Impulse oscillometry in adults with bronchiectasis.
RATIONALE
The usefulness of impulse oscillometry (IOS) in bronchiectasis has not been systematically investigated.


OBJECTIVES
To determine the usefulness of IOS parameters and their correlation with radiology, disease severity, sputum bacteriology, and spirometry, and to compare the changes in IOS parameters during exacerbations and convalescence of bronchiectasis.


METHODS
We recruited 100 patients with bronchiectasis and 28 healthy subjects. Receiver operating characteristic curve was plotted to analyze the diagnostic performance of IOS parameters. Chest high-resolution computed tomography (HRCT), Bronchiectasis Severity Index (BSI) assessment, sputum culture, and spirometry were performed. Correlation between IOS parameters and clinical indices was determined using the Spearman model. Changes in IOS parameters, compared with spirometry, during exacerbation were assessed in 16 patients with bronchiectasis.


MEASUREMENTS AND MAIN RESULTS
IOS parameters (in particular, resonant frequency) could discriminate patients with bronchiectasis from healthy subjects. Higher levels of IOS parameters were associated with Pseudomonas aeruginosa infection, dyshomogeneity, higher BSI and HRCT score, more bronchiectatic lobes, and cystic bronchiectasis (all P < 0.05). All IOS parameters but lung resistance at 5 Hz were positively correlated with the duration of bronchiectasis symptoms, number of bronchiectatic lobes, HRCT total scores, and BSI (all P < 0.05), but not sputum bacterial density (P > 0.05). IOS parameters, but not spirometric parameters, were not statistically different between peripheral and peripheral plus central segment bronchiectasis (all P > 0.05). Increased frequency dependence (higher resonance frequency or reactance area) was more likely to be associated with lower HRCT scores (≤5) than FEV1. Compared with FEV1, any single IOS parameter being abnormal was more common in mild bronchiectasis, particularly in patients with HRCT score of 5 or lower. IOS parameters were not statistically different from baseline to exacerbations and convalescence (all P > 0.05).


CONCLUSIONS
IOS parameters correlate with clinical indices and could reflect peripheral airway abnormality. An increased number of aberrant IOS parameters signals poorer clinical conditions. Increased frequency dependence might be a sensitive marker of mild bronchiectasis. Any single IOS parameter being abnormal sensitively reflects mild bronchiectasis. IOS parameters do not change significantly during bronchiectasis exacerbations. Clinical Trial registered with www.clinicaltrials.gov (NCT01761214).
['Guan|Wei-jie|WJ|', 'Gao|Yong-hua|YH|', 'Xu|Gang|G|', 'Lin|Zhi-ya|ZY|', 'Tang|Yan|Y|', 'Li|Hui-min|HM|', 'Lin|Zhi-min|ZM|', 'Zheng|Jin-ping|JP|', 'Chen|Rong-chang|RC|', 'Zhong|Nan-shan|NS|']
D000293:Adolescent D000328:Adult D000368:Aged D001987:Bronchiectasis D005260:Female D005541:Forced Expiratory Volume D006801:Humans D008297:Male D008875:Middle Aged D009991:Oscillometry D012372:ROC Curve D012189:Retrospective Studies D014057:Tomography, X-Ray Computed D055815:Young Adult
impulse oscillometry bronchiectasis bacteriology convalescence acute exacerbation