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

Abstract

Background: We studied the ability of 4 single-breath gas washout (SBW) tests to measure immediate effects of airway clearance in children with CF.

Methods: 25 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.

Results: SnIII 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.

Conclusions: With 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.

Keywords: CF; CO(2); CR; Children; Cystic fibrosis; DTG; FEV(1); He; ICC; LCI; MBW; MEF(25–75); N(2); PFT; PT; Physical therapy modalities; Pulmonary ventilation; Respiratory function test; SBW; SF(6); SIII; SnIII; carbon dioxide; chest physiotherapy; coefficient of repeatability (between-test repeatability); cystic fibrosis; double-tracer gas: 26.3% helium and 5% sulfur hexafluoride; forced expiratory volume in one second; helium; intra-class correlation coefficient (intra-test repeatability); lung clearance index; mean expiratory flow between 25 and 75% of expired volume; multiple-breath washout test; nitrogen; pulmonary function test; single-breath washout; slope of alveolar phase III from gas washout curves; sulfur hexafluoride; tidal volume normalized phase III slope from gas washout curves.