Spirometric determination of chronic obstructive pulmonary disease

摘要

The forced expiratory volume in 1 s (FEV_1): forced vital capacity (FVC) ratio is probably the most important spirometric parameter measured as it defines whether or not airway obstruction is present. An FEV_1/FVC ratio below the lower limit of normal (LLN) is diagnostic of airway obstruction. However, there is controversy surrounding the use of a fixed ratio of 70% for discriminating between obstructed and non-obstructed patients, and significant differences in the diagnosis of obstruction can occur depending on whether an FEV_1/FVC ratio of 70% or the LLN is used. Using an appropriate LLN for the FEV_1/FVC ratio is extremely important in order to avoid false-positives in older healthy adults and false-negatives in younger adults who may have early chronic obstructive pulmonary disease.