Discrepancy Between Airwave and Impulse Oscillometry Measurements of Impedance in Healthy Children

Area of Science:

• Pediatric Pulmonology
• Respiratory Physiology
• Medical Device Technology

Background:

• Respiratory oscillometry (OSC) is a non-invasive pulmonary function test for assessing respiratory impedance, particularly suitable for pediatric populations.
• Previous research indicated potential discrepancies in impedance values between different OSC devices, but direct comparisons in healthy children were lacking.

Purpose of the Study:

• To compare impedance measurements obtained from two different respiratory oscillometry devices: impulse oscillometry (IOS) and airwave oscillometry (AOS).
• To evaluate potential differences and biases between these instruments in a cohort of healthy children.

Main Methods:

• A cohort of 80 healthy children (ages 4-18) underwent both IOS and AOS testing in a randomized order.
• Linear regression analysis and Bland-Altman plots were employed to statistically compare the results from the two devices.

Main Results:

• Significant differences were observed between IOS and AOS for key parameters: resistance at 5 Hz (R5), reactance at 5 Hz (X5), area under the reactance curve (AX), and resonant frequency (Fres).
• IOS consistently yielded higher R5 and less negative X5 values compared to AOS.
• Bland-Altman analysis indicated proportional bias between the two oscillometry systems, suggesting measurement differences are not constant across the range of values.

Conclusions:

• This study demonstrates significant differences in respiratory impedance measurements between IOS and AOS devices in healthy children.
• These discrepancies may stem from variations in the pressure signals generated by each instrument.
• The findings suggest that normative values established on one OSC device may not be directly interchangeable with those from another, necessitating careful consideration in clinical practice and research.