Oscillometry Outcomes Before and After Hematopoietic Stem Cell Transplantation (HSCT)

Abstract

Rationale: HSCT recipients can experience various manifestations of opportunistic infection and graft vs host (GVH) disease in the lung. Oscillometry is a tidal breathing test with greater sensitivity to detect impairment than spirometry and may be a valuable tool to monitor lung function and screen for early manifestations of pulmonary infection or rejection. However, the effects of HSCT itself on oscillometry are unknown. Methods: We performed oscillometry (Tremofloã C100, Thorasys, Montreal, CA) at baseline and following HSCT in a cohort of 56 children at 3 of 4 centers to date: Cincinnati Children's Hospital, Children's Hospital of Philadelphia, University of Minnesota Children's Hospital, and Boston Children's Hospital. Children between the ages of 4 and 21 years were eligible for study. Of 56 subjects enrolled so far, 14 had oscillometry results both pre HSCT and within a window of 70-130 days post-transplant. Pre-HSCT z scores were compared to post- HSCT. Following ERS 2020 Guidelines, oscillometry was measured over recording periods of 30 seconds during tidal breathing using commercial equipment (Tremoflo, Thorasys Ltd, 5-37Hz) in at least three trials targeting a coefficient of variation of <15% in airway resistance (R) for the lowest frequency reported (R5). Variables reported were R5, reactance at 5Hz (X5), frequency dependence of R (R5-19), and area under the reactance curve (AX). Operators underwent a structured training program including quality control of data. Abnormality was defined as a z score of >1.96, using equipment-specific reference equations published by Ducharme et al. (ref) Results: Among the 14 patients who had oscillometry results both pre-HSCT and within 70-130 days post- HSCT, no significant changes were observed in median z -scores for R5 (p=0.46), X5(p= 0.88), R5- R19 (p= 0.25), AX (p=0.92) (Figure) by Mann-Whitney test analysis. Conclusions: We provide an overview of a multicenter study of oscillometry in a cohort of children undergoing HSCT, demonstrating that oscillometry testing pre- and post-HSCT at multiple centers is feasible in children. Our initial results indicate consistency of oscillometry measures without acute changes following HSCT. Thus, post HSCT oscillometry may provide a good baseline for future analyses examining subsequent changes, both acute and long-term pulmonary complications, in larger numbers of children undergoing HSCT.