Small airway dysfunction and flow and volume bronchodilator responsiveness in patients with chronic obstructive pulmonary disease
Received 9 February 2015
Accepted for publication 1 April 2015
Published 19 June 2015 Volume 2015:10(1) Pages 1191—1197
Checked for plagiarism Yes
Review by Single-blind
Peer reviewer comments 3
Editor who approved publication: Dr Richard Russell
Roberta Pisi,1 Marina Aiello,1 Andrea Zanini,2 Panagiota Tzani,1 Davide Paleari,3 Emilio Marangio,1 Antonio Spanevello,2,4 Gabriele Nicolini,5 Alfredo Chetta1
1Department of Clinical and Experimental Medicine, University of Parma, Parma, 2Division of Pneumology, IRCCS Rehabilitation Institute of Tradate, Salvatore Maugeri Foundation, Tradate, 3Medical Department, Chiesi Farmaceutici SpA, Parma, 4Department of Clinical and Experimental Medicine, University of Insubria, Varese, 5Corporate Clinical Development, Chiesi Farmaceutici SpA, Parma, Italy
Background: We investigated whether a relationship between small airways dysfunction and bronchodilator responsiveness exists in patients with chronic obstructive pulmonary disease (COPD).
Methods: We studied 100 (20 female; mean age: 68±10 years) patients with COPD (forced expiratory volume in 1 second [FEV1]: 55% pred ±21%; FEV1/forced vital capacity [FVC]: 53%±10%) by impulse oscillometry system. Resistance at 5 Hz and 20 Hz (R5 and R20, in kPa·s·L-1) and the fall in resistance from 5 Hz to 20 Hz (R5 – R20) were used as indices of total, proximal, and peripheral airway resistance; reactance at 5 Hz (X5, in kPa·s·L-1) was also measured. Significant response to bronchodilator (salbutamol 400 µg) was expressed as absolute (≥0.2 L) and percentage (≥12%) change relative to the prebronchodilator value of FEV1 (flow responders, FRs) and FVC (volume responders, VRs).
Results: Eighty out of 100 participants had R5 – R20 >0.03 kPa·s·L-1 (> upper normal limit) and, compared to patients with R5 – R20 ≤0.030 kPa·s·L-1, showed a poorer health status, lower values of FEV1, FVC, FEV1/FVC, and X5, along with higher values of residual volume/total lung capacity and R5 (P<0.05 for all comparisons). Compared to the 69 nonresponders and the 8 FRs, the 16 VRs had significantly higher R5 and R5 – R20 values (P<0.05), lower X5 values (P<0.05), and greater airflow obstruction and lung hyperinflation.
Conclusion: This study shows that peripheral airway resistance is increased in the vast majority of patients with COPD, who showed worse respiratory reactance, worse spirometry results, more severe lung hyperinflation, and poorer health status. Small airway dysfunction was also associated with the bronchodilator responsiveness in terms of FVC, but not in terms of FEV1.
Keywords: bronchodilator responsiveness, small airways, COPD
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