Airway Resistance Measurements in Children with Cystic Fibrosis

Abstract

Summary Background and Purpose Respiratory function test results are important indices of improvement in the treatment of respiratory infection in cystic fibrosis. The aim of this study was to assess the value of airways resistance measured by the interrupter technique (Rint) over a course of intravenous antibiotic treatment in children with cystic fibrosis. Methods Airways resistance was measured by the MicroRint at the beginning and end of treatment. Children aged five years and older also had respiratory function measured, using standard spirometry. Results Seventy-eight children were entered into the study. Children under two years of age were not able to achieve a satisfactory facemask seal. Six children under seven years of age could not provide satisfactory spirometric measurements but showed an improvement in Rint measurement. All respiratory function parameters improved significantly. Before and after treatment airways resistance values measured by the MicroRint showed a significant correlation with respiratory function test values measured by standard spirometry, eg for Rint and FEV 1 % predicted normal r=0.37 before treatment (p = 0.002), and r=0.39 after treatment (p = 0.002). Similar results were obtained for comparisons between Rint and FEF 25–75 % predicted normal values. The degree of change in the airways resistance values measured by the MicroRint when measurements at the beginning and end of treatment were compared did not show a significant correlation with the degree of change in spirometric values measured at the same times. Conclusions Children over two years of age tolerate Rint measurement well. In cystic fibrosis, over a course of intravenous antibiotic therapy, it may be a valuable additional measure of the response to treatment.