Abstract
Introduction: Cystic fibrosis (CF) lung disease is characterized by uneven ventilation distribution, which can be measured by the N2 multiple breath washout (MBW) and the vital capacity single breath washout (VC SBW) test. A MBW test is more time consuming than a VC SBW test.
Aims: To determine the prevalence of abnormal MBW and SBW test results in teenagers and adults with CF.
Methods: Spirometry and triplicates of N2 MBW and N2 VC SBW were performed in 31 subjects (9 females) with CF, aged 13-45 yrs (median 23 yrs) using the Exhalyzer D washout device. Washout results were related to 400 healthy control subjects for N2 MBW and 224 for N2 VC SBW.
Results: FEV1 was abnormal in 7/31 (23%) subjects, VC SBW phase III slope (SIII) was abnormal in 20/31 (65%), LCI 29/31 (94%), Scond 30/31 (97%), Sacin 24/31 (77%) and fast-to-slow regions specific ventilation ratio in 30/31 (97%). Among the 11 subjects with normal VC SBW SIII, 10 (91%) showed abnormal MBW results.
Consclusions: Abnormal N2 VC SBW SIII was seen in the majority of teenagers and adult CF subjects with normal FEV1, suggesting additional value of this method, but normal SIII does not exclude pathological MBW outcomes.
- Copyright ©the authors 2017