[Responder and non-responder in the bronchodilator test?]

Area of Science:

• Pulmonology
• Respiratory Medicine
• Pharmacology

Background:

• Chronic airflow obstruction, encompassing conditions like asthma and COPD, requires accurate diagnostic differentiation.
• Assessing airway reversibility is a common method, but its reliability in distinguishing between asthma and COPD is debated.

Purpose of the Study:

• To evaluate the efficacy of acute bronchodilator reversibility testing in patients with chronic airflow obstruction.
• To compare the immediate effects of salbutamol with the maximum 24-hour effects of various beta-2 agonists.
• To determine if acute reversibility tests can reliably differentiate between asthma and COPD.

Main Methods:

• 15 patients with chronic airflow obstruction received 0.2 mg salbutamol for a 15-minute "test effect" assessment.
• Maximum 24-hour effects of fenoterol, salbutamol, and salmeterol were determined in random order as "best effects".
• Airway obstruction was measured using FEV1, MEF50, MEF25, airway resistance (Raw), and thoracic gas volume (TGV).

Main Results:

• "Test effects" were significantly smaller than "best effects", often failing to reach the standard 15% change.
• Significant correlations were observed between FEV1 and Raw, MEF50, and MEF25, but with considerable individual variability.
• Reduced TGV after beta-2 agonist administration correlated significantly with baseline TGV values.

Conclusions:

• Acute reversibility tests may not reliably differentiate between responders and non-responders in chronic airflow obstruction.
• These tests can be misleading when used to differentiate between asthma and COPD.
• Further research may be needed to establish more accurate diagnostic markers for these conditions.