Lung clearance index (LCI) as a predictor of exercise limitation among CF patients.

Avramidou V, Hatziagorou E, Kampouras A, Hebestreit H, Kourouki E,
Kirvassilis F, Tsanakas J

Pediatr Pulmonol. 2018 Jan;53(1):81-87. doi: 10.1002/ppul.23833. Epub 2017 Sep

INTRODUCTION: FEV1 is often considered the gold standard to monitor lung disease
in cystic fibrosis (CF). Recently, there has been increasing interest in multiple
breath washout (MBW) and cardiopulmonary exercise testing (CPET) as alternative
or even more sensitive techniques. However, limited data exist on associations
among the above methods.
AIM: To evaluate the correlations between outcome measures of MBW and CPET and to
examine if ventilation inhomogeneity can predict exercise intolerance.
SUBJECTS AND METHODS: Ninety-seven children and adults with CF (47 males, mean
[range] age 14.9 (6.6; 26.7) years, mean FEV1 : 90.8% predicted, mean lung
clearance index [LCI]: 11.4, and mean peak oxygen uptake [VO2 peak]: 82.4%
predicted) performed spirometry, MBW, and CPET on the same day during their
admission or outpatient visit.
RESULTS: LCI, m1 /m0 , and m2 /m0 (P < 0.001) as well as VO2 peak%, breathing
reserve (BR), minute ventilation (VE)/VO2 (P < 0.001), and VE/carbon dioxide
release (VCO2 ) (P = 0.006) correlated significantly with FEV1 %. LCI, m1 /m0 ,
and m2 /m0 correlated with VO2 peak (P ≤ 0.001), VE (L/min) (P < 0.05), BR
(P < 0.01), VE/VO2 (P < 0.001), and VE/VCO2 (P < 0.01). Multiple regression
analysis showed that LCI could predict BR% (P < 0.001, r2 :0.272) and VE/VO2
(P < 0.001, r2 : 0.207) while LCI and FRC could predict VO2 peak% P < 0.001, r2 :
0.216) and VE/VCO2 (P < 0.001, r2 : 0.226).
CONCLUSION: Ventilation inhomogeneity as indicated by increased LCI is associated
with less efficient ventilation during strenuous exercise and negatively impacts
exercise capacity in CF.