Interrelationships between pulmonary function, demographic characteristics, and use of external ventilation in Later-Onset Pompe Disease

Topic:

Clinical Trials

Poster Number: M233

Author(s):

Julia Prascak, BS, University of Florida, Carmen Leon, MD, U of Florida, Stephanie Salabarria, BHSc, University of Florida, Yaneris Colon-Cortes, MD, University of Florida, Manuela Corti, PT, PhD, University of Florida, Barry J Byrne, MD, PhD, University of Florida, Virgilia Anton-Anton, PT, PhD, University of Toledo, Barbara Smith, PT, PhD, University of Florida

Pompe disease is an autosomal recessive condition characterized by the accumulation of lysosomal glycogen leading to progressive denervation and muscle dysfunction. The phrenic motor system is affected early in Pompe disease. As a result, patients frequently exhibit decreased respiratory function and require external ventilatory support, even while limb function remains comparatively preserved. The purpose of this study was to identify relationships between maximal inspiratory pressure (MIP), a noninvasive clinical estimate of inspiratory strength, and other common pulmonary functional tests (PFTs) used to track breathing function in Pompe disease. Individuals diagnosed with late-onset Pompe disease (n= 34, age: 52 +/- 11 years, MIP: 61 +/- 29 cm H2O) consented to undergo forced vital capacity (FVC), max inspiratory/expiratory pressure (MIP/MEP), and peak cough flow (PCF) testing in a single visit. Relationships between the PFTs and several demographic variables (e.g., age, age at diagnosis, height, weight, and use of ventilation) were assessed using Pearson’s correlation. Additionally, the effect of any external ventilation (BiPAP, CPAP, NIV, n=15) on function was assessed with independent t-tests. Strong positive correlations (p<0.005) were detected between nearly all PFTs; only the correlation between PCF and MIP was more moderate (r=0.426, p<0.05). Functional ambulation was present in 89% of independently breathing patients and 67% of ventilator-users. Those using any external ventilation were diagnosed at a younger age (p<0.05), had a lower FVC (p<0.005), and tended to have a lower PCF (p=0.051). However, BMI, MIP, or MEP did not differ based on ventilator use. A closer examination of the respiratory pressure data revealed a bimodal data distribution, suggesting external ventilation was prescribed for co-existent obstructive apneas in some patients, and for correction of hypoventilation in others. Physiological tests of diaphragm structure (ultrasound) or function (phrenic stimulation) could offer further insights.