Eliminating Saliva Contamination in Exhaled Breath Condensate (EBC)

<bold>Introduction:</bold> EBC biomarkers have diagnostic potential, but oral contaminants can nullify results. While the ERS task force recommends mouth breathing for EBC collection¹, mouthpieces induce salivation, and saliva traps risk aerosolising saliva.² This study examines mouthpiece (MP) versus facemask (FM) impact in 2 saliva trap designs. <bold>Methods:</bold> EBC was collected in triplicate at –78.5^oC using a novel device (PBM-Hale™, PulmoBioMed Ltd) over 15-30mins of tidal breathing. Salivary α-amylase contamination was quantified enzymatically (Salimetrics). <bold>Results:</bold> With an additive-sealed saliva trap, EBC yields (µL/min) were consistent across interfaces (15min - MP:124.7±11.7, FM:113.7±15.3; 30min - MP:104.7±5.7, FM:103.1±7.2), but facemasks reduced (p<0.01) fluid buildup in the trap (15min:0µL; 30min:3.3±5.8µL) vs. mouthpiece use (15min:333.3±145.7µL, 30min:505.0±366.3µL). No salivary amylase was found in EBC irrespective of facemask use or saliva pooled in the trap, demonstrating optimal trap design to prevent contamination via aerosolization. An interference-sealed saliva trap, however, caused saliva contamination (566±982mU/mL) via wicking. This newly identified EBC contamination route was mitigated with a facemask, reducing fluid buildup in the trap (MP:1.78±2.00mL; FM:25.0±35.3µL), and resulting in uncontaminated EBC. <bold>Conclusion:</bold> Using facemasks minimised saliva accumulation in the saliva trap, and fully-sealed traps prevented wicking, to eliminate salivary contamination in EBC. These methods enable uncontaminated EBC collection without affecting sampling rates, potentially improving biomarker sensitivity and diagnostic outcomes. ¹Horváth I, Barnes PJ, Loukides S, et al. ERJ 2017. ²Zamuruyev et al. J Breath Res; 2016