Spirometry

The presence of airflow limitation in COPD is assessed using spirometry.^1,2,3,4 Spirometry is recommended at the time of diagnosis and for the assessment of the severity of disease. 

Spirometry alone does not differentiate between airflow obstruction due to asthma or COPD but when used in conjunction with reversibility testing it gives an accepted diagnosis of COPD. In COPD, Forced Expiratory Volume in one second (FEV₁) is also used as a measure for assessing severity and prognosis, and monitoring disease progression.

Poorly reversible airflow limitation is indicated by the absolute reduction of postbronchodilator FEV₁ and Forced Vital Capacity (FVC) ratios. An FEV₁/FVC ratio < 0.70 indicates airflow obstruction that is not fully reversible.

GOLD guidelines classify COPD into four stages depending on the FEV₁ reading obtained using spirometry. The stages are defined in Table 1 along with appropriate treatment options.⁴

Table 1: Classification of COPD and appropriate treatment options.⁴
Adapted from the Global Strategy for the Diagnosis, Management, and Prevention of Chronic Obstructive Pulmonary Disease, Global Initiative for Chronic Obstructive Lung Disease (GOLD). Available from: http://www.goldcopd.org.

References

1. American Thoracic Society, European Respiratory Society. Standards for the diagnosis and management of patients with COPD. 2004. http://www.thoracic.org/clinical/copd-guidelines/index.php.
2. American Thoracic Society. Standards for the diagnosis and care of patients with chronic obstructive pulmonary disease. Am J Respir Crit Care Med 1995;152:S77-S121.
3. Siafakas NM, Vermeire P, Pride NB, et al. Optimal assessment and management of chronic obstructive pulmonary disease (COPD). The European Respiratory Society Task Force. Eur Respir J 1995;8:1398-1420.
4. Global Initiative for chronic obstructive lung disease: Global strategy for the diagnosis, management, and prevention of COPD. 2010. www.goldcopd.org.