Multiple breath washout can facilitate the diagnosis of lung graft-versus-host disease in children after allogeneic hematopoietic stem cell transplantation

Background: Chronic graft-versus-host disease (GvHD) in the lungs is a serious complication of allogeneic hematopoietic stem cell transplantation (HSCT) affecting the peripheral airways as obliterative bronchiolitis. Multiple Breath Washout (MBW) is a sensitive method for assessing the function of the small peripheral airways. The aim of this study was to examine whether MBW can facilitate an earlier diagnosis of lung GvHD. Methods: 110 children (mean age: 9,6 years) underwent allogeneic HSCT in Queen Silvias Children Hospital between 2006 and 2014. LCI (Lung Clearing Index) was determined in 62 children using MBW with sulphur hexafluoride (SF6) as tracer gas before and one year after HSCT. All children ≥ 6 years also performed spirometry. Results: Overall there was no significant difference in mean LCI before (7.09(0,8 SD)) and after HSCT (7.47(1,41 SD)) (p: 0.056). In 11/62 children LCI increased ≥ 1 unit one year after HSCT . 4 of these children were diagnosed with lung GvHD (3 within one year from HSCT and one after 3 years) based on clinical symptoms and lungfunction tests. LCI in children who developed lung GvHD was 6.60 (0.16 SD) before and 9,93 (2,79 SD) one year after HSCT. The other seven children with increased LCI ≥ 1 unit at one year have had repeated airway infections causing increased LCI. No child with an incease in LCI Conclusion: MBW can be used to identify children with lung GvHD after allogeneic HSCT. For earlier detection of lung GvHD, MBW should probably be done earlier than one year post HSCT. Prospective studies are required to confirm this.