Accuracy of forced oscillation technique to assess lung function in geriatric COPD population.
BACKGROUND
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.


OBJECTIVE
To study the use of FOT in the assessment of airflow limitation and air trapping in geriatric COPD patients.


METHODS
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.


CONCLUSIONS
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.
Medical and Geriatric Department, Respiratory Unit, Kwong Wah Hospital, Hong Kong, People's Republic of China.
Hoi Nam
HN
Tse
Medical and Geriatric Department, Respiratory Unit, Kwong Wah Hospital, Hong Kong, People's Republic of China.
Cee Zhung Steven
CZ
Tseng
Department of Tuberculosis and Chest Unit, Wong Tai Sin Hospital, Hong Kong, People's Republic of China.
King Ying
KY
Wong
Department of Tuberculosis and Chest Unit, Wong Tai Sin Hospital, Hong Kong, People's Republic of China.
Kwok Sang
KS
Yee
Medical and Geriatric Department, Respiratory Unit, Kwong Wah Hospital, Hong Kong, People's Republic of China.
Lai Yun
LY
Ng
D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D019540:Area Under Curve; D005260:Female; D005541:Forced Expiratory Volume; D015577:Geriatric Assessment / Q000379:methods*; D006723:Hong Kong; D006779:Hospitals, Public; D006801:Humans; D008168:Lung / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009991:Oscillometry; D010991:Plethysmography; D011237:Predictive Value of Tests; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis* / Q000503:physiopathology*; D012123:Pulmonary Ventilation; D012372:ROC Curve; D015203:Reproducibility of Results; D012129:Respiratory Function Tests / Q000379:methods*; D012720:Severity of Illness Index; D013147:Spirometry; D014797:Vital Capacity
air trapping; airflow limitation; chronic obstructive pulmonary disease