Daily variation in airway protective behaviors in ALS

Topic:

Clinical Trials

Poster Number: 97 S

Author(s):

May Smith-Hublou, PhD, University of Florida, Wagner Souza Leite, MS, University of Florida, Ushna Khan, MD, University of Florida, Sandra Kay Morgan, PhD, MSN, University of Florida, Gordon S Mitchell, PhD, University of Florida, Alicia Vose, PhD, CCC-SLP, University of Florida - JAX, Priscila Sales de Campos, PhD, State University of Santa Catarina, Michael T Pulley, MD, PhD, University of Florida- JAX, Nicholas Napoli, PhD, University of Florida, James Wymer, MD, University of Florida, Barbara Smith, PhD, PT, University of Florida

Background: People with amyotrophic lateral sclerosis (ALS) experience fatigue. Diurnal rhythms and other physiological/behavioral fluctuations can influence motor function. Although airway protective behaviors, including swallow and cough, are motor behaviors that may exhibit diurnal rhythms, little is known concerning how they vary throughout the day in people with ALS.

Objective: To compare airway protective behaviors (i.e. cough, frequency of saliva swallowing) in afternoon vs morning of the diurnal active phase.

Methods: Data are a secondary analysis of preliminary results from a randomized, controlled trial. Voluntary cough and saliva-swallow counts were measured during 1) morning (~ 8-9 AM) and 2) afternoon assessments (~ 4-5 PM, following a treatment placebo). Cough measures included peak inspiratory and expiratory flows (PIF, PEF), inspiratory and expiratory volumes (IV, EV), and cough volume acceleration (CVA). Swallow count was determined via combined nasal and oral airflow during 5 min of quiet breathing. Paired t-tests and Hedge’s g for effect size were used. Post-hoc analysis included counts of large individual changes among disease-onset types, noted when g>0.8 (cough) or differences exceeding 1 standard deviation (SD) of the baseline sample (swallow).

Results: Nine people with ALS (4 limb, 4 bulbar, 1 respiratory onset) completed the visit. From morning to afternoon, the only variable with group-level change was reduced PIF (p=.025). The limb-onset group had large decreases in 12 of 20 cough measurements (5 variables x 4) and a large increase in 1/20 measurements. The bulbar-onset group had large decreases in 6/20 and large increases in 5/20 measures. For saliva swallows, 1/4 limb and 2/4 bulbar-onset participants decreased by >1 SD, while 1/4 limb-onset participants increased.

Conclusion: Daily fluctuations in airway protective functions differ among individuals and onset types. This analysis is underpowered for definitive conclusions; however, our findings underscore the importance in considering within day individual-performance variability in research design and rehabilitation planning.