Exhaled breath analysis for diagnosis of acute respiratory distress syndrome

Acute Respiratory Distress Syndrome (ARDS) is common in patients with respiratory failure in the intensive care unit (ICU). Despite improvements in ventilation strategies, a high mortality remains exceeding 40% in the severe cases. Numerous pathways involved in this syndrome are known, but the exact pathophysiology of ARDS is still not entirely clear. Also, it is not yet possible to capture the processes at the bedside. The greatest challenges remain the early and objective recognition of ARDS. One of the methods that might increase recognition is exhaled breath analysis. Assessment of breath biomarkers has the major advantage that it can be performed entirely non-invasive.
In this thesis we focussed on non-invasive methods to diagnose ARDS. In a review minimally and non-invasive diagnostic methods assessing biological processes of ARDS on their diagnostic accuracy were listed, with taking into account the risk of bias. To gain insight in the reliability of the diagnosis, interobserver agreement among a panel of experts was quantified.
To bring exhaled breath analysis from bench to bedside a number of steps were taken. A novel point-of-care (POC) breath test for ARDS diagnosis was created and validated. Subsequently the diagnostic accuracy of the POC breath test was assessed in a large multicentre observational cohort study. At last the rest of the breath pattern using gas chromatography and mass spectrometry was assessed on possible biomarkers for ARDS.