title: Pressure oscillation amplitude after interruption of tidal breathing as an index of change in airway mechanics in preschool children.
abstract: Bronchodilator reversibility testing using change in airway resistance during interruption (Rint) is feasible in preschool children. Analysis of postocclusion oscillations of the mouth pressure-time transient (Pmo(t)), recorded during airflow interruption, may offer an alternative index of change in airway mechanics. We analyzed Pmo(t) oscillation amplitude in three different ways: 1) difference between the first relative maximum and minimum (AMxMn); 2) detection of the dominant frequency using Fourier analysis (AFS); and 3) curve-fitting based on a mathematical model (ACurv). In 25 asymptomatic asthmatic children, aged 2.5-5.6 years, who had undertaken reversibility testing, the correlation coefficients between baseline Rint and amplitude were: AMxMn r = -0.84, AFS r = -0.82, ACurv r = -0.84. The coefficient of variation (CoV) of readings contributing to baseline Rint measurement, as median (range), was 12% (5-24%), which was not significantly different from AFS or ACurv (P > 0.05). All parameters were significantly different postbronchodilator (P < 0.001). Using the sensitivity index, i.e., the change after intervention divided by the baseline standard deviation, ACurv was the most sensitive and Rint the least sensitive, with median (range) at 2.72 (-0.84 to 12.10) and 1.91 (-1.17 to 9.50), respectively (P = 0.005). Our results suggest that oscillation amplitude analysis may provide a sensitive index of change in airway mechanics in preschool children undertaking bronchodilator reversibility testing.
authors.affiliation: Department of Paediatric Respiratory Medicine, Royal London Hospital, Barts and London NHS Trust, London, UK. peter.bridge@bartsandthelondon.nhs.uk
authors.forename: Peter D
authors.initials: PD
authors.lastname: Bridge
authors.forename: David
authors.initials: D
authors.lastname: Wertheim
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Jackson
authors.forename: Sheila A
authors.initials: SA
authors.lastname: McKenzie
mesh_terms: D000403:Airway Resistance; D000420:Albuterol; D001249:Asthma / Q000175:diagnosis*; D001993:Bronchodilator Agents; D002675:Child, Preschool; D003936:Diagnosis, Computer-Assisted; D005260:Female; D006801:Humans; D008297:Male; D011312:Pressure; D012129:Respiratory Function Tests / Q000379:methods*; D015656:Respiratory Mechanics
chemical_list: D001993:Bronchodilator Agents; D000420:Albuterol