Treatment response of airway clearance assessed by single-breath washout in children with cystic fibrosis

BackgroundWe studied the ability of 4 single-breath gas washout (SBW) tests to measure immediate effects of airway clearance in children with CF.Methods25 children aged 4-16 years with CF performed pulmonary function tests to assess short-term variability at baseline and response to routine airway clearance. Tidal helium and sulfur hexafluoride (double-tracer gas: DTG) SBW, tidal capnography, tidal and vital capacity nitrogen (N2) SBW and spirometry were applied. We analyzed the gasses' phase III slope (SnIII - normalized for tidal volume) and FEV1 from spirometry.ResultsSnIII from tidal DTG-SBW, SnIII from vital capacity N2-SBW, and FEV1 improved significantly after airway clearance. From these tests, individual change of SnIII from tidal DTG-SBW and FEV1 exceeded short-term variability in 10 and 6 children.ConclusionsWith the tidal DTG-SBW, an easy and promising test for peripheral gas mixing efficiency, immediate pulmonary function response to airway clearance can be assessed in CF children.