Small airways function declines after allogeneic haematopoietic stem cell transplantation.

Area of Science:

• Pulmonology
• Transplantation Medicine
• Immunology

Background:

• Bronchiolitis obliterans (BO) is a significant complication following allogeneic hematopoietic stem cell transplantation (HSCT), affecting peripheral airways.
• Current detection methods like spirometry have low sensitivity, leading to delayed diagnosis.

Purpose of the Study:

• To investigate the relationship between peripheral airway function and time post-HSCT.
• To compare peripheral airway function with spirometry and clinical indices in stable HSCT recipients.

Main Methods:

• Lung function tests, including spirometry, exhaled nitric oxide, and forced oscillatory techniques.
• Measurement of ventilation heterogeneity using acinar (S(acin)) and conductive airways, and lung clearance index (LCI) via multiple breath nitrogen washout.
• Analysis of short-term changes in 22 patients with repeat visits.

Main Results:

• Acinar ventilation (S(acin)) was abnormal in 20 patients with normal spirometry, while no patients had airflow obstruction with normal S(acin).
• S(acin) and LCI showed significant worsening over time and correlated with chronic graft-versus-host disease.
• Time since HSCT was predicted by S(acin) and forced expiratory volume in 1 second % predicted.

Conclusions:

• Peripheral airway ventilation heterogeneity increases with time after HSCT.
• Acinar ventilation (S(acin)) may offer a more sensitive method for early BO detection than spirometry, warranting further prospective investigation.