PURPOSE: COPD has been suggested as a potential risk factor for tracheomalacia (TM). We tested the hypothesis that clinical and/or physiological parameters would correlate with excessive expiratory tracheal collapsibility in COPD.
METHODS: We prospectively studied of 100 adult patients meeting ATS/ERS criteria for COPD. Exclusion criteria included other risk factors for tracheal disease, pregnancy, recent acute respiratory illness or unstable cardiovascular disease. Patients underwent full pulmonary function tests and completed the Saint George’s respiratory questionnaire. Low-dose MDCT was performed at end-inhalation and during dynamic exhalation with spirometric monitoring. Patients willing to consent underwent flexible bronchoscopy. We examined correlations between percentage dynamic expiratory tracheal collapse measured 1 cm above the aortic arch (%coll) and PFTs, symptom severity and BMI.
RESULTS: Patients included 48 women and 52 men with mean age 65 +/-7 years; BMI 30.2 +/- 6.4; FEV1 64 +/-22 % of predicted and %coll 59 +/-18%. There was no significant correlation between %coll and PFT measures or symptom score. The %coll varied significantly by BMI with mean of 69 +/- 12% among patients with BMI >35 (n=20) compared to 57 +/-19% in others (P=.002). Obese subjects were significantly more symptomatic (mean SGRQ 48.1 obese and 35.6 non-obese, p=0.013) and had shorter 6 MWT distances (340m compared to 430m in non-obese, p=0.003); however, there were no significant differences in FEV1, lung volumes or diffusing capacity.
CONCLUSIONS: There are significant differences in the degree of expiratory tracheal collapse and symptom severity between obese and normal weight COPD subjects. Further studies are necessary to determine whether obesity is an independent predictor of tracheomalacia or if a synergistic relationship exists with COPD.
CLINICAL IMPLICATIONS: Should our results be confirmed in larger studies, CT and bronchoscopic screening for tracheomalacia may be indicated for symptomatic, obese COPD patients.
DISCLOSURE: The following authors have nothing to disclose: Gaetane Michaud, Carl O'Donnell, David Roberts, Stephen Loring, Mary Millett Pollack, Hilary Womble, Phillip Boiselle
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