Clinical Validation of the Tremoflo C2 Versus Tremoflo C100 in Asthmatic Patients 2-7 Years of Age

Abstract Rationale: Current asthma guidelines recommend spirometry for asthma diagnosis and management, although difficult in young children due to the effort-dependent maneuver. Airwave oscillometry system (AOS) is a non-invasive and effort-independent device that measures resistance and reactance from a range of frequencies and effective in assessing central and peripheral airways. Tremoflo C2 (Thorasys Inc., Montreal, Canada), which is a succession to Tremoflo C100, is smaller in size and weight, works wirelessly, and has a novel built-in user interface. The objectives are to determine the agreement between C2 and C100, demonstrate the validity of the current reference equation and several parameters that identify uncontrolled asthma, and evaluate the feasibility of two devices. Methods: We evaluated 53 patients aged 2-7 years of age with physician diagnosed asthma in the Allergy and Immunology outpatient clinic at Children's Hospital of Orange County (CHOC) from September 2023 to November 2023. Asthma severity and control were assessed using current asthma guideline criteria. Tremoflo AOS C2 and C100 were used to obtain three sets of valid measurements at mutually prime frequencies from 7 hertz (Hz) to 41 Hz. Four oscillometry metrics (R7, R7-19, AX, and X7) were measured and calculated. Bland-Altman plots were utilized to evaluate proportional bias. Using reference equations by Ducharme et al., small airway dysfunction (SAD) was defined as z-scores exceeding 1.645 residual standard deviation (RSD). After completion, feedback was provided by patients and operators. Results: Although 62.3% of patients were 5-7 years of age, 37.7% were 2-4 years, male gender, 84.9% having mild asthma severity, and 86.8% well-controlled. Overall intraclass correlation (ICC) showed good agreement (.80 in R7, R7-19, X7, and AX. Of the four major metrics, proportional bias was only seen for R7-R19 (p=.017). As the average R7-R19 metric increased, the difference between C2 and C100 also increased. There was no significant difference in SAD percentage between C2 and C100 throughout different patient characteristics. Survey results from both patients and operators were favorable for C2 given its small size and user-friendly interface. Conclusion: In our predominantly well-controlled, mild asthmatic population, there was good agreement for resistance and reactance values between the C2 and C100. Both devices demonstrated the validity of the current reference equation in patients and identified SAD even in patients that were diagnosed as well-controlled. All 53 participants were able to perform both devices, including the younger population. Both C2 and C100 were feasible with favorable feedback for C2.

Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.