title: Impulse oscillometry in adults with bronchiectasis.
abstract: BACKGROUND
  The usefulness of impulse oscillometry (IOS) in bronchiectasis has not been systematically investigated.
  
  
  OBJECTIVE
  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.
  
  
  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).
authors: 1 State Key Laboratory of Respiratory Disease, National Clinical Research Center for Respiratory Disease, Guangzhou Institute of Respiratory Disease, First Affiliated Hospital of Guangzhou Medical University, Guangzhou Medical University, Guangzhou, Guangdong, China.
authors: Wei-jie
authors: WJ
authors: Guan
authors: Yong-hua
authors: YH
authors: Gao
authors: Gang
authors: G
authors: Xu
authors: Zhi-ya
authors: ZY
authors: Lin
authors: Yan
authors: Y
authors: Tang
authors: Hui-min
authors: HM
authors: Li
authors: Zhi-min
authors: ZM
authors: Lin
authors: Jin-ping
authors: JP
authors: Zheng
authors: Rong-chang
authors: RC
authors: Chen
authors: Nan-shan
authors: NS
authors: Zhong
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001987:Bronchiectasis / Q000175:diagnosis* / Q000503:physiopathology; D005260:Female; D005541:Forced Expiratory Volume / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009991:Oscillometry / Q000379:methods*; D012372:ROC Curve; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed; D055815:Young Adult
keywords: acute exacerbation; bacteriology; bronchiectasis; convalescence; impulse oscillometry