Changes in lung volumes and airway responsiveness following haematopoietic stem cell transplantation

Changes in lung volume occur following haematopoietic stem cell transplantation (HSCT); airway hyperresponsiveness was occasionally reported, without mechanistic explanation. The present authors studied 17 patients by standard methacholine (MCh) challenge before and then 3 and 12 months after HSCT (n = 16 and n = 13, respectively). Another 6 patients were challenged before and 3 months after HSCT using a modified challenge to investigate the effect of deep inhalations. No patient developed bronchiolitis obliterans or bronchiolitis obliterans organising pneumonia. At 3 months, forced vital capacity (FVC) was significantly reduced by 0.33+/-0.55 L, forced expiratory volume in one second (FEV(1)) by 0.31+/-0.50 L, total lung capacity (TLC) by 0.39+/-0.37 L and single-breath diffusing capacity of the lung for carbon monoxide (D(L,CO)) by 15+/-12%. At 12 months, TLC decreased by 0.43+/-0.36 L and D(L,CO )by 8+/-8%. With standard challenge, no significant changes in FEV(1) response to MCh were observed after HSCT but FVC decreased significantly less after HSCT compared with prior to HSCT, suggesting less air trapping. With modified challenge, deep inhalations reversed the MCh-induced decrease in partial expiratory flow more after HSCT compared with before HSCT and this correlated with TLC decrements. In conclusion, an increase in airway responsiveness is unlikely after haematopoietic stem cell transplantation, at least in patients without pulmonary complications, and mechanisms opposing airway narrowing may blunt the bronchoconstrictor response.