Consensus statement for inert gas washout measurement using multiple- and single- breath tests

Abstract

Inert gas washout tests, performed using the single-or multiple-breath washout technique, were first described over 60 years ago. As measures of ventilation distribution inhomogeneity, they offer complementary information to standard lung function tests, such as spirometry, as well as improved feasibility across wider age ranges and improved sensitivity in the detection of early lung damage. These benefits have led to a resurgence of interest in these techniques from manufacturers, clinicians and researchers, yet detailed guidelines for washout equipment specifications, test performance and analysis are lacking. This manuscript provides recommendations about these aspects, applicable to both the paediatric and adult testing environment, whilst outlining the important principles that are essential for the reader to understand. These recommendations are evidence based, where possible, but in many places represent expert opinion from a working group with a large collective experience in the techniques discussed.Finally, the important issues that remain unanswered are highlighted. By addressing these important issues and directing future research, the hope is to facilitate the incorporation of these promising tests into routine clinical practice.

Is Lung Clearance Index (LCI) Affected by the Severity of Lung Disease in CF?

“…Two indices have been proposed [54] to assess the homogeneity of specific ventilation of partial lung units, Scond and Sacin. Scond is calculated as the linear regression of SnIII values between 1.5 and 6.0 TO (from the 6 th to the 15 th breath) and reflects the difference of gas transport through the conducting airways and Sacin, that is equal to the SnIII TO of the three first breaths minus the Scond contribution (based on the mean TO value of the three first breaths) and reflects the difference between parallel units to the acini [38,40,45].…”

Paediatrics in Barcelona

“…Several studies have reported multiple-breath washout (MBW) to be a feasible and potentially useful technique for research and clinical application in young children with cystic fibrosis (CF) [6]; indeed, a technical consensus statement on this technique has recently been published [7]. Several researchers are currently considering this technique from a technical viewpoint in young children and extending its implementation in the clinical setting to diseases other than CF.…”

Lung Function Tests in Preschool Children

“…The analysis of the normalized concentration of the slope of phase III of the washout curve is a more complicated method. Although a recent ERS/ATS statement has reported the standard operating procedure for MBW [16], several technical details still need to be agreed on as far as preschool children are concerned, and a standardization project on MBW in preschoolers is currently being conducted.…”