TY - JOUR T1 - Leaks during multiple-breath washout: characterisation and influence on outcomes JF - ERJ Open Research JO - erjor DO - 10.1183/23120541.00012-2017 VL - 4 IS - 1 SP - 00012-2017 AU - Nina Lenherr AU - Kathryn A. Ramsey AU - Kerstin Jost AU - Linn Hornwall AU - Florian Singer AU - Sophie Yammine AU - Philipp Latzin Y1 - 2018/01/01 UR - http://openres.ersjournals.com/content/4/1/00012-2017.abstract N2 - Nitrogen multiple-breath washout (N2MBW) is increasingly used in patients with cystic fibrosis. The current European Respiratory Society/American Thoracic Society consensus statement for MBW recommends the rejection of measurements with leaks. However, it is unclear whether this is necessary for all types of leaks. Here, our aim was to 1) model and 2) apply air leaks, and 3) to assess their influence on the primary MBW outcomes of lung clearance index and functional residual capacity.We investigated the influence of air leaks at various locations (pre-, intra- and post-capillary), sizes, durations and stages of the washout. Modelled leaks were applied to existing N2MBW data from 10 children by modifying breath tables. In addition, leaks were applied to the equipment during N2MBW measurements performed by one healthy adolescent.All modelled and applied leaks resulted in statistically significant but heterogeneous effects on lung clearance index and functional residual capacity. In all types of continuous inspiratory leaks exceeding a certain size, the end of the washout was not reached. For practical application, we illustrated six different “red flags”, i.e. signs that enable easy identification of leaks during measurements.Air leaks during measurement significantly influence N2MBW outcomes. The influence of leaks on MBW outcomes is dependent on the location, relation to breath cycle, duration, stage of washout and size of the leak. We identified a range of signs to help distinguish leaks from physiological noise.The influence of leaks on nitrogen MBW outcomes is complex, dynamic and dependent on the size, duration, location and position of leaks during the washout and breathing cycle http://ow.ly/PbHV30hB91H ER -