A pilot study to assess the feasibility of analysing expired breath in ventilated paediatric patients to diagnose infection

Each year, nearly 6000-7000 children are ventilated in UK paediatric intensive care units (PICU) for lower respiratory tract infections (LRTI). In the BRANCH study, we want to test whether the breath from children with LRTI contains a different profile of chemicals compared to children without LRTI and whether the profile can be used to identify the bug causing the LRTI. In adults and children with tuberculosis unique breath chemical profiles have been identified previously.As part of the study, we aim to recruit 25 ventilated children with a LRTI to serve as cases and 10 children ventilated for reasons other than LRTI (post-operative cases, for example) to serve as controls in a pilot study to check the feasibility of collecting and performing molecular analysis on expired ventilated air. The study would involve collecting breath samples from the expiratory (breathing out) part of the ventilator circuit for a short period of time (approximately 30 mins). This expired air would otherwise be wasted. The sample collected would be dispatched to a special laboratory for molecular analysis to look for volatile organic compounds (VOC). VOCs are a range of compounds produced by the lungs during normal metabolism as by-products which are breathed out. In the presence of a LRTI, the microorganisms in the lungs add to or change the composition and proportion of the VOCs exhaled out. This change in the VOC profile can be identified by molecular analysis.Imperial College have world-leading expertise in the techniques we are piloting in this vulnerable population, and once this project has gathered important preliminary data, we have the unique capability of advancing this research forward in a multi-centre prospective study in West London.