Comparison of spirometry with cardiopulmonary exercise test of chronic obstructive pulmonary disease

Na, Woon Tae; Park, Joo Ho; Lee, Go Eun; Kwon, Sun Jung; Son, Ji Woong; Na, Moon Jun; Choi, Eu Gene

Abstract

BACKGROUND/AIMS
Chronic obstructive pulmonary disease (COPD) is characterized by an incompletely reversible airflow limitation. Pulmonary function test (PFT) has been considered the gold standard test for diagnosis and severity evaluation in COPD. However, PFT by spirometry does not provide information about exercise performance in COPD patients. Therefore, the present study was performed to compare pulmonary function determined by spirometry with exercise function determined by cardiopulmonary exercise test (CPET) for grading of COPD.
METHODS
A total of 105 patients with airway obstruction were examined. The patients' mean age was 65 years, and the mean smoking history was 27 pack-years. The patients underwent spirometry and CPET. The results were analyzed by categorical statistical comparison, based on the Global Initiative for Chronic Obstructive Lung Disease (GOLD) and American Thoracic Society guidelines.
RESULTS
The two methods agreed on the classification of only 44 patients (42%). Of the remaining patients, 21 (20%) were found to be less severe according to CPET than according to PFT, whereas 40 (38%) were more severe. Those who were more severe according to CPET had significantly low maximal minute ventilation, low anaerobic threshold, low oxygen pulse, and high breathing reserve.
CONCLUSIONS
The present study revealed the large disagreement between the results of resting and exercise pulmonary function tests, and therefore suggests the need for a novel approach or guideline. Additional cardiological evaluation may be needed in patients classified as more severe according to CPET, who are assumed to have a greater degree of impairment of cardiovascular function.