Bronchodilator Responsiveness in Obliterative Bronchiolitis (BD-OB)

• Per Cent Change of Forced Expiratory Volume in 1 Second (FEV1) After Bronchodilators [ Time Frame: Baseline and 90 min after bronchodilators ] [ Designated as safety issue: No ]
  Following albuterol plus tiotropium inhalation, FEV1 increments ≥12 per cent as compared to baseline, in an individual subject, were considered as evidence of response to bronchodilators, according to the American Thoracic Society-European Respiratory Society standard criteria [Pellegrino et al. Eur Respir J 2005; 26: 948-968]. They were calculated as follows: [FEV1, expressed in liters (L), after bronchodilators - FEV1 (L) before bronchodilators/FEV1 (L) before bronchodilators x 100].
  
  
• Absolute Change of Forced Expiratory Volume in 1 Second (FEV1) After Bronchodilators [ Time Frame: Baseline and 90 min after bronchodilators ] [ Designated as safety issue: No ]
  Following albuterol plus tiotropium inhalation, FEV1 increments ≥0.20 liters (L) as compared to baseline, in an individual subject, were considered as evidence of response to bronchodilators, according to the American Thoracic Society-European Respiratory Society standard criteria [Pellegrino et al. Eur Respir J 2005; 26: 948-968]. They were calculated as follows: [FEV1 (L) after bronchodilators - FEV1 (L) before bronchodilators].
  
  
• Per Cent Change of Forced Vital Capacity (FVC) After Bronchodilators [ Time Frame: Baseline and 90 min after bronchodilators ] [ Designated as safety issue: No ]
  Following albuterol plus tiotropium inhalation, FVC increments ≥12 per cent as compared to baseline, in an individual subject, were considered as evidence of response to bronchodilators, according to the American Thoracic Society-European Respiratory Society standard criteria [Pellegrino et al. Eur Respir J 2005; 26: 948-968]. They were calculated as follows: [FVC, expressed in liters (L), after bronchodilators - FVC (L) before bronchodilators/FVC (L) before bronchodilators x 100].
  
  
• Absolute Change of Forced Vital Capacity (FVC) After Bronchodilators [ Time Frame: Baseline and 90 min after bronchodilators ] [ Designated as safety issue: No ]
  Following albuterol plus tiotropium inhalation, FVC increments ≥0.20 liters (L) compared with baseline, in an individual subject, were considered as evidence of response to bronchodilators, according to the American Thoracic Society-European Respiratory Society standard criteria [Pellegrino et al. Eur Respir J 2005; 26: 948-968]. They were calculated as follows: [FVC (L) after bronchodilators - FVC (L) before bronchodilators].
  
  
• Per Cent Change of Instantaneous Maximal Forced Expiratory Flow (V'Max) After Bronchodilators [ Time Frame: Baseline and 90 min after bronchodilators ] [ Designated as safety issue: No ]
  Following albuterol plus tiotropium inhalation, V'max increments ≥40 per cent as compared to baseline, in an individual subject, were considered as evidence of response to bronchodilators, according to Pellegrino et al. [Chest 1998; 114:1607-1612]. They were calculated as follows: [V'max, expressed in liters.second-1 (L.s-1), after bronchodilators - V'max (L.s-1) before bronchodilators/V'max (L.s-1) before bronchodilators x 100].
  
  
• Per Cent Change of Partial Forced Expiratory Flow (V'Part) After Bronchodilators [ Time Frame: Baseline and 90 min after bronchodilators ] [ Designated as safety issue: No ]
  Following albuterol plus tiotropium inhalation, V'part increments ≥40 per cent as compared to baseline, in an individual subject, were considered as evidence of response to bronchodilators, according to Pellegrino et al. [Chest 1998; 114:1607-1612]. They were calculated as follows: [V'part, expressed in liters.second-1 (L.s-1), after bronchodilators - V'part (L.s-1) before bronchodilators/V'part (L.s-1) before bronchodilators x 100].
  
  
• Per Cent Change of Residual Volume (RV) After Bronchodilators [ Time Frame: Baseline and 90 min after bronchodilators ] [ Designated as safety issue: No ]
  Following albuterol plus tiotropium inhalation, RV decrements ≥10 per cent as compared to baseline, in an individual subject, were considered as evidence of response to bronchodilators, according to O'Donnell et al. [Eur Respir J 2001; 18: 914-920]. They were calculated as follows: [RV, expressed in liters (L), before bronchodilators - RV (L) after bronchodilators/RV (L) after bronchodilators x 100].
  
  
• Absolute Change of Residual Volume (RV) After Bronchodilators [ Time Frame: Baseline and 90 min after bronchodilators ] [ Designated as safety issue: No ]
  Following albuterol plus tiotropium inhalation, RV decrements ≥0.30 liters (L) as compared to baseline, in an individual subject, were considered as evidence of response to bronchodilators, according to O'Donnell et al. [Eur Respir J 2001; 18: 914-920]. They were calculated as follows: [RV (L), before bronchodilators - RV (L) after bronchodilators].
  
  
• Per Cent Change of Functional Residual Capacity (FRC) After Bronchodilators [ Time Frame: Baseline and 90 min after bronchodilators ] [ Designated as safety issue: No ]
  Following albuterol plus tiotropium inhalation, FRC decrements ≥10 per cent as compared to baseline, in an individual subject, were considered as evidence of response to bronchodilators, according to O'Donnell et al. [Eur Respir J 2001; 18: 914-920]. They were calculated as follows: [FRC, expressed in liters (L), before bronchodilators - FRC (L) after bronchodilators/FRC (L) after bronchodilators x 100].
  
  
• Absolute Change of Functional Residual Capacity (FRC) After Bronchodilators [ Time Frame: Baseline and 90 min after bronchodilators ] [ Designated as safety issue: No ]
  Following albuterol plus tiotropium inhalation, FRC decrements ≥0.30 liters (L) as compared to baseline, in an individual subject, were considered as evidence of response to bronchodilators, according to O'Donnell et al. [Eur Respir J 2001; 18: 914-920]. They were calculated as follows: [FRC (L), before bronchodilators - FRC (L) after bronchodilators].
  
  

Obliterative bronchiolitis is a life-threatening non-infectious pulmonary complication of allogeneic hematopoietic stem cell transplantation (HSCT). It is characterized by the development of an obstructive abnormality which has been considered to be insensitive to bronchodilator treatments. However, this knowledge stems from measurements of forced expiratory volume in 1 s (FEV1) which is relatively insensitive to changes in small airway caliber. Moreover, it is known from studies in chronic obstructive pulmonary disease that symptoms improve after bronchodilator treatment even when FEV1 is minimally increased and correlate with the reduction of lung hyperinflation, which is the major consequence of severe expiratory airflow limitation. Therefore, measurements of airway caliber by parameters not affected by volume history and absolute lung volumes are preferable for assessing the effect of bronchodilator interventions.

In the current study, the bronchodilators responsiveness will be assessed by using not only spirometry but also measurements of absolute lung volumes and the forced expiratory flow of a partial maneuver (V'part) started from submaximal lung inflation, thus free of volume history effects.