Opening interrupter technique in pre-school children with chronic respiratory diseases: a perspective case-control study in the diagnosis of airway hyperesponsiveness.

Background: Optimal treatment for pediatric respiratory diseases is strictly related to follow-up evaluations of lung function. The aim of our study was to show the efficacy of the Opening Interrupter Technique in diagnosing the presence of airway obstruction in pre-school children. Materials and methods: Our study was a prospective case-control study, evaluating 82 patients affected by asthma and/or cystic fibrosis (CF) and 50 healthy pre-school children, as control group. All patients were 3- to 5-years old and they were followed by our Pediatric Department, University of Catania, Italy, from February 2011 to June 2012. Measurements of respiratory resistance (o-Rint) by the opening interrupter technique were made with the MasterScreen PFT device, Jaeger GmbH, Würzburg, Germany, during quiet breathing. The presence of airway obstruction was detected as a value of o-Rint higher than two standard deviations (SD) compared with the theoretical data. Results: We found higher values of o-Rint in asthmatic patients than in the control group, with a high statistical difference (p < 0.0001). The same results were found when we compared patients with CF and the control group (p < 0.0001). Nevertheless, we did not find any significant statistical difference between respiratory resistances measured in asthmatic and patients with CF (p > 0.05). There was a significant inverse correlation between o-Rint and height only in asthmatic and patients with CF, but not in healthy controls (p < 0.05). Conclusions: In our study, the opening interrupter technique was efficient in detecting the presence of obstruction in chronic patients affected by asthma and CF.