SESSION TITLE: COPD Diagnosis & Evaluation Posters
SESSION TYPE: Original Investigation Poster
PRESENTED ON: Wednesday, October 30, 2013 at 01:30 PM - 02:30 PM
PURPOSE: Difference between slow vital capacity (VC) and forced vital capacity (FVC) has been reported to be associated with airway collapse. The aim of this study was to investigate the difference and its association with airflow limitation in patients with chronic obstructive pulmonary disease (COPD).
METHODS: VC, FVC, and FEV1 were measured in all subjects according to ATS/ERS standards. VC maneuver was performed before FVC maneuver. VC was obtained by asking subjects to take in a full inspiration and then breathe out to the limit of full expiration, which is performed in a relaxed manner except near end-inspiration and end-expiration.
RESULTS: This study included 200 patients with COPD (152 males; GOLD stage II, 72; stage III, 114; and stage IV, 14.) in a stable condition. One hundred eight healthy subjects (82 males.) were used as a control group. The difference between VC and FVC (VC-FVC) was significantly larger in the COPD patients than in the controls (137.85±149.54 ml vs. 11.39±29.37 ml, respectively; p < 0.001). The FVC/VC ratio was observably lower in COPD patients than in the controls (94.05±6.18% vs. 99.62±1.01%, respectively; p < 0.001). Significant differences occurred in the VC-FVC among patients with moderate to very severe COPD (78.89±109.56 ml vs. 160.00±158.49 ml vs. 260.71±136.52 ml, respectively; p < 0.001). There was a significant negative correlation between VC-FVC and FEV1%(r = -0.388; p < 0.001). Meanwhile, a positive significant correlation occurred between FVC/VC% and FEV1% (r = 0.479; p < 0.001).
CONCLUSIONS: The VC-FVC or the FVC/VC ratio can be used as an index of severity of airflow limitation in patients with COPD. Due to the extent of the VC-FVC, this should be explored in follow up studies.
CLINICAL IMPLICATIONS: This is the first study to investigate the relationship between VC and FVC in a large group of COPD patients. The difference between VC and FVC is more easily obtained from spirometric results, which can be used to assess the severity of airway collapse in patients with COPD.
DISCLOSURE: The following authors have nothing to disclose: Wei Yuan, Haoyan Wang, Qiu-Fen Xu, Xu-Juan Zhao, Al Sperry, Shan Nie, Jian Zhang
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