The presence of airflow limitation has been identified as one of the main causes of dyspnea in patients with chronic obstructive pulmonary disease (1). Expiratory Flow Limitation (EFL) occurs when the airways become compressed which usually results when a pressure outside the airway exceeds the pressure inside the airway. As an airflow obstruction worsens, EFL appears at much lower flows for a given lung volume and it becomes present at rest or at least develops early during exercise (2).