Ventilation heterogeneity and lung tissue abnormalities in children after hematopoietic stem cell transplantation

Hematopoietic stem cell transplantation (HSCT) is a life-saving treatment for children with various malignant and nonmalignant hematological disorders. We aimed to evaluate the abnormalities after autologous and allogeneic HSCT in children by monitoring ventilation heterogeneity derived from nitrogen multiple breath washout (NMBW) data and lung ultrasonography. In addition, we aimed to find the effect of drugs used for conditioning and/or graft-versus-host disease prophylaxis on high ventilation heterogeneity in children after HSCT.

We carried out a cross-sectional study on pediatric HSCT recipients who received autologous and allogeneic grafts at least 3 months before enrollment and were younger than 18 years at the time of evaluation.

We enrolled nine patients after autologous and 23 after allogeneic HSCT in this study. The median time after HSCT and lung function assessment was 5.2 years. An abnormal lung clearance index (LCI) (≥5.7) was found in four out of nine patients in the auto-HSCT group and 16 out of 23 patients in the allo-HSCT group. Among the drugs used in the allo-HSCT group, busulfan was associated with lower median post-transplant conductive ventilation heterogeneity (S_cond) values (0.0010 vs. 0.0176). Patients with higher median S_cond values received fludarabine (0.0204 vs. 0.0002) and treosulfan (0.0289 vs. 0.0100). Out of all study participants, only three patients had large consolidations (≥5 mm) seen on pulmonary ultrasonography.

Our NMBW data allowed the detection of subclinical lung injury in long-term HSCT survivors. The ventilation heterogeneity in conductive airways was higher after treosulfan and fludarabine usage but lower after busulfan administration. The abnormal lung ultrasonography findings were not associated with the drugs used for conditioning.