Affiliations: International University of Health and Welfare, Tokyo, Japan,
Tokyo University Hospital, Tokyo, Japan,
Cook County Hospital, Chicago, IL
Correspondence to: Shinji Teramoto, MD, FCCP, 6-6-401 Sakae-cho Nerima-ku, Tokyo 176-0006, Japan; e-mail: firstname.lastname@example.org
To the Editor:
In a recent issue of CHEST (February 2002), Mokhlesi et al1speculated that the protective alterations in swallowing physiology (swallow maneuvers) may reduce the risk of aspiration in hyperinflated patients with COPD. As suggested by the authors, this is the first comprehensive study for assessment of swallowing function in stable hyperinflated patients with COPD. However the clinical implication may not yet be determined.2Shaker and coworkers3demonstrated that patients experiencing COPD exacerbations swallowed significantly more often by interrupting the inspiratory phase and resumed their respiration significantly more with inspiration. Further, Stein and coworkers4reported that cricopharengeal dysfunction was diagnosed in 17 of 25 COPD patients (68%) who experienced frequent exacerbations. The majority had dysphagia, and eight patients who underwent cricopharyngeal myotomy had significant improvement in swallowing and decrease in respiratory exacerbations. A higher prevalence of dysphagia in patients with COPD when compared with control subjects (17% vs 4%, respectively) has been also reported.5 These data indicate that the COPD patients are predisposed to oropharyngeal dysphagia. Thus, it is reasonable to speculate that the altered swallowing physiology may not be sufficient to reduce the chance of aspiration in hyperinflated patients with COPD.
We developed new methods for detection of swallowing disorders, ie, swallowing provocation test (SPT) and the simple swallowing provocation test (S-SPT).6–10 Using these tests, we found that more than 8 of 48 COPD patients (16.7%) showed an abnormal swallowing function. Our data support that the impaired swallowing function was frequently found in COPD patients. These methods, SPT and S-SPT, are very useful to differentiate the patients predisposed to aspiration in subjects with or without stroke.8 The S-SPT is more useful than the water swallowing test in differentiating patients predisposed to aspiration pneumonia, with high sensitivity and specificity. Clinically detectable aspiration is associated with increased morbidity. Silent aspiration remains a major difficulty. Considered together, COPD patients with swallowing disorders are at a risk of aspiration.
The occurrence of gastroesophageal reflux (GER) after bedtime is strongly associated with both asthma and respiratory symptoms.11 A variety of respiratory symptoms are associated with GER because the impaired swallowing reflex perturbs the inspiratory expiratory transition during deglutition in COPD patients. As a result, GER-related symptoms and aspiration may be increased in these patients. As suggested by the editorial of Mokhlesi et al,1 it is true that clinical research for oropharyngeal dysfunction in COPD patients is strongly needed. Because most of the COPD patients are elderly, age-related changes of swallowing function may also affect the oropharyngeal function in COPD patients.12–13
We appreciate the comments of Dr. Teramoto and colleagues on our article in CHEST (February 2002).1We agree that abnormal swallowing physiology and dysphagia are common in patients with COPD.2–3 In fact, we have reported that dysphagia is present in 17 to 20% of patients with moderate and severe COPD.1,4Our objective was to demonstrate that patients with stable COPD and hyperinflation are at increased risk of aspiration. Although patients with COPD demonstrated a lower resting laryngeal position, none of the 20 patients evaluated by a very comprehensive assessment of swallowing physiology had evidence of laryngeal penetration and aspiration. To our surprise, 45% of patients exhibited frequent swallowing maneuvers that seemed protective in nature. Whether these maneuvers are protective in acute exacerbation of COPD, where patients may develop worsening of hyperinflation and tachypnea, remains to be elucidated. In a small study by Shaker et al,5 10 patients were evaluated by a videofluoroscopy swallowing study both during acute exacerbation of COPD and after recovery from exacerbation. The investigators demonstrated that during exacerbation the patients swallowed significantly more in the inspiratory phase and resumed their respiration more with inspiration. However, none of the patients demonstrated any evidence of laryngeal penetration and gross aspiration.
The new methods for detection of swallowing disorders described by Teramoto and colleagues seem useful for a rapid bedside evaluation technique to assess a patient’s risk of aspiration.6–7 However, this technique cannot identify the exact location and mechanism of swallowing dysfunction; therefore, it should not replace a comprehensive videofluoroscopic swallow evaluation in research protocols.
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