Oscillometry detected subtle small-airway damage and stiffer lungs in children awaiting stem cell transplant, despite remaining in the normal range
As spirometry requires coordinated deep breathing and can be challenging for children to perform, researchers from the USA, as part of the TRANSPIRE study investigating lung complications in children undergoing hematopoietic stem cell transplantation (HSCT), explored the potential of oscillometry, a simple and child-friendly lung function test. Oscillometry detected subtle lung abnormalities before HSCT that conventional lung function testing may miss, suggesting that these children may be more vulnerable to future pulmonary complications.
Hematopoietic stem cell transplantation (HSCT) is the curative therapy for many childhood cancers, metabolic and immunologic disorders. However, many of these children later develop lung problems. They receive various treatments in preparation for the transplant, and for complications like infections or adverse immune reactions that may arise after transplantation. It remains unclear whether many of these lung abnormalities arise from the underlying disease, treatments received before transplantation, or the transplant process itself. Lung function is conventionally measured using spirometry, for which the children must inhale fully, blow out as hard as possible, and repeat the maneuver several times. Young children often cannot perform this correctly, particularly if they are sick.
A new
study published in the journal Pediatric Investigation on 29 June 2026 explored the role of a more convenient lung function test called oscillometry. It measures how easily air flows through the lungs and how stiff or flexible the lungs are while a person breathes normally. Because it requires only quiet breathing rather than repeated forceful breathing maneuvers, it is particularly suitable for young or medically fragile children.
“We wanted an alternate test that describes even the subtle physiologic abnormalities in lung function, before and after HSCT”, says Associate Professor Maureen B. Parenti, the first author of the paper. “
Our goals were to introduce oscillometry as a convenient and helpful routine test that can complement conventional lung function testing, as well as to determine whether the lung abnormalities arise primarily from transplantation itself or are already present because of the underlying disease or treatments received before HSCT,” She explains.
The researchers compared the oscillometry findings of 63 children enrolled across multiple pediatric centers participating in the TRANSPIRE study with those of 80 healthy children. TRANSPIRE is an ongoing multi-center research project sponsored by the National Institutes of Health (NIH), USA, tracking lung injuries in a large, diverse population of children and young adults who receive HSCT. Oscillometry was performed before HSCT and for up to two years after transplantation. They compared lung properties such as 'resistance,' a measure of how difficult it is for air to move through the airways; 'reactance,' which reflects how stretchy or stiff the lungs are; and 'resonant frequency (Fres)' and 'area under the reactance curve (AX),' measurements that reflect lung stiffness and how evenly air is distributed throughout the lungs. All values were standardized for the child's height because lung function normally improves as children grow taller.
About 90–95% of children were able to complete the test successfully, suggesting that routine oscillometry can be practical in most children, including younger ones. The study found that although most children's oscillometry results were within published normal reference ranges, comparison with healthy children revealed consistent differences in lung function. Children awaiting HSCT had higher small-airway resistance, meaning airflow through the smaller breathing tubes was more restricted. They also had a stiffer respiratory system and greater unevenness in airflow distribution throughout the lungs, as shown by more negative reactance values and higher AX and Fres measurements.
“These lung changes were independent of the type of disease. Whether it be cancers like leukemia, or inherited blood disorders or immune disorders, the baseline lung measurements remained similar”, explains Dr. Parenti.
The researchers continued testing the children for up to two years after the bone marrow transplant. No oscillometry parameter changed significantly during the two-year follow-up. Measurements remained similar regardless of baseline clinical status, spirometry findings, oxygen diffusing capacity, or lung imaging abnormalities. The researchers suggest that these abnormalities may have resulted from the children's underlying disease or treatments received before HSCT, such as chemotherapy, radiation, or immunosuppressive therapy, rather than from the transplant itself. They also note that lung infections before transplantation could have contributed to fibrosis or chronic airway disease.
The findings suggest that children preparing for HSCT may already have subtle respiratory abnormalities before transplantation, potentially related to their underlying disease or previous therapies rather than the transplant itself.
This study, the largest to evaluate oscillometry before pediatric HSCT, shows that children awaiting stem cell transplantation already have subtle but measurable lung abnormalities, including increased small-airway resistance, greater lung stiffness, and uneven airflow, even though their results generally remain within standard normal ranges. Oscillometry proved to be an easy, child-friendly test with a high success rate and may be valuable for detecting subtle respiratory abnormalities before transplantation and for monitoring lung health over time after HSCT.
***
Reference
Titles of original paper: Respiratory profile of pediatric patients undergoing hematopoietic stem cell transplantation studied by oscillometry – A TRANSPIRE cohort
Journal:
Pediatric Investigation
DOI:
https://doi.org/10.1002/ped4.70072
About Associate Professor Maureen B. Parenti
Dr. Maureen B. Parenti is an Associate Professor of Clinical Pediatrics at the Perelman School of Medicine, University of Pennsylvania, and an Attending Pediatric Pulmonologist at Children's Hospital of Philadelphia (CHOP). A board-certified pediatric pulmonologist, her clinical and research interests focus on pediatric lung diseases, lung transplantation, and respiratory outcomes in children with complex medical conditions.