BreathDx – Molecular Analysis of Exhaled Breath as a Diagnostic Test for Ventilator–Associated Pneumonia

Intensive Care Units (ICUs) treat and monitor critically ill or unstable patients who may be unable to breathe on their own and whose organs may not be working properly. Medical equipment supports organ function until the patient recovers. Mechanical ventilators (‘life support machines’) support breathing. While this technology works well, patients on mechanical ventilators can develop life-threatening lung infections (pneumonia) as a complication. Pneumonia is treated quickly and effectively with antibiotic drugs. However, because patients on ventilators are already ill, it is not possible to diagnose pneumonia quickly and accurately. Therefore many mechanically ventilated patients will also receive antibiotic treatments ‘just in case’ which means that antibiotics will be used unnecessarily. A consequence of antibiotic overuse is that infecting bugs (microorganisms) become resistant so that it will be difficult to treat life- threatening pneumonia in the future. We need to develop new technologies to help decide quickly who has developed pneumonia during their time on mechanical ventilation. Recently, we have discovered that it is possible and safe to capture and measure breath chemicals of patients who are mechanically ventilated. The chemical profiles appear to distinguish patients acquiring dangerous lung microorganisms. This exciting finding implies that we could use these chemical patterns to determine quickly who is likely to require antibiotics and who does not. To progress this idea, we now wish to use our breath capture system in ICU ventilated patients suspected of developing pneumonia and, using analysis already developed in our laboratories, we will seek proof that these chemicals can distinguish between the presence and absence of pneumonia. At project completion we will be able to decide whether our innovation is ready for clinical testing across ICUs in Europe.

1) Molecular analysis of breath can be used to discriminate between patients that are suspected of ventilator-associated pneumonia (VAP) who have positive cultures and who have negative cultures with high sensitivity (which could limit antibiotic use).

2) Molecular analysis of breath can be used to specifically detect the causative pathogen in patients that are suspected of VAP (so that antibiotics can be targeted).

Only 1 time point: all samples are taken at time of recruitment.

This is a diagnostic multicentre cross-sectional observational proof of concept study. Included patients will have been intubated and mechanically ventilated for at least 48 hours (based on the definition of VAP) and clinically suspected of having VAP. Exhaled air samples will be taken within 24 hours after the patient is suspected of VAP. Broncho-alveolar lavage fluid will be collected to clinically determine the presence of VAP.