Interrupter resistance (Rint) technique can be easily and successfully performed in preschool children. The establishment of Rint short-term
repeatability is essential to interpret any Rint change after a
pharmacological intervention. AIMS OF THE STUDY: In preschool children with
asthma or
chronic cough: (1) to assess two indices of short-term
repeatability: (a) intra-measurement and (b) within-occasion between-test
repeatability; (2) to study the relationship between short-term
repeatability and
bronchodilator response (BDR). RESULTS: Rint intra-measurement
repeatability assessed by the
coefficient of variation was similar at baseline and after
bronchodilator in
asthmatics and in coughers (
median 10% and 12%, respectively). There was no significant difference between
asthmatics and coughers for both coefficient of
repeatability (CR) (0.25 kPa L(-1)s and 32% of predicted vs 0.16 kPa L(-1) s and 21% of predicted, respectively) and BDR (
median -14.7% vs -21.1% of predicted, respectively). However, in 20% of the study children, baseline variability of Rint modified the significance of the BDR. CONCLUSION: In the present study, Rint short-term
repeatability was similar to that of previous studies. Similar Rint
repeatability in coughers and in
asthmatic children favored the use of
asthmatic CR for both populations, and a -35%
cut-off as a positive BDR. In 20% of study children, baseline Rint variability could influence the significance of the BDR. In order to improve assessment of BDR using Rint, further studies are needed (1) to compare the variability of Rint to other resistance measurement techniques and (2) to define the best method for Rint calculation and for expression of BDR.
