Measurement of vital capacity in amyotrophic lateral sclerosis – Forced and slowly performed

Introduction: Amyotrophic lateral sclerosis (ALS) is an incurable and highly disabling progressive neurodegenerative disease, with degenerating respiratory muscles restricting pulmonary function.Vital capacity is the single most critical pulmonary measurement. Forced spirometry is widely used to measure pulmonary function. However, slowly performed measurements may give a better image of lung volumes in neurological disorders, as the mechanisms to perform forceful muscular activity are disturbed. Aims and objectives: Cross-sectional population-based study of twenty ALS patients and twenty healthy age and gender matched controls was conducted to analyze the relationship between forced vital capacity (FVC) and slow vital capacity (SVC). Methods: FVC and SVC were measured seated. Independent and dependent sample t-tests were used for group comparisons as appropriate. Reported p-values are two tailed, values < 0.05 considered significant. Results: Conclusions: SVC was significantly higher than FVC in ALS. In healthy controls FVC was significantly higher than SVC. In patients with ALS, slowly performed vital capacity measurements may describe lung volumes more accurately.