PLoS ONE (Jan 2017)

Physiologic Determinants of Exercise Capacity in Pulmonary Langerhans Cell Histiocytosis: A Multidimensional Analysis.

  • Camille Rolland-Debord,
  • Stephanie Fry,
  • Jonathan Giovannelli,
  • Carole Langlois,
  • Nicolas Bricout,
  • Bernard Aguilaniu,
  • Agnes Bellocq,
  • Olivier Le Rouzic,
  • Stephane Dominique,
  • Alain Delobbe,
  • Geraldine François,
  • Abdellatif Tazi,
  • Benoit Wallaert,
  • Cecile Chenivesse

DOI
https://doi.org/10.1371/journal.pone.0170035
Journal volume & issue
Vol. 12, no. 1
p. e0170035

Abstract

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BACKGROUND:Reduced exercise capacity severely impacts quality of life in pulmonary Langerhans cell histiocytosis. Ascertaining mechanisms that impair exercise capacity is necessary to identify targets for symptomatic treatments. METHODS:Dyspnea, pulmonary function tests and cardiopulmonary exercise test were analysed in 62 study participants. Data were compared between subjects with impaired and normal aerobic capacity (V'O2 peak less than 84% versus 84% predicted or more). Data were reduced using a principal component analysis. Multivariate analysis included V'O2 peak as the dependent variable and principal components as covariates. RESULTS:V'O2 peak was reduced in 44 subjects (71%). Subjects with impaired aerobic capacity presented: (i) decreased FEV1, FVC, FEV1/FVC, DLCO and DLCO/VA and increased AaDO2, (ii) increased ventilatory equivalents at ventilatory threshold, VD/VT peak, AaDO2 peak and PaCO2 peak and decreased ventilatory reserve and PaO2 peak. There was no difference between groups in dyspnea scores. Principal component analysis extracted 4 principal components interpreted as follows: PC1: gas exchange; PC2: "pseudorestriction"; PC3: exercise-induced hyperpnea; PC4: air trapping. Multivariate analysis explained 65% of V'O2 peak. The 4 principal components were independently associated with V'O2 peak (βcoefficients: PC1: 9.3 [4.6; 14], PC2: 7.5 [3; 11.9], PC3: -5.3 [-9.6;-1.], PC4: -9.8 [-14,9;-4.7]). CONCLUSION:Impaired exercise capacity is frequent in pulmonary Langerhans cell histiocytosis. It is mainly caused by pulmonary changes but is not associated with increased dyspnea intensity. Therefore, treating the lung represents a relevant approach for improving exercise capacity, even in patients experiencing mild dyspnea.