Impulse oscillometry as a noninvasive measure to diagnose tracheobronchomalacia
Sunday, March 4, 2018
South Hall A2 (Convention Center)
Yoomie J. Lee, MD, Nathan Rabinovitch, MD MPH
RATIONALE: Children with recurrent wheezing who do not respond optimally to conventional asthma treatment may have concurrent floppiness of central airways or tracheobronchomalacia (TBM). Presently, TBM is diagnosed by bronchoscopy or in some cases with specific pulmonary function tests that cannot be performed in younger children. Impulse oscillometry (IOS) is a noninvasive, effort-independent method of measuring and distinguishing airway resistance in central vs. peripheral airways. We therefore hypothesized that IOS could be used to diagnose TBM in children with wheezing.

METHODS: A retrospective case series of 16 patients, 4 to 21 years of age with a history of wheezing +/- TBM who had performed IOS was analyzed. The diagnosis of TBM had been made in five of the sixteen patients based on positive bronchoscopy, increased SVC/FVC ratio or decreased FEV1 after albuterol. Logistic regression analysis was performed to determine the predictive value of the IOS derived “central airway resistance” (Rcentral) parameter with control for body mass index (BMI).

RESULTS: A significant (p=0.02) association was observed between low Rcentral controlled for by BMI, and the presence of TBM. Four out of 5 TBM patients had Rcentral levels at or below the optimal cut-off point (80% sensitivity) and 10 out of 11 patients without TBM had Rcentral levels above this cut-off point (91% specificity). The area under the curve (AUC) for this model was 0.87.

CONCLUSIONS: IOS derived central airway resistance corrected for BMI, is a useful, noninvasive highly sensitive and specific parameter that can be used to diagnose TBM in children.