Predictors of Peak Expiratory Cough Flow in Individuals with Amyotrophic Lateral Sclerosis.

Dystussia is prevalent in individuals with amyotrophic lateral sclerosis (ALS), leading to a diminished physiologic capacity to effectively defend the airway. We aimed to identify predictors of peak expiratory cough flow rate in individuals with ALS. One hundred and thirty-four individuals with a confirmed diagnosis of ALS (El-Escorial criteria revised) completed the ALS Functional Rating Scale-Revised (ALSFRS-R) and underwent pulmonary function and cough spirometry testing. Pearson's correlation coefficients and hierarchical multiple regression modeling were conducted to determine predictors of voluntary cough peak expiratory flow rate (p < 0.05). The full model including age, bulbar disease, cough spirometry metrics, and respiratory parameters had a marginal R2 = 0.635, F (7, 126) = 30.241, p < 0.0005, adjusted R2 = 0.61. Maximum expiratory pressure, compression phase, and vital capacity did not contribute and were therefore removed (p < 0.05). The most parsimonious predictive model included age, bulbar disease, peak inspiratory flow rate and duration, peak expiratory rise time, and inspiratory pressure generation with a marginal R2 = 0.543. Although expiratory pressure generation has historically served as the therapeutic target to improve dystussia in ALS, the current dataset highlighted that the inability to quickly and forcefully inspire during the inspiratory phase of voluntary cough places patients at a mechanical disadvantage to generate subsequent high-velocity expiratory airflow to clear the airway. Thus, therapeutic training programs that include both inspiratory and expiratory strength targets may optimize airway clearance capacity in this challenging patient population.

Swallowing Safety and Efficiency Impairment Profiles in Individuals with Amyotrophic Lateral Sclerosis.

Dysphagia is common in individuals with amyotrophic lateral sclerosis (ALS) and associated with reductions in quality of life and health-related outcomes. Despite the high prevalence of dysphagia in ALS, functional impairment profiles of swallowing safety and efficiency have not been comprehensively examined. We therefore aimed to determine the relative prevalence of unsafe and inefficient swallowing in a large cohort of individuals with ALS. We further sought to examine the impact of global and bulbar disease progression (Amyotrophic Lateral Sclerosis Functional Rating Scale-Revised "ALSFRS-R" total and bulbar scores, respectively), disease duration, and onset type on swallowing impairment profiles. One hundred individuals with ALS completed a standardized videofluoroscopic swallowing examination Two independent and blinded raters performed validated ratings of safety (Penetration-Aspiration Scale, PAS) and efficiency (Analysis of Swallowing Physiology: Events, Kinematics, and Timing, ASPEKT % residue). Binary classifications of safety (unsafe: PAS ≥ 3), efficiency (inefficient: total residue ≥ 3% of C2-42) and global swallowing status were derived. The ALSFRS-R was completed to derive ALSFRS-R total and bulbar subscale scores. Demographic data (disease duration and onset type) for each participant was also recorded.  Descriptives, 2 × 2 contingency tables with Fishers exact test, and independent samples t-tests were performed (α = 0.05). Prevalence of unsafe and inefficient swallowing was 48% and 73%, respectively. Global swallowing profiles were, in rank order: unsafe and inefficient (39%), inefficient but safe (34%), safe and efficient (18%), and unsafe but efficient (9%). There were no differences in global disease progression or disease duration across swallowing impairment profiles. ALSFRS-R bulbar subscale scores were significantly lower in unsafe versus safe swallowers, p < 0.05. Spinal onset patients had a greater proportion of safe swallowers as compared to bulbar onset patients (p = 0.000, Fisher's exact test). Both spinal and bulbar onset patients demonstrated a higher prevalence of inefficient swallowers as compared to efficient swallowers (p = 0.04, Fisher's exact test). Dysphagia was prevalent in this group of individuals with ALS. Approximately half demonstrated safety impairments and two-thirds had impairments in swallowing efficiency. Inefficient swallowing was approximately four times more likely to be the initial functional impairment in patients with one pathophysiologic functional impairment. A longitudinal study is needed to examine the temporal evolution of dysphagia in ALS.