Pulmonary function tests (maximum inspiratory pressure, maximum expiratory pressure, vital capacity, forced vital capacity) predict ventilator use in late-onset Pompe disease

In patients with Late-Onset Pompe Disease (LOPD), progressive respiratory muscle involvement leads to reduced pulmonary function, with respiratory failure the most common cause of mortality. Early disease manifestations include sleep-disordered breathing, which can be treated with non-invasive ventilation; however, progressive diurnal deficits can require invasive ventilation. To determine if pulmonary function tests (PFTs) predict the thresholds for ventilation and wheelchair use, a systematic literature review identified cross-sectional clinical patient data (N = 174) that was classified into ventilation and wheelchair cohorts. PFTs included maximum inspiratory pressure (MIP), maximum expiratory pressure (MEP), forced vital capacity (FVC), and vital capacity (VC), with vital capacities measured in the upright (-U) and supine (-S) positions. Receiver operating characteristic (ROC) curves were used to calculate cut-points (CP) and area under the curve (AUC). For all ventilation and mobility thresholds tested, ROC analyses demonstrated AUC values from 86-89% for MIP, 72-96% for MEP, and 74-96% for all vital capacity metrics. Thus, PFTs are useful in predicting the thresholds for nighttime ventilation, daytime ventilation, and wheelchair use, with MIP and VC-U having both high AUC values and consistency. The PFT mobility CPs were low (MIP CP = 0.9 kPa, MEP, CP = 2.6 kPa, VC-U CP = 19% predicted), suggesting an endurance component associated with wheelchair use.