Alternative methods for assessing bronchodilator reversibility in chronic obstructive pulmonary disease

Area of Science:

• Pulmonary Medicine
• Respiratory Physiology

Background:

• Bronchodilator reversibility testing is standard for COPD but lacks predictive value for symptom improvement.
• Alternative lung mechanics assessments like end-expiratory lung volume and negative expiratory pressure (NEP) correlate with breathlessness but haven't been evaluated in bronchodilator testing.
• Tidal airflow limitation is a key feature in COPD patients.

Purpose of the Study:

• To evaluate the utility of inspiratory capacity (IC) and negative expiratory pressure (NEP) as endpoints in bronchodilator reversibility testing for COPD.
• To compare the responsiveness of IC and NEP to standard spirometry (FEV1) after bronchodilator administration in COPD patients.

Main Methods:

• Twenty clinically stable COPD patients with tidal flow limitation underwent spirometry, IC, and NEP measurements.
• Measurements were taken before and after saline inhalation, and after nebulized salbutamol, ipratropium bromide, or their combination.
• A randomized crossover design was used to compare treatment orders.

Main Results:

• Salbutamol and ipratropium significantly improved FEV1 and lung volumes, with further increases after combination therapy.
• Tidal volume and mean expiratory flow increased with bronchodilators, but significant breathlessness reduction only occurred with combination treatment.
• NEP scores did not correlate with subsequent lung volume changes, and IC changes were larger than FEV1 changes.

Conclusions:

• Negative expiratory pressure (NEP) is unsuitable for assessing acute bronchodilator responsiveness in COPD.
• Changes in inspiratory capacity (IC) may be more sensitive indicators of bronchodilator response than FEV1.
• The study found no clear distinction between reversible and irreversible COPD groups based on the tested outcome measures.