Accuracy of forced oscillation technique to assess lung function in geriatric COPD population
Authors Tse HN, Tseng CZS, Wong KY, Yee KS, Ng LY
Received 10 December 2015
Accepted for publication 19 February 2016
Published 26 May 2016 Volume 2016:11(1) Pages 1105—1118
Checked for plagiarism Yes
Review by Single-blind
Peer reviewers approved by Professor Hsiao-Chi Chuang
Peer reviewer comments 2
Editor who approved publication: Dr Richard Russell
Hoi Nam Tse,1 Cee Zhung Steven Tseng,1 King Ying Wong,2 Kwok Sang Yee,2 Lai Yun Ng1
1Medical and Geriatric Department, Respiratory Unit, Kwong Wah Hospital, 2Department of Tuberculosis and Chest Unit, Wong Tai Sin Hospital, Hong Kong, People’s Republic of China
Introduction: Performing lung function test in geriatric patients has never been an easy task. With well-established evidence indicating impaired small airway function and air trapping in patients with geriatric COPD, utilizing forced oscillation technique (FOT) as a supplementary tool may aid in the assessment of lung function in this population.
Aims: To study the use of FOT in the assessment of airflow limitation and air trapping in geriatric COPD patients.
Study design: A cross-sectional study in a public hospital in Hong Kong. ClinicalTrials.gov ID: NCT01553812.
Methods: Geriatric patients who had spirometry-diagnosed COPD were recruited, with both FOT and plethysmography performed. “Resistance” and “reactance” FOT parameters were compared to plethysmography for the assessment of air trapping and airflow limitation.
Results: In total, 158 COPD subjects with a mean age of 71.9±0.7 years and percentage of forced expiratory volume in 1 second of 53.4±1.7 L were recruited. FOT values had a good correlation (r=0.4–0.7) to spirometric data. In general, X values (reactance) were better than R values (resistance), showing a higher correlation with spirometric data in airflow limitation (r=0.07–0.49 vs 0.61–0.67), small airway (r=0.05–0.48 vs 0.56–0.65), and lung volume (r=0.12–0.29 vs 0.43–0.49). In addition, resonance frequency (Fres) and frequency dependence (FDep) could well identify the severe type (percentage of forced expiratory volume in 1 second <50%) of COPD with high sensitivity (0.76, 0.71) and specificity (0.72, 0.64) (area under the curve: 0.8 and 0.77, respectively). Moreover, X values could stratify different severities of air trapping, while R values could not.
Conclusion: FOT may act as a simple and accurate tool in the assessment of severity of airflow limitation, small and central airway function, and air trapping in patients with geriatric COPD who have difficulties performing conventional lung function test. Moreover, reactance parameters were better than resistance parameters in correlation with air trapping.
Keywords: airflow limitation, air trapping, chronic obstructive pulmonary disease
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