Relationship between changes in lung volume and flow volume (FV) curve in amyotrophic lateral sclerosis

Abstract

Amyotrophic lateral sclerosis (ALS) is a very progressive disease that leads to respiratory failure followed by death a few years after onset in ~50% of patients. Spirometry is generally essential for respiration control; however, it is virtually impossible to perform in ALS patients because of weakness in their respiratory muscles. Consequently, there is no definitive consensus in introducing forced expiration in spirometry in ALS patients. We analyzed the relationship between changes in lung volume and flow volume (FV) curve in ALS patients (n = 11) to obtain findings that can indicate the possibility of introducing forced expiration. In the course of disease progression, the FV curve (discontinuation of expiration end segment) indicating the disturbance in abdominal breathing appeared first, followed by that (abnormal shape in descending limb) indicating the disturbance in both abdominal and chest breathing, and finally that (low peak) indicating the disturbance in chest breathing, in this particular order. The %FVCs were 100%, 80%, and 50% for the appearance of disturbance in abdominal breathing, that in both abdominal and chest breathing, and that in chest breathing, respectively. These findings should be utilized as a basis for introducing forced expiration in spirometry in ALS patients.