Pneumologie 2016; 70 - P44
DOI: 10.1055/s-0036-1572013

LCI measurement is coming of age

K Husemann 1, Y Zhukhovitskaya 2, M Kohlhäufl 2, F Singer 4
  • 1Praxis für Pneumologie und Allergologie, Mvz Klinikum Kempten
  • 2Zentrum für Pneumologie und Thoraxchirurgie, Klinik Schillerhöhe
  • 4Kinderklinik, Universitätsspital Bern; Kinderklinik, Universitätsspital Zürich

Background: Lung clearance index (LCI) derived from multiple-breath washout (MBW) is an established proxy of small airways function in children with cystic fibrosis (CF). Yet, LCI has not been systematically studied in adults with prevalent chronic lung diseases using available and validated MBW setups and protocols.

Methods: 33 asymptomatic smokers and 54 patients with chronic obstructive airway disease (asthma n = 20, COPD n = 20, CF n = 14) performed spirometry and nitrogen (N2)-MBW using the ExhalyzerD® in a tertiary care center. LCI was analysed at 2 endpoints: at 1/40th (standard) and earlier at 1/20th (shortened) of starting N2 concentration. Outcomes were (i) prevalence of abnormal FEV1 and standard and shortened LCI, (ii) association and agreement between LCIs, and (iii) time savings achieved by the shortened protocol.

Results: All smokers had normal FEV1, while standard LCI was abnormal in 12/33 (36%). In patients FEV1 and LCI were abnormal in 33/54 (61%) and in 43/54 (80%), respectively. Stratifying into the different disease groups, asthma, COPD, and CF, FEV1 was abnormal in 6/20, 18/20, and 9/14; Standard LCI was abnormal in 10/20, 20/20, 13/14, respectively. 12/21 (57%) patients with normal FEV1 showed abnormal LCI. The association between standard and shortened LCI was high for absolute values as well as Z-Scores (R2= 0.94, p < 0.0001, R2= 0,93 p < 0.001) and overall agreement of both LCI in categories normal vs. abnormal was excellent (Kappa = 0.95). Mean (SD) or average percent time savings were 220 (100)s or 32% in smokers, 280 (120)s or 32% in asthma, 540 (300)s or 41% in COPD, 630 (440)s or 45% in CF.

Conclusion: Small airways disease can be detected in 36% of asymptomatic smokers and in 57% of patients with obstructive lung diseases despite normal spirometry. LCI measurement appears clinically applicable as validated setups and standard and shortened protocols are available. The shortened protocol allows time savings about 30 – 45% of total test time.