Repeatability of Pressure Oscillation Amplitudes during the Interrupter Measurement of Respiratory Resistance

Abstract

Interrupter resistance (Rint) technique for assessing respiratory mechanics requires minimal cooperation and can therefore be successfully performed in young children. Analysis of recorded oscillations of the mouth pressure (Pmo) has been suggested to provide additional indices of change in airway mechanics. The aim of this study was to establish the repeatability of pressure oscillation amplitudes.

Children performed two sets of Rint measurements. Further analysis of Pmo tracings was performed using MATLAB software. Pmo data were normalized to the last recorded pressure and afterwards oscillation amplitudes (Amp) were found as the difference between the first Pmo maximum and minimum. Intra-measurement repeatability was assessed by the coefficient of variation (CV) and between-test repeatability - by the coefficient of repeatability (CR).

92 young children (aged 3 to 7 years) were studied (49 of them healthy, 18 wheezers and 25 coughers). Median CV values for both measurements were 14% and 15% for Rint, and 14% and 13% for Amp. Our between-test Rint repeatability was similar to that of previous studies (CR was 0.23 kPa.L^− 1.s or 33.3% of baseline value). CR for Amp was 0.24 or 27.6% of baseline value. There was no significant difference between groups of children.

We measured short term repeatability for the most simple pressure oscillation amplitude and found that this is similar to Rint repeatability.