Detection of Post- Hematopoietic Stem Cell Transplant Bronchiolitis Obliterans Syndrome (BOS)-The Use of Airway...

Bronchiolitis obliterans syndrome (BOS) is a devastating complication of allogeneic hematopoietic stem cell transplantation (HSCT) characterized by onset of obstructive lung disease. Oscillometry is a novel pulmonary function assessment technology which superimposes pressure waves on normal tidal breathing, and the alterations in flow and pressure caused by the external waves are measured. Oscillometry assesses physiological parameters that provide insight into respiratory mechanics. We hypothesized that oscillometry may allow for detection of small airway disease to diagnose BOS, especially in children unable to perform spirometry.

We conducted a cross-sectional study to characterize oscillometry findings in patients with BOS compared to a control cohort of HSCT patients without BOS. PFT testing were performed on all patients at the time of oscillometry testing.

Thirty-six patients post HSCT were approached, 18 with BOS and 18 controls. These two groups were similar in demographic parameters. BOS patients had significantly abnormal spirometry values. Oscillometry results demonstrated significant differences between the two cohorts in X5, AX, R5, R5-19 and (R5-19)/R5. There were significant differences between BOS and transplant control groups when assessing the association between oscillometry parameter and spirometry parameters.

In our cohort oscillometry revealed significant differences between the BOS and non- BOS cohort. Resistance at R5 Hz and the difference between R5-R19 Hz, which characterizes peripheral lung resistance, were both abnormally increased when compared with non- BOS subjects. In addition, reactance parameters, X5 and AX, which correlate with lung stiffness demonstrated significant differences between the BOS and non- BOS cohorts. Our data reveal a strong correlation between oscillometric and spirometric abnormalities in patients with established BOS originally identified by standard spirometry testing. In addition, oscillometry suggests localization of increased resistance in the lung periphery supporting our hypothesis that oscillometry might be complementary to spirometry, and enhance our ability to diagnose BOS.

ClinicalTrials.gov identifier: NCT04098445.