Early loss of diaphragm thickening in ambulatory patients with late-onset Pompe disease

Topic:

Clinical Trials

Poster Number: M232

Author(s):

James May, B.S, University of Florida, Carmen Leon, MD, U of Florida, Yaneris Colon-Cortes, MD, University of Florida, Stephanie Salabarria, BHSc, University of Florida, Manuela Corti, PT, PhD, University of Florida, Barry J Byrne, MD, PhD, University of Florida, Barbara Smith, PT, PhD, University of Florida

Background: Pompe disease is an inherited glycogen storage disease characterized by early diaphragm dysfunction that leads to progressive loss of breathing function, often seen even when ambulation remains preserved. Maximal inspiratory pressure (MIP) is an established clinical estimate of inspiratory muscle force, but is not specific to the diaphragm. Our aim was to evaluate the utility of diaphragm ultrasound as a more specific, non-invasive metric of diaphragm function.
Methods: Cross-sectional study of participants with genetically confirmed late-onset Pompe disease who underwent diaphragm ultrasound during resting breathing and deepest breathing efforts, along with standard pulmonary function tests that included MIP and forced vital capacity (FVC). Mean ( SD) reported for continuous variables.
Results: Ten ambulatory patients were included. The sample encompassed a wide range of ages (35.8 ± 18.6 years), Body mass index (BMI) (24.42 ± 5.3), and FVC (84.7% ± 21.3% of predicted value). . During resting breathing, diaphragm excursion was significantly correlated only to BMI (r=.801, p<0.005). The resting thickening fraction (TF) tended to decrease with age (p=0.096); with increasing age, declines in MIP (p=0.05) and FVC (p=0.063) were also detected. During deep breathing, subjects with a preserved FVC tended to exhibit greater diaphragm excursion (p=0.067). However, no clear relationship was identified between MIP and deep-breath diaphragm excursion (p=0.844) or TF (p=0.706), suggesting a compensatory recruitment of inspiratory accessory muscles in early-stage disease. Diaphragm excursion and TF were not significantly correlated, which suggests that the activation of expiratory muscles during both resting and deepest breaths preserves lung volume, even as TF becomes restricted. Conclusions: These findings suggest that ultrasound measurements of diaphragm excursion and TF may offer unique insights into diaphragm involvement as well as compensatory measures to preserve maximal pulmonary functional capacity. Longitudinal investigation may help to understand the trajectory of diaphragm involvement in people with Pompe disease.