used to monitor respiratory function but may be difficult to perform in some children. • Noninvasive assessment of diaphragmatic function in children with DMD is still limited.

• Thoracic USG provides a simple, reproducible, and noninvasive method to evaluate diaphragmatic morphology and motion in children with DMD. • The study demonstrated that non-ambulant children have increased DT but reduced functional indices, reflecting structural adaptation to disease progression. • Significant correlations between USG measurements, spirometric parameters, and PSQ scores highlight the potential of USG as a valuable adjunct tool in respiratory monitoring and early detection of sleep-related breathing disorders in children with DMD.