1. Bronchodilator Responses in Respiratory Impedance, Hyperinflation and Gas Trapping in COPD
- Author
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Claude S. Farah, Gregory G. King, Stella Watson, Cindy Thamrin, Stephen Milne, and Christoph Hammans
- Subjects
Pulmonary and Respiratory Medicine ,Spirometry ,Male ,medicine.medical_specialty ,medicine.drug_class ,Diagnostic Techniques, Respiratory System ,030204 cardiovascular system & hematology ,Quinolones ,Severity of Illness Index ,Inspiratory Capacity ,03 medical and health sciences ,Pulmonary Disease, Chronic Obstructive ,0302 clinical medicine ,Internal medicine ,Bronchodilator ,Forced Expiratory Volume ,Oscillometry ,Medicine ,Plethysmograph ,Humans ,Lung volumes ,Respiratory system ,Aged ,Plethysmography, Whole Body ,COPD ,medicine.diagnostic_test ,business.industry ,Airway Resistance ,Total Lung Capacity ,Middle Aged ,medicine.disease ,respiratory tract diseases ,Bronchodilator Agents ,Residual Volume ,030228 respiratory system ,Indans ,Cardiology ,Indacaterol ,Pulmonary Diffusing Capacity ,Female ,business ,medicine.drug - Abstract
Hyperinflation, gas trapping and their responses to long-acting bronchodilator are clinically important in COPD. The forced oscillation technique (FOT) measures of respiratory system resistance and reactance are sensitive markers of bronchodilator response in COPD. The relationships between changes in resistance and reactance, and changes in hyperinflation and gas trapping, following long-acting bronchodilator (LA-BD) have not been studied. 15 subjects with mild-moderate COPD underwent FOT, spirometry then body plethysmography, before and 2 hours after a single 150 microg dose of the LA-BD indacaterol. Hyperinflation was quantified as the inspiratory capacity to total lung capacity ratio (IC/TLC), and gas trapping as residual volume to TLC ratio (RV/TLC). At baseline, FOT parameters were moderately correlated with IC/TLC (|r| 0.53-0.73, p < 0.05). At 2 hours post-LA-BD, there were moderate correlations between change in FOT and change in RV/TLC (|r| 0.60-0.82, p < 0.05). Baseline FOT parameters also correlated with the subsequent post-LA-BD change in both IC/TLC (|r| 0.54-0.62, p < 0.05) and RV/TLC (|r| 0.57-0.76, p < 0.05). FOT impedance reflects hyperinflation and gas trapping in COPD, and the potential for long-acting bronchodilator responsiveness. These results provide us with further insight into the physiological mechanisms of action of long-acting bronchodilator treatment, and may be clinically useful for predicting treatment responses.
- Published
- 2018