Alternative inert gas washout outcomes in patients with primary ciliary dyskinesia

Abstract

The lung clearance index (LCI) derived from a nitrogen multiple breath washout test (N-MBW) is a promising tool to assess small airways disease in primary ciliary dyskinesia, but it is difficult to apply in routine clinical settings because of its long measuring time. In this study, we aimed to assess alternative indices derived from shorter washout protocols.49 patients with primary ciliary dyskinesia (mean age 14.7±6.6 years) and 37 controls (mean age 14.3±1.4 years) performed N-MBW and double-tracer gas (DTG) single-breath washout tests. Global (LCI and moment ratio (M/M)), conductive (S) and acinar ventilation inhomogeneity (DTG Slope III (S-DTG)) were determined for each individual. The main outcomes were 1) the ability to detect abnormal lung function from washout indices (>1.64 z-scores) and 2) measurement duration.The prevalence of abnormal values for LCI was 37 out of 47 (79%), for LCI was 34 out of 47 (72%), for M/M was 34 out of 47 (72%), for S was 36 out of 46 (78%) and for S-DTG was 12 out of 35 (34%). Mean±sd duration of measurement was 19.8±11.2 min for LCI, 10.8±4.6 min for LCI and 8.6±2.3 min for SCompared to standard LCI, ventilation inhomogeneity was detected by LCI, moment ratio and S with comparable sensitivity while measurement duration was significantly shorter. Longitudinal studies will show which outcome is most suitable and practical in terms of sensitivity, duration and variability within the course of primary ciliary dyskinesia lung disease.

Multiple breath washout: A new and promising lung function test for patients with idiopathic pulmonary fibrosis

“…Both global (LCI) and S acin are sensitive to evaluate disease extent and progression in small airway diseases . Although chronic obstructive and productive lung diseases have been primary applications for N 2 ‐MBW previously, LCI and S acin were highly abnormal in IPF.…”

“…N 2 ‐MBW is a free tidal breathing test. The main outcome parameter is the lung clearance index (LCI) which has been shown to measure global ventilation inhomogeneity, a recognized biomarker of peripheral airway disease in different paediatric and adult lung diseases, but data for parenchymal diseases are scarce. In this pilot study, we examined the clinical properties of N2‐MBW in IPF.…”

The Swiss Primary Ciliary Dyskinesia registry: objectives, methods and first results

“…The study shows that most lobectomised patients have poor lung function that continues to decline after surgery. In an effort to find ways to include more sensitive measures of lung function in routine clinical settings, another study aimed to assess alternatives to the lung clearance index (LCI) derived from a shorter protocol for the nitrogen multiple breath washout test (MBW) [21] . All patients included in CH-PCD with available MBW measurements were included with German patients in this study, which found a 79% prevalence of abnormal values for LCI2.5% and 72% for the significantly shorter LCI5%.…”

Hypertonic saline in patients with primary ciliary dyskinesia: on the road to evidence-based treatment for a rare lung disease

“…Also, spirometry (forced vital capacity, forced expiratory volume in 1 s and forced expiratory flow at 25-75% of FVC) was used to measure lung function, but spirometry measures mainly proximal obstruction. Patients with PCD, like those with CF, primarily have peripheral airway obstruction that is picked up much better by gas washout techniques [14][15][16]. 4) Although the study nearly reached the target sample size, it was underpowered mainly because observed variability of the outcomes was larger than anticipated.…”

“…This study's data and further observational data collected in international datasets such as the Provalf cohort planned as part of the European Union COST Action BEAT-PCD [26], the international PCD (iPCD) cohort study [27], and the international PCD registry [28] will be important. 3) We need more sensitive outcome measures such as disease-specific quality-of-life instruments (not yet available when this study was conducted) and sensitive lung function measurements [14,16]. 4) We should design interventions that account for the multisystem aspect of PCD.…”