Relationship between Exacerbations of Chronic Obstructive Pulmonary Disease (COPD) and Swallowing Function with Airway-Protection

Abstract

Objective: Recently, it has been found that exacerbation of COPD is related to aspiration. Accordingly, to prevent COPD it is important to investigate how specific respiratory and swallowing functions are related to exacerbation of COPD. In this study, we investigated swallowing function in addition to respiratory function for outpatients with COPD, and examined the relation between these investigation functions and exacerbation history.

Method: The subjects were 34 outpatients (29 males, 5 females) with COPD. If exacerbation was diagnosed as such according to the criteria of the Japan Respiratory Society and hospitalization was indicated, there were 11 people who had a history of exacerbation and 13 people who had no history of exacerbation. We evaluated MASA. In addition, we investigated the presence of penetration/aspiration when swallowing 10 mL of liquid by videofluoroscopic examination of swallowing. In the spirometry, Forced Vital Capacity (FVC), Forced Expiratory Volume in 1 s (FEV1), % Forced Expiratory Volume in 1 s (%FEV1), Peak Expiratory Flow (PEF), etc. were considered. Next, we examined the optimum cut-off value (co) that can classify the presence or absence of exacerbation history most effectively for each item (function), and the relationship between each function and exacerbation history. In the statistical analysis, we used Fisher's exact test or χ² test, and examined significant relationships between each item and exacerbation history.

Result: %FEV1 (co: 42.0%, p＜0.05) had a significant relationship with exacerbation history. There was no significant relationship between exacerbation history and MASA, FVC, PEF.

Discussion: The MASAs were considered not to reflect the history of exacerbation in the subjects of this study where decline in swallowing function did not become obvious. On the other hand, %FEV1 was significant, although PEF was not significant. This is because PEF reflects only expiratory flow rate, but FEV1 etc. reflects expiratory flow volume as well as expiratory flow rate; that is, in terms of airway-protection against aspiration, it is important to consider expiratory flow volume as well as expiratory flow rate.